Method and apparatus for supporting self-configuration and self-optimization in communication system

Abstract

The disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. According to an aspect of the present disclosure, a method performed by a first base station operating as a secondary node (SN) in a dual connectivity of a user equipment (UE) in a communication system includes initiating a subsequent conditional primary secondary cell group (SCG) cell (PSCell) addition or change (SCPAC); receiving, from a second base station operating as a mater node (MN) in the dual connectivity, a message for reporting information on an SCG failure; and performing an analysis of a cause for the SCG failure. In case that a time duration from execution of the SCPAC to the SCG failure is larger than a configured threshold or the time duration is not reported by the UE, and there is a suitable PSCell different from a PSCell where the UE stayed when the SCG failure occurred, the cause for the SCG failure is a Too Late SCPAC execution.

Description

METHOD AND APPARATUS FOR SUPPORTING SELF-CONFIGURATION AND SELF-OPTIMIZATION IN COMMUNICATION SYSTEM

[0001] The application relates to wireless communication technology, and in particular to methods and devices supporting self-configuration and self-optimization.

[0002] 5G mobile communication technologies define broad frequency bands such that high transmission rates and new services are possible, and can be implemented not only in "Sub 6GHz" bands such as 3.5GHz, but also in "Above 6GHz" bands referred to as mmWave including 28GHz and 39GHz. In addition, it has been considered to implement 6G mobile communication technologies (referred to as Beyond 5G systems) in terahertz bands (for example, 95GHz to 3THz bands) in order to accomplish transmission rates fifty times faster than 5G mobile communication technologies and ultra-low latencies one-tenth of 5G mobile communication technologies.

[0003] At the beginning of the development of 5G mobile communication technologies, in order to support services and to satisfy performance requirements in connection with enhanced Mobile BroadBand (eMBB), Ultra Reliable Low Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), there has been ongoing standardization regarding beamforming and massive MIMO for mitigating radio-wave path loss and increasing radio-wave transmission distances in mmWave, supporting numerologies (for example, operating multiple subcarrier spacings) for efficiently utilizing mmWave resources and dynamic operation of slot formats, initial access technologies for supporting multi-beam transmission and broadbands, definition and operation of BWP (BandWidth Part), new channel coding methods such as a LDPC (Low Density Parity Check) code for large amount of data transmission and a polar code for highly reliable transmission of control information, L2 pre-processing, and network slicing for providing a dedicated network specialized to a specific service.

[0004] Currently, there are ongoing discussions regarding improvement and performance enhancement of initial 5G mobile communication technologies in view of services to be supported by 5G mobile communication technologies, and there has been physical layer standardization regarding technologies such as V2X (Vehicle-to-everything) for aiding driving determination by autonomous vehicles based on information regarding positions and states of vehicles transmitted by the vehicles and for enhancing user convenience, NR-U (New Radio Unlicensed) aimed at system operations conforming to various regulation-related requirements in unlicensed bands, NR UE Power Saving, Non-Terrestrial Network (NTN) which is UE-satellite direct communication for providing coverage in an area in which communication with terrestrial networks is unavailable, and positioning.

[0005] Moreover, there has been ongoing standardization in air interface architecture / protocol regarding technologies such as Industrial Internet of Things (IIoT) for supporting new services through interworking and convergence with other industries, IAB (Integrated Access and Backhaul) for providing a node for network service area expansion by supporting a wireless backhaul link and an access link in an integrated manner, mobility enhancement including conditional handover and DAPS (Dual Active Protocol Stack) handover, and two-step random access for simplifying random access procedures (2-step RACH for NR). There also has been ongoing standardization in system architecture / service regarding a 5G baseline architecture (for example, service based architecture or service based interface) for combining Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) for receiving services based on UE positions.

[0006] As 5G mobile communication systems are commercialized, connected devices that have been exponentially increasing will be connected to communication networks, and it is accordingly expected that enhanced functions and performances of 5G mobile communication systems and integrated operations of connected devices will be necessary. To this end, new research is scheduled in connection with eXtended Reality (XR) for efficiently supporting AR (Augmented Reality), VR (Virtual Reality), MR (Mixed Reality) and the like, 5G performance improvement and complexity reduction by utilizing Artificial Intelligence (AI) and Machine Learning (ML), AI service support, metaverse service support, and drone communication.

[0007] Furthermore, such development of 5G mobile communication systems will serve as a basis for developing not only new waveforms for providing coverage in terahertz bands of 6G mobile communication technologies, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), array antennas and large-scale antennas, metamaterial-based lenses and antennas for improving coverage of terahertz band signals, high-dimensional space multiplexing technology using OAM (Orbital Angular Momentum), and RIS (Reconfigurable Intelligent Surface), but also full-duplex technology for increasing frequency efficiency of 6G mobile communication technologies and improving system networks, AI-based communication technology for implementing system optimization by utilizing satellites and AI (Artificial Intelligence) from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technology for implementing services at levels of complexity exceeding the limit of UE operation capability by utilizing ultra-high-performance communication and computing resources.

[0008] In order to meet an increasing demand for wireless data communication services since a deployment of 4G communication system, efforts have been made to develop an improved 5G or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called "beyond 4G network" or "post LTE system".

[0009] Wireless communication is one of the most successful innovations in modern history. Recently, a number of subscribers of wireless communication services has exceeded 5 billion, and it continues growing rapidly. With the increasing popularity of smart phones and other mobile data devices (such as tablet computers, notebook computers, netbooks, e-book readers and machine-type devices) in consumers and enterprises, a demand for wireless data services is growing rapidly. In order to meet rapid growth of mobile data services and support new applications and deployments, it is very important to improve efficiency and coverage of wireless interfaces.

[0010] For enhanced mobility solutions, how to support mobility robustness during a dual connectivity is a current problem that needs to be solved.

[0011] According to an aspect of the present disclosure, a method performed by a first base station operating as a secondary node (SN) in a dual connectivity of a user equipment (UE) in a communication system is provided. The method includes initiating a subsequent conditional primary secondary cell group (SCG) cell (PSCell) addition or change (SCPAC); receiving, from a second base station operating as a mater node (MN) in the dual connectivity, a message for reporting information on an SCG failure; and performing an analysis of a cause for the SCG failure. In case that a time duration from execution of the SCPAC to the SCG failure is larger than a configured threshold or the time duration is not reported by the UE, and there is a suitable PSCell different from a PSCell where the UE stayed when the SCG failure occurred, the cause for the SCG failure is a Too Late SCPAC execution.

[0012] According to an aspect of the present disclosure, a method performed by a second base station operating as an MN in a dual connectivity of a UE in a communication system is provided. The method includes receiving, from the UE, information on an SCG failure; performing an initial analysis for the SCG failure and determining a type of PSCell addition or change; in case that the type of PSCell addition or change is an SCPAC imitated by a first base station operating as an SN in the dual connectivity, transmitting, to the first base station, a message for reporting the information on the SCG failure, which triggers an analysis of a cause for the SCG failure. In case that a time duration from execution of the SCPAC to the SCG failure is larger than a configured threshold or the time duration is not reported by the UE, and there is a suitable PSCell different from a PSCell where the UE stayed when the SCG failure occurred, the cause for the SCG failure is a Too Late SCPAC execution.

[0013] According to an aspect of the present disclosure, a first base station operating as an SN in a dual connectivity of a UE in a communication system is provided. The first base station includes a transceiver and a controller. The controller is configured to initiate an SCPAC, receive, from a second base station operating as an MN in the dual connectivity via the transceiver, a message for reporting information on an SCG failure, and perform an analysis of a cause for the SCG failure, In case that a time duration from execution of the SCPAC to the SCG failure is larger than a configured threshold or the time duration is not reported by the UE, and there is a suitable PSCell different from a PSCell where the UE stayed when the SCG failure occurred, the cause for the SCG failure is a Too Late SCPAC execution.

[0014] According to an aspect of the present disclosure, a second base station operating as an MN in a dual connectivity of a UE in a communication system is provided. The second base station includes a transceiver and a controller. The controller is configured to receive, from the UE, SCG failure information, perform an initial analysis for an SCG failure and determining a type of primary SCG cell (PSCell) addition or change, and in case that the type of PSCell addition or change is an SCPAC imitated by a first base station operating as an SN in the dual connectivity, transmit, to the first base station via the transceiver, a message for reporting the information on the SCG failure, which triggers an analysis of a cause for the SCG failure. In case that a time duration from execution of the SCPAC to the SCG failure is larger than a configured threshold or the time duration is not reported by the UE, and there is a suitable PSCell different from a PSCell where the UE stayed when the SCG failure occurred, the cause for the SCG failure is a Too Late SCPAC execution.

[0015] According to an aspect of the present disclosure, there is provided a method performed by a first network node of a communication system, comprising: receiving, from a User Equipment (UE) first information comprising information related to a failure, the failure related to a Secondary Cell Group (SCG); deciding which network node causes the failure based at least on the information related to the failure, wherein the information related to the failure comprises at least one of: information related to subsequent conditional Primary SCG Cell (PSCell) addition or change (S-CPAC), cell identity information related to the PSCell, information related to a SCG and / or a Master Cell Group (MCG).

[0016] According to an embodiment of the present disclosure, the method further includes: sending indication or report information on the failure to the node that causes the failure or the second node.

[0017] According to an embodiment of the present disclosure, the method further includes: determining a type of the failure based on at least part of the information related to the failure.

[0018] According to an embodiment of the present disclosure, the method further includes: forwarding the information related to the failure to the node that causes the failure.

[0019] According to an embodiment of the present disclosure, wherein the information related to the S-CPAC comprises at least one of: indication information on whether the S-CPAC was executed, a time duration from the S-CPAC execution to the failure, S-CPAC execution condition(s), a time duration from the UE receiving S-CPAC configuration to the failure, a time duration from the UE receiving the S-CPAC configuration to the S-CPAC execution, indication information on an S-CPAC execution condition being fulfilled for execution, information on the S-CPAC execution condition(s) which was fulfilled first, a time duration between two S-CPAC execution conditions being fulfilled, indication information on the S-CPAC, initial S-CPAC execution condition(s), following S-CPAC execution condition(s), indication information on an initial S-CPAC failure or a following S-CPAC failure; or wherein the cell identity information related to the PSCell comprises at least one of: a cell identity of a failed PSCell, a cell identity of a source PSCell of the latest PSCell change, a cell list of S-CPAC candidate PSCells; or wherein the information relaed to the SCG and / or the MCG comprises at least one of: a status of the SCG, a SCG failure time, status of the MCG.

