Methods, apparatuses and non-transitory computer readable mediums for optimizing configuration management

Abstract

A user equipment (UE), including at least one memory storing instructions, and at least one processor configured to execute the instructions to cause the UE to, obtain an indication as part of a handover candidate configuration of a target cell, the indication including information identifying whether a secondary cell group (SCG) configuration in a handover candidate configuration of a prepared candidate target primary secondary cell is same as a SCG configuration of a current serving primary secondary cell, or whether a SCG configuration in a handover candidate configuration of a prepared candidate primary cell is same as a SCG configuration of a current serving primary cell.

Description

METHODS. APPARATUSES AND NON-TRANSITORY COMPUTER READABLE MEDIUMS FOR OPTIMIZING CONFIGURATION MANAGEMENTTECHNICAL FIELD

[0001] This application relates generally to methods, apparatuses and non-transitory computer readable mediums for optimizing configuration management for inter-central unit (CU) lower layered triggered mobility (LTM) dual connectivity (DC) scenarios.BACKGROUND

[0002] A mobile telecommunication network or cellular network (generally referred to herein as a communication network) enables communications between two or more communication devices, provides communication devices access to a data network, delivers services provided by third-party applications to communication devices, or provides services offered by the communication network to communication devices.

[0003] A communication network and communication devices may operate in accordance with cellular technologies (otherwise referred to as radio access technologies), such as GSM, UTMS, LTE, LIE- A, and NR. Cellular technologies are standardized by various standards organization, such as the Third Generation Partnership Project (3 GPP) or ETSI (European Telecommunications Standards Institute). 3GPP is currently developing standards for 5th generation cellular technologies (generally referred to a 5G or NR standards) and 6thgeneration cellular technologies (generally referred to a 6G standards). Communication networks that operate in accordance with 5G or NR standards are generally referred to as 5G networks and communication networks that operate in accordance with 6G standards are generally referred to as 6G networks.

[0004] A communication network (e.g., a 5G network or a 6G network) includes access networks (e.g., radio access networks) that can communicate wirelessly with one or multiplecommunication devices by sharing available resources (e.g., bandwidth, transmit power, etc.) of the access network (e.g., radio access network). A communication network can also establish reliable, secure connectivity between communication devices and a core network of the communication network via access networks. A communication network (e.g., a 5G network) may provide enhanced mobile broadband services (e.g., telephony, video, data, short message services), ultra-reliable low-latency communication services (e.g., XR services), or massive machine type communication services to communication devices.SUMMARY

[0005] The scope of protection sought for various example embodiments are set out by the independent claims. Some example embodiments and / or features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various example embodiments.

[0006] In at least one example embodiment, a user equipment (UE), may comprise: at least one memory storing instructions; and at least one processor is configured to execute the instructions to cause the UE to, obtain an indication as part of a handover candidate configuration of a target cell, the indication including information identifying whether a secondary cell group (SCG) configuration in a handover candidate configuration of a prepared candidate target primary secondary cell is same as a SCG configuration of a current serving primary secondary cell, or whether a SCG configuration in a handover candidate configuration of a prepared candidate primary cell is same as a SCG configuration of a current serving primary cell.

[0007] In at least one example embodiment, the at least one processor is configured to execute the instructions to cause the UE to maintain a current master cell group (MCG) configuration orgenerate an MCG configuration based on the handover candidate configuration of the prepared candidate target primary secondary cell.

[0008] In at least one example embodiment, the at least one processor is configured to execute the instructions to cause the UE to retain the current MCG configuration during a cell switch to at least the target cell in response to the information indicating that the SCG configuration in the handover candidate configuration of the candidate target primary secondary cell is the same as the SCG configuration of the current serving primary secondary cell.

[0009] In at least one example embodiment, the at least one processor is configured to execute the instructions to cause the UE to, generate candidate configuration for switching to the prepared candidate target primary secondary cell by constructing the SCG configuration of the handover candidate configuration of the prepared candidate target primary secondary cell and retaining the current MCG configuration in response to the information indicating the SCG configuration in the handover candidate configuration of the prepared candidate target primary secondary cell is the same as the SCG configuration of the current serving primary secondary cell, and switch to at least the prepared candidate target primary secondary cell using the generated candidate configuration.

[0010] In at least one example embodiment, the handover is a Layerl / Layer2 Triggered Mobility (LTM).

[0011] In at least one example embodiment, the at least one processor is configured to execute instructions to cause the UE to switch to the prepared candidate target primary secondary cell from the current serving primary secondary cell while being served by a primary cell through a master node.

[0012] In at least one example embodiment, the at least one processor is configured to execute the instructions to cause the UE to perform a release and add operation or not perform the release and add operation based on the obtained indication.

[0013] In at least one example embodiment, the at least one processor is configured to execute the instructions to cause the UE to perform the release and add operation during a switch to the prepared candidate primary cell in response to the information indicating that the SCG configuration of the prepared candidate primary cell and the SCG configuration of the current serving primary cell are not the same.

[0014] In at least one example embodiment, the at least one processor is configured to execute the instructions to cause the UE to not perform the release and add operation during a switch to the prepared candidate primary cell in response to the information indicating that the SCG configurations of the prepared candidate primary cell and the SCG configuration of the current serving primary cell are the same.

[0015] In at least one example embodiment, the release and add operation is a SCG configuration release and add operation.

[0016] In at least one example embodiment, a network node may comprise at least one memory storing instructions; and at least one processor that is configured to execute the instructions to cause the network node to, obtain a secondary cell group (SCG) configuration of a target primary secondary cell; obtain a SCG configuration of a current primary secondary cell; determine whether the SCG configuration of the target primary secondary cell is same as the SCG configuration of the current primary secondary cell; and send an indication in a handover candidate configuration of a candidate cell to a user equipment (UE) including information to identify whether the SCGconfiguration of the target primary secondary cell is the same as the SCG configuration of the current primary secondary cell.

[0017] In at least one example embodiment, the at least one processor is configured to execute the instructions to cause the network node to provide the UE access to a primary cell.

[0018] In at least one example embodiment, the network node is a radio access network base station.

[0019] In at least one example embodiment, the at least one processor is configured to execute the instructions to cause the network node to send the indication in the handover candidate configuration of each prepared candidate cell to the UE as part of a RRC Reconfiguration message.

[0020] In at least one example embodiment, the at least one processor is configured to execute the instructions to cause the network node to initiate a target cell switch based on a message received from the current primary secondary cell.

[0021] In at least one example embodiment, a network node, may comprise at least one memory storing instructions; and at least one processor that is configured to execute the instructions to cause the network node to, determine whether a secondary cell group (SCG) configuration for each of a number of candidate cells in a prepared candidate master node are same; and send an indication of a handover candidate configuration of the prepared candidate master node to a user equipment (UE) including information to identify whether the SCG configuration for each of the number of candidate cells in the prepared candidate master node are the same.

[0022] In at least one example embodiment, the at least one processor is configured to execute the instructions to cause the network node to provide a primary cell connected to the UE access to the prepared candidate master node.

[0023] In at least one example embodiment, the network node is a radio access network base station.

[0024] In at least one example embodiment, the at least one processor is configured to execute the instructions to cause the network node to send the indication in each of the handover candidate configurations of the prepared candidate master node to the UE as part of a RRC Reconfiguration message.

[0025] In at least one example embodiment, the handover is a Layerl / Layer2 Triggered Mobility (LTM).

[0026] One or more example embodiments also provide a computer program, or computer program product including a computer program, comprising instructions that, when executed by the at least one processor of a user equipment (UE) or network node, etc., cause the respective applicable apparatus to perform one or more methods described herein.

[0027] Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Example embodiments will become more fully understood from the detailed description given herein below and the accompanying drawings, wherein like elements are represented by like reference numerals, which are given by way of illustration only and thus are not limited of the present inventive concepts.

[0029] FIG. 1 illustrates an example of a communication network in which example embodiments may be implemented;

[0030] FIG. 2 illustrates an example signaling diagram for lower layer triggered mobility (LTM) according to one or more example embodiments;

[0031] FIG. 3 illustrates an example signaling diagram for inter-master node (MN) handover with / without a MN initiated secondary node (SN) change procedure according to one or more example embodiments;

[0032] FIG. 4 illustrates an example scenario for inter-centralized unit (CU) secondary cell group lower layer triggered mobility (LTM) according to one or more example embodiments;

[0033] FIG. 5 illustrates another example scenario for inter-centralized unit (CU) secondary cell group lower layer triggered mobility (LTM) according to one or more example embodiments;

[0034] FIG. 6 illustrates an example scenario of inter-centralized unit (CU) and intra-CU lower layer triggered mobility (LTM) according to one or more example embodiments;

[0035] FIG. 7A illustrates an example signaling diagram for including master cell group (MCG) information in a message according to one or more example embodiments;

[0036] FIG. 7B illustrates an example signaling diagram for applying the message of FIG. 7A by a user equipment (UE) according to one or more example embodiments;

[0037] FIG. 8A illustrates an example signaling diagram for including secondary cell group (SCG) information in a message according to one or more example embodiments;

[0038] FIG. 8B illustrates an example signaling diagram for applying the message of FIG. 8A by a UE according to one or more example embodiments;

[0039] FIG. 9 is an example flowchart of a method of operating a user equipment according to various example embodiments;

[0040] FIG. 10 is an example flowchart of a method of operating a network node according to various example embodiments.

