Secondary cell group change based on dual connectivity

Abstract

Example embodiments of the present disclosure relate to dual connectivity based (DC based) secondary cell group changes. A method includes receiving, from a first network device, an indication to initiate a dual connectivity based secondary cell group change; adding a first cell to the secondary cell group based on the indication, the first cell being provided by the first network device and serving the user equipment; deactivating a primary cell group including the first cell; receiving, from the first network device, an inter-secondary node handover configuration for a secondary cell group change based on dual connectivity; and handover from the first cell to a second cell based on the inter-secondary node handover configuration, the second cell being provided by the second network device and included in the target secondary cell group.

Description

Technical Field

[0001] Various example embodiments generally relate to the telecommunications field, and more particularly to methods, apparatus, devices, and computer-readable storage media for secondary cell group changes based on dual connectivity (DC). Background Technology

[0002] When a user equipment (UE) moves from the coverage area of ​​one cell to another, a serving cell change needs to be performed at some point. Low-layer triggered mobility (LTM), also known as Layer 1 (L1) / Layer 2 (L2) based inter-cell mobility, has been introduced to enable serving cell changes via L1 / L2 signaling. LTM helps reduce latency, overhead, and downtime during handover. Summary of the Invention

[0003] In a first aspect, a user equipment is provided. The user equipment includes: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, cause the user equipment operating in a single-connectivity mode to at least: receive from a first network device an instruction to initiate a secondary cell group change based on dual connectivity; add a first cell or a second cell to the secondary cell group based on the instruction, the first cell being provided by the first network device and serving the user equipment, and the second cell being provided by a second network device; and deactivate a primary cell group including the first cell.

[0004] In a second aspect, a first network device is provided. The first network device includes: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, cause the first network device to at least: receive at least one measurement related to a second cell provided by a second network device from a user equipment operating in single-connectivity mode; determine, based on the at least one measurement, to initiate a dual-connectivity-based secondary cell group change for the user equipment; send an instruction to the user equipment to initiate the dual-connectivity-based secondary cell group change; and, based on the determination, cause the user equipment to enter dual-connectivity mode from single-connectivity mode.

[0005] Thirdly, a second network device is provided. The second network device includes: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, cause the second network device to at least: receive from a first network device a request for the addition of a secondary node, the request instructing the secondary node to add a dual-connectivity-based secondary cell group change for a user equipment; and, based on the request, determine that a primary cell group will be deactivated by the user equipment for the dual-connectivity-based secondary cell group change.

[0006] In a fourth aspect, a method is provided. The method includes: receiving from a first network device an instruction to initiate a secondary cell group change based on dual connectivity; adding a first cell or a second cell to the secondary cell group based on the instruction, wherein the first cell is provided by the first network device and serves user equipment, and the second cell is provided by a second network device; and deactivating a primary cell group including the first cell.

[0007] In a fifth aspect, a method is provided. The method includes: receiving from a user equipment operating in single-connectivity mode at least one measurement related to a second cell provided by a second network device; determining, based on the at least one measurement, to initiate a dual-connectivity-based secondary cell group change for the user equipment; sending to the user equipment an indication to initiate the dual-connectivity-based secondary cell group change; and, based on the determination, causing the user equipment to enter dual-connectivity mode from single-connectivity mode.

[0008] In a sixth aspect, a method is provided. The method includes: receiving from a first network device a request for adding a secondary node, the request instructing the secondary node to add a dual-connectivity-based secondary cell group change for a user equipment; and based on the request, determining that a primary cell group will be deactivated by the user equipment for use in the dual-connectivity-based secondary cell group change.

[0009] A seventh aspect provides a first apparatus. The first apparatus includes: components for receiving from a first network device an instruction to initiate a secondary cell group change based on dual connectivity; components for adding a first cell or a second cell to the secondary cell group based on the instruction, the first cell being provided by the first network device and serving a user equipment, and the second cell being provided by a second network device; and components for deactivating a primary cell group including the first cell.

[0010] Eighthly, a second apparatus is provided. The second apparatus includes: means for receiving, from a user equipment operating in a single-connectivity mode, at least one measurement related to a second cell provided by a second network device; means for determining, based on the at least one measurement, to initiate a dual-connectivity-based secondary cell group change for the user equipment; means for sending to the user equipment an indication to initiate a dual-connectivity-based secondary cell group change; and means for determining, to cause the user equipment to enter a dual-connectivity mode from a single-connectivity mode.

[0011] In a ninth aspect, a third apparatus is provided. The third apparatus includes: components for receiving from a first network device a request for adding a secondary node, the request instructing the secondary node to add a dual-connectivity-based secondary cell group change for a user equipment; and components for determining, based on the request, that a primary cell group will be deactivated by the user equipment for use in the dual-connectivity-based secondary cell group change.

[0012] In a tenth aspect, a computer-readable medium is provided. The computer-readable medium includes instructions stored thereon for causing a device to at least execute the method according to the fourth aspect.

[0013] In the eleventh aspect, a computer-readable medium is provided. The computer-readable medium includes instructions stored thereon for causing a device to at least execute the method according to the fifth aspect.

[0014] In a twelfth aspect, a computer-readable medium is provided. The computer-readable medium includes instructions stored thereon for causing a device to at least execute the method according to the sixth aspect.

[0015] In a thirteenth aspect, a user equipment is provided. The user equipment includes: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, cause the user equipment operating in a single-connectivity mode to at least: receive from a first network device an instruction to initiate a secondary cell group change based on dual connectivity; add a first cell to a secondary cell group based on the instruction, the first cell being provided by the first network device and serving the user equipment; deactivate a primary cell group including the first cell; receive from the first network device an inter-node handover configuration for the secondary cell group change based on dual connectivity; and handover from the first cell to a second cell based on the inter-node handover configuration, the second cell being provided by a second network device and included in a target secondary cell group.

[0016] In a fourteenth aspect, a first network device is provided. The first network device includes: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, cause the first network device to at least: receive from a user equipment operating in single-connectivity mode a measurement report identifying a second cell provided by a second network device; determine, based on the measurement report, to initiate a dual-connectivity-based secondary cell group change for the user equipment; send to the user equipment an instruction for initiating the dual-connectivity-based secondary cell group change; and send to the user equipment a secondary node handover configuration for the dual-connectivity-based secondary cell group change.

[0017] In a fifteenth aspect, a method is provided. The method includes: receiving from a first network device an instruction to initiate a secondary cell group change based on dual connectivity; adding a first cell to the secondary cell group based on the instruction, the first cell being provided by the first network device and serving user equipment; deactivating a primary cell group including the first cell; receiving from the first network device an inter-node handover configuration for the secondary cell group change based on dual connectivity; and handing over from the first cell to a second cell based on the inter-node handover configuration, the second cell being provided by a second network device and included in a target secondary cell group.

[0018] In a sixteenth aspect, a method is provided. The method includes: receiving from a user equipment operating in single-connectivity mode a measurement report identifying a second cell provided by a second network device; determining, based on the measurement report, to initiate a dual-connectivity-based secondary cell group change for the user equipment; sending to the user equipment an instruction for initiating the dual-connectivity-based secondary cell group change; and sending to the user equipment a secondary node handover configuration for the dual-connectivity-based secondary cell group change.

[0019] In a seventeenth aspect, a first apparatus is provided. The first apparatus includes: components for receiving from a first network device an instruction to initiate a dual-connectivity-based secondary cell group change; components for adding a first cell to a secondary cell group based on the instruction, the first cell being provided by the first network device and serving a user equipment; components for deactivating a primary cell group including the first cell; components for receiving from the first network device an inter-node handover configuration for the dual-connectivity-based secondary cell group change; and components for handing over from the first cell to a second cell based on the inter-node handover configuration, the second cell being provided by a second network device and included in a target secondary cell group.

[0020] In an eighteenth aspect, a second apparatus is provided. The second apparatus includes: components for receiving, from a user equipment operating in single-connectivity mode, a measurement report identifying a second cell provided by a second network device; components for determining, based on the measurement report, a secondary cell group change to be initiated for the user equipment based on dual-connectivity; components for sending to the user equipment an indication to initiate the secondary cell group change based on dual-connectivity; and components for sending to the user equipment a secondary node handover configuration for the secondary cell group change based on dual-connectivity.

[0021] In a nineteenth aspect, a computer-readable medium is provided. The computer-readable medium includes instructions stored thereon for causing a device to at least execute the method according to the fifteenth aspect.

[0022] In a twentieth aspect, a computer-readable medium is provided. The computer-readable medium includes instructions stored thereon for causing a device to at least execute the method according to the sixteenth aspect.

[0023] In a twenty-first aspect, a user equipment is provided. The user equipment includes: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, cause the user equipment operating in a single-connection manner to at least: receive from a first network device an inter-node handover configuration for a dual-connection-based secondary cell group change; perform at least one measurement related to a second cell provided by a second network device; report the at least one measurement to the first network device; receive from the first network device an instruction to initiate a dual-connection-based secondary cell group change; initiate a cell handover from a first cell provided by the first network device to a second cell based on the inter-node handover configuration; add the second cell to the secondary cell group based on the instruction; and deactivate a primary cell group including the first cell.

[0024] In a twenty-second aspect, a first network device is provided. The first network device includes: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, cause the first network device to at least: receive from a user equipment operating in single-connectivity mode a measurement report identifying a second cell provided by a second network device; determine, based on the measurement report, to initiate a dual-connectivity-based secondary cell group change for the user equipment; based on the determination, send to the user equipment a secondary node handover configuration for the dual-connectivity-based secondary cell group change; receive from the first network device at least one measurement related to the second cell; and based on the at least one measurement, send to the user equipment an instruction to initiate a dual-connectivity-based secondary cell group change to activate a secondary cell group for the user equipment.

[0025] In a twenty-third aspect, a method is provided. The method includes: receiving from a first network device a secondary node handover configuration for a secondary cell group change based on dual connectivity; performing at least one measurement related to a second cell provided by a second network device; reporting the at least one measurement to the first network device; receiving from the first network device an indication for initiating a secondary cell group change based on dual connectivity; initiating a cell handover from a first cell provided by the first network device to a second cell based on the secondary node handover configuration; adding the second cell to the secondary cell group based on the indication; and deactivating a primary cell group including the first cell.

[0026] In a twenty-fourth aspect, a method is provided. The method includes: receiving from a user equipment operating in single-connectivity mode a measurement report identifying a second cell provided by a second network device; determining, based on the measurement report, to initiate a dual-connectivity-based secondary cell group change for the user equipment; based on the determination, sending to the user equipment a secondary node handover configuration for the dual-connectivity-based secondary cell group change; receiving from a first network device at least one measurement related to the second cell; and based on the at least one measurement, sending to the user equipment an instruction to initiate a dual-connectivity-based secondary cell group change to activate a secondary cell group for the user equipment.

[0027] A twenty-fifth aspect provides a first apparatus. The first apparatus includes: components for receiving from a first network device a secondary node handover configuration for a secondary cell group change based on dual connectivity; components for performing at least one measurement related to a second cell provided by a second network device; components for reporting the at least one measurement to the first network device; components for receiving from the first network device an indication for initiating a secondary cell group change based on dual connectivity; components for initiating a cell handover from a first cell to a second cell provided by the first network device based on the secondary node handover configuration; components for adding the second cell to a secondary cell group based on the indication; and components for deactivating a primary cell group including the first cell.