[0020] According to an embodiment of the present disclosure, wherein the indication or report information on the failure includes at least one of: a cell identity of the source PSCell, a cell identity of a target PSCell or a cell identity of the failed PSCell, a cell identity of a suitable PSCell, SCG failure information received from the UE, a list of candidate PSCell(s) recommended by an MN or a source SN, initial S-CPAC execution condition(s), following S-CPAC execution condition(s), a list of candidate PSCell(s) selected by a target SN or a candidate target SN, a list of PSCell(s) not accepted by a target SN or a candidate target SN in the list of candidate PSCell(s) recommended by the MN or the source SN, a maximum number of prepared PSCells, estimated reachability, a SCG failure time, a type of failure.

[0021] According to another aspect of the present disclosure, there is provided a method performed by a first network node of a communication system, comprising: transmitting at least one of first, second, third and fourth configuration information on a successful Primary SCG Cell (PSCell) addition / change report to a user equipment (UE); receiving, from the UE, information indicating that the successful PSCell modification report is available, wherein the successful PSCell modification report comprises one or more of: time information related to the successful PSCell modification report, identity information related to a primary cell, a source PSCell, a target PSCell related to a PSCell modification, a cause of the successful PSCell modification, information related to a timer configured by the first node, time information related to a PSCell modification, mobility information of the UE, information on a node initiating the PSCell modification.

[0022] According to an embodiment of the present disclosure, the method further includes: sending a request for the successful PSCell modification report to the first node, and receiving modification report on the successful PSCell from the UE.

[0023] According to an embodiment of the present disclosure, the method further comprises receiving the first configuration information on the successful modification report from the second node.

[0024] According to an embodiment of the present disclosure, the method further comprises receiving the third configuration information and / or the fourth configuration information on the successful PSCell modification report from a third node.

[0025] According to an embodiment of the present disclosure, the method further includes: sending the information on the successful PSCell modification report to a fifth node, wherein the fifth node is determined based on the successful PSCell modification report.

[0026] According to an embodiment of the present disclosure, wherein the first configuration information includes at least one of configuration of a successful primary SCG cell change report triggered by a timer 310 and / or T312 and configuration of the successful primary SCG cell change report triggered by a timer T304; or wherein the second configuration information comprises configuration of the successful primary SCG cell change report triggered by the timer T310 and / or the timer T312, or wherein the third configuration information comprises configuration of the successful primary SCG cell change report triggered by the timer T310 and / or the timer T312, or wherein the fourth configuration information comprises configuration of the successful primary SCG cell change report triggered by the timer T304.

[0027] According to another aspect of the present disclosure, a method performed by a first network node of a communication system is provided, including: receiving, from a user equipment (UE), a message including information on a primary SCG cell PSCell selected by the UE, and sending, to a target secondary node, Secondary Cell Group (SCG) history information of the UE, wherein the SCG history information of the UE includes information on PSCell(s) arranged in time order.

[0028] According to an embodiment of the present disclosure, wherein the SCG history information of the UE is sent through a secondary node reconfiguration complete message, wherein information on the PSCell includes at least one of: identity information of the PSCell, dwell time information of the UE, and cell type information.

[0029] According to an embodiment of the present disclosure, wherein the SCG history information of the UE is used to detect whether the PSCell change has a problem.

[0030] According to another aspect of the present disclosure, there is provided a method performed by a user equipment (UE) of a communication system, comprising: saving, by the UE, information related to a failure, the failure related to a Secondary Cell Group (SCG); sending first information comprising the information related to the failure to a first network node, wherein the information related to the failure comprises at least one of: information related to subsequent conditional Primary SCG Cell (PSCell) addition or change (S-CPAC), cell identity information related to a PSCell, information related to the SCG and / or a Master Cell Group (MCG).

[0031] According to an embodiment of the present disclosure, wherein the information related to the S-CPAC comprises at least one of: indication information on whether the S-CPAC was executed, a time duration from the S-CPAC execution to the failure, a time duration from UE reception of S-CPAC configuration to the failure, a time duration from the UE reception of the S-CPAC configuration to the S-CPAC execution, indication information on an S-CPAC execution condition being fulfilled for execution, information on the S-CPAC execution condition which was fulfilled first, a time duration between two S-CPAC execution conditions being fulfilled, indication information on the S-CPAC, initial S-CPAC execution condition(s), following S-CPAC execution condition(s), following S-CPAC execution condition(s), indication information on an initial S-CPAC failure or a following S-CPAC failure; or wherein the cell identity information related to the PSCell comprises at least one of: a cell identity of a failed PSCell, a cell identity of a source PSCell of the latest PSCell change, a cell list of S-CPAC candidate PSCells; or wherein the information relaed to the SCG and / or the MCG comprises at least one of: status of SCG, SCG failure time, status of MCG.

[0032] According to an embodiment of the present disclosure, wherein indication or report information on the failure is sent to the node causing the failure or the second node, wherein the indication or report information on the failure includes at least one of: the cell identity of the source PSCell, a cell identity of a target PSCell or a cell identity of the failed PSCell, a cell identity of a suitable PSCell, SCG failure information received from the UE, a list of candidate PSCell(s) recommended by an MN or a source SN, an initial S-CPAC execution condition, a following S-CPAC execution condition, a list of candidate PSCell(s) selected by a target SN or a candidate target SN, a list of PSCell(s) not accepted by a target SN or a candidate target SN in the list of candidate PSCell(s) recommended by the MN or the source SN, a maximum number of prepared PSCells, estimated reachability, a SCG failure time, a type of failure.

[0033] According to another aspect of the present disclosure, there is provided a method performed by a user equipment (UE) of a communication system, comprising: receiving at least one of first, second, third and fourth configuration information on a successful Primary SCG Cell (PSCell) modification report from a first network node; sending information indicating that the successful PSCell modification report is available to a first network node, wherein the successful PSCell modification report comprises one or more of: time information related to the successful PSCell modification report, identity information related to a primary cell, a source PSCell, a target PSCell related to a PSCell modification, a cause of the successful PSCell modification, information related to a timer configured by the first node, time information related to a PSCell modification, mobility information of the UE, information on node initiating the PSCell modification.

[0034] According to an embodiment of the present disclosure, wherein the first configuration information includes at least one of: configuration of a successful primary SCG cell change report triggered by a timer 310 and / or T312 and configuration of the successful primary SCG cell change report triggered by a timer T304; or wherein the second configuration information comprises configuration of the successful primary SCG cell change report triggered by the timer T310 and / or the timer T312, or wherein the third configuration information comprises configuration of the successful primary SCG cell change report triggered by the timer T310 and / or the timer T312, or wherein the fourth configuration information comprises configuration of the successful primary SCG cell change report triggered by the timer T304.

[0035] According to another aspect of the present disclosure, there is provided a method performed by a user equipment (UE) of a communication system, comprising: selecting a target Primary SCG Cell (PSCell), transmitting, to a first network node, a message comprising information on the target PSCell selected by the UE, wherein Secondary Cell Group (SCG) history information of the UE is transmitted to a target secondary node in response to the information on the Primary SCG Cell (PSCell) selected by the UE, wherein the SCG history information of the UE comprises information on PSCell (s) arranged in time order.

[0036] According to an embodiment of the present disclosure, wherein the SCG history information of the UE is sent through a secondary node reconfiguration complete message, wherein the information on the PSCell includes at least one of: identity information of the PSCell, dwell time information on the UE, and cell type information.

[0037] According to an embodiment of the present disclosure, wherein the SCG history information of the UE is used to detect if there is a problem with the PSCell change.

[0038] According to another aspect of the present disclosure, there is provided a first network node device in a communication system, comprising: a transceiver configured to receive and transmit signals; and a processor coupled with the transceiver and configured to control the network node device to perform a method according to embodiments of the present disclosure.

[0039] In accordance with another aspect of the present disclosure, there is provided a user equipment (UE) in a communication system, including: a transceiver configured to receive and transmit signals; and a processor coupled with the transceiver and configured to control the UE device to perform a method according to embodiments of the present disclosure.

[0040] Through the method of supporting self-configuration and self-optimization of the present disclosure, in case of supporting the dual connectivity, problems in a handover or PSCell modification process is correctly identified, including a failures, a potential failure in a successful procedure, or an unnecessary handover or PSCell modification procedure (such as a ping-pong handover or PSCell modification), for carrying out reasonable optimization, reducing occurrence of subsequent failures, ensuring service continuity and reducing labor costs of operators.

[0041] Figure 1 is a system architecture diagram of System Architecture Evolution (SAE);

[0042] Figure 2 is a schematic diagram of the initial overall architecture of 5G;

[0043] Figure 3 is an example flow chart of Method 1 for supporting self-configuration and self-optimization according to the present disclosure;

[0044] Figure 4 is an example flow chart of Method 2 for supporting self-configuration and self-optimization according to the present disclosure;

[0045] Figure 5 is an exemplary flow chart of Method 3 for supporting self-configuration and self-optimization according to the present disclosure;

[0046] Figure 6 is an example signal flow diagram of Embodiment 1 of Method 1 for supporting self-configuration and self-optimization according to the present disclosure;

[0047] Figure 7 is an example signal flow diagram of Embodiment 2 of Method 1 for supporting self-configuration and self-optimization according to the present disclosure;

[0048] Figure 8 is an example signal flow diagram of Embodiment 3 of Method 2 for supporting self-configuration and self-optimization according to the present disclosure;

[0049] Figure 9 is an example signal flow diagram of Embodiment 4 of Method 3 for supporting self-configuration and self-optimization according to the present disclosure;

[0050] Figure 10 is an example flow chart of Method 4 that supports self-configuration and self-optimization;

[0051] Figure 11 is an example signal flow diagram of Embodiment 5 of Method 4 for supporting self-configuration and self-optimization in accordance with the present disclosure;

[0052] Figure 12 is an example flowchart of Method 5 for supporting self-configuration and self-optimization;

[0053] Figure 13 is an example flowchart of Method 6 for supporting self-configuration and self-optimization;

[0054] Figure 14 is an example flowchart of Method 7 for supporting self-configuration and self-optimization;

[0055] Figure 15 is an example flowchart of Method 8 for supporting self-configuration and self-optimization;

[0056] Figure 16 is a block diagram of a network node according to an embodiment of the present disclosure; and

[0057] Figure 17 is a block diagram of a user equipment (UE) according to an embodiment of the present disclosure.