[0041] FIG. 11 is an example flowchart of a method of operating a network node according to various example embodiments;

[0042] FIG. 12 illustrates an example of an apparatus according to various example embodiments;

[0043] FIG. 13 is pseudo code illustrating a message including information associated with a master cell group (MCG) change according to one or more example embodiments; and

[0044] FIG. 14 is pseudo code illustrating a message including information associated with a secondary cell group (SCG) change according to one or more example embodiments.

[0045] The various features and advantages of the non-limiting example embodiments herein may become more apparent upon review of the detailed description in conjunction with the accompanying drawings. The accompanying drawings are merely provided for illustrative purposes and should not be interpreted to limit the scope of the claims. The accompany drawings are not to be considered as drawn to scale unless explicitly noted. For purposes of clarity, various dimensions of the drawings may have been exaggerated.DETALIED DESCRIPTION

[0046] Various example embodiments will now be described more fully with reference to the accompanying drawings in which some example embodiments are shown.

[0047] Although the specification may refer to “an”, “one”, or “some” example embodiment(s) in several locations of the text, this does not necessarily mean that each reference is made to the same example embodiment(s), or that a particular feature only applies to a single example embodiment. Single features of different example embodiments may also be combined to provide other example embodiments. Further, when a particular feature, structure, or characteristic isdescribed in connection of an example embodiment, it is within the knowledge of one skilled in the art to apply such feature, structure, or characteristic in connection with other example embodiments whether or not explicitly described. It shall be understood that although the terms “first,” “second” and the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another.

[0048] For the purposes of the present disclosure, the phrases “at least one of A or B”, “at least one of A and B”, and “A and / or B” means (A), (B), or (A and B). For the purposes of the present disclosure, the phrase “A, B, and / or C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C).

[0049] Various example embodiments described may be implemented in a communication network, such as any of the following radio access technologies (RATs): Worldwide Interoperability for Micro-wave Access (WiMAX), Global System for Mobile communications (GSM, 2G), GSM EDGE radio access Network (GERAN), General Packet Radio Service (GRPS), Universal Mobile Telecommunication System (UMTS, 3G) based on basic wide-band-code division multiple access (W-CDMA), high-speed packet access (HSPA), Long Term Evolution (LTE), LTE -Advanced, and enhanced LTE (eLTE), 5G (also called NR), or any future RAT such as 6G. Moreover, communication within the communication network may utilize any proper wireless communication technology, comprising but not limited to: Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Frequency Division Duplex (FDD), Time Division Duplex (TDD), Multiple-Input Multiple-Output (MIMO), Orthogonal Frequency Division Multiple (OFDM), and / or Discrete Fourier Transform spread OFDM (DFT-s-OFDM).

[0050] As used herein, the term “network device” or “network node” refers to a node in a communication network via which user equipment may access the network and / or which is capable of controlling radio communication and managing radio resources within a cell. The network node or network device may be referred to as a base station (BS), an access point (AP) or an access node. The network device may be, depending on the applied technology, for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), an NR NB (also referred to as a gNB), a Remote Radio Unit (RRU), a radio head (RH), a remote radio head (RRH), a relay, an Integrated Access and Backhaul (IAB) node, a low power node, a non-terrestrial network (NTN) or nonground network device such as a satellite network device, a low earth orbit (LEO) satellite and a geosynchronous earth orbit (GEO) satellite, or an aircraft network device.

[0051] Moreover, in connection of split radio access network (RAN), the network device may refer to a centralized unit (CU) of a base station and / or a distributed unit (DU) of a base station. An interface between CU and DU may be referred to as an Fl inter-face in NR. In the split RAN architecture, node operations may be carried out, at least partly, in the central / centralized unit, CU, (e.g. server, host or node) operationally coupled to the DU, (e.g. a radio head / node). One CU may control one or more DUs, acting at least as transmit / receive (Tx / Rx) nodes. In some embodiments, the DUs may comprise e.g. a radio link control (RLC), medium access control (MAC) layer and a physical (PHY) layer, whereas the CU may comprise the layers above RLC layer, such as a packet data convergence protocol (PDCP) lay-er, a radio resource control (RRC) and an internet protocol (IP) layers. Other functional splits are possible too. In practice, any processing task may be performed in either the CU or the DU and the boundary where the responsibility is shifted between the CU and the DU may depend on the applied implementation.

[0052] The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example, a terminal device may be referred to as a communication device, user equipment (UE), a Subscriber Station (SS), or a Mobile Station (MS). The terminal device may include a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones a tablet, a wearable terminal device, a personal digital assistant (PDA), portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, USB dongles, an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like.

[0053] A term “resource”, as used herein, may refer to radio resources in time domain, in frequency do-main, in space domain, and / or in code domain. Some examples of resources include e.g. a physical resource block (PRB), a radio frame, a subframe, a time slot, a subband, a frequency region, a sub-carrier, a beam, etc. The term “transmission” and / or “reception” may refer to wirelessly transmitting and / or receiving via a wireless propagation channel on radio resources.

[0054] FIG. 1 illustrates an example of a communication network in which example embodiments may be implemented.

[0055] Referring to FIG. 1 , the communication network or a cellular communication network may comprise a first network node 110 providing one or more cells, such as a first cell 100, and a second network node 112 providing one or more other cells, such as a second cell 102. Each cellmay be, e.g., a macro cell, a micro cell, femto, or a pico cell, for example. The cell may define a coverage area or a service area of the corresponding access node.

[0056] The first network node 110 may provide a first user equipment (UE) 120 (one or more UEs) with wireless access to the communication network. The wireless access may comprise downlink (DL) communication from the first network node 110 to the first UE 120 and uplink (UL) communication from the first UE 120 to the first network node 110. Examples of uplink channels comprise physical uplink control channel (PUCCH) for transmitting or sending control information and physical uplink shared channel (PUSCH) for transmitting or sending data towards the network. Examples of downlink channels comprise physical downlink control channel (PDCCH) for transmitting or sending control information and physical downlink shared channel (PDSCH) for transmitting or sending data towards the user equipment.

[0057] There may be a plurality of UEs, such as first UE 120 and second UE 122, in the system. Each of them may be served by the same or by different network nodes, such as a first network node 110 and a second network node 112. Each UE may be configured with dual connectivity (DC), wherein the UE, e.g., first UE 120, may be connected to multiple network nodes, such as first and second network nodes 110, 112. The first and second UEs 120, 122 may communicate with each other, in case device-to-device (D2D) communication interface is established between them via a so-called sidelink (SL). Such D2D communications may be referred to as machine-to-machine, peer-to-peer (P2P) communications, or vehicle-to-vehicle (V2V), for example.

[0058] In an example of multiple network nodes, such as first and second network nodes 110, 112, in the communication network, the network nodes may be connected to each other via an interface. LTE specifications call such an interface as X2 interface. An interface between an LTE node and a 5G node, or between two 5G nodes may be called Xn interface.

[0059] The first and second network nodes 110 and 112 may be further connected via another interface to a core network 116 of the communication network. The LTE specifications specify the core network as an evolved packet core (EPC), and the core network may comprise e.g., a mobility management entity (MME) and a gateway node. The MME may handle mobility of terminal devices in a tracking area encompassing a plurality of cells and handle signaling connections between the terminal devices and the core network. The gateway node may handle data routing in the core network and to / from the terminal devices. The 5G specifications specify the core network as a 5G core (5GC). The 5G core may comprise e.g., an access and mobility management function (AMF) and a user plane function / gateway (UPF) and other functions. The AMF may handle termination of non-access stratum (NAS) signaling, NAS ciphering & integrity protection, access authentication and authorization, security context management. The UPF node may support packet routing and forwarding, packet inspection and quality of service (QoS) handling, for example.

[0060] Various example embodiments herein may be described with reference to handovers that take place with dual connectivity. In reference to this, mention is made to Primary Secondary Cells (PSCells), Primary Cells (PCells), and Secondary Cells (SCells). The following will outline features of PSCells in relation to 5GNew Radio, using terminology found therein. However, it is understood that the presently described principles are not limited to such terminology and may be applied to other systems having a similar architecture. For example, in multi-radio-dual connectivity (MR-DC), a Primary Cell (PCell) may be a Long Term Evolution (LTE) cell (e.g., Evolved-Universal Terrestrial Radio Access-New Radio-dual connectivity (EN-DC)).

[0061] PSCells are a type of cell currently defined in 5G New Radio, along with PCells, SCells and Special Cells (SpCells). A PCell may be used as part of an initial access between a UE and an access network and is considered to be a main cell in a master cell group (MCG). A PSCellmay be comprised as part of a secondary cell group (SCG). The SpCells and SCells may be in at least one of a master cell group (MCG) and the SCG.

[0062] The cells may be controlled by network nodes. There are two different types of network nodes in 5G New Radio: Master nodes (which provide a control plane connection to a core network); and Secondary Nodes (which do not have control plane connections to the core network). The Master and Secondary nodes may both provide user plane (e.g., data) connections to the core network. The Master node may control the PCell. In addition to the PCell, the Master node may control at least one PSCell, although this is not always the case. The Secondary node may control at least one PSCell.

[0063] FIG. 2 illustrates an example signaling diagram for lower layer triggered mobility (LTM) according to one or more example embodiments.

[0064] Referring to FIG. 2, in dual connectivity (DC) UE 202 will have a radio link with a primary cell as well as a primary secondary cell. For example, the UE 202 is served by the primary cell with a master node (MN) 204, such as a first network node 110 (e.g., gNB), providing access to the primary cell. The UE is also served by the primary secondary cell, which enables higher throughput, with a secondary node (SN) or a source-secondary node (S-SN) 206, such as a second network node 112 (e.g., gNB), providing access to the primary secondary cell.