[0028] In a twenty-sixth aspect, a second apparatus is provided. The second apparatus includes: components for receiving from a user equipment operating in single-connectivity mode a measurement report identifying a second cell provided by a second network device; components for determining, based on the measurement report, a secondary cell group change to be initiated for the user equipment based on dual-connectivity; components for sending, based on the determination, an inter-node handover configuration for the secondary cell group change based on dual-connectivity; components for receiving from a first network device at least one measurement related to the second cell; and components for sending, based on the at least one measurement, an instruction to the user equipment to initiate a secondary cell group change based on dual-connectivity to activate the secondary cell group for the user equipment.

[0029] In a twenty-seventh aspect, a computer-readable medium is provided. The computer-readable medium includes instructions stored thereon for causing a device to at least execute the method according to a twenty-third aspect.

[0030] In a twenty-eighth aspect, a computer-readable medium is provided. The computer-readable medium includes instructions stored thereon for causing a device to at least execute the method according to a twenty-fourth aspect.

[0031] It should be understood that the summary section is not intended to identify key or essential features of the embodiments, nor is it intended to limit the scope. Other features will become readily apparent from the following description. Attached Figure Description

[0032] Some exemplary embodiments will now be described with reference to the accompanying drawings, in which: Figure 1 An example communication environment in which the serving cell of LTM can be changed is shown, in which example embodiments are illustrated.

[0033] Figure 2 An example next-generation radio access network (NG-RAN) architecture is shown.

[0034] Figure 3An example procedure for inter-CU LTM cell handover is shown according to some example embodiments.

[0035] Figure 4 An example signaling flow based on DC-based SCG changes is shown according to some example embodiments.

[0036] Figure 5 An example signaling flow based on DC-based SCG changes is shown, according to some other example embodiments.

[0037] Figure 6 An example scenario of DC-based SCG modification is shown according to some example embodiments.

[0038] Figure 7 An example signaling flow based on DC-based SCG changes is shown in an example scenario according to some example embodiments.

[0039] Figure 8 An example process for DC-based SCG modification is shown in an example scenario according to some example embodiments.

[0040] Figure 9 Another example scenario of DC-based SCG modification is shown according to some example embodiments.

[0041] Figure 10 An example signaling flow based on DC-based SCG changes is shown in another example scenario according to some example embodiments.

[0042] Figure 11 An example process for DC-based SCG change is shown in another example scenario according to some example embodiments.

[0043] Figure 12 A flowchart of an example method implemented at a user device according to some example embodiments is shown.

[0044] Figure 13 A flowchart of an example method implemented at a first network device according to some example embodiments is shown.

[0045] Figure 14 A flowchart of an example method implemented at a second network device according to some example embodiments is shown.

[0046] Figure 15 A flowchart of an example method implemented at a user device according to some example embodiments is shown.

[0047] Figure 16 A flowchart is shown of an example method implemented at a location service device of a first network device according to some example embodiments.

[0048] Figure 17 A flowchart of an example method implemented at a user device according to some example embodiments is shown.

[0049] Figure 18 A flowchart of an example method implemented at a first network device according to some example embodiments is shown.

[0050] Figure 19 A simplified block diagram of a device suitable for implementing the example embodiments is shown.

[0051] Figure 20 Examples of computer-readable media, which may be in the form of CDs, DVDs, or other optical storage discs, are shown. Detailed Implementation

[0052] The principles will now be described with reference to some exemplary embodiments. It should be understood that these embodiments are described for illustrative purposes only and to assist those skilled in the art in understanding and implementing this disclosure, and do not imply any limitation on the scope of this disclosure. The embodiments described herein can be implemented in various ways other than those described below.

[0053] In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0054] References to "an embodiment," "embodiment," "example embodiment," etc., in this disclosure indicate that the described embodiments may include specific features, structures, or characteristics, but not every embodiment includes such specific features, structures, or characteristics. Furthermore, such phrases do not necessarily refer to the same embodiment. In addition, when a specific feature, structure, or characteristic is described in connection with an embodiment, it is to be noted that those skilled in the art will recognize, whether explicitly described or not, that such features, structures, or characteristics apply in conjunction with other embodiments.

[0055] It should be understood that although the terms "first," "second," etc., preceding the noun(s) 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, and they do not restrict the order of the noun(s). For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element, without departing from the scope of the exemplary embodiments. As used herein, the term "and / or" includes any and all combinations of one or more of the listed terms.

[0056] As used herein, “at least one of the following: ” and “at least one of ” and similar terms, wherein a list of two or more elements is connected by “and” or “or”, means at least one of the elements, or at least any two or more of the elements, or at least all of the elements.

[0057] As used herein, unless explicitly stated otherwise, the execution step “in response to A” does not indicate that the step is executed immediately after “A” occurs, and one or more intermediate steps may be included.

[0058] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. As used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It will be further understood that the terms “comprising,” “including,” “having,” “having,” “including,” and / or “containing” as used herein specify the presence of the stated features, elements, and / or components, etc., but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof.

[0059] As used in this application, the term "circuit" may refer to one or more of the following: (a) Hardware circuit implementation only (such as pure analog implementation and / or digital circuit implementation); and (b) Combinations of hardware circuitry and software, such as (if applicable): (i) (multiple) analog and analog combinations / or digital hardware circuits with software / firmware (ii) Any part of a hardware processor having software (including (multiple) digital signal processors, software, and (multiple) memories), which work together to enable a device (such as a mobile phone or server) to perform various functions; and (c) Hardware circuitry and / or processors that require software (e.g., firmware) for operation, such as being a microprocessor or part of a microprocessor, but which may be absent when operation does not require software.

[0060] This definition of "circuit" applies to all uses of the term in this application (including any claims). As a further example, as used herein, the term "circuit" also encompasses only hardware circuitry or processors (or processors), or portions of hardware circuitry or processors and their accompanying software and / or firmware implementations. For example, where applicable to specific claim elements, the term "circuit" also encompasses baseband integrated circuits or processor integrated circuits for mobile devices, or similar integrated circuits in servers, cellular network devices, or other computing or network devices.

[0061] As used herein, the term "communication network" refers to a network that conforms to any suitable communication standard, such as New Radio (NR), Long Term Evolution (LTE), LTE-A Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High-Speed ​​Packet Access (HSPA), Narrowband Internet of Things (NB-IoT), etc. Furthermore, communication between user equipment and network equipment in a communication network can be performed according to any suitable generation of communication protocol, including but not limited to first-generation (1G), second-generation (2G), 2.5G, 2.75G, third-generation (3G), fourth-generation (4G), 4.5G, fifth-generation (5G), 5.5G, sixth-generation (6G) communication protocols, wireless local area network communication protocols (such as IEEE 802.11), and / or any other currently known or future-developed protocols. Furthermore, communication can utilize any suitable wireless communication technology, including 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 Access (OFDM), Discrete Fourier Transform Extended OFDM (DFT-s-OFDM), and / or any other currently known or future-developed technology. Embodiments can be applied to a variety of communication systems. Given the rapid development of communication, there will certainly be future types of communication technologies and systems that can be utilized to implement this disclosure. The scope should not be considered limited to the aforementioned systems.

[0062] As used herein, the term "network device" refers to a node in a communications network through which user equipment accesses and receives services. Depending on the terminology and technologies applied, network devices may include base stations (BS) or access points (APs), such as Node B (or NB), evolved Node B (eNode B or eNB), NR NB (also known as gNB), Remote Radio Unit (RRU), Radio Header (RH), Remote Radio Header End (RRH), repeater, Integrated Access and Backhaul (IAB) node, low-power node (such as femtoseconds, picoseconds), non-terrestrial network (NTN) or non-terrestrial network equipment (such as satellite network equipment, low Earth orbit (LEO) satellites and geostationary Earth orbit (GEO) satellites), spacecraft network equipment, etc. In some example embodiments, network devices may utilize a separate radio access network (RAN) architecture, where network devices include centralized units (CUs) and distributed units (DUs).

[0063] The term "user equipment" refers to any terminal device capable of wireless communication. By way of example and not limitation, a terminal device may also be referred to as a communication device, user equipment (UE), subscriber station (SS), portable subscriber station, mobile station (MS), or access terminal (AT). Terminal devices may include, but are not limited to, mobile phones, cellular phones, smartphones, Voice over IP (VoIP) phones, wireless local loop phones, tablets, wearable terminal devices, personal digital assistants (PDAs), portable computers, desktop computers, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback devices, in-vehicle wireless terminal devices, wireless endpoints, mobile stations, laptop embedded devices (LEEs), laptop-mounted devices (LMEs), USB dongles, smart devices, wireless customer premises equipment (CPEs), Internet of Things (IoT) devices, watches or other wearable devices, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in the context of industrial and / or automated processing chains), consumer electronic devices, devices operating on commercial and / or industrial wireless networks, etc. User equipment may also correspond to the mobile terminal (MT) portion of an IAB node (e.g., a relay node). In the following description, the terms "terminal equipment," "user equipment," "user equipment," and "UE" are used interchangeably.

[0064] Figure 1 An example communication environment 100 in which example embodiments may be implemented is illustrated. In the communication environment 100, a user equipment 105 (such as a UE) may be present. The user equipment 105 is currently located in a first cell 110 (also referred to as "serving cell 110") provided by a first network device 115 (also referred to as "serving network device 115", such as a serving gNB). When the user equipment 105 moves, there may be candidate target cells to which the user equipment 105 can switch. For example, a second cell 120 provided by a second network device 125 and a third cell 130 provided by a third network device 135 may be considered candidate target cells or target cells. Accordingly, the second network device 125 and the third network device 135 may be referred to as target network devices (such as target gNBs).

[0065] In some example embodiments, the transmission direction from the first network device 115, the second network device 125, or the third network device 135 to the user equipment 105 is referred to as the downlink (DL). The transmission direction from the user equipment 105 to the first network device 115, the second network device 125, or the third network device 135 is referred to as the uplink (UL). In the DL, the first network device 115, the second network device 125, or the third network device 135 is a transmitting (TX) device (or transmitter), and the user equipment 105 is a receiving (RX) device (or receiver). In the UL, the user equipment 105 is a TX device (or transmitter), and the first network device 115, the second network device 125, or the third network device 135 is an RX device (or receiver).

[0066] In the communication environment 100, user equipment 105 can operate in single-connectivity (SC) mode or dual-connectivity (DC) mode. In DC operation, user equipment 105 can be served by a primary cell group (MCG) and a secondary cell group (SCG). An MCG is a cell group associated with a primary node (MN) (such as the first network device 115), including a primary cell (PCell) and one or more optional secondary cells (SCells). An SCG is a cell group associated with a secondary node (SN) (such as the second network device 125), including a primary and secondary cell (PSCell) and one or more optional SCells.

[0067] Radio link failure (RLF) can be declared separately for the MCG and the SCG. If an RLF is detected for the MCG and fast MCG link recovery is configured and the SCG is not deactivated, user equipment 115 can trigger fast MCG link recovery. Otherwise, user equipment 115 can initiate an RRC connection re-establishment procedure. During PSCell addition or change, if an RLF is detected for the MCG, user equipment 115 can initiate an RRC connection re-establishment procedure.

[0068] During fast MCG link recovery, User Equipment 115 can deactivate or suspend MCG transmissions for all radio bearers (except Signaling Radio Bearer 0 (SRB0)) and the Backhaul (BH) RLC channel (if any). User Equipment 115 can report the failure to the MN via SCG using a separate SRB1 or SRB3 SCG branch, for example, by using an MCGFailureInformation message. SRB1 is the MN's signaling radio bearer, which is security-protected, and SRB3 is the SCG's signaling radio bearer. In other words, User Equipment 115 can use the SCG link as a secondary link to indicate to the network that the MCG link has failed and needs to be reconfigured.