[0058] In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are some, but not all, of the embodiments of the present disclosure. Based on the described embodiments of the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present disclosure.

[0059] Before undertaking the detailed description below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document. The term "couple" and its derivatives refer to any direct or indirect communication between two or more elements, whether or not those elements are in physical contact with one another. The terms "transmit," "receive," and "communicate," as well as derivatives thereof, encompass both direct and indirect communication. The terms "include" and "comprise," as well as derivatives thereof, mean inclusion without limitation. The term "or" is inclusive, meaning and / or. The phrase "associated with," as well as derivatives thereof, means to include, be included within, connect to, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, have a relationship to or with, or the like. The term "controller" means any device, system or part thereof that controls at least one operation. Such a controller may be implemented in hardware, or in a combination of hardware and software and / or firmware. The functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. The phrase "at least one of," when used with a list of items, means that different combinations of one or more of the listed items may be used, and only one item in the list may be needed. For example, "at least one of: A, B, and C" includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C. For example, "at least one of: A, B, or C" includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C.

[0060] Moreover, various functions described below can be implemented or supported by one or more computer programs, each of which is formed from computer readable program code and embodied in a computer readable medium. The terms "application" and "program" refer to one or more computer programs, software components, sets of instructions, procedures, functions, objects, classes, instances, related data, or a portion thereof adapted for implementation in a suitable computer readable program code. The phrase "computer readable program code" includes any type of computer code, including source code, object code, and executable code. The phrase "computer readable medium" includes any type of medium capable of being accessed by a computer, such as Read-Only Memory (ROM), Random Access Memory (RAM), a hard disk drive, a compact disc (CD), a digital video disc (DVD), or any other type of memory. A "non-transitory" computer readable medium excludes wired, wireless, optical, or other communication links that transport transitory electrical or other signals. A non-transitory computer readable medium includes media where data can be permanently stored and media where data can be stored and later overwritten, such as a rewritable optical disc or an erasable memory device.

[0061] The terminology used herein to describe embodiments of the disclosure is not intended to limit and / or define the scope of the disclosure. For example, unless otherwise defined, technical terms or scientific terms used in this disclosure shall have their ordinary meanings understood by those of ordinary skill in the art to which this application belongs.

[0062] It should be understood that "first," "second," and similar words used in this disclosure do not denote any order, quantity, or importance, but are merely used to distinguish between different components. Unless the context clearly indicates otherwise, the singular forms "a," "an," "the," and similar words do not denote a limitation of quantity, but rather denote the presence of at least one.

[0063] As used herein any reference to "one example" or "an example," "one embodiment," or "an embodiment" means that a particular element, feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrases "in one embodiment" or "in an example" in various places in the specification are not necessarily all referring to the same embodiment.

[0064] As used herein, "a portion of something means" at least some of that thing, and thus may mean less than all of that thing or all of that thing. Thus, "a portion of a thing includes the entire thing as a special case, i.e., the entire thing is an example of a portion of the thing.

[0065] It will be further understood that the terms "include" or "include" and similar words mean that the elements or items appearing before the word include the elements or items listed after the word and their equivalents, but do not exclude other elements or items. Words such as "connect" or "connect" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right", etc. are only used to express relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0066] The various embodiments discussed below to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged wireless communication system. For example, although the following detailed description of embodiments of the present disclosure will be directed to LTE and 5G communication systems, those skilled in the art may understand that the main points of the present disclosure may also be slightly modified without substantially departing from the scope of the present disclosure. Can be applied to other communication systems having similar technical backgrounds and channel formats. The technical solutions of the embodiments of this application can be applied to various communication systems. For example, the communication systems can include global system for mobile communications (GSM) systems, code division multiple access (CDMA) systems, wideband code division multiple access (CDMA) systems, wideband code division multiple access (WCDMA) System, general packet radio service (GPRS), long term evolution (LTE) system, LTE frequency division duplex (FDD) System, LTE time division duplex (TDD), universal mobile telecommunications system (UMTS), worldwide interoperability for microwave access (WiMAX) communication system, 5th generation (5th generation, 5G) system or new radio (new radio, NR), etc. In addition, the technical solutions of the embodiments of this application can be applied to future-oriented communication technologies. In addition, the technical solutions of the embodiments of this application can be applied to future-oriented communication technologies.

[0067] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the present disclosure as defined by the claims and their equivalents. This description includes various specific details to assist in that understanding but are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications can be made to the various embodiments described herein without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.

[0068] The terms and phrases used in the following description and claims are not limited to their dictionary meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the present disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of various embodiments of the present disclosure is provided for illustration purpose only and not for the purpose of limiting the present disclosure as defined by the appended claims and their equivalents.

[0069] It is to be understood that the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Thus, for example, reference to "a component surface" includes reference to one or more of such surfaces.

[0070] The terms "include" or "may include" refer to the presence of corresponding disclosed functions, operations, or components that may be used in various embodiments of the present disclosure, and do not limit the presence of one or more additional functions, operations, or features. Furthermore, the terms "include" or "have" may be construed to indicate certain characteristics, numbers, steps, operations, constituent elements, components, or combinations thereof, but should not be construed to exclude one or more other characteristics, numbers, steps, operations, constituent elements, components, or combinations thereof.

[0071] The term "or" as used in various embodiments of the present disclosure includes any of the listed terms and all combinations thereof. For example, "A or B" may include A, may include B, or may include both A and B.

[0072] Unless defined differently, all terms (including technical terms or scientific terms) used in this disclosure have the same meaning as understood by those skilled in the art to which this disclosure belongs. Common terms as defined in dictionaries are interpreted to have meanings consistent with the context in the relevant technical field, and should not be interpreted ideally or overly formally unless expressly so defined in this disclosure.

[0073] Figures 1 to 17, discussed below and various embodiments for describing the principles of the present disclosure in this patent document are only for illustration and should not be interpreted as limiting the scope of the disclosure in any way. Those skilled in the art will understand that the principles of the present disclosure can be implemented in any suitably arranged system or device.

[0074] Figure 1 is an exemplary system architecture 100 of system architecture evolution (SAE). User equipment (UE) 101 is a terminal device for receiving data. An evolved universal terrestrial radio access network (E-UTRAN) 102 is a radio access network, which includes a macro base station (eNodeB / NodeB) that provides UE with interfaces to access the radio network. A mobility management entity (MME) 103 is responsible for managing mobility context, session context and security information of the UE. A serving gateway (SGW) 104 mainly provides functions of user plane, and the MME 103 and the SGW 104 may be in the same physical entity. A packet data network gateway (PGW) 105 is responsible for functions of charging, lawful interception, etc., and may be in the same physical entity as the SGW 104. A policy and charging rules function entity (PCRF) 106 provides quality of service (QoS) policies and charging criteria. A general packet radio service support node (SGSN) 108 is a network node device that provides routing for data transmission in a universal mobile telecommunications system (UMTS). A home subscriber server (HSS)109 is a home subsystem of the UE, and is responsible for protecting user information including a current location of the user equipment, an address of a serving node, user security information, and packet data context of the user equipment, etc.

[0075] Figure 2 is an exemplary system architecture 200 according to various embodiments of the present disclosure. Other embodiments of the system architecture 200 can be used without departing from the scope of the present disclosure.

[0076] User equipment (UE) 201 is a terminal device for receiving data. A next generation radio access network (NG-RAN) 202 is a radio access network, which includes a base station (a gNB or an eNB connected to 5G core network 5GC, and the eNB connected to the 5GC is also called ng-gNB) that provides UE with interfaces to access the radio network. An access control and mobility management function entity (AMF) 203 is responsible for managing mobility context and security information of the UE. A user plane function entity (UPF) 204 mainly provides functions of user plane. A session management function entity SMF 205 is responsible for session management. A data network (DN) 206 includes, for example, services of operators, access of Internet and service of third parties.

[0077] The exemplary embodiments of the present disclosure are further described below in conjunction with the accompanying drawings.

[0078] The text and drawings are provided as examples only to assist in understanding the present disclosure. They should not be construed as limiting the scope of the disclosure in any way. Although certain embodiments and examples have been provided, it will be apparent to those skilled in the art, based upon this disclosure, that changes can be made to the embodiments and examples shown without departing from the scope of the disclosure.

[0079] In order to improve the reliability of addition or change of a Primary SCG Cell (PSCell, SpCell (a primary cell of a master or secondary cell group) of a secondary cell group), a Conditional PSCell Change (CPC) is defined in the current technology. Furthermore, a Conditional PSCell Addition (CPA, Conditional PSCell Addition) and a Conditional PSCell Addition or Change (CPAC, Conditional PSCell Addition or Change) are defined in the current technology. The CPC can be internal to a Secondary Node (SN, Secondary Node) or inter-SN. In the current technology, the Subsequent Conditional PSCell Addition or Change (also called Subsequent CPAC or S-CPAC) procedure is further defined. In the S-CPAC, when the network configures the S-CPAC for the UE, after the UE performs the first CPA or CPC (CPA / CPC) (in the S-CPAC, it can also be called performing the initial S-CPAC), completing the PSCell addition or change, the UE retains S-CPAC configuration for executing the following (or next) S-CPAC (following Subsequent CPAC / S-CPAC). The configured execution conditions for the initial S-CPAC execution may be referred to as initial S-CPAC execution condition, and the execution conditions for the following (or next) S-CPAC execution may be referred to as the following (or next) S-CPAC execution conditions.