[0065] Still referring to FIG. 2, FIG. 2 illustrates an example signaling diagram where the S-SN 206 initiates an inter-secondary node secondary cell group Layer- 1 / Layer-2 Triggered Mobility (Inter-SN SCG LTM). Such procedure may also be referred to as inter-CU SCG LTM, which may also be referred to as inter-gNB handover. In step 1, the S-SN 206 initiates the inter-SN SCG LTM procedure by sending the SN Change Required message to the MN 204 providing a list of candidate PSCell(s) for inter-SN SCG LTM preparation. The candidate list of PSCell(s) refers toa list of candidate primary secondary cells with a candidate SN 208 other potential candidate SN(s) 210, such as other potential network nodes (e.g., gNB), providing access to the candidate primary secondary cells. The SN Change Required message may include an SCG reference configuration. S-SN 206 may additionally send measurement results of candidate PSCells to the MN 204.

[0066] In step 2, the MN requests each candidate SN 208, 210 to allocate resources for the UE 202 by means of the SN Addition procedure. The MN 204 also provides a list of KSN (e.g., a list of key secondary nodes) and associated sk-Counter values for each candidate SN 210, and forwards the received measurement results to each candidate SN 208, 210. For example, the key secondary nodes and sk-Counter values are part of the security and mobility management process, and help to ensure secure communication and manage handovers between nodes. The MN 204 may select one of the candidate SN(s) 208 and / or 210 and request that the selected one of the candidate SN(s) 208 and / or 210 provide a reference SCG configuration as part of the SN Addition Request. Once obtained, the MN 204 provides the reference configuration to the other one of the candidate SN(s) (e.g., candidate SN 208 and / or 210) that was not selected. The other one of the candidate SN(s) (e.g., candidate SN 208 and / or 210) provides the SCG part configuration of each candidate PSCell that the other one of the candidate SN(s) (e.g., candidate SN 208 and / or 210) provides access to, and may also provide the LI RS (e.g. a list of SSB or a list of CSI-RS) configuration for LI measurement, the early UL sync configuration, and the TCI-state configuration.

[0067] Each of the candidate SNs 208, 210 determines the LTM candidate cells based on the measurement results (if provided) and an upper limit for the number of PSCells that can be prepared by each candidate SN 208, 210. In step 3, each candidate SN 208, 210 provides the SCG part configuration of each candidate PSCell, and may also provide the LI RS (e.g. a list of SSB ora list of CSI-RS) configuration for LI measurement, early UL / DL sync configuration, by sending SN Addition Request Acknowledge message to the MN 204.

[0068] In step 4, for the one candidate SN 208 and / or 210 that uses MCG resources of the MN 204, the MN 204 provides Xn-U DL TNL address information in the Xn-U Address Indication message to the one candidate SN 208 and / or 210. For example, if the candidate SN 210 uses MCG resources of the MN 204, the MN 205 provides Xn-U DL TNL address information in the Xn-U Address indication message to the one candidate SN 210.

[0069] In step 5, the MN 204 sends the received LI RS configuration, early UL / DL sync configuration of candidate cells to the S-SN 206 via SN Modification Request message.

[0070] In step 6, the S-SN 206 generates the common CSI resource configuration for LI measurement on candidate PSCells. The S-SN 206 sends the generated common CSI resource configuration and the updated source SCG configuration to the MN 204 via SN modification request acknowledge message.

[0071] In step 7, the MN 204 transfers, during the LTM preparation phase, the common CSI resource configuration and the collected information of candidate cells to each candidate SN 208, 210 via the SN Modification Request message.

[0072] In step 8, the candidate SN 208, 210 responds with the updated candidate SCG configuration to the MN 204 via the SN Modification Request Acknowledge message.

[0073] In step 9, the MN 204 generates the reference configuration for SN initiated inter-CU SCG LTM, which may include the MCG part of the reference configuration generated by the MN 204 (if any), together with the SCG part of the reference configuration generated by the S-SN 206 and / or the candidate SN 208, 210. The MN 204 sends an RRCReconfiguration message to the UE including the inter-SN SCG LTM configuration, e.g., a list of RRCReconfiguration messages, inwhich each RRCReconfiguration message contains the SCG configuration received from each of the candidate SNs 208, 210 in step 3, and possibly an MCG configuration. In at least one example embodiment, the RRCReconfiguration message can also include an updated MCG configuration, as well as the NR RRCReconfiguration message generated by the S-SN 206, e.g., to configure the required measurements.

[0074] In step 10, the UE 202 applies the RRCReconfiguration message received in step 9, stores the inter-SN SCG LTM configuration and replies to the MN 204 with an RRCReconfigurationComplete message, including an SN RRCReconfigurationComplete message directed towards the S-SN 206.

[0075] In step 11, the MN 204 informs the S-SN 206 with the SN RRCReconfigurationComplete message via SN Change Confirm message, to indicate that SCG LTM is prepared.

[0076] In step 12, the S-SN 206 may perform early data forwarding, which may involve forwarding data to each of the candidate target nodes 208, 210.

[0077] In step 13, the UE 202 may perform DL synchronization with the LTM candidate cell(s) provided by each of the candidate target nodes 208, 210 before receiving the cell switch command.

[0078] In step 14a, the UE 202 may perform UL synchronization with LTM candidate cell(s) provided by each of the candidate SNs 208, 210 before receiving the cell switch command, as specified in clause 9.2.3.5.2 in TS 38.300 [3],

[0079] In step 14b, each of the candidate SNs 208, 210 transfer the calculated TA value of candidate cell(s) to the S-SN 206 via the MN 204 via the TA Information Transfer procedure. The UE 202 performs LI measurements on the configured LTM candidate cell(s) and transmits LImeasurement reports to the S-SN 206, if the LI measurement configuration in RRCReconfiguration is received in step 9.

[0080] In step 16, the S-SN 206 decides to execute cell switch to a candidate PSCell provided by one of the candidate SNs 208 and / or 210. In step 17, the S-SN 206 transmits, to the UE 202, an LTM cell switch command MAC CE triggering cell switch by including a target configuration ID and other related information for the target PSCell, as specified in clause 9.2.3.5.2 in TS 38.300 [3], The UE 202 applies the candidate configuration indicated by the target configuration ID including PSCell change.

[0081] In step 18, the S-SN 206 sends a notification to the MN 204 by Cell Switch Notification Procedure, and in step 19 the MN 204 sends the notification received in step 18 to the one candidate SN 208 and / or 210 that the cell switch was executed for to indicate the triggering of LTM.

[0082] In step 20, the UE 202 performs the random-access procedure towards the target PSCell, if the UE 202 does not have valid TA of the target PSCell.

[0083] In step 21, the UE 202 sends an MN RRCReconfigurationComplete message to the MN 204, which includes an SN RRCReconfigurationComplete message directed to the candidate SN 208.

[0084] In step 22, the MN 204 informs the candidate SN 208 that the UE 202 has completed the reconfiguration procedure successfully via the SN Reconfiguration Complete message, including the SN RRCReconfigurationComplete message.

[0085] In step 23, the candidate SN 208 sends an Access Success message to the S-SN 206.

[0086] In step 24, the MN 204 provides Xn-U DL TNL address information in the Xn-U Address Indication message to the S-SN 206.

[0087] In step 25, the S-SN 206 sends a SN status transfer message to the MN 204, and in step 26 the MN 204 sends the SN status transfer message to the candidate SN 208. The SN status transfer is a process that may ensure that the packet data convergence protocol (PDCP) sequence numbers and other relevant status information are transferred from the S-SN 206 to the candidate SN 208.

[0088] In step 27, data forwarding may take place from the S-SN 206 side. For example data may be forwarded from the UPF 212 to candidate SN 208 via the MN 204. In step 28, a PDU Session Path Update Procedure may take place, and in step 29, a UE Context Release message may be sent by the MN 204 to the S-SN 206.

[0089] According to example embodiments, steps 12-29 may be performed multiple times for subsequent SCG LTM cell switch execution using the SCG LTM candidate configuration(s) provided in step 9.

[0090] According to example embodiments, Inter-MN handover with / without MN initiated SN change may be used to transfer UE context data from a source MN to a target and / or candidate MN while the UE context at the SN is kept or moved to another SN. During an Inter-Master Node handover, the target and / or candidate MN decides whether to keep or change the SN (or release the SN). Only intra-RAT Inter-Master node handover with / without SN change is supported (e.g., no transition from NGEN-DC to NR-DC). Inter-MN MCG LTM with SCG release or with SCG configuration change in the same SN, inter-MN or intra-MN MCG LTM with SCG addition are supported.

[0091] FIG. 3 illustrates an example signaling diagram for inter-master node (MN) handover with / without a MN initiated secondary node (SN) change procedure according to one or more example embodiments.

[0092] Referring to FIG. 3, in example embodiments, for an Inter-Master Node handover without Secondary Node change, the source SN 306 and the target and / or candidate SN 308 shown in FIG. 3 are the same node.

[0093] Still referring to FIG. 3, in step S31, the source MN 304 starts the handover procedure by initiating the Xn Handover Preparation procedure including both MCG and SCG configuration. The source MN 304 includes the source SN UE XnAP ID, SN ID and the UE context in the source SN 306 in the Handover Request message. A source SN UE XnAp ID is an identifier that identifies the UE 302 over the Xn interface within the source SN 306. According to various example embodiments, the source MN 304 may trigger the MN-initiated SN modification procedure (to the source SN 306) to retrieve the current SCG configuration and the QMC configuration information managed by the source SN 306 and to allow provision of data forwarding related information prior to step S31.