[0069] In some example embodiments, the first network device 115, the second network device 125, or the third network device 135 may operate as a gNB utilizing a separate radio access network (RAN) architecture. Figure 2 An example overall NG-RAN architecture 200 is shown. NG-RAN 205 via NG may include one or more gNBs (e.g., gNB 210-1 and 210-2) that provide network access to UE 215 by providing control and user plane protocol termination. A gNB may include a gNB-CU and one or more gNB-DUs. For example, as... Figure 2 As shown, gNB 210-1 may include gNB-CU 220-1 and gNB-DU 225-1. gNB 210-2 may include gNB-CU 220-2 and two gNB-DUs 225-2 and 225-3. gNB-CU and gNB-DU can be connected via the F1 interface. One gNB-DU can be connected to one or more gNB-CUs.

[0070] The gNB-CU 220-1 or 220-2 can host the Radio Resource Control (RRC), Service Data Adaptation Protocol (SDAP), and Packet Data Convergence Protocol (PDCP) layers or entities of the gNB 210-1 or 210-2. The gNB-CU 220-1 or 220-2 can control the operation of the corresponding gNB-DU. The gNB-DU 225-1, 225-2, or 225-3 can host the Radio Link Control (RLC), Media Access Control (MAC), and Physical (PHY) layers or entities of the gNB 210-1 or 210-2. The operation of the gNB-DU 225-1, 225-2, or 225-3 can be partially controlled by the gNB-CU 220-1 or 220-2. A gNB-DU can support one or more cells. A cell can be supported by only one gNB-DU.

[0071] The gNB-CU may include a gNB-CU control plane (gNB-CU-CP), which hosts the control plane portions of the gNB-CU's RRC layer and PDCP layer. The gNB-CU may also include a gNB-CU user plane (gNB-CU-UP), which hosts the user plane portions of the gNB-CU's PDCP and SDAP layers. The gNB-CU-CP can connect to the gNB-CU-UP via an E1 interface. Additionally, the gNB-CU-CP can terminate the F1-C interface connected to the gNB-DU, and the gNB-CU-UP can terminate the F1-U interface connected to the gNB-DU. For discussion purposes, the gNB-CU may also be referred to as a CU, and the gNB-DU may also be referred to as a DU.

[0072] In Architecture 200, LTM cell change is supported for UE 215. For example, a cell change decision can be made at the MAC layer in the DU based on L1 / L2 measurements. LTM cell change can include intra-CU LTM cell change, where the source DU and the target DU may share or belong to the same CU. In the intra-CU LTM cell change scenario, the RRC or Data Radio Bearer (DRB) terminates at the same gNB-CU. LTM cell change can alternatively include inter-CU LTM cell change, where the source DU and the target DU belong to the source CU and the target CU, respectively. The term "intra-CU LTM" can also be referred to as "gNB intra-LTM" or "gNB CU intra-LTM," which refers to LTM occurring between different DUs in the same CU of a gNB. The term "gNB inter-LTM" can also be referred to as "gNB inter-LTM" or "gNB inter-CU LTM," which refers to LTM occurring between different CUs of a gNB. The term "cell change" can also be referred to as "cell handover" or "cell handover."

[0073] In some example embodiments, such as Figure 2 As shown, UE 215 initially connects to DU 225-1 of gNB 210-1, where DU 225-1 supports cell 230-1. DU 225-1 can establish an F1-C interface with the CU-CP of gNB 210-1 and an F1-U interface with the CU-UP of gNB 210. As mentioned above, CU 220-1 hosts the PDCP layer of gNB 210-1, while DU 225-1 hosts the RLC layer of gNB 210-1.

[0074] When UE 215 moves toward cell 230-2 supported by DU 225-2, an inter-CU LTM cell handover can be performed. After the inter-CU LTM cell handover, UE 215 can connect to DU 225-2 of gNB 210-2. DU 225-2 can establish an F1-C interface with the CU-CP of gNB 210-2 and an F1-U interface with the CU-UP of gNB 210-2. The PDCP entity can be re-established by CU 220-2, and the RLC entity can be re-established by DU 225-2.

[0075] During the aforementioned processes of inter-CU LTM cell handover or cell change, the security key may need to be updated after the cell change. Updating the security key may lead to PDCP re-establishment, as the new PDCP will use the new key to begin encrypting packets. PDCP re-establishment may disrupt PDCP and RLC continuity, requiring the re-establishment of PDCP and RLC entities. This can also increase UE reconfiguration time, as the UE must configure the new key. Furthermore, in inter-CU LTM, handover from RRC / DRB to the target gNB-CU may have the following disadvantages or complexities: a complete L2 reset is required, path switching / data forwarding is required, subsequent mobility processing is not direct, and significant changes to standard specifications are needed.

[0076] According to some example embodiments, a solution for DC-based SCG change is provided. The term "DC-based SCG change" will also / can be referred to as "Inter-CU LTM," "Inter-CU LTM cell handover," "Anchored Inter-CU LTM," "DC-based LTM," "MCG deactivation DC operation," "SCG-only LTM operation," or "DC-based SCG LTM operation only." In this solution, for inter-CU LTM cell handover, user equipment 105 can switch from SC operation to DC operation. For example, the target configuration for inter-CU LTM cell handover can be prepared as a DC configuration, where the serving cell is the PCell and the target cell is the PSCell.

[0077] In some example embodiments, the DC configuration for inter-CU LTM cell handover differs from the conventional DC configuration. For example, when applying a target PSCell configuration or a target SCG configuration, the following changes are applicable compared to the conventional DC configuration: User Equipment 105 may stop radio link monitoring and beam failure detection (BFD) of the MCG after the PSCell is successfully added to the SCG; User Equipment 105 may stop MCG measurement configuration and reporting; and User Equipment 105 may maintain the PDCP entity using the MN but add the RLC, MAC, and PHY entities of the SN. In some example embodiments, the PCell configuration or MCG configuration may be kept in a suspended state, meaning that the PCell configuration or MCG configuration is not actively used but is stored at User Equipment 105. In an alternative, when a subsequent inter-CU LTM cell handover is triggered toward the PCell, User Equipment 105 may activate the PCell configuration and suspend the SCG configuration, similar to the behavior of User Equipment 105 in a previous cell handover toward the PSCell.

[0078] As an example, the following will refer to Figure 3 Example procedure for LTM cell handover between CUs 300. Figure 3As shown, UE305 initially connects to DU1 310 in single-connectivity (SC) mode, where DU1 310 provides cell1 (cell 1) 315. DU1 310 can establish an F1-C interface with CU-CP1 320 and an F1-U interface with CU-UP1 325. RRC connections can be established between UE305 and CU-CP1 320, and DRB connections can be established between UE305 and CU-UP1 325. The PDCP layer terminates at CU-CP1 320 and CU-UP1 325, while the RLC layer terminates at DU1 310. After the inter-CU LTM cell handover is triggered, UE305 connects to DU1 310 (in other words, gNB1 in the PCell of the MCG) and DU2 330 in the DC node, where DU1 310 provides cell1 315 as the PCell of the MCG, and DU2 330 provides cell2 (cell 2) 335 as the PSCell of the SCG. As shown, the PDCP layer still terminates at CU-CP1 320 and CU-UP1 325, but the RLC layer is changed to terminate at DU2 330.

[0079] In this way, security and PDCP can be anchored to the MN (e.g., the gNB hosting CU-CP1 320 and CU-UP1 325), and therefore security and PDCP resets are not required, thereby reducing cell handover latency and improving cell handover efficiency. Subsequently, radio links (e.g., the radio link between UE 305 and DU2 330) can be flexibly modified via PSCell changes, which can be enabled via inter-SN LTM.

[0080] The following will refer to Figures 4 to 11 Some example implementations are described in detail.

[0081] Now for reference Figure 4 This illustrates an example signaling flow 400 of DC-based SCG modification according to some example embodiments. Signaling flow 400 involves user equipment 105 and a first network device 115, which can initially operate as a source MN or serving MN of user equipment 105.

[0082] like Figure 4 As shown, the first network device 115 sends (420) an indication to the user equipment 105 operating in SC mode to initiate a DC-based SCG change. Correspondingly, the user equipment 105 receives (425) an indication to initiate a DC-based SCG change from the first network device 115. This indication can be sent to the user equipment 105 via at least one of RRC signaling and MAC signaling. Some example embodiments in this regard will be referred to. Figure 8 and 11 Describe in detail in the following paragraphs.

[0083] Based on this instruction, user equipment 105 adds either the first cell 110 or the second cell 120 to the (430) SCG. Therefore, user equipment 105 can, for example, use a method similar to... Figure 3 The illustrated process switches from SC operation to DC operation. On the other hand, the first network device 115 causes the user equipment 105 to enter (423) DC mode from SC mode (or converts the UE's SC configuration to DC configuration). In a scenario of cell handover from a first cell 110 provided by the first network device 115 to a second cell 120 provided by the second network device 125, the MCG for the user equipment 105 includes the first cell 110 provided by the first network device (e.g., as a PCell), and the SCG for the user equipment 105 includes the second cell 120 provided by the second network device 125 (e.g., as a PSCell), which can operate as the target SN of the user equipment 105. In a regular mobility process that does not use a DC-based SCG procedure, the target SN can be considered as the target MN. The user equipment 105 deactivates (435) the MCG including the first cell 110. For example, the UE can add the first cell to the SCG and then perform a cell handover from the first cell to the second cell. As another example, a UE can initiate a cell handover from a first cell to a second cell during a cell handover and add the second cell to the SCG.

[0084] Deactivation of the MCG may include at least one of the following: resetting at least one of the radio link control entity, media access control entity, and physical layer entity for the primary cell group; stopping at least one of radio link monitoring and associated timers and radio link failure detection for the primary cell group; stopping beam failure detection for the primary cell group; stopping at least one or all measurements for the primary cell group; and converting the signaling radio bearer for the primary cell group to a separate bearer for both the primary and secondary cell groups, wherein the portion of the separate bearer corresponding to the primary cell group is disabled.

[0085] It may exceed the ability of UE 105 to maintain a combined MCG and SCG configuration. However, UE 105 is capable of, or is assumed to be capable of, maintaining either an MCG or SCG configuration. UE capabilities indicating support for new features can be new capabilities. UE capabilities indicating support for new features can be a combination of existing capabilities. UE capabilities indicating support for new features can be a subset of existing capabilities. According to some example embodiments, a DC framework is used, but only one link is active for UE 105 at a time. Thus, even if UE 105 has only a single transceiver for a single link or is only capable of having one active link, UE 105 can maintain the bearer terminated by the MCG. Therefore, UE 105 does not need to change the PDCP termination point. In this case, UE 105 can maintain the PDCP entity for the MCG. Therefore, security key changes, PDCP re-establishment, and path handover are not required, thereby improving cell handover efficiency.

[0086] For example, an instruction to initiate a DC-based SCG change can be referred to as a DC-based SCG change configuration. This configuration may include at least one of the following: instructions to add a first cell to the SCG; instructions to add a second cell to the SCG; instructions to deactivate the MCG including the first cell; instructions to trigger a re-establishment process based on the detection of an RLF for the SCG; and instructions to treat the SCG RLF as an MCG RLF.

[0087] In some example embodiments, user equipment 105 may trigger a re-establishment process based on the detection of an RLF for the SCG, based on an indication used to initiate a DC-based SCG change. As described above, RLFs are declared for the MCG and SCG respectively. When a DC-based SCG change is configured, user equipment 105 may treat an RLF for the SCG (also known as an SCG RLF) as an RLF for the MCG (also known as an MCG RLF), and then trigger a re-establishment process based on the detection of the SCG RLF. In this way, even if the MCG is suspended and (only) the SCG is active, an SCG RLF (such as an MCG RLF) can trigger a re-establishment process. If a DC-based SCG change is not configured, user equipment 105 may initiate an SCG failure information procedure to report an SCG RLF, for example, as specified in the standard.