[0080] According to embodiments of the present disclosure, unreasonable configuration or triggering of the S-CPAC may lead to a Secondary Cell Group (SCG) failure or a potential failure during a S-CPAC procedure. According to an embodiment of the present disclosure, unreasonable configuration or triggering of the PSCell change may result in ping-pong in a PSCell change during the PSCell procedure. The PSCell change includes a normal PSCell change, a conditional handover with SCG, a CPAC, an S-CPAC, etc.

[0081] According to embodiments of the present disclosure, under the dual connectivity, the master node may also be called the master base station, and the secondary node may also be called the secondary base station.

[0082] As understood by those skilled in the art, a "timer" as described in this disclosure may also be referred to as a timing or a time, and these terms are used interchangeably in this disclosure.

[0083] As understood by those skilled in the art, in this disclosure, a conditional PSCell change (CPC) and a conditional PSCell addition (CPA), or a subsequent conditional PSCell addition or change (S-CPAC) may also be considered as a handover or modification of the cell.

[0084] Note that herein, unless explicitly stated to the contrary, "base station" and "node" are used interchangeably, e.g., a master node may also be referred to as a master base station, a secondary node may also be referred to as a secondary base station, a source node may also be referred to as a source base station, a target node may also be referred to as a target base station, a candidate node may also be referred to as a candidate base station, other nodes may also be referred to as other base station, and so on, to name a few. The other base station or node may also be a central unit (CU) in the base station and may also be a central unit control plane (CU-CP) in the base station. The nodes may also be other functional entities in a Radio Access Network (RAN), to which the disclosure is not limited.

[0085] An example of Method 1 of the present disclosure that supports self-configuration and self-optimization is shown in Figure 3. The method comprises the steps of:

[0086]

[0087] Step 301: a UE fails and saves information related to a failure.

[0088] The failure may be one or more of an S-CPAC execution failure, a SCG failure after an S-CPAC execution, and a Radio Link Failure (RLF) after an S-CPAC execution, but the present disclosure is not limited thereto, it can also be other types of failures that occur in the secondary cell. The information related to the failure includes information on the secondary cell group failure (SCG failure information).

[0089] Step 302: the UE sends the information related to the failure to the master node. The information related to the failure includes information on the secondary cell group failure.

[0090] The information on the secondary cell group failure includes one or more of the following information elements:

[0091] - indication information on whether a Subsequent CPAC (S-CPAC) is executed;

[0092] - a time duration from the Subsequent CPAC execution to the failure;

[0093] - a cell identity of a failed PSCell. The cell identity may be a global cell identity, or a physical cell identity and frequency information. The global cell identity may also contain a Tracking Area Code, TAC, or a tracking area identity of the cell; for a failure in a PSCell change procedure, the cell identity of the failed PSCell is the cell identity of a target PSCell;

[0094] - a cell identity of a source PSCell of the latest PSCell change. The cell identity may be a global cell identity, or a physical cell identity and frequency information. It may also contain a tracking area code TAC or a tracking area identity of the cell; in the S-CPAC procedure, the cell identity is a cell identity of a source PSCell of the latest CPAC execution. The latest CPAC execution may be an initial S-CPAC execution or a following S-CPAC execution. For the following S-CPAC executions, the source PSCell of the latest CPAC execution is a candidate PSCell of the S-CPAC, and information on the candidate PSCell is included in a conditional reconfiguration information element (ConditionalReconfiguration IE). The cell identity of the source PSCell of the recent PSCell change may also be called previousPSCellId;

[0095] - a cell list of subsequent CPAC candidate PSCells. A candidate PSCells list of the subsequent CPAC, or indication information on being candidate PSCell of the subsequent CPAC for cells in measurement result may be included, and one or more PSCells that are candidate PSCells of subsequent CPAC but not in the measurement result may also be included in the secondary cell group failure information. Each candidate PSCell includes a cell identity, which may be a global cell identity. The cell identity may also include a tracking area code TAC;

[0096] - subsequent CPAC execution condition(s). Subsequent CPAC execution condition(s) can be one or more. For each candidate PSCell, there are one or more execution conditions;

[0097] - a time duration from reception of a subsequent CPAC configuration by the UE to the failure;

[0098] - a time duration from reception of the subsequent CPAC configuration by the UE to the subsequent CPAC execution;

[0099] - when a subsequent CPAC execution condition is fulfilled for execution, indication information corresponding to the subsequent CPAC execution condition being fulfilled for execution, and / or cell identity information of the PSCell corresponding to the execution condition being fulfilled;

[0100] - information on the subsequent CPAC execution condition which was fulfilled first;

[0101] - a time duration between two subsequent CPAC execution conditions being fulfilled, for example the time duration may be a time duration between two subsequent CPAC execution conditions being fulfilled;

[0102] - indication information on the subsequent CPAC, the indication information being indication information that the subsequent CPAC is configured;

[0103] - status of an SCG, e.g., whether the SCG is activated or deactivated, e.g., SCG Suspend;

[0104] - initial S-CPAC execution condition(s). The initial S-CPAC execution condition(s) are configured by a master node if the S-CPAC is triggered by the master node, and the initial S-CPAC execution condition(s) are configured by a source secondary node if the S-CPAC is triggered by the source secondary node. The S-CPAC execution condition(s) can be one or more. There are one or more S-CPAC execution conditions for each candidate PSCell;

[0105] - following S-CPAC execution condition(s). The following S-CPAC execution condition(s) are configured by the candidate secondary node. The following S-CPAC execution conditions can be one or more. There are one or more S-CPAC execution conditions for each candidate PSCell;

[0106] - an SCG failure time, which indicates a time duration from the recent execution of an RRC reconfiguration message containing information on a PSCell handover to the SCG failure. For the S-CPAC procedure, the SCG failure time is a time duration from the recent execution of the RRC reconfiguration message contained in the conditional reconfiguration information element (IE,ConditionalReconfiguration) to the failure. The conditional reconfiguration information element is sent to the UE by the network and contains S-CPAC configuration or configuration information, and the S-CPAC configuration includes at least one of: information on S-CPAC candidate cells, the initial S-CPAC execution condition(s), the following S-CPAC configuration, and conditional RRC reconfiguration corresponding to the S-CPAC candidate cell(s). The following S-CPAC configuration includes a candidate cell list for the following S-CPAC procedure and the S-CPAC execution condition(s) for each candidate cell, when each candidate PSCell of the S-CPAC is used as a serving PSCell. The conditional RRC reconfiguration includes the RRC reconfiguration message;

[0107] - indication information on an initial S-CPAC failure or a following S-CPAC failure;

[0108] - status of an MCG (Master Cell Group), such as whether the MCG is active or inactive, and such as the MCG is suspended;.

[0109] - indication information on the S-CPAC being triggered by an MN or an SN.

[0110] The above-mentioned failure may be an SCG failure, but the present disclosure is not limited thereto, and may also be other types of failures that occur in the secondary cell.

[0111] Step 303: the master node (MN) decides which node causes the failure. For example, it may be decided whether the node causing the failure is a master node or a source secondary node (source SN) or a target secondary node or other candidate target secondary nodes. In the embodiment of the present disclosure, in the S-CPAC, the source secondary node is a source secondary node of the recent S-CPAC, and the source PSCell is a source PSCell of the recent S-CPAC. The target secondary node or candidate target secondary node is a target secondary node or candidate target secondary node of the recent S-CPAC. The recent S-CPAC can also be said to be the latest PSCell change during the S-CPAC procedure.

[0112] The master node can also directly forward the SCG failure information to the secondary node where the failure occurred.

[0113] The master node determines which node causes the failure based on the information in the SCG failure information received from the UE and / or information saved by the MN.

[0114] The master node may also determine a type of failure, such as too early PSCell change, too late PSCell change or triggering a PSCell change to a wrong PSCell.

[0115] If the UE has an SCG failure after staying a PSCell for a long time, for example, the UE does not report the time duration from the S-CPAC execution to the failure occurring or the time duration from the S-CPAC execution to the failure occurring reported by the UE is larger than a configured threshold, there is a suitable PSCell different from the PSCell where the UE stayed when the failure occurred, then it is the too late S-CPAC execution. The MN knows the suitable PSCell based on a measurement report received from the UE, or the MN knows the suitable PSCell based on the measurement report received from the UE and information saved by the MN.

[0116] Too early PSCell change: there is a recent S-CPAC execution or PSCell change before the failure occurred e.g. according to indication of the S-CPAC execution or according to the time duration from the S-CPAC execution to the failure occurring being smaller than a configured threshold, and the source PSCell is a suitable PSCell then it is the too early PSCell change. The MN or the source node that triggered the PSCell change knows the suitable PSCell from the measurement report received from the UE, or the MN or the source node that triggered the PSCell change knows the suitable PSCell from the measurement report received from the UE and information saved by the MN or the source node that triggered the PSCell change. The SCG failure can be a failure that occurs shortly after a successful change from the source PSCell to the target PSCell or a failure that occurs during the PSCell change procedure. The source PSCell is a source PSCell of the latest PSCell change.

[0117] Too early S-CPAC execution: the S-CPAC execution fails or the SCG failure occurs shortly after the successful S-CPAC execution, there is no suitable PSCell based on the measurement report received from the UE, or it is known that there is no suitable PSCell based on the measurement report received from the UE and information saved by the node. For example, based on the indication of the S-CPAC execution or based on the time duration from the S-CPAC execution to the failure occurring being smaller than a configured threshold, and there is no suitable PSCell, then it is the too early S-CPAC execution. The MN knows that there is no suitable PSCell from the measurement report received from the UE, or the MN knows that there is no suitable PSCell from the measurement report received from the UE and information saved by the MN.