[0094] In step S32, if the target MN 310 decides to keep the UE context in the source SN 306, the target MN 310 sends SN Addition Request message to the source SN 306 including the SN UE XnAP ID as a reference to the UE context in the source SN 306 that was established by the source MN 304. If the target MN 310 decides to change the source SN 306 allowing delta configuration, the target MN 310 sends the SN Addition Request message to the target SN 308 including the UE context in the source SN 306 that was established by the source MN 304. Otherwise, the target MN 310 may send the SN Addition Request to the target SN 308 including neither the SN UE XnAP ID nor the UE context in the source SN 306 that was established by the source MN 304. Allowing delta configuration refers to an operation where only changes (deltas) from a previous configuration are transmitted, rather than sending the entire configuration again.

[0095] In step S33, the target SN 308 replies with SN Addition Request Acknowledge. The target SN 308 may include the indication of the full or delta RRC configuration. For example, the target SN 308 may include the indication of the full RRC configuration (e.g., entire RRC configuration) or delta RRC configuration (e.g., the changes (deltas) from the previous delta RRC configuration).

[0096] In step S33a, for SN terminated bearers of the target SN 308 using MCG resources, the target MN 310 provides Xn-U DL TNL address information in the Xn-U Address Indication message.

[0097] In step S34, the target MN 310 includes within the Handover Request Acknowledge message the MN RRC reconfiguration message to be sent to the UE 302 in order to perform the handover, and may also provide forwarding addresses to the source MN 304. If PDU session split is performed in the target side during handover procedure, more than one data forwarding addresses corresponding to each node are included in the Handover Request Acknowledge message. The target MN 310 indicates to the source MN 304 that the UE context in the source SN 306 is kept if the target MN 310 and the source SN 306 decided to keep the UE context in the source SN 306 in step S32 and step S33.

[0098] In step S35a, the source MN 304 sends SN Release Request message to the source SN 306 including a Cause indicating MCG mobility. In step S35b, the source SN 306 acknowledges the release request. In some example embodiments, the source MN 304 indicates to the source SN 306 that the UE context in source SN 306 is being kept, if the source SN 306 receives the indication from the target MN 310. For example, if the source SN 306 receives the indication that the UE context is kept in the source SN 306, the source SN 306 keeps the UE context.

[0099] In step S35c, the source MN 304 sends XN-U Address Indication message to the source SN 306 to transfer data forwarding information. More than one data forwarding addresses may be provided if the PDU session is split in the target side.

[0100] In step S36, the source MN 304 triggers the UE 302 to perform handover and apply the new configuration.

[0101] In step S37, the UE 302 synchronizes to the target MN 310 via a Random Access Procedure. In step S38, the UE 302 sends an RRC reconfiguration complete message to the target MN 310.

[0102] In step S39, if the UE 302 is configured with bearers requiring SCG radio resources, the UE 302 synchronizes to the target SN 308.

[0103] In step S40, if the RRC connection reconfiguration procedure was successful, the target MN 310 informs the target SN 308 via SN Reconfiguration Complete message.

[0104] In step S41a, the source SN 306 sends the Secondary RAT Data Usage Report message to the source MN 306 and includes the data volumes delivered to and received from the UE 302 over the NR / E-UTRA radio.

[0105] In step S41b, the source MN 304 sends the Secondary RAT Report message to AMF 314 to provide information on the used NR / E-UTRA resource.

[0106] In step S42a the source MN 304 receives a SN Status message from the source SN 306. In step S42b, for bearers using RLC AM, the source MN 306 sends the SN Status Transfer message to the target MN 310, including, if needed, the SN Status received from the source SN 306. In step S42c, the target MN 310 forwards the SN Status to the target SN 308, if needed.

[0107] In step S43, if applicable, data forwarding takes place from the source side. For example, if the source SN 306 is kept, data forwarding may be omitted for source SN 306 terminated bearers or QoS flows kept in the source SN 306.

[0108] In step S44, the target MN 310 initiates the Path Switch procedure by sending a path switch request to the AMF 314. In step S45, the UPF 312 and the AMF 314 perform bearer modification. In steps S46A and S46B new paths are sent from the UPF 312 to the target MN 310 and the target SN 308. For example, if the target MN 310 includes multiple DL TEIDs for one PDU session in the Path Switch Request message, multiple UL TEID of the UPF 312 for the PDU session should be included in the Path Switch Ack message, in step S47, in case there is TEID update in UPF 312. If new UL TEIDs of the UPF 312 for target SN 308 are included, the target MN 310 performs MN initiated SN Modification procedure to provide them to the target SN 308.

[0109] In step S48, the target MN 310 initiates the UE Context Release procedure towards the source MN 304.

[0110] In step S49, upon reception of the UE Context Release message from source MN 304, the source SN 306 releases C-plane related resources associated to the UE context towards the source MN 304. Any ongoing data forwarding may continue. The source SN 306 shall not release the UE context associated with the target MN 310 if the UE context kept indication was included in the SN Release Request message in steps S35a and S35b.

[0111] With reference to FIGS. 1-3, 3GPP RAN 2 has indicated an agreement that it is up to the network (NW) to ensure that the complete configuration includes the MCG part and SCG part configuration when UE combines the reference and candidate configuration for inter-CU SCG LTM. The reference configuration for inter-CU SCG LTM at least includes an SCG part, FFS on MCG part. The candidate configuration and reference configuration are modeled as an MNRRCReconfiguration message. The MN generates the MCG part of the reference configuration (if any), while the SN (source or candidate) generates the SCG part of the reference configuration. The existing field mrdc-ReleaseAndAdd is always included when SCG configuration is included during an MCG LTM execution.

[0112] From the above agreement, the inter-CU SCG and MCG LTM candidate configurations may have both MCG and SCG parts and shall be modelled as MN RRCReconfiguration message. Additionally, the SCG part in the inter-CU MCG LTM candidate configuration shall be included in the MRDC-SecondaryCellGroupConfig information element (IE). For example, in the case of inter-CU SCG LTM, each candidate SN may prepare SCG configuration with the bearer mapping to SCG resources same as at the source SN or each or some of the candidate SNs may prepare SCG configuration with the bearer mapping to SCG resources different from the source SN. In various example embodiments, for inter-CU SCG LTM, the SCG configuration prepared by each candidate secondary node (SN) may be same and / or similar to the SCG configuration at the current and / or source SN. For intra-CU master cell group (MCG) LTM is performed. Some example embodiments for inter-CU SCG LTM and intra-CU MCG LTM will be described below with reference to FIGS. 4-6.

[0113] FIG. 4 illustrates an example scenario for inter-centralized unit (CU) secondary cell group lower layer triggered mobility (LTM) according to one or more example embodiments.

[0114] Referring to FIG. 4, when the MN 402 initiates inter-CU SCG LTM preparation of candidate and / or target secondary nodes 406 for SCG LTM, the MN 402 includes the SCG LTM candidate configurations at the MN 402 and the S-SN 404 when the MN 402 initiates the inter-CU SCG LTM. Thus, the S-SN 404 prepares a current SCG LTM configuration at the S-SN 404. For example, the current SCG LTM configuration prepared at the S-SN 404 may be the SCGconfiguration SCG1 associated with a bearer mapping to SCG resources at the S-SN 404. A candidate and / or target serving node 406 (e.g., T-SN1 406 illustrated in FIG. 4) may also prepare a candidate SCG configuration SCG2 that may be associated with a bearer mapping to SCG resources at the T-SN1 406. In various example embodiments, if the T-SN1 406 is not able to map or prepare the SCG resources similar or same as the S-SN 404, then some of the SCG resources may be mapped to the MCG resources at the MN 402. For example, the MCG configuration MCG2 for the SCG2 at the T-SN1 406 is different than the current MCG1 and SCG1.

[0115] FIG. 5 illustrates another example scenario for inter-centralized unit (CU) secondary cell group lower layer triggered mobility (LTM) according to one or more example embodiments.

[0116] Referring to FIG. 5, when the MN 502 initiates inter-CU SCG LTM preparation of candidate secondary nodes for SCG LTM, the MN 502 includes the SCG LTM candidate configurations at the MN 502 and the S-SN 504 when the MN 502 initiates the inter-CU SCG LTM. Thus, the S-SN 504 prepares a current SCG configuration SCG1 at the S-SN 504. For example, SCG1 prepared at the S-SN 504 may be associated with a bearer mapping to SCG resources at the S-SN 504. A candidate and / or target serving node 506 (e.g., T-SN1 illustrated in FIG. 5) may also prepare a candidate SCG configuration SCG2 that may be associated with a bearer mapping to SCG resources at the T-SN1 506, and another candidate and / or target serving node 508 (e.g., T-SN2 illustrated in FIG. 5) may prepare a candidate SCG configuration SCG3 associated with a bearer mapping to SCG resources at T-SN2 508. If T-SN1 506 and T-SN2 508 are able to map their respective SCG resources (e.g., SCG2, SCG3) to SCG1, then SCG3=SCG2=SCG1. Accordingly, because SCG configurations (e.g., SCG2, SCG3) are same or similar to the current SCG configuration SCG1, then the MCG configuration remains unchanged. Thus, whatever the current MCG configuration is when connected to the S-SN 504 (e.g., MCG1),the same MCG1 remains when a UE (e.g., UE 120 in FIG. 1) moves or transitions from a current SN (e.g., S-SN) to another SN, such as T-SN1 506.