[0088] In some example embodiments, based on an instruction to initiate a DC-based SCG change, User Equipment 105 may reset at least one of the RLC entity, MAC entity, and PHY layer entity for MCG. Alternatively or additionally, User Equipment 105 may stop at least one of radio link monitoring and RLF detection for MCG. Alternatively or additionally, User Equipment 105 may stop beam failure detection for MCG. Stopping monitoring and / or detection can prevent triggering failure recovery and thus disrupting the operation of User Equipment 105, thereby improving communication efficiency. Alternatively or additionally, User Equipment 105 may stop measurements for MCG, for example, thereby saving processing resources and improving resource utilization at User Equipment 105.

[0089] Alternatively or additionally, User Equipment 105 may convert an SRB (e.g., SRB1) used for MCG to a separate bearer for both MCG and SCG, wherein the MCG-related portion of the separate bearer is disabled. In some example embodiments, User Equipment 105 may need to be configured with a separate bearer for SRB1. In some example embodiments, User Equipment 105 may need to convert all bearers to MN-terminated SCG bearers. In this case, user plane packets may be anchored at the first network device 115 (which provides the MCG PDCP entity), and the packets may be routed to the target cell as either a separate bearer service or an SCG bearer service.

[0090] In some example embodiments, such as Figure 4 As shown, before user equipment 105 receives (420) an instruction to initiate a DC-based SCG change, user equipment 105 may perform at least one measurement related to the second cell 120 and report (405) the at least one measurement to the first network device 115. Accordingly, the first network device 115 may receive (410) at least one measurement related to the second cell 120 from user equipment 105. Then, the first network device 115 may determine (415) to initiate a DC-based SCG change for user equipment 105 based on the at least one measurement.

[0091] In some example embodiments, determination (415) may be based on the Quality of Service (QoS) requirements of user equipment 105. For example, user equipment 105 with strict QoS requirements may require reduced downtime. For such user equipment, the network may determine to initiate a DC-based SCG change to reduce downtime due to cell handover.

[0092] In some example embodiments, such as Figure 4As shown, the first network device 115 can send (440) an inter-SN handover configuration for DC-based SCG change to the user equipment 105. Correspondingly, the user equipment 105 can receive (445) an inter-SN handover configuration for DC-based SCG change from the first network device 115. Here, inter-SN handover can also be referred to as inter-SN LTM. In some example embodiments, the inter-SN handover configuration can be sent to the user equipment 105 via RRC signaling. Some example embodiments in this regard will be referred to... Figure 8 and 11 Describe in detail in the following paragraphs.

[0093] User equipment 105 can then initiate (450) a cell handover from first cell 110 to second cell 120 based on the inter-SN handover configuration. In some example embodiments, the inter-SN handover configuration may include at least one SCG configuration of at least one candidate cell. The at least one candidate cell may include second cell 120. Therefore, user equipment 105 can hand over to second cell 120 based on the SCG configuration of at least one candidate cell.

[0094] In some example embodiments, during subsequent cell handover, user equipment 105 may replace the SCG configuration of the second cell 120 with a different SCG configuration of a different third cell provided by another network device. For example, when user equipment 105 moves further toward the third cell 130 provided by the third network device 135, user equipment 105 may replace the SCG configuration of the second cell 120 with the SCG configuration of the third cell 130.

[0095] In some example embodiments, all candidate configurations can be prepared as a DC configuration, where the target cell is the PSCell. The SCG configuration can be prepared as a full configuration or a reference incremental configuration. The inter-SN handover configuration can include all candidate configurations. During the initial cell handover, the MCG is suspended as described above. For subsequent cell handovers, the user equipment 105 can replace the SCG configuration with the target SCG configuration, which can be a full configuration or a reference incremental configuration.

[0096] In some example embodiments, if the initial PCell / MCG or MN configuration (e.g., as the first cell 110 of the PCell) is released, for example via RRC reconfiguration (e.g., release of MN-PDCP), the network can configure a role switch to convert the current serving cell of the SN (e.g., the second cell 120 operating as a PSCell) to the PCell. This may result in a relocation of the PDCP anchor. For example, the PDCP entity may be relocated or re-anchored at the second network device 125. As part of this reconfiguration, other candidate configurations may also be prepared as the DC configuration using the current serving cell as the PCell.

[0097] To support DC-based SCG changes for user equipment 105, interaction may be required between a first network device 115 acting as the source MN and a second network device 125 acting as the target SN. The following will refer to... Figure 5 Some example implementations of this are described.

[0098] Figure 5 An example signaling flow 500 of a DC-based SCG change method according to some example embodiments is shown. The signaling flow 700 relates to a first network device 115 that can operate as a source MN of user equipment 105; and a second network device 125 that can operate as a target SN of user equipment 105.

[0099] like Figure 5 As shown, the first network device 115 sends (505) a request for SN addition to the second network device 125, and the request indicates that the SN addition is used for the DC-based SCG change of the user equipment 105. Accordingly, the second network device 125 receives (510) a request for SN addition from the first network device 115.

[0100] Based on the request, the second network device 125 determines (515) that the MCG will be deactivated by the user equipment 105 for DC-based SCG changes. Then, the second network device 125 sends (520) a response to the request to the first network device 115. Accordingly, the first network device 115 receives (525) a response to the request from the second network device 125. In some example embodiments, the request (505) sent from the first network device 110 to the second network device 125 may identify a second cell 120 provided by the second network device 125. In these example embodiments, the response to the request may include the SCG configuration of the second cell 120 based on the determination (515) of the second network device 125. For example, knowing that the MCG of the user equipment 105 will be suspended, the second network device 125 may provide a PSCell configuration.

[0101] In some example embodiments, the request may indicate that the bearer terminated by the MN will be used for user equipment 105, and the SCG bearer will be allocated by the second network device 125 for the bearer terminated by the MN. Accordingly, the SCG configuration included in the response to the request may exclude SRBs (e.g., SRB3) used for the SCG including the second cell 120.

[0102] After receiving a response (525) from the second network device 125, the first network device 115 sends an inter-SN handover configuration (440) to the user equipment 105. The inter-SN handover configuration may include the SCG configuration of the second cell 120, which may be included in the response from the second network device 125.

[0103] In some example embodiments, the SCG configuration may include an SCG RLF configuration that will be used to trigger the re-establishment process. For example, as described above, if user equipment 105 detects an SCG RLF, it may trigger a re-establishment process based on the SCG RLF configuration. User equipment 105 may treat the SCG RLF as an MCG RLF.

[0104] DC-based SCG changes can be initiated in various UE mobility scenarios. In the example scenario, when UE 105 is stationary in a serving cell such as the first cell 110, a DC-based SCG change can be triggered. The following will refer to... Figures 6 to 8 Some example implementations of this scenario are described.

[0105] Figure 6 An example scenario 600 for triggering a DC-based SCG change is illustrated according to some example embodiments. In scenario 600, a DC-based SCG change occurs when user equipment 105 is stationary at the first cell 110, which is the serving cell.

[0106] like Figure 6 As shown, User Equipment 105 is located in the first cell 110, represented by PCell0. Initially, User Equipment 105 can be served by a first network device 115 that can operate as an MN. In the case where the first network device 115 operates in a RAN-separated architecture including CUs and DUs, User Equipment 105 can be served by the MN CU and MN DU in PCell0. When the network initiates a DC-based SCG change, PCell0 can be added to the SCG as a PSCell represented by PSCell0. Accordingly, the first network device 115 can be added as an SN. Then, User Equipment 105 can be served by the MN CU in PCell0 and the SNDU in PSCell0. Furthermore, other network devices (e.g., a second network device 125 and a third network device 135) can be prepared as SNs. When User Equipment 105 moves toward the second cell 120 (represented by PSCell1), an inter-SN LTM can be triggered. In this case, User Equipment 105 can perform a PSCell change from PSCell0 to PSCell1.

[0107] Figure 7An example signaling flow 700 based on DC-based SCG changes is shown in scenario 600 according to some example embodiments. For example... Figure 7 As shown, user equipment 105 operating in single-connection (SC) mode sends (705) a measurement report identifying a second cell 120 provided by a second network device 125 to a first network device 115. Accordingly, the first network device 115 receives (710) the measurement report from user equipment 105. In some example embodiments, the measurement report may include L1, L2, or L3 measurement reports.

[0108] Based on the measurement report, the first network device 115 determines (715) to initiate a DC-based SCG change for the user equipment 105. Then, the first network device 115 sends (720) an instruction to the user equipment 105 to initiate the DC-based SCG change. Accordingly, the user equipment 105 receives (725) the instruction from the first network device 115. Based on the instruction, the user equipment 105 adds (730) the first cell 110 to the SCG and deactivates (735) the MCG including the first cell 110.

[0109] The first network device 115 also sends (740) an inter-SN handover configuration to the user equipment 105. Accordingly, the user equipment 105 receives (745) an inter-SN handover configuration from the first network device 115. Based on this configuration, the user equipment 105 hands over (750) from the first cell 110 to the second cell 120. In some example embodiments, the user equipment 105 may maintain a PDCP entity for the MCG.

[0110] In some example embodiments, an indication of a DC-based SCG change may be carried in RRC signaling, such as an RRC reconfiguration message. After receiving the (725) RRC reconfiguration message, user equipment 105 may perform a random access procedure with the first network device 115 to convert the first cell 110 to a PSCell. Then, user equipment 105 may send an RRC reconfiguration complete message to the first network device 115.

[0111] In some other example embodiments, PSCell addition without random access can be allowed. In these example embodiments, user equipment 105 can add the first cell 110 to the PSCell without a random access procedure. In this case, after receiving an RRC reconfiguration message, user equipment 105 can send an RRC reconfiguration complete message to the first network device 115 without performing a random access procedure with the first network device 115 to convert the first cell 110 into a PSCell.

[0112] In some example embodiments, during a subsequent cell handover, user equipment 105 may replace the SCG configuration of the second cell 120 with a different SCG configuration of another cell provided by another network device. This other cell may be a third cell 130 provided by a third network device 135. Alternatively or additionally, the other cell may be a first cell 110. For example, when user equipment 105 moves back to the first cell 110, user equipment 105 may replace the SCG configuration of the second cell 120 with the SCG configuration of the first cell 110 prepared during the initial cell handover.

[0113] It should be understood that the above reference Figure 4 All operations and / or characteristics described in relation to user equipment 105 and first network device 115 also apply to signaling flow 700 and have similar effects. For the sake of simplicity, they will not be described in detail hereafter.

[0114] To support DC-based SCG changes for user equipment 105 in scenario 600, some interaction may be required between the first network device 115 (source MN) and the second network device 125 (target SN). (See above for reference.) Figure 5 All operations and / or features described in relation to the first network device 115 and the second network device 125 are equally applicable to scenario 600 and have similar effects. For the sake of simplicity, they will not be described in detail hereafter.

[0115] The following will refer to Figure 8 Describe the example process in scenario 600. In such a case... Figure 8 In the illustrated process 800, User Equipment 105 can operate in the SC of a first network device 115 as an MN (801) and has two MN-terminated MCG bearers, such as DRB-1 and DRB-2. User Equipment 105 can send (803) L3 measurement reports to identify neighboring cells from other network devices (such as gNBs). For example, User Equipment 105 can send a measurement report to the first network device 115 identifying a second cell 120 provided by a second network device 125.