[0118] Trigger of PSCell change to wrong PSCell: there is a recent S-CPAC execution or PSCell change before the failure occurred, for example, according to the indication of the S-CPAC execution or according to the time duration from the S-CPAC execution to the failure occurring being smaller than a configured threshold, the suitable PSCell is not the source PSCell or the target PSCell, then it is the trigger of the PSCell change to the wrong PSCell. The MN knows the suitable PSCell based on the measurement report received from the UE, or the MN knows the suitable PSCell based on the measurement report received from the UE and information saved by the MN. The SCG failure can be a failure that occurs shortly after a successful change from the source PSCell to the target PSCell or a failure that occurs during the PSCell change procedure. The source PSCell is a source PSCell of the latest PSCell change. The target PSCell is a target PSCell of the latest PSCell change.

[0119] For the too late PSCell change, the MN and the source SN are the node that causes the failure.

[0120] For the too early PSCell change, if the PSCell change is triggered by the MN and is the initial S-CPAC, then the MN is the node that causes the failure. If the PSCell change is triggered by the source SN and is the initial S-CPAC, the source SN is the node that causes the failure. If the MN triggers the corresponding CPA execution too early, the MN is the node that causes the failure. For the following too early PSCell change, the SN of the corresponding source PSCell is the node that causes the failure.

[0121] For the trigger of the PSCell change to the wrong PSCell, if the PSCell change is triggered by the MN and is the initial S-CPAC, the MN is the node that causes the failure. If the PSCell change is triggered by the source SN and is the initial S-CPAC, the source SN is the node that causes the failure. For the following trigger of the PSCell change to the wrong PSCell, the SN of the corresponding source PSCell is the node that causes the failure.

[0122] For the trigger of the PSCell change to the wrong PSCell, the MN can further determine whether the failure is caused by unreasonable S-CPAC candidate cell configuration or unreasonable S-CPAC execution condition configuration. If the suitable cell is not among the S-CPAC candidate cells configured to the UE, it is a failure caused by unreasonable S-CPAC candidate cell configuration. For the initial S-CPAC, the source base station triggering the PSCell change causes the problem if the suitable cell is not in the S-CPAC candidate cell list recommended by the source base station triggering the PSCell change (the MN or source SN), e.g. the MN causes the problem if the PSCell change is triggered by the MN, the source SN causes the problem if the PSCell change is triggered by the source SN. If the suitable cell is in the S-CPAC candidate cell list recommended by the source base station (the MN or the source SN) that triggered the PSCell change, but is not in the candidate PSCell list selected by the target SN or candidate target SN, the failure is caused by the target SN or the candidate target SN. For the following S-CPAC, if the suitable cell is not in the S-CPAC candidate cell list configured by the source secondary base station of the following S-CPAC, the problem is caused by the corresponding source secondary base station.

[0123] The MN or the source SN can also determine whether the failure is caused due to unsuitable setting of the estimated reachability. For example, the estimated reachability, which is sent to the candidate target SN by the MN or by the source SN through the MN, is set too low, resulting in that the target SN or the candidate SN do not select the candidate cell as the selected candidate cell or does not allocate suitable resources to the candidate cell in time, and the suitable cell is in the candidate SN. In this case, the MN or the source SN is the node that causes the failure. If the estimated reachability is decided by the source SN, the failure is caused by the source SN.

[0124] The MN or the source SN can also determine whether the failure is caused by unsuitable setting of the maximum number of prepared PSCells. For example, the maximum number of the prepared PSCells which is sent to the candidate target SN by the MN or by the source SN through the MN, is too low, resulting in that the target SN or the candidate SN do not select the candidate cell as the selected candidate cell, and the suitable cell is in the candidate SN. In this case, the MN or the source SN is the node that causes the failure. If the estimated reachability is decided by the source SN, the failure is caused by the source SN.

[0125] The above description of triggering the PSCell change to the wrong PSCell takes the CPC as an example, and the same applies to the procedure of the CPA and the procedure of the S-CPAC.

[0126] If the MN is the node that causes the failure, step 304 does not need to be performed. If the problem is caused by the source SN, the target SN, or the candidate target SN, step 304 is performed.

[0127] Step 304: the master node sends an secondary cell group failure indication or report to the node that causes the failure. The node causing the failure can be the source SN, the target SN or the candidate target SN.

[0128] According to the description in step 303, the MN knows whether the failure is caused by the source SN, the target SN or the candidate target SN.

[0129] The MN can send information on the secondary cell group failure to the node causing the problem through a secondary cell group failure information report message or other messages.

[0130] The message sent by the master node to the node causing the problem contains one or more of the following information elements:

[0131] - a cell identity of the source PSCell;

[0132] -a cell identity of the target PSCell or a cell identity of the failed PSCell;

[0133] -a cell identity of the suitable PSCell;

[0134] -SCG failure information received from the UE;

[0135] -a list of candidate PSCells recommended by the MN or the source SN; each candidate PSCell includes a cell identity, which may be a global cell identity, which may also include a tracking area code (TAC);

[0136] -initial S-CPAC execution condition(s), there are one or more execution conditions for each candidate PSCell;

[0137] -following S-CPAC execution conditions, there are one or more execution conditions for each candidate PSCell;

[0138] -a list of candidate PSCells selected by the target SN or candidate target SN; each candidate PSCell includes a cell identity, which may be a global cell identity, which may also include a tracking area code (TAC). The message may include the list of candidate PSCells selected by the target SN or the candidate target SN, or by including indication information whether a PSCell is selected by the target SN or the candidate target SN in the list of candidate PSCells recommended by the MN or the source SN, the target SN or the candidate target SN knows which candidate PSCell in the candidate PSCell list recommended by the MN or the source SN is selected by the target SN or the candidate target SN and which candidate PSCell is not selected by the target SN or the candidate target SN according to the indication information in the list of candidate PSCells recommended by the MN or the source SN;

[0139] -a list of PSCells that are not selected by the target SN or the candidate target SN in the list of candidate PSCell recommended by the MN or the source SN;

[0140] -maximum number of prepared PSCells;

[0141] -estimated reachability;

[0142] -an SCG failure time;

[0143] -a type of failure, including the too early PSCell change, the too late PSCell change, the trigger of the PSCell change to the wrong PSCell, the unsuitable S-CPAC candidate cell configuration, the unsuitable S-CPAC execution condition, the unsuitable maximum number of prepared PSCells, and / or the unsuitable estimated reachability configuration. The information is included when the MN determines the type of failure, and is not included if the type of failure is determined by the SN that causes the problem.

[0144] If the MN only determines which node causes the failure, the source SN, target SN or candidate target SN determines the type of failure after receiving the message from the MN, For example, the too early PSCell change, the too late PSCell change or the trigger of the PSCell change to the wrong PSCell.

[0145] If the UE has an SCG failure after staying a PSCell for a long time, for example, the UE does not report the time duration from the S-CPAC execution to the failure occurring or the time duration from the S-CPAC execution to the failure occurring reported by the UE is larger than a configured threshold, there is a suitable PSCell different from the PSCell where the UE stayed when the failure occurred, then it is the too late S-CPAC execution.. The SN knows the suitable PSCell based on the measurement report received from the UE, or the SN knows the suitable PSCell based on the measurement report received from the UE and the information saved by the SN. The measurement report received from the UE is received through the SCG failure information received by the MN from the UE.

[0146] Too early PSCell change: there is a recent S-CPAC execution or PSCell change before the failure occurred, for example, according to indication of the S-CPAC execution or according to the time duration from the S-CPAC execution to the failure occurring being smaller than a configured threshold, and the source PSCell is a suitable PSCell, then it is the too early PSCell change. The SN knows the suitable PSCell based on the measurement report received from the UE, or the SN knows the suitable PSCell based on the measurement report received from the UE and the information saved by the SN. The SCG failure can be a failure that occurs shortly after a successful change from the source PSCell to the target PSCell or a failure that occurs during the PSCell change procedure. The source PSCell is a source PSCell of the recent PSCell change. The measurement report received from the UE is received through the SCG failure information received by the MN from the UE.

[0147] Trigger of PSCell change to wrong PSCell: there is a recent S-CPAC execution or PSCell change before the failure occurred, for example, according to the indication of the S-CPAC execution or according to the time duration from the S-CPAC execution to the failure occurring being smaller than a configured threshold, the suitable PSCell is not the source PSCell or the target PSCell, then it is the trigger of the PSCell change to the wrong PSCell. The SN knows the suitable PSCell based on the measurement report received from the UE, or the SN knows the suitable PSCell based on the measurement report received from the UE and the information saved by the SN. The SCG failure can be a failure that occurs shortly after a successful change from the source PSCell to the target PSCell or a failure that occurs during the PSCell change procedure. The source PSCell is a source PSCell of the recent PSCell change. The target PSCell is a target PSCell of the recent PSCell change. The measurement report received from the UE is received through the SCG failure information received by the MN from the UE.

[0148] The source SN can further determine whether the failure is caused by unreasonable CPC / S-CPAC candidate cell configuration or unreasonable CPC / S-CPAC execution condition configuration. If the suitable cell is not among the CPC / S-CPAC candidate cells configured to the UE, the failure is caused by unreasonable CPC / S-CPAC candidate cell configuration. If the suitable cell is not in the list of CPC / S-CPAC candidate cells recommended by the source SN triggering the PSCell change, the problem is caused by the source SN triggering the PSCell change. If the suitable cell is in the list of CPC / S-CPAC candidate cells recommended by the source SN that triggered the PSCell change, but is not in the list of candidate PSCells selected by the target SN or candidate target SN, the failure is caused by the target SN or candidate target SN. For the trigger of the PSCell change to the wrong PSCell, the source SN can further determine whether the failure is caused by unreasonable candidate cell configuration. The source SN may determine whether the failure is caused by unsuitable maximum number of prepared PSCells and / or unsuitable estimated reachability configuration.