[0117] FIG. 6 illustrates an example scenario of inter-centralized unit (CU) and intra-CU lower layer triggered mobility (LTM) according to one or more example embodiments.

[0118] Referring to FIG. 6, if the target and / or candidate cell provided by S-SN 606 belongs to the same serving master node and / or target master node (e.g., S-MN 602 and / or T-MN 604), such a scenario is intra-cell, because the target and / or candidate cell of S-SN 606 belongs to the same node, such as S-MN 602 and / or T-MN 604. For example, if the UE 608 is being served by a cell under the S-MN 602 whereas a candidate cell belongs to T-MN 604, then such a scenario is a combination of inter-CU and intra-CU MCG LTM. When the inter-CU + intra-CU MCG LTM is initially prepared, the S-MN 602 is going to prepare the MC-LTM configuration if there are intraserving master node cells (PCell 1, PCell 2), and intra PCell configuration (MCG1, MCG2), and there is an intra-MN configuration as well. Here, for example as shown in FIG. 6, if the UE 608 is being served by PCell 1 and PSCell 1 or PCell 2 and PSCell 1, then the MCG LTM candidate configurations are candidate config 1 and candidate config 2, which is inter-CU MCG LTM.

[0119] FIG. 7A and 7B illustrate an example signaling diagram for including master cell group (MCG) information in a message according to one or more example embodiments.

[0120] Referring to FIGS. 7A-7B, the signaling diagram for including master cell group (MCG) information in a message relates to when a UE 703 is configured with dual connectivity. Suboperations and / or steps with regard to step 2, Inter-CU SCGLTM preparation may be similar to those described with reference to FIG. 2, and thus duplicate descriptions will not be repeated.

[0121] Referring to FIGS. 7A-7B, at S706, the UE sends L3 measurements to SN1 707. At S708, SN1 707 prepares inter-CU SCGLTM and initiates inter-CU SCGLTM by sending a SNChange Required message to the MN 705. For example, the UE 703 is served by at least a primary cell (PCell 1 or PCell 2) with MN 705 providing access to the primary cell (PCelll or PCell2). The UE 703 is also served by a primary secondary cell (PSCelll) with a current and / or source primary node (SN1) 707 providing access to PSCelll. For purposes of discussion, as an example, for inter-CU SCG LTM, the UE 703 is switching to primary secondary cell (PSCell 2) with a candidate and / or target primary node (SN2) 709 providing access to PSCell2.

[0122] Still referring to FIGS. 7A-7B, at S710, SN1 707 sends an SN Change Required message to MN 705, which is the same as SN Change Required in step 1 of FIG. 2. At S712, MN 705 sends a SN Addition Request to SN2709, which is the same as SN Addition Request in step 2 of FIG. 2. At S714, SN2709 sends an SN Additional Request Acknowledge to MN 705, which is the same the SN Addition Request Acknowledge in step 3 of FIG. 2. For example, at S714, the SN Addition Request Acknowledge sent by SN2 includes an LTM candidate configuration, which may include at least the SCG reference configuration, and a delta configuration provided by SN2 709. At S716, MN 705 sends an SN Modification Request to SN1 707, which is the same the SN Modification Request in step 5 of FIG. 2. At S718, SN 1 707 sends a SN Modification Confirmation to MN 705, which is the same as the SN Modification Request Acknowledge in step 6 of FIG. 2, in response to receiving the SN Modification request.

[0123] At S720, the MN 705, checks if the SCG configurations prepared by all candidate SNs are the same and / or similar. For example, MN 705 determines whether the candidate SCG configuration included in the Addition Request Acknowledge received from SN2 709 at S714 is the same as and / or similar to the a current SCG configuration (e.g., SCG Reference Config in FIGS. 7A-7B) that was provided by SN1707 at S710. In response to determining that the candidate SCG configuration provided by SN2 709 is the same as and / or similar to the current SCGconfiguration provided by SN1 707, MN 705 includes an indication of whether or not the current SCG configuration provided by SN1 707 and the candidate SCG configuration provided by SN2 709 are the same and / or similar in the LTM candidate configuration. At S722, the MN 705 sends an RRC reconfiguration message to the UE 703. The RRC reconfiguration message sent to the UE 703 by the MN 705 at S722 may be similar to the RCC reconfiguration message sent at step 9 in FIG. 2. However, in at least one example embodiment, at S722, MN 705 includes the indication of whether or not the current SCG configuration provided by SN1 707 and the candidate SCG configuration provided by SN2 709 are the same and / or similar as part of the LTM candidate configuration that is sent via the RRC Reconfiguration message from the MN 705 to the UE 703.

[0124] For example, as illustrated in FIGS. 7A-7B, the indication as part of the LTM candidate configuration that is sent in the RRC Reconfiguration message from the MN 705 to the UE 703 may include an MCG unchanged indicator. If the candidate SCG configuration provided by SN2 709 is same as and / or similar to the current SCG configuration provided by SN1 707, the indicator indicates ‘MCG unchagned’. If the candidate SCG configuration provided by SN2709 is not the same as and / or not similar to the current SCG configuration provided by SN1 707, the message does not indicate ‘MCG unchanged.

[0125] At S724, the UE 703, in response to receiving the RRC Reconfiguration message from the MN 705 and obtaining the indication as part of the LTM candidate configuration included in the RRC reconfiguration message, maintains and / or retains the current MCG configuration of the message or generates MCG configuration based on the LTM candidate configuration of the target and / or candidate cell (e.g., PSCell 2) provided by SN2 709. Thus, in one or more example embodiments, when the UE 705 receives the indication to maintain and / or retain the current MCG configuration, the UE 705 may not generate and / or reconstruct the MCG configuration part of theLTM candidate configuration during every-CU SCG LTM cell switch, thereby optimizing RRC signaling and UE behavior.

[0126] At S726, the UE 703 sends an RRC reconfiguration complete to the MN 705. At S728, the MN 705 sends an SN Change Confirm to SN1, which is the same as the SN Change Confirm in step 11 of FIG. 2. At S730, the UE 703 sends an LI measurement report to the MN 705, which is the same as the LI measurement report in step 15 of FIG. 2. At S732, SN1 707 performs Early TA Acquisition, and at S734, SN1 707 sends a PDCCH order to UE 703.

[0127] At S736, UE 703 may perform DL synchronization with candidate cells (e.g., PSCell 2) of SN2709, which is the same as the DL synchronization with candidate cells in step 13 of FIG.2. At S738, the UE 703 may perform UL synchronization with candidate cell (e.g., PSCell 2) of SN2709, which is the same as UL synchronization with candidate cell described with reference to step 14 in FIG. 2.

[0128] At S740, the UE 703 sends LI measurement report to SN1 707, which is the same as the LI measurement report in step SI 5 of FIG. 2. At S742, SN1 707 sends a MAC CE cell switch command to the UE 703, which is the same as the Cell Switch Command (MAC CE) in step S17 of FIG. 2.

[0129] At S744, during inter-CU SCG LTM execution, if the LTM candidate configuration received by the UE 703 contains ‘MCG_UNCHANGED = TRUE’, then the UE 703 executes the LTM cell switch to PSCell2 provided by SN2 709 by retaining the current MCG configuration. For example, as shown at S744, during inter-CU SCG LTM, the UE 703 keeps the MCG unchanged and generates a candidate configuration for PSCell2 provided by SN2 709 by constructing the SCG configuration provided by SN2 and retaining the current MCG configuration.

[0130] At S746 the UE 703 and SN2 709 perform a RACH procedure, and at S748, SN2 709 becomes the new serving SN for the UE 703. At S750, the UE 703 keeps the MCG unchanged and combines only the SCG reference and delta to generate the candidate config.

[0131] At S752, the UE 703 sends a RRC Reconfiguration complete to the SN2, and at S754, the UE 703 accesses the target and / or candidate cell (e.g., PSCell2) at SN2709.

[0132] FIGS. 8A-8B illustrate an example signaling diagram for including secondary cell group (SCG) information in a message according to one or more example embodiments.

[0133] Referring to FIGS. 8A-8B, the signaling diagram for including secondary cell group (SCG) information in a message relates to when a UE 803 is configured with dual connectivity. Sub-operations and / or steps with regard FIG. 8A may be similar to those described with reference to FIG. 3, and thus duplicate descriptions will not be repeated.

[0134] Referring to FIGS. 8A-8B, at S802 UE 803 sends A3 event based measurement report to a current and / or source master node (e.g., S-MN 805). At S804, S-MN 805 performs an LTM decision. At S806, S-MN 805 performs an SN Modification Procedure with S-SN-CU 807 to retrieve a current SCG configuration from S-SN-CU 807. In some example embodiments, S-SN-CU 807 is the current and / or serving secondary node (SN). At S808, S-MN 805 starts a handover procedure by sending a handover request to a target and / or candidate master node (e.g., T-MN1 809), which is the same handover request at S31 of FIG. 3. At S810, T-MN1 809 performs an admission control procedure. At S812 T-MN1 809 sends a Handover Request Acknowledge to S-MN 805, which is the same as the Handover Request Acknowledge in S34 of FIG. 3. At S814, S-MN 805 may send a Handover Request to T-MN2811, which may be the same as the Handover Request in S31 of FIG. 3. At S816, T-MN2 811 performs Admission Control. At S818, T-MN2 811 sends an SN Addition Request to S-SN-CU 807, which is the same as the SN Addition Requestin S32 of FIG. 3. At S820, S-SN-CU 807 sends an SN Addition Request Acknowledge to T-MN2 811, which is the same as the SN Addition Request Acknowledge in S33 of FIG. 3. At S822, T-MN2 811 sends a Handover Request Acknowledge to S-MN 805, which is the same as the Handover Request Acknowledge in S34 of FIG. 3.