[0116] The first network device 115 can determine (805) whether to initiate an anchored inter-CU LTM for user equipment 250 based on a measurement report. In other words, the first network device 115 can decide that it must use an anchored inter-CU LTM procedure for user equipment 105. This decision can be made by the first network device 115 based on the QoS requirements of user equipment 105. For example, to support the QoS of user equipment 105, the first network device 115 can decide to initiate an anchored inter-CU LTM procedure to avoid PDCP reset and reduce downtime.

[0117] In some example embodiments, before configuring the target cell configuration, the first network device 115 can convert the SC configuration of the user equipment 105 to the DC configuration by adding a PCell (e.g., the first cell 110) as a PSCell and disabling the MCG configuration. Later in the second phase, the first network device 115 can prepare candidate network devices for inter-SN LTM.

[0118] The first network device 115, as the source network device, can send (807) an indication to the user equipment 105 to initiate an anchored inter-CU LTM. For example, this indication can be associated with an RRC reconfiguration message (also known as an "RRC reconfiguration" message). Reconfiguration ()) together. Accordingly, user equipment 105 may receive (809) from first network device 115 to indicate the following RRC reconfiguration: initiating anchored CU inter-LTM, adding PCell as PSCell of SCG, removing MCG configuration, and / or RLF and BFD for MCG.

[0119] User equipment 105 may apply (811) the anchored inter-CU LTM configuration indicated by the RRCReconfiguration message. For example, user equipment 105 may reset the RLC, MAC, and PHY entities for MCG. User equipment 105 may stop RLM for MCG. For example, any measurements related to RLM may be stopped. User equipment 105 may stop BFD for MCG. For example, any measurements related to BFD may be stopped. User equipment 105 may add the current PCell (serving cell, e.g., first cell 110) as PSCell. If SCG RLF is detected, user equipment 105 may trigger re-establishment. User equipment 105 may stop MCG measurements. User equipment 105 may need to be configured with a separate bearer with SRB1 as an SRB for MCG. User equipment 105 may need to convert all bearers to SCG bearers terminated by MN. User equipment 105 may convert SRB1 to a separate bearer (also known as SRB1 separate bearer or separate SRB1) and disable a portion of the SRB1 separate bearer for MCG.

[0120] User equipment 105 can perform (813) a random access procedure with the first network device 115 to convert the first cell 110 into a PSCell. For example, user equipment 105 can initiate random access to a PCell to initiate the conversion from PCell to PSCell. This can be done without the addition of a PSCell that does not require random access. Alternatively, if the addition of a PSCell that does not require random access is allowed, random access can be skipped, and user equipment 105 can add a PCell as a PSCell without a random access procedure.

[0121] If a random access procedure is used, the first network device 115 can receive (815) a random access request from the user equipment 105. The first network device 115 can send (817) a random access response (RAR) to the user equipment 105. Accordingly, the user equipment 105 can receive (819) a RAR from the first network device 115 via a PSCell. The user equipment 105 can then send (821) an RRC reconfiguration complete message (also known as RRCReconfiguration complete) to the first network device 115, for example, on the SCG bearer of the separate SRB 1. This completes the conversion of the user equipment 105's single-connectivity configuration to an anchored inter-CU LTM configuration. Thus, security and PDCP can be anchored to the first network device 115 operating as an MN. The radio link can be flexibly changed via a PSCell change enabled on a DC-based SCG change.

[0122] After, simultaneously with, or before the PCell to PSCell conversion, the first network device 115, acting as the source MN (source SN), may send (825) a request for SN addition (also called an SN addition request) to the second network device 125, in order to initiate an SN addition process for the second network device 125, which is operating as the target SN. Accordingly, the second network device 120 may receive (827) the SN addition request. During the SN addition process, the first network device 115 may instruct the SN addition to be used for the inter-CU LTM process of anchoring. In addition, the first network device 115, acting as the source MN, may instruct that the bearer of the MN termination will be used and request the second network device 125 to allocate an SCG bearer for the bearer of the MN termination.

[0123] The second network device 125 can determine (829) that the user equipment 105 will disable the MCG during the anchored inter-CU LTM operation. Knowing that the MCG will be suspended, the second network device 125 can use the "anchored inter-CU LTM" procedure to provide PSCell configuration. In the example, as described above, the second network device 125 can add an SCG RLF configuration to trigger the re-establishment procedure. Optionally, the second network device 125 can not configure SRB3 (as an SRB for the SCG) to avoid PDCP reconfiguration during PSCell change. The second network device 125 can send (831) an SN add request acknowledgment (ACK), which is a response to the SN add request.

[0124] The first network device 115 may send (835) inter-SN LTM configuration to the user equipment 105, for example, via RRC signaling (such as an RRC reconfiguration message). For example, the first network device 115 may use RRCReconfiguration to configure the user equipment 105 to add inter-SN LTM configuration. Accordingly, the user equipment 105 may receive (837) RRCReconfiguration including the inter-SN LTM configuration. Then, the user equipment 105 may send (839) RRCReconfiguration complete to the first network device 115, for example, on the SCG bearer of the separate SRB1, to acknowledge receipt of the inter-SN LTM configuration. Accordingly, the first network device 115 may receive (841) RRCReconfiguration complete.

[0125] When a PDCP entity terminates in the first network device 115, user equipment 105 can perform (843) inter-SN LTM without requiring a security reset. For example, user equipment 105 can use the inter-SN LTM procedure to move between cells and avoid PDCP reset and security updates because there is no SN-terminated bearer and the MN is maintained as anchored, and the MN-terminated bearer continues to use the same key.

[0126] In addition to scenario 600, when user equipment 105 is at the boundary of the current serving cell (e.g., first cell 110) and is about to perform LTM to the target cell (e.g., second cell 120), a DC-based SCG change can be triggered in another scenario. (See below for reference.) Figures 9 to 11 Some example implementations of this scenario are described.

[0127] Figure 9 An example scenario 900 for triggering a DC-based SCG change according to some other example embodiments is shown. In scenario 900, the DC-based SCG change occurs during LTM execution, for example, when user equipment 105 is at or near the boundary of first cell 110 and is about to execute LTM to second cell 120.

[0128] like Figure 9As shown, User Equipment 105 is located in a first cell 110 (which is the serving cell), represented by PCell0, and moves to a second cell 120, which is the target cell. Initially, User Equipment 105 can be served by a first network device 115, which can operate as an MN. If the first network device 115 operates in a RAN-separated architecture including CUs and DUs, User Equipment 105 can be served by the MN CU in PCell0. When User Equipment 105 moves toward the second cell 120 and reaches the boundary of the first cell 110, the network can initiate a DC-based SCG change. In this case, other network devices (e.g., the second network device 125 and the third network device 135) can be prepared as SNs. If User Equipment 105 moves within the coverage of one of the SNs, User Equipment 105 can perform SN addition and disable all MCG bearers without interruption. For example, when User Equipment 105 moves to the second cell 120, User Equipment 105 can add the second cell 120 as a PSCell represented by PSCell 1, while deactivating all MCG bearers.

[0129] Figure 10 An example signaling flow 1000 based on DC-based SCG modification is shown in scenario 900 according to some example embodiments. For example... Figure 10 As shown, user equipment 105 operating in SC mode sends (1005) a measurement report identifying a second cell 120 provided by a second network device 125 to a first network device 115. Accordingly, the first network device 115 receives (1010) the measurement report from user equipment 105. In some example embodiments, the measurement report may include L1, L2, or L3 measurement reports.

[0130] Based on the measurement report, the first network device 115 determines (1015) to initiate a DC-based SCG change for the user equipment 105. The first network device 115 sends (1020) an inter-SN handover configuration to the user equipment 105. Accordingly, the user equipment 105 receives (1025) an inter-SN handover configuration from the first network device 115. For example, the inter-SN handover configuration may be carried in RRC and / or MAC signaling.

[0131] User equipment 105 performs (1030) at least one measurement related to the second cell 120, and then sends (1035) the at least one measurement to the first network device 115. Accordingly, the first network device 115 receives (1040) the at least one measurement from user equipment 105. Then, the first network device 115 sends (1045) an indication to user equipment 105 to initiate a DC-based SCG change. Accordingly, user equipment 105 receives (1050) the indication from the first network device 115. For example, the indication to initiate a DC-based SCG change may be carried in RRC and / or MAC signaling.

[0132] In some example embodiments, the inter-SN handover configuration can also be used to configure DC-based SCG changes. For example, the inter-SN handover configuration can be sent by the first network device 110 in RRC signaling (1020) to indicate that a DC-based SCG change is configured for user equipment 105. The first network device 115 can then activate the DC-based SCG change using a MAC control element (CE) that includes an indication for initiating the DC-based SCG change.

[0133] Upon receiving (1050) the instruction, User Equipment 105 initiates (1055) a cell handover from first cell 110 to second cell 120 based on the inter-SN handover configuration received (1025) from first network device 115. User Equipment 105 adds (1060) second cell 110 to the SCG and deactivates (1065) the MCG including first cell 110. In some example embodiments, User Equipment 105 may maintain a PDCP entity for the MCG.

[0134] In some example embodiments, user equipment 105 may perform a random access procedure with second network device 125 to convert second cell 120 into a PSCell. User equipment 105 may then send an RRC reconfiguration complete message to second network device 115. In some other example embodiments, PSCell addition without random access may be allowed. In these example embodiments, user equipment 105 may add second cell 120 as a PSCell to the SCG without a random access procedure. In this case, user equipment 105 may directly send an RRC reconfiguration complete message to second network device 125 without a random access procedure with second network device 125 to add second cell 120 as a PSCell.

[0135] It should be understood that the above reference Figure 4 and Figure 7All operations and / or characteristics described in relation to user equipment 105 and first network device 115 also apply to signaling flow 1000 and have similar effects. For the sake of simplicity, they will not be described in detail hereafter.

[0136] To support DC-based SCG changes for user equipment 105 in scenario 900, some interaction may be required between the first network device 115 (source MN) and the second network device 125 (target SN). (See above for reference.) Figure 5 All operations and / or features described in relation to the first network device 115 and the second network device 125 are equally applicable to scenario 900 and have similar effects. For the sake of simplicity, they will not be described in detail hereafter.

[0137] The following will refer to Figure 11 Describe the example process in scenario 900. In such a case... Figure 11 In the illustrated process 1100, user equipment 105 can operate in the SC with the first network device 115 as the MN (1101) and has two MN-terminated MCG bearers, such as DRB-1 and DRB-2. User equipment 105 can send (1103) L3 measurement reports to identify neighboring cells from other network devices (such as gNBs).

[0138] Due to the QoS requirements of user equipment 105, the first network device 115 can determine (1105) to initiate an anchored inter-CU LTM for user equipment 250. For example, to support the QoS of user equipment 105, the first network device 115 can decide to initiate an anchored inter-CU LTM procedure to avoid PDCP reset and reduce downtime. Unlike procedure 800, there is no change in the role of the source cell (e.g., first cell 110) in procedure 1100. The first network device 115 can prepare candidate network devices for inter-SN LTM.

[0139] In process 1100, since user equipment 105 is about to lose coverage of the serving cell (e.g., first cell 110), the first network device 115 can first perform a non-disruptive SN addition process. Figure 11As shown, a first network device 115, which can operate as a source MN, can send (1107) an SN add request to a second network device 125 to initiate an SN add process to the second network device 125, which can operate as a target MN. Correspondingly, the second network device 125 can receive (1109) an SN add request from the first network device 115. During the SN add process, the first network device 115 can instruct the SN add for the inter-CU LTM process used for anchoring. Furthermore, the first network device 115, as the source MN, can instruct that a bearer terminating the MN will be used and request the second network device 125 to allocate an SCG bearer for the bearer terminating the MN.