[0149] For failures caused by the target SN or the candidate target SN, there are two modes in the present disclosure to indicate the failure to the target SN or candidate target SN:

[0150] Mode 1: the MN determines that the problem is caused by the target SN or the candidate target SN. The specific method is as described in step 303. The MN sends indication or report information on the SCG failure to the target SN or candidate target SN. The message includes a list of candidate PSCells recommended by the MN or the source SN, indication information that a PSCell in the list of the candidate PSCells recommended by the MN or the source SN is accepted by the target SN or the candidate target SN, indication information that a PSCell in the list of candidate PSCells recommended by the MN or the source SN is not accepted by the target SN or the candidate target SN, the maximum number of prepared PSCells, a list of candidate PSCells selected by the target SN or the candidate target SN, a cell identity of the suitable PSCell, SCG failure information, a cell identity of the source PSCell, a cell identity of the target PSCell, a cell identity of the failed PSCell, a cell identity of the suitable PSCell which is not selected by the target SN or the candidate target SN, indication information that the selected candidate PSCell is not suitable, and / or an SCG failure time. The SCG failure information is the SCG failure information received from the UE. Each candidate PSCell includes a cell identity, which may be a global cell identity, which may also include a tracking area code (TAC).

[0151] Mode 2: the MN sends indication or report information on the SCG failure to the source SN, and the source SN further determines the type of failure. If the source SN determines the problem is caused by the target SN or the candidate target SN, the source SN sends a message to the MN. The message sent by the source SN to the MN comprises an MN UE Access Protocol (AP) identity, an SN UE AP ID, a list of candidate PSCells recommended by the MN or the source SN, indication information that a PSCell in the list of the candidate PSCells recommended by the MN or the source SN is accepted by the target SN or the candidate target SN, indication information that a PSCell in the list of candidate PSCells recommended by the MN or the source SN is not accepted by the target SN or the candidate target SN, the maximum number of prepared PSCells, a list of candidate PSCells selected by the target SN or the candidate target SN, a cell identity of the suitable PSCell, SCG failure information, a cell identity of the source PSCell, a cell identity of the target PSCell, a cell identity of the failed PSCell, a cell identity of the suitable PSCell which is not selected by the target SN or the candidate target SN, indication information that the selected candidate PSCell is not suitable, and / or an SCG failure time. Each candidate PSCell includes a cell identity, which may be a global cell identity, which may also include a tracking area code (TAC). The source SN can send the above information to the MN through an SCG failure transfer message or other messages. The MN sends a message to the target SN or candidate target SN, and information contained in the message is the same as those in Mode 1 and will not be described again here.

[0152] The source SN may also determine whether the failure is caused by an improper setting of the estimated reachability, for example, the estimated reachability sent by the source SN to the candidate target SN via the MN is set too low, and the suitable cell is at the candidate SN. In this case, the source SN is the node causing the failure. The source SN can also determine whether the failure is caused by the unsuitable setting of the maximum number of prepared PSCells. For example, the maximum number of prepared PSCells sent by the source SN to the candidate target SN via the MN is too low, resulting in that the target SN or the candidate SN does not select the suitable cell as the selected candidate cell, and the suitable cell is at the candidate SN. In this case, the source SN is the node causing the failure.

[0153] The node causing the failure (the source SN, the target SN or the candidate target SN, or the MN) optimizes the CPC reasonably.

[0154] The above description of the trigger of the PSCell change to the wrong PSCell is taking the CPC as an example, and the same applies to the procedure of the CPA.

[0155] At this point, the Method 1 for supporting self-configuration and self-optimization of the present disclosure is completed, which can support the robustness of the PSCell change during the enhanced mobility procedure, for example, in the S-CPAC, correctly identify a cause of the failure, in order to perform reasonable optimization, reduce occurrence of failures, ensure service continuity, and reduce labor costs of operators.

[0156] An example of Method 2 of the present disclosure that supports self-configuration and self-optimization is shown in Figure 4. This method may be used for how to configure a successful PSCell change or addition report of a UE during secondary node addition and / or change procedure in the S-CPAC. In embodiments of the present disclosure, the secondary node addition and / or change may also be referred to as a secondary node modification, and the PSCell change or addition may also be referred to as a PSCell modification.

[0157] In embodiments of the present disclosure, each node may be as follows:

[0158] A first node is a single base station or a single node in the case of a single connectivity; and a Master node (MN) in the case of a dual connectivity;

[0159] A second node is a candidate target secondary node or target secondary node. In the S-CPAC, there may be one or more candidate target secondary nodes;

[0160] A third node is the source secondary node in the case of a dual connectivity.

[0161] If the first node triggers the S-CPAC, the method includes steps 401-405.

[0162] If the third node triggers the S-CPAC, the method includes steps 400-405.

[0163] The specific steps are described as follows:

[0164] Step 400: the first node receives third configuration information and / or fourth configuration information on successful PSCell change report sent by the third node.

[0165] Under the dual connectivity, if the third node, that is, the source secondary node (S-SN), triggers the S-CPAC, the S-SN will provide the third configuration information on the successful PSCell change report. The third configuration information is used for triggering / generating a successful PSCell report during the initial S-CPAC execution, i.e., the initial CPC execution.

[0166] The third configuration information on the successful PSCell change report includes at least one of the following information:

[0167] - the timer T310 and / or T312 trigger(s) in successful PSCell change report (SPR) configuration. The configuration includes at least one of the following information:

[0168] ■a threshold of the timer T310 and / or a threshold of the timerT312. Herein, the threshold is a timer percentage threshold.

[0169] if the cell in the source SN is a candidate PSCell of the S-CPAC, the source SN will also provide the fourth configuration information on the successful primary SCG cell change report. The fourth configuration information includes successful primary SCG cell change reporting (SPR) configuration the timer T304 trigger. In the S-CPAC, during the following S-CPAC, the third node serves as the target secondary node or the candidate target secondary node, and the configuration is used as configuration of the successful primary SCG cell change report provided by the target secondary node or the candidate target secondary node. The configuration includes at least one of the following information:

[0170] ■a threshold of the timer T304.

[0171] In an embodiment of the disclosure, the threshold is a timer percentage threshold.

[0172] Step 401: the first node receives the first configuration information on the successful primary SCG cell change report sent from the second node.

[0173] In the embodiment of the present disclosure, the successful primary SCG cell change report and its configuration are also applicable to the situation of secondary cell addition, and the successful primary SCG cell change report can also be called a successful primary SCG cell change or addition report, and the configuration of the successful primary SCG cell change report can also be called configuration of the primary SCG cell change report or addition report. For convenience of description, the successful primary SCG cell change report and the configuration of the successful primary SCG cell change report are uniformly used in the present disclosure.

[0174] The first configuration information on the successful primary SCG cell change report includes at least one of the following information:

[0175] - timer T310 and / or T312 trigger(s) in successful primary SCG cell change report (SPR) configuration. In the S-CPAC, after the UE executes the S-CPAC and accesses to the second node, the second node will serve as the source node of the UE during the following S-CPAC, and the configuration is used as the successful primary SCG cell change report configuration provided by the source secondary node. The configuration includes at least one of the following information:

[0176] ■a threshold of the timer T310 and / or a threshold of the timer T312.

[0177] - timer T304 trigger in successful primary SCG cell change report (SPR) configuration . In the S-CPAC, during the initial S-CPAC or the following S-CPAC, the second node serves as the target secondary node or the candidate target secondary node, and the configuration is used as configuration of the successful primary SCG cell change report provided by the target secondary node or the candidate target secondary node. The configuration includes at least one of the following information:

[0178] ■ a threshold for the timer T304.

[0179] In an embodiment of the present disclosure, the threshold is a timer percentage threshold.

[0180] When the first node triggers the S-CPAC, the first node selects a candidate PSCell, sends a message to the node to which the candidate PSCell belongs (the second node, that is, the target SN or the candidate target SN), to request configuration of the candidate PSCells for the S-CPAC and provides related configuration. The message may be an SN addition request message, or a request message.

[0181] The second node sends to the first node a response message. The message includes the first configuration information on the successful primary SCG cell change report. The message may be an SN addition request acknowledge message, or other messages.

[0182] Step 402: the first node sends, to the UE, the first configuration information on the successful primary SCG cell change report and / or the second configuration information on the successful primary SCG cell change report and / or the third configuration information on the successful primary SCG cell change report and / or the fourth configuration information on the successful primary SCG cell change report.

[0183] Under the dual connectivity, if the first node, that is, the master node (MN), triggers the S-CPAC, the MN will provide the second configuration information on the successful primary SCG cell change report to the UE. The configuration information is used for triggering / generating a successful primary SCG cell change report during the initial S-CPAC execution, that is, during the initial CPC execution. If the third node, that is, the source secondary node (S-SN), triggers the S-CPAC, the MN sends the third configuration information on the successful primary SCG cell change report and / or the fourth configuration information on the successful primary SCG cell change report provided by the S-SN received in step 400 to the UE.

[0184] The first configuration information is received by the first node from the second node in step 401.

[0185] The second configuration information on the successful primary SCG cell change report includes at least one of the following information:

[0186] - the timer T310 and / or T312 trigger(s) in successful primary SCG cell change report (SPR) configuration. The configuration includes at least one of the following information:

[0187] ■a threshold of the timer T310 and / or a threshold of the timer T312. Herein, the threshold is a timer percentage threshold.

[0188] When the first node triggers the S-CPAC,

[0189] - if it is a single connectivity situation, in step 402, the first node sends the first configuration information on the successful primary SCG cell change report received from step 401 to the UE.

[0190] - if it is a dual connectivity situation, in step 402, the first node sends the first configuration information on the successful primary SCG cell change report received from step 401 and / or the second configuration information on the successful primary SCG cell change report provided by the MN to the UE.

[0191] When the second node triggers the S-CPAC,

[0192] - the first node sends, to the UE, the third configuration information on the successful primary SCG cell change report and / or the fourth configuration information on the successful primary SCG cell change report provided by the S-SN which is received in step 400, and / or the first configuration information on the successful primary SCG cell change report received in step 401.

[0193] The UE saves the successful primary SCG cell change report. When the configuration of the successful primary SCG cell change report is fulfilled, the UE saves information on the successful primary SCG cell change report.