[0135] At S824, the S-MN 805 checks if there are intra-CU candidate PCells prepared by each inter-MN candidate node that have identical SCG configurations. For example, S-MN 805 determines whether PCell3 and PCell4 prepared by T-MN 1 809 have identical SCG configurations and S-MN 805 determines whether PCell5 and PCell6 prepared by T-MN2 811 have identical SCG configurations. If S-MN 805 determines that there are intra-CU candidate PCells prepared by each inter-MN candidate node that have identical SCG configurations, S-MN 805 includes an indication as part of LTM candidate configuration. For example, if S-MN 805 determines that PCell3 and PCell4 prepared by T-MN1 809 have MCG1 configuration and MCG2 configuration, respectively, but have identical SCG configurations (e.g., SCG1) then the S-MN 805 includes SCG_UNCHANGED_IDICATOR=TRUE as SCG configuration in the LTM configuration for each of PCell3 and PCell4 prepared by T-MN1 809 as they are identical during intra-CU LTM from PCell3 to PCell3. For example, if S-MN 805 determines that PCell5 and PCell6 prepared by T-MN2 811 have MCG3 configuration and MCG4 configuration respectively, but have identical SCG configurations (e.g., SCG2), then S-MN 805 includes SCG_UNCHANGED_INDICATOR=TRUE as SCG configuration in the LTM configuration for each of PCell5 and PCell6 prepared by T-MN2 811 as they are identical during intra-CU LTM from PCell5 to PCell6. However, S-MN 805 determines that PCell4 prepared by T-MN1 809 has MCG2 configuration and SCG1 configuration and that PCell5 prepared by T-MN2811 has MCG3 configuration and SCG2 configuration, then S-MN 805 includesSCG_UNCHAINGED_INDICATOR=FALSE as the SCG configuration in the LTM configuration for each of PCell4 and PCell5 are different during inter-CU LTM from PCell4 to PCell5.

[0136] At S826, the indication, described above with respect to S824, is as part of the LTM candidate configuration in a RRC Reconfiguration message is sent to the UE 803. At S828, the UE 803 stores the received RRC reconfiguration.

[0137] At S828, the UE 803 stores the obtained LTM candidate configuration received as part of the RRC Reconfiguration message sent by the S-MN 805. At S830, the UE sends an RRC Reconfiguration message complete to the S-MN 805, which the same as the RRC Reconfiguration complete message in S38 of FIG. 3.

[0138] At S832, the UE 803 sends an LI measurement report to the S-MN 805, which may be the same as the send LI measurement report at step SI 5 in FIG. 2. At S834, the S-MN 805 sends a PDCCH order to the UE 803. At S836, the UE 803 and T-MN1 809 perform an early sync procedure. At S838, S-MN triggers for serving cell change, and at S840, the S-MN 805 sends a MAC CE cell switch command to the UE 803. At S842, the UE 83 triggers inter-CU MCG LTM cell change. At S844, the UE 803 and the T-MN1 809 perform a RACH operation. At S846, UE 803 sends a RRC Reconfiguration complete message to T-MN1 809, which is the same as the RRC reconfiguration complete at S38 of FIG. 3. At S848, T-MN1 809 sends a Handover success message to S-MN 805.

[0139] At S850, the UE 803 and S-SN-CU 807 prepare an SCG Release and Add procedure. For example, in intra-CU MCG LTM with SCG, the SCG candidate configuration is prepared to have an MRDC-SecondaryCellGroupConfig ReleaseAndAdd, such that at the time of intra-CU or inter-CU MCG LTM execution, a ReleaseAndAdd of the SCG configuration is performed.

[0140] At S852. The UE 803 sends an LI measurement report to T-MN1 809, and at S854, T-MN1 809 may send a PDCCH order to the UE 803. The UE 803 my respond with an Early Sync to the T-MN1 809. At S858, T-MN1 809 triggers for a serving cell change from S-MN 805 to T-MN1 809. At, S860, T-MN1 809 may send a MAC CE Cell Switch Command to 803, and triggers, at S862 an intra-CU LTM PCell change at the UE 803 with a same SCG configuration. At S864, the UE 803 and the T-MN1 809 perform a RACH procedure. At S866, the UE 803 sends a RRC Reconfiguration complete message to T-MN1 809, and receives a Handover Success message at S868. At S870, intra-CU LTM PCell change was triggered, and the UE 803 determined that the SCG candidate configuration of T-MN1 809 was the same as a current SCG configuration, ‘SCG_UNCHANGED_IND=TRUE’, the UE actions involved in the ReleaseAndAdd procedure of a current SCG is not performed. Therefore, in some example embodiments, overhead associated with the ReleaseAndAdd procedure is avoided.

[0141] FIGS. 9-10 is an example flowchart of a method of operating a user equipment according to various example embodiments. For example purposes, the method shown in FIGS.9-10 will be discussed with regard to the environment shown in FIG. 1 and the signaling diagrams illustrated in FIGS. 8A-8B and 9A-9B. Example embodiments should not, however, be limited to this example.

[0142] Referring to FIG. 9, in the method 900 of operating a user equipment (UE) (e.g., one of the first UE 120 and / or the second UE 122), at S910, the UE obtains an indication as part of a handover candidate configuration of a target cell, the indication including information identifying whether a secondary cell group (SCG) configuration in a handover candidate configuration of a prepared candidate target primary secondary cell is same as a SCG configuration of a current serving primary secondary cell, or whether a SCG configuration in a handover candidateconfiguration of a prepared candidate primary cell is same as a SCG configuration of a current serving primary cell, as described herein in the disclosure.

[0143] FIG. 10 is an example flowchart of a method of operating a network node according to various example embodiments.

[0144] Referring to FIG. 10, in the method 1000 of operating network node (e.g., first network node 110 and / or second network 112), at S1010, the network node obtains a secondary cell group (SCG) configuration of a target primary secondary cell. At SI 020, the network node obtains a SCG configuration of a current primary secondary cell, at SI 030, the network node determines whether the whether the SCG configuration of the target primary secondary cell is same as the SCG configuration of the current primary secondary cell, and at SI 040, sends an indication of a handover candidate configuration of a candidate cell to a user equipment (UE) including information to identify whether the primary SCG configuration of the target primary secondary cell is the same as the SCG configuration of the current primary secondary cell, as described herein in the disclosure.

[0145] FIG. 11 illustrates an example flowchart of a method of operating a network node according to various example embodiments.

[0146] Referring to FIG. 11, in the method 1100 of operating a network node (e.g., first network node 110 and / or second network node 112), at operation SI 110, the network node determines whether a secondary cell group (SCG) configuration for each of a number of candidate cells in a prepared candidate master node are the same, and, at SI 120, sends an indication of a handover candidate configuration of the prepared candidate master node to a user equipment (UE) including information to identify whether the SCG configuration for each of the number of candidate cells in the prepared candidate master node are the same, as described herein in this disclosure.

[0147] FIG. 12 illustrates an example of an apparatus according to various example embodiments.

[0148] Referring to FIG. 12, FIG. 12 illustrates, by way of example, a block diagram of an apparatus 1200. The apparatus 1200 comprises, for example, at least one processor 1220 and at least one memory 1210 storing instructions that, when executed by the at least one processor 1220, cause the apparatus 1200 at least to perform the method or methods as disclosed herein, and any of the various example embodiments thereof. In an example, the at least one memory 1210 and the instructions (e.g., a computer program code, software, etc.), are configured, with the at least one processor 1220, to cause the apparatus 1200 to perform the method or methods as disclosed herein, and any of the various example embodiments thereof.

[0149] The at least one processor 1220 may comprise circuitry, or be constituted as circuitry or circuitries, the circuitry or circuitries being configured to perform phases of methods in accordance with example embodiments described herein. As used in this application, the term “circuitry” may refer to one or more or all of the following: (a) hardware-only circuit implementations, such as implementations in only analog and / or digital circuitry, and (b) combinations of hardware circuits and software, such as, as applicable: (i) a combination of analog and / or digital hardware circuit(s) with software / firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a user equipment, to perform various functions) and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation. This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers animplementation of merely a hard-ware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0150] The at least one memory 1210 may be implemented using any suitable data storage technology. The at least one memory 1210 may comprise a database for storing data. The at least one memory 1210 may be at least in part external to the apparatus 1200 but accessible to the apparatus 1200.

[0151] The instructions may be comprised in a computer readable medium or a non-transitory computer readable medium. A term non-transitory, as used herein, is a limitation of the medium itself (e.g., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., random-access memory, RAM, vs. read only memory, ROM).

[0152] For example, the apparatus 1200 is a terminal device may be referred to as a communication device, user equipment (UE), a Subscriber Station (SS), or a Mobile Station (MS). In some example embodiments, the apparatus 1200 may be a node in a communication network via which user equipment may access the network and / or which is capable of controlling radio communication and managing radio resources within a cell. For example, the apparatus 1200 may be a base station (BS), an access point (AP) or an access node. The apparatus 1200 may be, depending on the applied technology, for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), an NR NB (also referred to as a gNB), a Remote Radio Unit (RRU), a radio head (RH), a remote radio head (RRH), a relay, an Integrated Access and Backhaul (IAB) node, a low power node, a non-terrestrial network (NTN) or non-ground network device such as a satellitenetwork device, a low earth orbit (LEO) satellite and a geosynchronous earth orbit (GEO) satellite, or an aircraft network device. The apparatus 1200 may be caused to perform any one or more embodiments described herein.