[0140] The second network device 125 can determine (1111) that the user equipment 105 will disable the MCG during the anchored CU inter-LTM operation. The subsequent operations (1113, 1115) of the first network device 115 and the second network device 125 in process 1100 are similar to those in process 800 and will not be described again here.

[0141] Then, the first network device 115 and the user equipment 105 can transmit (1117, 1119) an RRC reconfiguration message including the inter-SN handover configuration, and then transmit (1121, 1123) an RRC reconfiguration completion message, just as the first network device 115 and the user equipment 105 perform the actions (835, 837, 839, 841) in process 800.

[0142] Subsequently, as User Equipment 105 moves (1125), it gradually loses coverage of the source cell (e.g., first cell 110). User Equipment 105 can then begin measuring candidate cells. The User Equipment can begin measurements according to the inter-SN handover configuration. In this example, User Equipment 105 moves under the coverage of Second Network Device 125. User Equipment 105 can perform (1127) candidate cell measurements under Second Network Device 125 and send (1129) an L1 measurement report under MCG to First Network Device 115 to report the candidate cell measurements (e.g., second cell 120) under Second Network Device 125. Accordingly, First Network Device 115 can receive (1131) the measurement report from User Equipment 105.

[0143] Due to the QoS requirements of user equipment 105, first network device 115 can determine (1133) to initiate anchored inter-CU LTM for user equipment 105 based on measurement reports. Then, first network device 115 can send (1135) MAC CE to user equipment 105 to trigger the anchored inter-CU LTM procedure. MAC CE can instruct the triggering of SCG addition and deactivation MCG.

[0144] After user equipment 105 receives (1137) MAC CE, user equipment 105 may apply (1139) the anchored CU-to-CU LTM configuration indicated by MAC CE. The operation of user equipment 105 is similar to that in procedure 800 / 811, and its details will not be repeated.

[0145] Then, user equipment 105 can initiate (1141) random access with the second network device 125 to initiate a transition from the second cell 120 to the PSCell. Accordingly, the second network device 125 can receive (1143) a random access request from user equipment 105. If no random access-free PSCell addition is available, the access procedure is performed. Alternatively, if random access-free PSCell addition is permitted, random access can be skipped.

[0146] The second network device 125 can send a (1145) RAR to the user equipment 105. Correspondingly, the user equipment 105 can receive a (1147) RAR from the second network device 125 via PSCell. Then, the user equipment 105 can send an (1149) RRC reconfiguration complete message to the second network device 125 over the SCG bearer of the separate SRB 1. This completes the transition of the connection from the user equipment 105 to the anchored CU inter-LTM configuration.

[0147] In this way, security and PDCP can be anchored to the MN (e.g., the first network device 115), and the radio link can be flexibly changed via PSCell change, which can be enabled via inter-SN LTM. Subsequently, user equipment 105 can use the inter-SN LTM procedure to move between cells and avoid PDCP reset and security updates because there is no SN-terminated bearer and the MN is kept the same as the anchored one, and the MN-terminated bearer continues to use the same key.

[0148] Figure 12 A flowchart of an example method 1200 implemented at a user equipment according to some example embodiments is shown. For the purposes of discussion, method 1200 will be described from the perspective of user equipment 105.

[0149] At box 1210, user equipment 105 receives from a first network device an instruction to initiate a dual-connectivity-based secondary cell group change.

[0150] At box 1220, user equipment 105 adds a first cell or a second cell to a secondary cell group based on an instruction. The first cell is provided by a first network device and serves the user equipment, and the second cell is provided by a second network device.

[0151] At frame 1230, user equipment 105 deactivates the primary cell group including the first cell.

[0152] In some example embodiments, user equipment 105 may maintain packet data aggregation protocol entities for the primary cell group.

[0153] In some example embodiments, user equipment 105 may trigger a re-establishment process based on the detection of a radio link failure for the secondary cell group.

[0154] In some example embodiments, user equipment 105 may perform at least one of the following based on the instruction: resetting at least one of the radio link control entity, media access control entity, and physical layer entity for the primary cell group; stopping at least one of radio link monitoring and radio link failure detection for the primary cell group; stopping beam failure detection for the primary cell group; stopping measurements for the primary cell group; treating radio link failures for the secondary cell group as radio link failures for the primary cell group; and converting the signaling radio bearer for the primary cell group to a separate bearer for both the primary and secondary cell groups, wherein the portion of the separate bearer corresponding to the primary cell group is disabled.

[0155] In some example embodiments, user equipment 105 may receive a secondary node handover configuration for secondary cell group change based on dual connectivity from a first network device; and initiate a cell handover from the first cell to the second cell based on the secondary node handover configuration.

[0156] In some example embodiments, the handover configuration between secondary nodes may include at least one secondary cell group configuration of at least one candidate cell, wherein the at least one candidate cell includes a second cell.

[0157] In some example embodiments, the handover configuration between secondary nodes can be sent to the user equipment via radio resource control signaling.

[0158] In some example embodiments, user equipment 105 may perform at least one measurement related to a second cell; and report at least one measurement to a first network device, wherein the indication is received from the first network device after the at least one measurement is reported.

[0159] In some example embodiments, the indication may be received via at least one of radio resource control signaling and media access control signaling.

[0160] In some example embodiments, user equipment 105 may replace the secondary cell group configuration of the second cell with a different secondary cell group configuration of a third cell provided by another network device.

[0161] Figure 13A flowchart of an example method 1300 implemented at a first network device according to some example embodiments is shown. For the purposes of discussion, method 1300 will be described from the perspective of the first network device 115.

[0162] At box 1310, the first network device 115 receives at least one measurement related to the second cell provided by the second network device from a user equipment operating in single-connection mode.

[0163] At frame 1320, the first network device 115 determines, based on at least one measurement, to initiate a dual-connectivity secondary cell group change for the user equipment.

[0164] At frame 1330, the first network device 115 sends an instruction to the user equipment to initiate a dual-connectivity-based secondary cell group change.

[0165] At box 1340, the first network device 115 causes the user equipment to switch from single-connection mode to dual-connection mode based on this determination.

[0166] In some example implementations, the determination can be based on the quality of service requirements of the user equipment.

[0167] In some example embodiments, the first network device 115 may send a secondary node handover configuration to the user equipment for secondary cell group changes based on dual connectivity.

[0168] In some example embodiments, the handover configuration between secondary nodes may include at least one secondary cell group configuration of at least one candidate cell, wherein the at least one candidate cell includes a second cell.

[0169] In some example embodiments, the handover configuration between secondary nodes can be sent to the user equipment via radio resource control signaling.

[0170] In some example embodiments, the first network device 115 may send a request to the second network device for the addition of a secondary node, the request indicating that the addition of the secondary node is used for a dual-connectivity-based secondary cell group change; and receive a response from the second network device to the request, wherein the handover configuration between secondary nodes is sent to the user equipment after the response is received.

[0171] In some example embodiments, the response may include the secondary cell group configuration of the second cell.

[0172] In some example embodiments, the request may also indicate that the bearer terminated by the primary node will be used for the user equipment, and that the secondary cell group bearer will be allocated by a second network device for the bearer terminated by the primary node.

[0173] In some example embodiments, the instruction may be sent to the user equipment via at least one of radio resource control signaling and media access control signaling.

[0174] Figure 14 A flowchart of an example method 1400 implemented at a second network device according to some example embodiments is shown. For the purposes of discussion, method 1400 will be described from the perspective of the second network device 125.

[0175] At box 1410, the second network device 125 receives a request from the first network device for adding a secondary node, the request instructing the secondary node to add a dual-connectivity-based secondary cell group change used by the user equipment.

[0176] At box 1420, the second network device 125 determines, based on the request, that the primary cell group will be deactivated by the user equipment for use in changing the secondary cell group based on dual connectivity.

[0177] In some example embodiments, the request may also indicate that the bearer terminated by the primary node will be used for the user equipment, and that the secondary cell group bearer will be allocated by a second network device for the bearer terminated by the primary node.

[0178] In some example embodiments, the request may identify a second cell provided by a second network device, and in some example embodiments, the second network device 125 may send the secondary cell group configuration of the second cell to the first network device based on the determination.

[0179] In some example embodiments, the secondary cell group configuration may include a secondary cell group radio link failure configuration to be used to trigger the re-establishment process.

[0180] In some example embodiments, the secondary cell group configuration can exclude signaling radio bearers used for secondary cell groups that include a second cell.

[0181] In some example embodiments, the first means capable of performing method 1200 may include components for performing the corresponding operations of method 1200 and / or any example embodiments of one or more of the example embodiments described herein. The components may be implemented in any suitable form. For example, the components may be implemented in a circuit or software module. The first means may be implemented as or included in user equipment 105.

[0182] In some example embodiments, the second means capable of performing method 1300 may include components for performing the corresponding operations of method 1300 and / or any example embodiment of one or more of the example embodiments described herein. The components may be implemented in any suitable form. For example, the components may be implemented in a circuit or software module. The second means may be implemented as or included in the first network device 115.

[0183] In some example embodiments, the third means capable of performing method 1400 may include components for performing the corresponding operations of method 1400 and / or any example embodiment of one or more of the example embodiments described herein. The components may be implemented in any suitable form. For example, the components may be implemented in a circuit or software module. The third means may be implemented as or included in the second network device 125.

[0184] Figure 15 A flowchart of an example method 1500 implemented at a user device according to some example embodiments is shown. For the purposes of discussion, method 1500 will be described from the perspective of user device 105.

[0185] At box 1510, user equipment 105 receives from a first network device an instruction to initiate a dual-connectivity-based secondary cell group change.

[0186] At box 1520, user equipment 105 adds a first cell to the secondary cell group based on an instruction. The first cell is provided by a first network device and serves the user equipment.

[0187] At frame 1530, user equipment 105 deactivates the primary cell group including the first cell.

[0188] At box 1540, user equipment 105 receives from a first network device a handover configuration between secondary nodes for secondary cell group changes based on dual connectivity.

[0189] At frame 1550, user equipment 105 switches from a first cell to a second cell based on a secondary node handover configuration, the second cell being provided by a second network device and included in the target secondary cell group.

[0190] In some example embodiments, user equipment 105 may maintain packet data aggregation protocol entities for the primary cell group.

[0191] In some example embodiments, user equipment 105 may perform at least one of the following based on the instruction: resetting at least one of the radio link control entity, media access control entity, and physical layer entity for the primary cell group; stopping at least one of radio link monitoring and radio link failure detection for the primary cell group; stopping beam failure detection for the primary cell group; stopping measurements for the primary cell group; triggering a re-establishment process based on the detection of a radio link failure for the secondary cell group; and converting the signaling radio bearer for the primary cell group to a separate bearer for both the primary and secondary cell groups, wherein a portion of the separate bearer corresponding to the primary cell group is disabled.

[0192] In some example embodiments, user equipment 105 may send a measurement report identifying a second cell to a first network device, wherein the indication is received from the first network device after the measurement report has been sent.

[0193] In some example embodiments, the indication may be received via radio resource control signaling.

[0194] In some example embodiments, the indication may be carried in a radio resource control reconfiguration message.

[0195] In some example embodiments, user equipment 105 may, in response to receiving a radio resource control reconfiguration message, perform a random access procedure with a first network device to convert the first cell into a primary / secondary cell; and send a radio resource control reconfiguration completion message to the first network device.