[0194] The information saved by the UE includes one or more of the following:

[0195] - a time duration from reception of the successful primary SCG cell change report configuration to transmission of the successful primary SCG cell change report;

[0196] - a time duration from the UE saving the successful primary SCG cell change report to the UE sending the successful primary SCG cell change report;

[0197] - a time duration from executing the primary SCG cell change or addition to sending the primary SCG cell change report;

[0198] - cell information on the primary cell when the primary SCG cell is changed or added. The cell information on the primary cell includes a cell identity of the primary cell and / or a tracking area identity where the primary cell is located. The primary SCG cells change or addition corresponds to a primary SCG cell change or addition corresponding to the successful primary SCG cell change report;

[0199] - cell information on the source PSCell. The cell information includes a cell identity of the cell and / or a tracking area identity where the cell is located. The identity can be represented using sourcePSCellId. In the S-CPAC, the source PSCell is a source PSCell of the latest PSCell change. For example, if the report is sent by the UE due to the initial S-CPAC execution, the source PSCell is the initial source PSCell, that is, the PSCell in the initial source SN. If the report is sent by the UE due to the following S-CPAC execution, then the source PSCell is a PSCell in the source SN of the latest PSCell change;

[0200] - a cell identity of the target PSCell. The cell information includes the cell identity of the cell and / or a tracking area identity where the cell is located. The identity can be represented using targetPSCellID. In the S-CPAC, the target PSCell is the PSCell that the UE accesses after executing the S-CPAC. The S-CPAC execution comprises the initial S-CPAC and the following S-CPAC execution;

[0201] - a C-RNTI (Cell-Radio Network Temporary Identifier) assigned by the source PSCell, the source PSCell being the same as above;

[0202] - a C-RNTI assigned by the target PSCell, the target PSCell being the same as above;

[0203] - a cell identity of the PCell;

[0204] - a C-RNTI assigned by the PCell;

[0205] - UE location information;

[0206] - a cause of the successful PSCell change report, that is, a cause of triggering the SPR. The cause includes:

[0207] ■a cause of the timer T310 or T312;

[0208] ■a cause for the timer T304;

[0209] ■a cause for the timer T316.

[0210] - common random access information;

[0211] - for the CPC or CPA, the successful primary SCG cell change report sent by the UE may also include the time duration from the CPC or CPA configuration to the CPC or CPA execution;

[0212] - whether the MN or the SN initiates the primary SCG cell change;

[0213] - measurement result of the UE;

[0214] - a threshold of the T310, a threshold of the T312 and / or a threshold of the T304 configured by the MN. When the MN configures the threshold of the T310, the threshold for the T312, and / or the threshold of the T304, the successful primary SCG cell change report includes the threshold of the T310, the threshold of the T312, and / or the threshold of the T304;

[0215] - mobility information of the UE in the PCell of the MN, mobility information of the UE in the source PSCell, and / or mobility information of the UE in the target PSCell;

[0216] - information on whether the MN or the SN initiates the primary SCG cell change, received by the UE from the RRC reconfiguration message;

[0217] - a time duration from the S-CPAC configuration to the initial S-CPAC execution;

[0218] - whether the MN or the SN initiates the S-CPAC;

[0219] - information on whether the S-CPAC is initiated by the MN or the SN, received by the UE from the RRC reconfiguration message.

[0220] Step 403: the UE sends a message to the first node or the fourth node, the message contains information on the successful primary SCG cell change report being available. In an embodiment of the present disclosure, the fourth node may also be the second node or the third node. If the UE has the saved successful primary SCG cell change report, the UE sends information on the successful primary SCG cell change report being available to the first node or the fourth node. The method for the UE to save the successful primary SCG cell change report is the same as in step 402, and will not be described again here.

[0221] The message may be an RRC reconfiguration complete message, an RRC reestablishment complete message, an RRC establishment complete message, or other messages.

[0222] Step 404: the first node or the fourth node requests the successful primary SCG cell change report from the UE, and receives the successful primary SCG cell change report sent by the UE. The first node or the fourth node may request the successful primary SCG cell change report through a UE information request message or other message. The first node or the fourth node receives the successful primary SCG cell change report sent from the UE. The UE may send information on the successful PSCell change report to the first node or the fourth node through a UE information response message or other RRC messages.

[0223] The successful primary SCG cell change report (SPR) includes the same as step 402 and will not be described again here.

[0224] If the fourth node receives the successful primary SCG cell change report (SPR), the fourth node sends the received SPR to the first node. The fourth node knows the first node according to the cell identity of the Pcell in the received message.

[0225] Step 405: the first node sends the received SPR to the relevant node. The relevant node is a node that needs to perform cause analysis or a node that needs to perform optimization. The relevant node may be a MN, or a source SN, or a target SN, or a candidate target SN.

[0226] The first node determines which node the SPR is sent to based on the information contained in the received SPR. The specific determination method is as follows:

[0227] When the first node triggers the S-CPAC,

[0228] - if the cause of triggering the SPR is the timer T310 and / or T312:

[0229] ■if the received source PSCell identity (sourcePSCellId) is an identity of the source PSCell when executing the initial S-CPAC, root cause analysis and optimization is performed by the first node;

[0230] ■if the received source PSCell identity (sourcePSCellId) is an identity of the source PSCell when executing the following S-CPAC, the first node sends the SPR to the SN controlling the cell indicated by the sourcePSCellId, that is, the SN of the cell indicated by the sourcePSCellId is located, that is, the current source SN.

[0231] - if the cause of triggering the SPR is the timer T304:

[0232] ■the first node sends the SPR to the SN controlling the cell indicated by the target PSCell identity (targetPSCellID), that is, the target SN.

[0233] When the third node triggers the initial S-CPAC,

[0234] - if the cause of triggering the SPR is the timer T310 and / or T312:

[0235] ■the first node sends the SPR to the SN controlling the cell indicated by the sourcePSCellId, that is, the source SN.

[0236] - if the cause of triggering the SPR is the timer T304:

[0237] ■the first node sends the SPR to the SN controlling the cell indicated by the targetPSCellID, that is, the target SN.

[0238] In the S-CPAC, after the UE completes the initial S-CPAC execution and successfully accesses the target PSCell (at this time, the target SN becomes the new source SN, that is, the current source SN), the UE determines whether to generate the SPR report based on SPR configuration of the new source SN and target SN or candidate target SN. Therefore, steps 403-405 will be repeated.

[0239] In the embodiment of the present disclosure, in the following S-CPAC, the UE will determine whether to generate the SPR report based on the configuration of the successful primary SCG cell change report provided by the current source SN, and the configuration of the successful primary SCG cell change report provided by the candidate target SN corresponding to the current source SN.

[0240] At this point, the Method 2 of supporting self-configuration and self-optimization of the present disclosure is completed. This method can support, in the case of the successful primary SCG cell change or addition, for example, during the S-CPAC procedure, correct identification of potential failures, for performing reasonable optimization, avoiding occurrence of failures, ensuring service continuity, and reducing labor costs of operators.

[0241] An example of Method 3 of the present disclosure that supports self-configuration and self-optimization is shown in Figure 5. This method may be used in the S-CPAC during the secondary node addition and / or change procedure to provide detection of whether there is ping-pong in the PSCell change. In embodiments of the present disclosure, the secondary node addition and / or change may also be referred to as the secondary node modification, and the PSCell change or addition may also be referred to as the PSCell change. The specific steps of Method 3 are described as follows:

[0242] Step 501: a UE accesses a target PSCell and sends a message to a master node.

[0243] In the S-CPAC, the UE evaluates execution conditions and accesses a candidate PSCell that fulfills the execution conditions. The UE sends a message to the master node, the message includes information on the target PSCell selected by the UE, an SN RRC response which need to be sent to the target SN, and also includes an RRC reconfiguration message sent by the UE to the SN.

[0244] The message may be an RRC reconfiguration complete message, or other messages.

[0245] Step 502: the master node sends SCG history information on the UE to the target secondary node.

[0246] When the master node receives the information on the target PSCell selected by the UE, the master node sends a message to the target SN. The message contains the SCG history information of the UE. The message may be an SN reconfiguration complete message, or other messages. The message contains at least one of the following information:

[0247] - SCG history information on the UE. The history information includes an information list of PSCells that the UE has visited. The information list includes information on one or more PSCells in the time order in which the UE accessed. The information on the PSCells includes at least one of the following information:

[0248] ■a cell identity, which is a cell identity of the PSCell, that is, a cell identity of the PSCell that the UE has visited. The identity may be a CGI, or other cell identity;

[0249] ■a UE staying time, that is, the time the UE stays in the cell;

[0250] ■a type of the cell.

[0251] - an RRC reconfiguration complete message, which is an RRC reconfiguration complete message sent by the UE to the SN.

[0252] In an embodiment of the present disclosure, in the S-CPAC, the UE will perform PSCell handover (or PSCell change) multiple times, so the same PSCell may appear in the list multiple times. The PSCell appearing at the most front of the list is the most recently accessed PSCell.

[0253] Step 503: the target secondary node saves the SCG history information on the UE. The SCG history information may be used to detect whether there is a ping-pong handover of the PSCell.

[0254] The target SN receives the SCG history information of the UE sent by the master node. Based on the history information, it can be determined the PSCell that the UE has accessed and the time the UE stayed in the PSCell, so as to detect whether there is ping-pong handover of the PSCell in the UE.

[0255] In the S-CPAC, the UE evaluates the execution conditions in the following S-CPAC, and selects the target PSCell for the handover (or change) among the candidate PSCells that fulfill the execution conditions. Since the UE will perform the following S-CPAC multiple times, such as performing the CPC multiple times, the PSCell change will be performed between candidate PSCells. Therefore, in the S-CPAC, steps 501-503 are repeated.

[0256] At this point, the Method 3 of supporting self-configuration and self-optimization of the present disclosure is completed. This method can support correctly identifying whether there is a ping-pong handover of PSCell in case of the successful primary SCG cell change or addition, for example, under the S-CPAC, in order to perform reasonable optimization, avoid unnecessary handover, avoid unnecessary processing by the network and the UE, ensure service continuity, and reduce labor costs of operators.

[0257] An example of Embodiment 1 of the Method 1 of supporting self-configuration and self-optimization of the present disclosure is shown in Figure 6. The steps of the method when it is applied to the initial S-CPAC are as follows.