[0153] The apparatus 1200 comprises a communication interface 1230. The communication interface 1230 may provide the apparatus 1200 with communication capabilities. The communication interface 1230 may comprise a receiver configured to receive information in accordance with at least one cellular or non-cellular standard. The communication interface 1230 may comprise a transmitter configured to transmit or send information in accordance with at least one cellular or non-cellular standard. The receiver may comprise more than one receiver. The transmitter may comprise more than one transmitter. The communication interface 1230 may comprise a transceiver configured to receive and transmit or send information in accordance with at least one cellular or non-cellular standard. The transceiver may comprise more than one transceiver.

[0154] FIG. 13 is pseudo code illustrating information associated with master cell group (MCG) change according to one or more example embodiments.

[0155] Referring to FIG. 13, an example implementation of the information 1300 described with reference to FIGS. 7A-7B is shown according to at least one example embodiment. Referring to FIGS. 7A-7B and 13, in at least one example, the information 1300 included in message (e.g., RRCReconfiguration) may include information 1300, such as LTM-Configuration information that includes an indication 1310 to a UE to retain a current MCG configuration as information associated with whether secondary cell group (SCG) configurations of at least one candidate cell and another candidate cell are the same and / or similar. For example, the field LTM-noMCGConFIGChangeId-r!9 1310 in the information 1300 may indicate that the current MCGremains unchanged. In at least one example embodiment, the information 1300 may further include information on whether at least one candidate secondary cell group (SCG) configuration is same as a current SCG configuration. For example, the field OPTIONAL, — Cond inter-CU SCGLTM 1320 in the information may indicate that the candidate SCG configuration is the same as the current SCG configuration, and therefore indicates that the candidate SCG configuration has a same MCG configuration as the current MCG configuration.

[0156] FIG. 14 is pseudo code illustrating information associated with secondary cell group (SCG) change according to one or more example embodiments.

[0157] Referring to FIG. 14, an example implementation of the information 1400 described with reference to FIGS. 8A-8B is shown according to at least one example embodiment. Referring to FIGS. 8A-8B and 14, in at least one example, the information 1400 included in message (e.g., RRCReconfiguration) may include information 1400, such as LTM-Configuration information that includes an indication 1410 to a UE that secondary cell group (SCG) configurations of at least one candidate cell and another candidate cell are same and / or similar. For example, the field LTM-noSCGConfigChangeId-rl9 1410 in information 1400 may indicate that the SCG configurations across the candidate cells are identical (e.g., “true”). In at least one example embodiment, the information 1400 may further include information on whether to perform a release and add operation or not perform a release and add operation. For example, the field OPTIONAL, — Cond intra-CU MCG LTM 1420 in the information 1400 may indicate that the SCG configurations of at least one candidate cell and another candidate cell are the same, and therefore during switching to at least one candidate cell ReleaseAndAdd of the SCG configuration is not performed.

[0158] In at least one example embodiment, at least some of the processes described herein may be carried out by an apparatus comprising means for carrying out at least some of thedescribed processes. Means for performing method steps as disclosed herein may include software and / or hardware components of the apparatus 1200. For example, the at least one processor 1220, the memory 1210, and the computer program code form means for carrying out the method or methods as disclosed herein, and any of the embodiments thereof. As used herein the term “means” is to be construed in singular form, e.g., referring to a single element, or in plural form, e.g., referring to a combination of single elements. Therefore, terminology “means for [performing A, B, C]”, is to be interpreted to cover an apparatus in which there is only one means for performing A, B and C, or where there are separate means for performing A, B and C, or partially or fully over-lapping means for performing A, B, C. Further, terminology “means for performing A, means for performing B, means for performing C” is to be interpreted to cover an apparatus in which there is only one means for performing A, B and C, or where there are separate means for performing A, B and C, or partially or fully overlapping means for performing A, B, C.

[0159] Illustrative embodiment 1. A method of operating a user equipment (UE), the method comprising: obtaining an indication as part of a handover candidate configuration of a target cell, the indication including information identifying whether a secondary cell group (SCG) configuration in a handover candidate configuration of a prepared candidate target primary secondary cell is same as a SCG configuration of a current serving primary secondary cell, or whether a SCG configuration in a handover candidate configuration of a prepared candidate primary cell is same as a SCG configuration of a current serving primary cell.

[0160] Illustrative embodiment 2. The method of illustrative embodiment 1, wherein the method comprises maintaining a current master cell group (MCG) configuration or generate an MCG configuration based on the handover candidate configuration of the prepared candidate target primary secondary cell.

[0161] Illustrative embodiment 3. The method of illustrative embodiment 2, wherein method comprises retaining the current MCG configuration during a cell switch to at least the target cell in response to the information indicating that the SCG configuration in the handover candidate configuration of the candidate target primary secondary cell is the same as the SCG configuration of the current serving primary secondary cell.

[0162] Illustrative embodiment 4. The method of illustrative embodiment 3, wherein the method comprises, generating candidate configuration for switching to the prepared candidate target primary secondary cell by constructing the SCG configuration of the handover candidate configuration of the prepared candidate target primary secondary cell and retaining the current MCG configuration in response to the information indicating the SCG configuration in the handover candidate configuration of the prepared candidate target primary secondary cell is the same as the SCG configuration of the current serving primary secondary cell, and switching to at least the prepared candidate target primary secondary cell using the generated candidate configuration.

[0163] Illustrative embodiment 5. The method of illustrative embodiment 1, wherein the handover is a Layerl / Layer2 Triggered Mobility (LTM).

[0164] Illustrative embodiment 6. The method of any one of illustrative embodiments 1-5, wherein the method comprises switching to the prepared candidate target primary secondary cell from the current serving primary secondary cell while being served by a primary cell through a master node.

[0165] Illustrative embodiment 7. The method of illustrative embodiment 1, wherein the method comprises performing a release and add operation or not performing the release and add operation based on the obtained indication.

[0166] Illustrative embodiment 8. The method of illustrative embodiment 7, wherein the method comprises performing the release and add operation during a switch to the prepared candidate primary cell in response to the information indicating that the SCG configuration of the prepared candidate primary cell and the SCG configuration of the current serving primary cell are not the same.

[0167] Illustrative embodiment 9. The method of illustrative embodiment 7, wherein the method comprises not performing the release and add operation during a switch to the prepared candidate primary cell in response to the information indicating that the SCG configurations of the prepared candidate primary cell and the SCG configuration of the current serving primary cell are the same.

[0168] Illustrative embodiment 10. The method of any one of illustrative embodiments 7-9, wherein the release and add operation is a SCG configuration release and add operation.

[0169] Illustrative embodiment 11. A user equipment (UE), comprising: means for obtaining an indication as part of a handover candidate configuration of a target cell, the indication including information identifying whether a secondary cell group (SCG) configuration in a handover candidate configuration of a prepared candidate target primary secondary cell is same as a SCG configuration of a current serving primary secondary cell, or whether a SCG configuration in a handover candidate configuration of a prepared candidate primary cell is same as a SCG configuration of a current serving primary cell.

[0170] Illustrative embodiment 12. The UE of illustrative embodiment 11, wherein the UE further comprises means for maintaining a current master cell group (MCG) configuration or generate an MCG configuration based on the handover candidate configuration of the prepared candidate target primary secondary cell.

[0171] Illustrative embodiment 13. The UE of illustrative embodiment 12, wherein the UE further comprises means for retaining the current MCG configuration during a cell switch to at least the target cell in response to the information indicating that the SCG configuration in the handover candidate configuration of the candidate target primary secondary cell is the same as the SCG configuration of the current serving primary secondary cell.

[0172] Illustrative embodiment 14. The UE of illustrative embodiment 13, wherein the UE further comprises, means for generating candidate configuration for switching to the prepared candidate target primary secondary cell by constructing the SCG configuration of the handover candidate configuration of the prepared candidate target primary secondary cell and retaining the current MCG configuration in response to the information indicating the SCG configuration in the handover candidate configuration of the prepared candidate target primary secondary cell is the same as the SCG configuration of the current serving primary secondary cell, and switching to at least the prepared candidate target primary secondary cell using the generated candidate configuration.

[0173] Illustrative embodiment 15. The UE of illustrative embodiment 12, wherein the handover is a Layerl / Layer2 Triggered Mobility (LTM).

[0174] Illustrative embodiment 16. The UE of illustrative embodiment 12, wherein the UE comprises means for switching to the prepared candidate target primary secondary cell from the current serving primary secondary cell while being served by a primary cell through a master node.

[0175] Illustrative embodiment 17. The UE of illustrative embodiment 11, wherein the UE comprises means for performing a release and add operation or not performing the release and add operation based on the obtained indication.

[0176] Illustrative embodiment 18. The UE of illustrative embodiment 17, wherein the UE comprises means for performing the release and add operation during a switch to the target cell in response to the information indicating that the SCG configuration of the target cell and the current SCG configuration are not the same.