[0196] In some example embodiments, user equipment 105 may send a radio resource control reconfiguration complete message to a first network device in response to receiving a radio resource control reconfiguration message, without performing a random access procedure with the first network device to convert the first cell into a primary or secondary cell.

[0197] In some example embodiments, the handover configuration between secondary nodes may include at least one secondary cell group configuration of at least one candidate cell, wherein the at least one candidate cell includes a second cell.

[0198] In some example embodiments, the handover configuration between secondary nodes can be sent to the user equipment via radio resource control signaling.

[0199] In some example embodiments, user equipment 105 may replace the secondary cell group configuration of the second cell with another secondary cell group configuration of another cell provided by another network device, wherein the other cell is the first cell or the third cell.

[0200] Figure 16 A flowchart of an example method 1600 implemented at a first network device according to some example embodiments is shown. For the purposes of discussion, method 1600 will be described from the perspective of the first network device 115.

[0201] At frame 1610, the first network device 115 receives a measurement report from a user equipment operating in single-connection mode, identifying a second cell provided by the second network device.

[0202] At frame 1620, the first network device 115 determines, based on the measurement report, to initiate a dual-connectivity secondary cell group change for the user equipment.

[0203] At frame 1630, the first network device 115 sends an instruction to the user equipment to initiate a dual-connectivity-based secondary cell group change.

[0204] At frame 1640, the first network device 115 sends the user equipment a handover configuration between secondary nodes for secondary cell group changes based on dual connectivity.

[0205] In some example implementations, the determination can be based on the quality of service requirements of the user equipment.

[0206] In some example embodiments, the first network device 115 may, based on this determination, cause the user equipment to switch from a single-connection mode to a dual-connection mode.

[0207] In some example embodiments, the first network device 115 may, based on this determination, add the first cell to the secondary cell group of the user equipment, wherein the first cell is provided by the first network device and serves the user equipment; and disable the primary cell group of the user equipment that includes the first cell.

[0208] In some example embodiments, the first network device 115 may send a request to the second network device for the addition of a secondary node, the request indicating that the addition of the secondary node is used for a dual-connectivity-based secondary cell group change; and receive a response from the second network device to the request, wherein the handover configuration between secondary nodes is sent to the user equipment after the response is received.

[0209] In some example embodiments, the response may include the secondary cell group configuration of the second cell.

[0210] In some example embodiments, the request may also indicate that the bearer terminated by the primary node will be used for the user equipment, and that the secondary cell group bearer will be allocated by a second network device for the bearer terminated by the primary node.

[0211] In some example embodiments, the handover configuration between secondary nodes includes at least one secondary cell group configuration of at least one candidate cell, wherein the at least one candidate cell includes a second cell.

[0212] In some example embodiments, the handover configuration between secondary nodes can be sent to the user equipment via radio resource control signaling.

[0213] In some example embodiments, the instruction may be sent to the user equipment via radio resource control signaling.

[0214] In some example embodiments, the indication may be carried in a radio resource control reconfiguration message.

[0215] In some example embodiments, the first network device 115 may receive a random access request for a first cell from the user equipment, the random access request being used to convert the first cell into a primary or secondary cell of the user equipment; and receive a radio resource control reconfiguration completion message from the user equipment.

[0216] In some example embodiments, in response to sending a Radio Resource Control (RFC) reconfiguration message to a User Equipment (UE), a first network device 115 can receive a RRFC reconfiguration complete message from the UE without requiring a random access procedure for the UE.

[0217] In some example embodiments, the first means capable of performing method 1500 may include components for performing the corresponding operations of method 1500 and / or any example embodiment of one or more of the example embodiments described herein. The components may be implemented in any suitable form. For example, the components may be implemented in a circuit or software module. The first means may be implemented as or included in user equipment 105.

[0218] In some example embodiments, the second means capable of performing method 1600 may include components for performing the corresponding operations of method 1600 and / or any example embodiment of one or more of the example embodiments described herein. The components may be implemented in any suitable form. For example, the components may be implemented in a circuit or software module. The second means may be implemented as or included in the first network device 115.

[0219] Figure 17 A flowchart of an example method 1700 implemented at a user device according to some example embodiments is shown. For the purposes of discussion, method 1700 will be described from the perspective of user device 105.

[0220] At box 1710, user equipment 105 receives from a first network device a handover configuration between secondary nodes for secondary cell group changes based on dual connectivity.

[0221] At box 1720, user equipment 105 performs at least one measurement related to the second cell provided by the second network device.

[0222] At frame 1730, user equipment 105 reports at least one measurement to the first network device.

[0223] At frame 1740, user equipment 105 receives from the first network device an instruction to initiate a dual-connectivity-based secondary cell group change.

[0224] At frame 1750, user equipment 105 initiates a cell handover from a first cell provided by a first network device to a second cell based on the handover configuration between secondary nodes.

[0225] At box 1760, user equipment 105 adds a second cell to the secondary cell group based on an instruction.

[0226] At frame 1770, user equipment 105 deactivates the primary cell group including the first cell.

[0227] In some example embodiments, user equipment 105 may maintain packet data aggregation protocol entities for the primary cell group.

[0228] In some example embodiments, user equipment 105 may perform at least one of the following based on the instruction: resetting at least one of the radio link control entity, media access control entity, and physical layer entity for the primary cell group; stopping at least one of radio link monitoring and radio link failure detection for the primary cell group; stopping beam failure detection for the primary cell group; stopping measurements for the primary cell group; triggering a re-establishment process based on the detection of a radio link failure for the secondary cell group; and converting the signaling radio bearer for the primary cell group to a separate bearer for both the primary and secondary cell groups, wherein a portion of the separate bearer corresponding to the primary cell group is disabled.

[0229] In some example embodiments, the first cell is used as the primary cell of the user equipment. In some example embodiments, the user equipment 105 can keep the primary cell configuration of the first cell in a suspended state; and in response to switching back to the first cell, activate the primary cell configuration if the secondary cell group configuration is suspended.

[0230] In some example embodiments, user equipment 105 may send a measurement report identifying a second cell to a first network device, wherein the handover configuration between secondary nodes is received from the first network device after the measurement report is sent.

[0231] In some example embodiments, the handover configuration between secondary nodes can be received via radio resource control signaling.

[0232] In some example embodiments, the indication may be received via media access control signaling.

[0233] In some example embodiments, user equipment 105 may perform a random access procedure with a second network device to convert the second cell into a primary / secondary cell; and send a radio resource control reconfiguration completion message to the second network device.

[0234] In some example embodiments, user equipment 105 may send a radio resource control reconfiguration complete message to a second network device without requiring a random access procedure with the second cell to convert the second cell into a primary / secondary cell.

[0235] In some example embodiments, the handover configuration between secondary nodes may include at least one secondary cell group configuration of at least one candidate cell, wherein the at least one candidate cell includes a second cell.

[0236] In some example embodiments, user equipment 105 may replace the secondary cell group configuration of the second cell with a different secondary cell group configuration of a third cell provided by another network device.

[0237] Figure 18 A flowchart of an example method 1800 implemented at a first network device according to some example embodiments is shown. For the purposes of discussion, method 1800 will be described from the perspective of the first network device 115.

[0238] At frame 1810, the first network device 115 receives a measurement report from a user equipment operating in single-connection mode, identifying a second cell provided by the second network device.

[0239] At frame 1820, the first network device 115 determines, based on the measurement report, to initiate a dual-connectivity secondary cell group change for the user equipment.

[0240] In box 1830, the first network device 115 sends the secondary node handover configuration for secondary cell group changes based on the determination to the user equipment.

[0241] At frame 1840, the first network device 115 receives at least one measurement related to the second cell from the first network device.

[0242] At frame 1850, the first network device 115 sends an instruction to the user equipment based on at least one measurement to initiate a dual-connectivity-based secondary cell group change to activate the secondary cell group for the user equipment.

[0243] In some example embodiments, this determination may be based on the user equipment's quality of service requirements.

[0244] In some example embodiments, the first network device 115 may send a request to the second network device for the addition of a secondary node, the request indicating that the addition of the secondary node is used for a dual-connectivity-based secondary cell group change; and receive a response from the second network device to the request, wherein the handover configuration between secondary nodes is sent to the user equipment after the response is received.

[0245] In some example embodiments, the response may include the secondary cell group configuration of the second cell.

[0246] In some example embodiments, the request may also indicate that the bearer terminated by the primary node will be used for the user equipment, and that the secondary cell group bearer will be allocated by a second network device for the bearer terminated by the primary node.

[0247] In some example embodiments, the handover configuration between secondary nodes may include at least one secondary cell group configuration of at least one candidate cell, wherein the at least one candidate cell includes a second cell.

[0248] In some example embodiments, the handover configuration between secondary nodes can be sent to the user equipment via radio resource control signaling.

[0249] In some example embodiments, the instruction may be sent to the user equipment via media access control signaling.

[0250] In some example embodiments, the first means capable of performing method 1700 may include components for performing the corresponding operations of method 1700 and / or any example embodiments of one or more of the example embodiments described herein. The components may be implemented in any suitable form. For example, the components may be implemented in a circuit or software module. The first means may be implemented as or included in user equipment 105.

[0251] In some example embodiments, the second means capable of performing method 1800 may include components for performing the corresponding operations of method 1800 and / or any example embodiment of one or more of the example embodiments described herein. The components may be implemented in any suitable form. For example, the components may be implemented in a circuit or software module. The second means may be implemented as or included in the first network device 115.

[0252] Figure 19 This is a simplified block diagram suitable for implementing the example embodiment of device 1900. Device 1900 may be provided to implement a communication device. As shown, device 1900 includes one or more processors 1910, one or more memories 1920 coupled to processor 1910, and one or more communication modules 1940 coupled to processor 1910.

[0253] Communication module 1940 is used for bidirectional communication. Communication module 1940 has one or more communication interfaces to facilitate communication with one or more other modules or devices. The communication interface can represent any interface necessary for communication with other network elements. In some example embodiments, communication module 1940 may include at least one antenna.

[0254] Processor 1910 can be any type suitable for a local technology network, and by way of non-limiting example, can include one or more of the following: general-purpose computer, special-purpose computer, microprocessor, digital signal processor (DSP), and processor based on a multi-core processor architecture. Device 1900 can have multiple processors, such as application-specific integrated circuit chips that are time-dependent on a clock of a synchronous main processor.

[0255] Memory 1920 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, read-only memory (ROM) 1924, electrically programmable read-only memory (EPROM), flash memory, hard disk, optical disc (CD), digital video disc (DVD), optical disc, laser disc, and other magnetic and / or optical storage. Examples of volatile memories include, but are not limited to, random access memory (RAM) 1922 and other volatile memories that will not persist during power outages.

[0256] Computer program 1930 includes computer-executable instructions that are executed by an associated processor 1910. The instructions of program 1930 may include instructions for performing operations / actions in some example embodiments. Program 1930 may be stored in memory, such as ROM 1924. Processor 1910 can perform any suitable actions and processes by loading program 1930 into RAM 1922.

[0257] The example embodiment can be implemented by program 1930, enabling device 1900 to perform as described in the reference. Figures 6 to 20 Any process discussed in this disclosure. Example embodiments may also be implemented in hardware or a combination of software and hardware.