[0177] Illustrative embodiment 19. The UE of illustrative embodiment 17, wherein the UE comprises means for not performing the release and add operation during a switch to the prepared candidate primary cell in response to the information indicating that the SCG configurations of the prepared candidate primary cell and the SCG configuration of the current serving primary cell are the same.

[0178] Illustrative embodiment 20. The UE of any one of illustrative embodiment 17-19, wherein the release and add operation is a SCG configuration release and add operation.

[0179] Illustrative embodiment 21. A method of operating network node, comprising: obtaining a secondary cell group (SCG) configuration of a target primary secondary cell; obtaining a SCG configuration of a current primary secondary cell; determining whether the SCG configuration of the target primary secondary cell is same as the SCG configuration of the current primary secondary cell; and sending an indication in a handover candidate configuration of a candidate cell to a user equipment (UE) including information to identify whether the SCG configuration of the target primary secondary cell is the same as the SCG configuration of the current primary secondary cell.

[0180] Illustrative embodiment 22. The method of illustrative embodiment 21, wherein the method comprises providing the UE access to a primary cell.

[0181] Illustrative embodiment 23. The method of any one of illustrative embodiments 21-22, wherein the network node is a radio access network base station.

[0182] Illustrative embodiment 24. The method of any one of illustrative embodiments 21-23, wherein the method further comprises sending the indication in the handover candidate configuration of each prepared candidate cell to the UE as part of a RRC Reconfiguration message.

[0183] Illustrative embodiment 25. The method of any one of illustrative embodiment 21-25, wherein the method further comprises initiating a target cell switch based on a message received from the current primary secondary cell.

[0184] Illustrative embodiment 26. A network node, comprising: means for obtaining a secondary cell group (SCG) configuration of a target primary secondary cell; means for obtaining a SCG configuration of a current primary secondary cell; means for determining whether the SCG configuration of the target primary secondary cell is same as the SCG configuration of the current primary secondary cell; and means for sending an indication in a handover candidate configuration of a candidate cell to a user equipment (UE) including information to identify whether the SCG configuration of the target primary secondary cell is the same as the SCG configuration of the current primary secondary cell.

[0185] Illustrative embodiment 27. The network node of illustrative embodiment 26, wherein the network node comprises means for providing the UE access to a primary cell.

[0186] Illustrative embodiment 28. The network node of any one of illustrative embodiments 26-27, wherein the network node is a radio access network base station.

[0187] Illustrative embodiment 29. The network node of any one of illustrative embodiment 26-28, wherein the network node comprises means for sending the indication in the handover candidate configuration of each prepared candidate cell to the UE as part of a RRC Reconfiguration message.

[0188] Illustrative embodiment 30. The network node of any one of illustrative embodiment 26-29, wherein the network node comprises means for initiating a target cell switch based on a message received from the current primary secondary cell.

[0189] Illustrative embodiment 31. A method of operating network node, the method comprising: determining whether a secondary cell group (SCG) configuration for each of a number of candidate cells in a prepared candidate master node are same; and sending an indication of a handover candidate configuration of the prepared candidate master node to a user equipment (UE) including information to identify whether the SCG configuration for each of the number of candidate cells in the prepared candidate master node are the same.

[0190] Illustrative embodiment 32. The method of illustrative embodiment 31, wherein the method comprises providing a primary cell connected to the UE access to the prepared candidate master node.

[0191] Illustrative embodiment 33. The method of any one of illustrative embodiments 31-32, wherein the network node is a radio access network base station.

[0192] Illustrative embodiment 34. The method of any one of illustrative embodiments 31-33, wherein the method comprises sending the indication in each of the handover candidate configurations of the prepared candidate master node to the UE as part of a RRC Reconfiguration message.

[0193] Illustrative embodiment 35. The method of any one of illustrative embodiments 31-35, wherein the handover is a Layerl / Layer2 Triggered Mobility (LTM).

[0194] Illustrative embodiment 36. A network node, comprising: means for determining whether a secondary cell group (SCG) configuration for each of a number of candidate cells in a prepared candidate master node are same; and means for sending an indication of a handovercandidate configuration of the prepared candidate master node to a user equipment (UE) including information to identify whether the SCG configuration for each of the number of candidate cells in the prepared candidate master node are the same.

[0195] Illustrative embodiment 37. The network node of illustrative embodiment 36, wherein the network node comprises means for providing a primary cell connected to the UE access to the prepared candidate master node.

[0196] Illustrative embodiment 38. The network node of illustrative embodiment 36, wherein the network node is a radio access network base station.

[0197] Illustrative embodiment 39. The network node of illustrative embodiment 36, wherein the network node comprises means for sending the indication in each of the handover candidate configurations of the prepared candidate master node to the UE as part of a RRC Reconfiguration message.

[0198] Illustrative embodiment 40. The network node of illustrative embodiment 36, wherein the handover is a Layerl / Layer2 Triggered Mobility (LTM).

Claims

WHAT IS CLAIMED IS:

1. A user equipment (UE), comprising:at least one memory storing instructions; andat least one processor is configured to execute the instructions to cause the UE to, obtain an indication as part of a handover candidate configuration of a target cell, the indication including information identifyingwhether a secondary cell group (SCG) configuration in a handover candidate configuration of a prepared candidate target primary secondary cell is same as a SCG configuration of a current serving primary secondary cell, orwhether a SCG configuration in a handover candidate configuration of a prepared candidate primary cell is same as a SCG configuration of a current serving primary cell.

2. The UE of claim 1, wherein the at least one processor is configured to execute the instructions to cause the UE to maintain a current master cell group (MCG) configuration or generate an MCG configuration based on the handover candidate configuration of the prepared candidate target primary secondary cell.

3. The UE of claim 2, wherein the at least one processor is configured to execute the instructions to cause the UE to retain the current MCG configuration during a cell switch to at least the target cell in response to the information indicating that the SCG configuration in the handover candidate configuration of the candidate target primary secondary cell is the same as the SCG configuration of the current serving primary secondary cell.

4. The UE of claim 3, wherein the at least one processor is configured to execute the instructions to cause the UE to,generate candidate configuration for switching to the prepared candidate target primary secondary cell by constructing the SCG configuration of the handover candidate configuration of the prepared candidate target primary secondary cell and retaining the current MCG configuration in response to the information indicating the SCG configuration in the handover candidate47configuration of the prepared candidate target primary secondary cell is the same as the SCG configuration of the current serving primary secondary cell, andswitch to at least the prepared candidate target primary secondary cell using the generated candidate configuration.

5. The UE of claim 2, wherein the handover is a Layerl / Layer2 Triggered Mobility (LTM).

6. The UE of claim 2, wherein the at least one processor is configured to execute instructions to cause the UE to switch to the prepared candidate target primary secondary cell from the current serving primary secondary cell while being served by a primary cell through a master node.

7. The UE of claim 1, wherein the at least one processor is configured to execute the instructions to cause the UE to perform a release and add operation or not perform the release and add operation based on the obtained indication.

8. The UE of claim 7, wherein the at least one processor is configured to execute the instructions to cause the UE to perform the release and add operation during a switch to the prepared candidate primary cell in response to the information indicating that the SCG configuration of the prepared candidate primary cell and the SCG configuration of the current serving primary cell are not the same.

9. The UE of claim 7, wherein the at least one processor is configured to execute the instructions to cause the UE to not perform the release and add operation during a switch to the prepared candidate primary cell in response to the information indicating that the SCG configurations of the prepared candidate primary cell and the SCG configuration of the current serving primary cell are the same.

10. The UE of claim 7, wherein the release and add operation is a SCG configuration release and add operation.

11. A network node, comprising:at least one memory storing instructions; andat least one processor that is configured to execute the instructions to cause the network node to,obtain a secondary cell group (SCG) configuration of a target primary secondary cell;obtain a SCG configuration of a current primary secondary cell;determine whether the SCG configuration of the target primary secondary cell is same as the SCG configuration of the current primary secondary cell; andsend an indication in a handover candidate configuration of a candidate cell to a user equipment (UE) including information to identify whether the SCG configuration of the target primary secondary cell is the same as the SCG configuration of the current primary secondary cell.

12. The network node of claim 11, wherein, the at least one processor is configured to execute the instructions to cause the network node to provide the UE access to a primary cell.

13. The network node of claim 11, wherein the network node is a radio access network base station.

14. The network node of claim 11, wherein the at least one processor is configured to execute the instructions to cause the network node to send the indication in the handover candidate configuration of each prepared candidate cell to the UE as part of a RRC Reconfiguration message.

15. The network node of claim 11, wherein the at least one processor is configured to execute the instructions to cause the network node to initiate a target cell switch based on a message received from the current primary secondary cell.

16. A network node, comprising:at least one memory storing instructions; andat least one processor that is configured to execute the instructions to cause the network node to,determine whether a secondary cell group (SCG) configuration for each of a number of candidate cells in a prepared candidate master node are same; andsend an indication of a handover candidate configuration of the prepared candidate master node to a user equipment (UE) including information to identify whether the SCG configuration for each of the number of candidate cells in the prepared candidate master node are the same.

17. The network node of claim 16, wherein the at least one processor is configured to execute the instructions to cause the network node to provide a primary cell connected to the UE access to the prepared candidate master node.

18. The network node of claim 16, wherein the network node is a radio access network base station.

19. The network node of claim 16, wherein the at least one processor is configured to execute the instructions to cause the network node to send the indication in each of the handover candidate configurations of the prepared candidate master node to the UE as part of a RRC Reconfiguration message.

20. The network node of claim 16, wherein the handover is a Layerl / Layer2 Triggered Mobility (LTM).

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