[0258] In some example embodiments, program 1930 may be tangibly contained in a computer-readable medium, which may be included in device 1900 (such as in memory 1920) or in other storage devices accessible to device 1900. Device 1900 may load program 1930 from the computer-readable medium into RAM 1922 for execution. In some example embodiments, the computer-readable medium may include any type of non-transitory storage medium, such as ROM, EPROM, flash memory, hard disk, CD, DVD, etc. As used herein, the term "non-transitory" refers to a limitation on the medium itself (i.e., tangible, not tactile), rather than a limitation on the persistence of data storage (e.g., RAM versus ROM).

[0259] Figure 20 An example of a computer-readable medium 2000, which may be in the form of a CD, DVD, or other optical storage disc, is shown. Program 1930 is stored on the computer-readable medium 2000.

[0260] In general, various embodiments can be implemented in hardware or dedicated circuitry, software, logic, or any combination thereof. Some aspects can be implemented in hardware, and others can be implemented in firmware or software executable by a controller, microprocessor, or other computing device. Although various aspects of the embodiments are shown and described as block diagrams, flowcharts, or using some other graphical representation, it should be understood that the blocks, apparatuses, systems, techniques, or methods described herein can be implemented in hardware, software, firmware, dedicated circuitry or logic, general-purpose hardware or controllers or other computing devices, or some combination thereof, as examples of non-limiting examples.

[0261] Some example embodiments also provide at least one computer program product tangibly stored on a computer-readable medium, such as a non-transitory computer-readable medium. The computer program product includes computer-executable instructions, such as those included in a program module, which are executed in a device on a target physical or virtual processor to perform any of the methods described above. Typically, a program module includes routines, programs, libraries, objects, classes, components, data structures, etc., that perform a particular task or implement a particular abstract data type. In various embodiments, the functionality of a program module can be combined or split among program modules as needed. The machine-executable instructions for a program module can execute within a local or distributed device. In a distributed device, the program module can reside on both local and remote storage media.

[0262] The program code used to execute the method can be written in any combination of one or more programming languages. The program code can be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing device, such that when executed by the processor or controller, the program code enables the functions / operations specified in the flowchart and / or block diagram to be implemented. The program code can be executed entirely on the machine, partially on the machine, as a standalone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0263] In this context, computer program code or related data can be carried by any suitable carrier to enable a device, apparatus, or processor to perform the various processes and operations described above. Examples of carriers include signals, computer-readable media, etc.

[0264] Computer-readable media can be computer-readable signal media or computer-readable storage media. Computer-readable media can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatuses, or devices, or any suitable combination thereof. More specific examples of computer-readable storage media will include electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable optical disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0265] Furthermore, although operations are described in a specific order, this should not be construed as requiring that such operations be performed in the specific order shown or sequentially, or that all shown operations be performed to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the discussion above, these should not be interpreted as limitations on the scope, but rather as descriptions of features that may be specific to a particular embodiment. Unless explicitly stated otherwise, certain features described in the context of a single embodiment may also be implemented in combination in a single embodiment. Conversely, unless explicitly stated otherwise, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments.

[0266] Although this disclosure has been described in language specific to structural features and / or methodological actions, it should be understood that the disclosure as defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are disclosed as exemplary forms of implementing the claims.

[0267] 1. A user equipment, comprising: At least one processor; and At least one memory storing instructions that, when executed by the at least one processor, cause the user equipment operating in single-connection mode to at least: Receive an instruction from the first network device to initiate a dual-connectivity-based secondary cell group change; Based on the instruction, a first cell is added to the secondary cell group, the first cell being provided by the first network device and serving the user equipment; Deactivation includes the primary cell group of the first cell; Receive from the first network device the inter-node handover configuration for the dual-connectivity-based secondary cell group change; and Based on the inter-secondary node handover configuration, the user switches from the first cell to the second cell, which is provided by the second network device and included in the target secondary cell group.

[0268] 2. The user equipment according to Clause 1, wherein the instructions, when executed by the at least one processor, further cause the user equipment to: Maintain the packet data aggregation protocol entity used for the primary cell group.

[0269] 3. The user equipment according to clause 1 or 2, wherein the instructions, when executed by the at least one processor, further cause the user equipment to: Based on the instructions, perform at least one of the following: Reset at least one of the radio link control entity, media access control entity, and physical layer entity used for the primary cell group; Stop at least one of radio link monitoring and radio link failure detection for the primary cell group; Stop beam failure detection for the aforementioned primary cell group; Stop the measurement of the main cell group; Based on the detection of a radio link failure for the secondary cell group, a reconstruction process is triggered; and The signaling radio bearer used for the primary cell group is converted into a separate bearer used for both the primary cell group and the secondary cell group, wherein the portion of the separate bearer corresponding to the primary cell group is disabled.

[0270] 4. The user equipment according to any one of clauses 1 to 3, wherein the instructions, when executed by the at least one processor, further cause the user equipment to: Send a measurement report identifying the second cell to the first network device. The indication is received from the first network device after the measurement report is sent.

[0271] 5. The user equipment according to any one of Clauses 1 to 4, wherein the instruction is received via radio resource control signaling.

[0272] 6. The user equipment according to any one of Clauses 1 to 5, wherein the indication is carried in a radio resource control reconfiguration message.

[0273] 7. The user equipment according to Clause 6, wherein the instructions, when executed by the at least one processor, further cause the user equipment to: In response to receiving the Radio Resource Control reconfiguration message, a random access procedure with the first network device is performed to convert the first cell into a primary / secondary cell; and Send a radio resource control reconfiguration complete message to the first network device.

[0274] 8. The user equipment according to Clause 6, wherein the instructions, when executed by the at least one processor, further cause the user equipment to: In response to receiving the Radio Resource Control Reconfiguration message, a Radio Resource Control Reconfiguration Complete message is sent to the first network device without requiring a random access procedure with the first network device to convert the first cell into a primary / secondary cell.

[0275] 9. The user equipment according to any one of Clauses 1 to 8, wherein the inter-secondary node handover configuration includes at least one secondary cell group configuration of at least one candidate cell, wherein the at least one candidate cell includes the second cell.

[0276] 10. The user equipment according to any one of clauses 1 to 9, wherein the inter-secondary node handover configuration is transmitted to the user equipment via radio resource control signaling.

[0277] 11. The user equipment according to any one of clauses 1 to 10, wherein the instructions, when executed by the at least one processor, further cause the user equipment to: Replace the secondary cell group configuration of the second cell with another secondary cell group configuration of another cell provided by another network device, wherein the other cell is the first cell or the third cell.

[0278] 12. A first network device, comprising: At least one processor; and At least one memory storing instructions that, when executed by the at least one processor, cause the first network device to at least: Receive a measurement report from a user equipment operating in single-connection mode, identifying the second cell provided by a second network device; Based on the measurement report, it is determined to initiate a dual-connectivity-based secondary cell group change for the user equipment; Send an instruction to the user equipment to initiate a secondary cell group change based on dual connectivity; and Send the user equipment the inter-node handover configuration for the change of the secondary cell group based on dual connectivity.

[0279] 13. The first network device as described in Clause 12, wherein the determination is based on the quality of service requirements of the user equipment.

[0280] 14. The first network device according to clause 12 or 13, wherein the instructions, when executed by the at least one processor, further cause the first network device to: Based on the determination, the user equipment is switched from the single-connection mode to the dual-connection mode.

[0281] 15. A first network device according to any one of clauses 12 to 14, wherein the instructions, when executed by the at least one processor, further cause the first network device to: Based on the determination, a first cell is added to the secondary cell group of the user equipment, wherein the first cell is provided by and serves the user equipment by the first network device; and The user equipment that is disabled includes the primary cell group of the first cell.

[0282] 16. A first network device according to any one of clauses 12 to 15, wherein the instructions, when executed by the at least one processor, further cause the first network device to: Send a request to the second network device for the addition of a secondary node, the request indicating that the addition of the secondary node is used for the dual-connectivity-based secondary cell group change; and Receive a response to the request from the second network device. The inter-secondary node handover configuration is sent to the user equipment after the response is received.

[0283] 17. The first network device as described in Clause 16, wherein the response includes the secondary cell group configuration of the second cell.

[0284] 18. The first network device according to Clause 16 or 17, wherein the request further indicates that the bearer terminated by the primary node will be used for the user equipment, and the secondary cell group bearer will be allocated by the second network device for the bearer terminated by the primary node.

[0285] 19. A first network device according to any one of clauses 12 to 18, wherein the inter-secondary node handover configuration includes at least one secondary cell group configuration of at least one candidate cell, wherein the at least one candidate cell includes the second cell.

[0286] 20. A second network device, comprising: At least one processor; and At least one memory storing instructions that, when executed by the at least one processor, cause the second network device to at least: Receive a request from a first network device for adding a secondary node, the request indicating that the secondary node be added for a dual-connectivity-based secondary cell group change used by a user equipment; and Based on the request, it is determined that the primary cell group will be deactivated by the user equipment for use in the dual-connectivity-based secondary cell group change.

Claims

1. A user equipment, comprising: At least one processor; as well as At least one memory storing instructions that, when executed by the at least one processor, cause the user equipment operating in single-connection mode to at least: Receive an instruction from the first network device to initiate a dual-connectivity-based secondary cell group change; Based on the instruction, a first cell is added to the secondary cell group, the first cell being provided by the first network device and serving the user equipment; Deactivation includes the primary cell group of the first cell; Receive inter-node handover configuration for the dual-connectivity-based secondary cell group change from the first network device; as well as Based on the inter-secondary node handover configuration, the user switches from the first cell to the second cell, which is provided by the second network device and included in the target secondary cell group.

2. The user equipment of claim 1, wherein the instructions, when executed by the at least one processor, further cause the user equipment to: Maintain the packet data aggregation protocol entity used for the primary cell group.

3. The user equipment according to claim 1 or 2, wherein the instructions, when executed by the at least one processor, further cause the user equipment to: Based on the instructions, perform at least one of the following: Reset at least one of the radio link control entity, media access control entity, and physical layer entity used for the primary cell group; Stop at least one of radio link monitoring and radio link failure detection for the primary cell group; Stop beam failure detection for the aforementioned primary cell group; Stop measurements of the primary cell group; A reconstruction process is triggered based on the detection of a radio link failure for the secondary cell group. as well as The signaling radio bearer used for the primary cell group is converted into a separate bearer used for both the primary cell group and the secondary cell group, wherein the portion of the separate bearer corresponding to the primary cell group is disabled.

4. The user equipment according to claim 1 or 2, wherein the instructions, when executed by the at least one processor, further cause the user equipment to: Send a measurement report identifying the second cell to the first network device. The indication is received from the first network device after the measurement report is sent.

5. The user equipment according to claim 1 or 2, wherein the indication is received via radio resource control signaling.

6. The user equipment according to claim 1 or 2, wherein the indication is carried in a radio resource control reconfiguration message.

7. The user equipment of claim 6, wherein the instructions, when executed by the at least one processor, further cause the user equipment to: In response to receiving the Radio Resource Control reconfiguration message, a random access procedure with the first network device is performed to convert the first cell into a primary / secondary cell; and Send a radio resource control reconfiguration complete message to the first network device.

8. The user equipment of claim 6, wherein the instructions, when executed by the at least one processor, further cause the user equipment to: In response to receiving the Radio Resource Control Reconfiguration message, a Radio Resource Control Reconfiguration Complete message is sent to the first network device without requiring a random access procedure with the first network device to convert the first cell into a primary / secondary cell.

9. The user equipment according to claim 1 or 2, wherein the inter-secondary node handover configuration includes at least one secondary cell group configuration of at least one candidate cell, wherein the at least one candidate cell includes the second cell.

10. The user equipment according to claim 1 or 2, wherein the inter-secondary node handover configuration is transmitted to the user equipment via radio resource control signaling.

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