[0258] The UE is in dual connectivity mode and is connected to an MN and a source SN (S-SN) at the same time.

[0259] Step 601: the S-SN sends an SN change required message to the MN. The message contains identities of candidate target nodes. The message may also contain a list of candidate PSCells proposed by the source SN and initial S-CPAC execution condition(s) of the S-CPAC, and the maximum number of PSCells that can be prepared by each candidate target SN. For the S- CPAC procedure triggered by the MN, this step does not need to be performed. Each candidate PSCell includes a cell identity, which may be a global cell identity. The global cell identity may also contain a Tracking Area Code (TAC). For each candidate PSCell, there are one or more execution conditions.

[0260] The MN saves information on the S-CPAC procedure triggered by the S-SN.

[0261] Step 602: the MN sends an SN addition request message to one or more target SNs or candidate target SNs. The message contains at least one of the following information:

[0262] - information indicating that the request is used for the S-CPAC;

[0263] - measurement results. If the S-CPAC is triggered by the MN, the measurement result is measurement result provided by the MN and contains measurement result of the candidate PSCells proposed by the MN; if the S-CPAC is triggered by the source SN, the measurement result is provided by the SN and may include measurement result for the cells that are not candidate PSCells of the S-CPAC;

[0264] - maximum number of candidate PSCells, which indicates the maximum number of candidate PSCells that the target SN or the candidate target SN can prepare;

[0265] - information on other candidate target SNs, which includes information on one or more other candidate target SNs. The information includes a list of candidate PSCells of each other candidate target SN, and the SN receiving the message selects the candidate PSCells for the next S-CPAC. If the MN triggers the S-CPAC, the list of candidate PSCells is provided by the MN; if the S-CPAC is triggered by the S-SN, the list of candidate PSCells is provided by the SN. The list of candidate PSCells may contain a list of candidate cell directly, or may be a measurement result.

[0266] The MN saves information whether the MN or the S-SN triggered the S-CPAC procedure.

[0267] Step 603: the target SN or other candidate target SN sends an SN addition request acknowledge message to the MN.

[0268] The message contains at least one of the following information:

[0269] - a list of prepared candidate PSCells. The target or candidate target SN selects the prepared candidate PSCells based on the candidate PSCell proposed by the MN or the S-SN;

[0270] - information on the next S-CPAC, for each prepared candidate PSCell there is one next S-CPAC information. The information includes at least one of the following information:

[0271] ■a list of candidate PSCells, containing candidate PSCells for the next S-CPAC;

[0272] ■execution conditions, including execution conditions for the next S-CPAC.

[0273] If the list of prepared candidate PSCells received from the candidate target SN is different from the list of candidate PSCells proposed in step 601 or 602, then steps 603a and 603b will be performed. Through an SN modification procedure, all candidate target SNs are provided with the list of prepared candidate PSCells updated by other candidate target SNs.

[0274] Step 603a: the MN sends a message to the candidate target SN for providing the list of prepared candidate PSCells updated by other candidate target SNs. The message may be an SN modification request message, or other messages.

[0275] Step 603b: the candidate target SN sends a message to the MN for confirmation. The updated SCG configuration and / or execution conditions for the following S-CPAC are provided. The message may be an SN modification request acknowledge message, or other messages.

[0276] Step 604, the MN send a radio resource control (RRC) reconfiguration message to the UE. The message includes the S-CPAC configuration.

[0277] Step 605: the UE saves the S-CPAC configuration and sends an RRC reconfiguration complete message to the MN. The RRC reconfiguration complete message is an RRC Reconfiguration Complete *.

[0278] The UE starts evaluating the execution conditions. In the S-CPAC, the execution condition evaluation is an initial execution condition evaluation, that is, an initial S-CPAC execution condition evaluation.

[0279] Step 605a: the MN sends an SN change acknowledge message to the source SN.

[0280] Step 606: if the execution condition of one candidate PSCell is satisfied, the UE sends the RRC reconfiguration complete message to the MN. The message contains information on the selected target PSCell. The UE uses the RRC reconfiguration message corresponding to the target PSCell for configuration. In the S-CPAC, the execution conditions are initial S-CPAC execution conditions. The RRC reconfiguration complete message is an RRC Reconfiguration Complete **.

[0281] Step 607: the UE performs a random access procedure to the target SN and synchronizes to the target SN.

[0282] The UE may fail when executing the initial S-CPAC to the target SN. In correspondence to the failure of the S-CPAC execution, step 607 fails to be executed or does not need to be executed.

[0283] According to an embodiment of the present disclosure, the order of steps 606 and 607 is not limited.

[0284] Steps 607a-607b: the MN triggers the SN modification request procedure, instructing the SN to stop sending data to the UE. The SN is a source SN or the last serving SN. If it is the source SN, when the source SN is the candidate target SN, the MN will trigger the SN modification request procedure, otherwise the MN will trigger an SN release procedure.

[0285] Step 608: an SCG failure occurs. The SCG failure may be a failure that occurs during the UE executes the initial S-CPAC and accesses the target SN, or a failure that occurs after executing the procedure of step 607. The UE saves information related to the failure. The information related to the failure is the information on the secondary cell group failure described in step 302, and will not be described again here.

[0286] Step 609: the UE sends SCG failure information to the MN. The information contained in the SCG failure information is the same as that described in step 302, and will not be described again here. The UE may send the SCG failure information in step 302 to the MN through an existing SCG failure information message or other RRC messages.

[0287] At step 610, the MN determines which node causes the failure. The determination method of the MN is the same as that in step 303 and will not be described again here. The MN can also further determine the type of the failure, and the specific determination method is the same as that in step 303 and will not be described again here.

[0288] If the failure is caused by the MN, the procedure ends and subsequent steps do not need to be performed.

[0289] For the problem caused by the source SN, step 611 is performed.

[0290] For the problem caused by the target SN or the candidate target SN, if the PSCell change is triggered by the MN, step 613 is performed directly. For the problem caused by the target SN or the candidate target SN, if the PSCell change is triggered by the source SN, in correspondence to the Mode 1 of the present disclosure (the Mode 1 in step 304), step 613 is directly executed; In correspondence to Mode 2 of the present disclosure (Mode 2 in step 304), step 611, step 612 and step 613 are performed.

[0291] Step 611: the MN sends a SCG failure information report message to the source SN. The information contained in the message is the same as that sent by the MN to the source SN in step 304, and will not be described again here. The message sent by the MN to the source SN may be an existing SCG failure information report or other messages. If the type of the failure is determined by the source SN, the determination method of the source SN is the same as that described in step 304.

[0292] If a suitable PSCell is recommended by the source SN and the target SN or the candidate target SNs does not select the suitable PSCell as the candidate PSCell, step 612 is performed.

[0293] Step 612: the source SN sends an SCG failure indication or an SCG failure transfer message to the MN, and information contained in the message is the same as the content sent to the MN by the source SN in step 304, and will not be described again here. The source SN may send the information described in step 304 to the MN through an existing SCG failure transfer messages or other messages.

[0294] Step 613: the MN sends the SCG failure information report to the target SN or other candidate target SNs. The information contained in the SCG failure information report is the same as the information sent by the MN to the target SN or other candidate target SNs in step 304, and will not be described again here. The MN can send the SCG failure information to the target SN or other candidate target SNs through an existing SCG failure information report or other messages.

[0295] At this point, the description of the embodiment of the Method 1 for supporting self-configuration and self-optimization of the present disclosure is completed. Through this embodiment, the robustness of the PSCell changes in the S-CPAC can be supported during the enhanced mobility procedure, the cause of failure is correctly identified, in order to perform reasonable optimization, reduce occurrence of the failure, ensure service continuity, and reduce labor costs of operators.

[0296] An example of Embodiment 2 of Method 1 of the present disclosure supporting self-configuration and self-optimization is shown in Figure 7. The steps of the method when it is used for the following S-CPAC are as follows.

[0297] The UE is in a dual connectivity mode and is connected to an MN and an source SN (S-SN) at the same time.

[0298] Steps 701-706 are the same as steps 601-606 and will not be described again here.

[0299] Step 706a: the MN sends an SN reconfiguration complete message to the target SN. According to information on the target PSCell selected by the UE received in step 706, if the target PSCell selected by the UE belongs to the target SN, the MN sends the SN reconfiguration complete message to the target SN, indicating the target PSCell selected by the UE.

[0300] Step 707: the UE performs a random access procedure to the target SN, synchronizes to the target SN, and accesses the target PSCell. The UE performs the initial S-CPAC and accesses the target cell. At this time, the target SN (SN2) becomes new source SN, and the target PSCell becomes new source PSCell. The candidate PSCell of the next S-CPAC configured by the target PSCell becomes the candidate PSCell, and the SN which the candidate PSCell belongs to is new candidate SN. If the cell of the initial source SN (SN1) is configured as the candidate PSCell of the following S-CPAC, then at this time, the initial source SN (SN1) also becomes the candidate target SN.

[0301] In the embodiment of the present disclosure, the order of steps 706 and 707 is not limited.

[0302] Step 707a-707b: the MN triggers an SN modification request procedure, instructing the SN to stop sending data to the UE. The SN is the last serving SN.

[0303] The UE starts to perform the next execution condition evaluation. In the S-CPAC, the next execution condition evaluation is the next S-CPAC execution condition evaluation. When the UE completes the initial S-CPAC execution, the next S-CPAC execution condition evaluation will be performed.

[0304] If there is a candidate PSCell that fulfils the next S-CPAC execution condition, the UE selects the target PSCell of the next S-CPAC and performs step 707c.

[0305] Step 707c is the same as step 706 and will not be described again here.

[0306] Step 707d: the UE performs a random access procedure to the target SN, synchronizes to the new target SN, and accesses the new target PSCell. At this time, the source SN of the UE is SN2, the target SN is SN3, and the candidate target SN is SN1.

[0307] The UE may fail when executing the next S-CPAC to the new target SN. Corresponding to the failure of the S-CPAC execution, step 707d fails to execute or does not need to be executed.

[0308] Step 708: the SCG failure occurs. The SCG failure may be a failure that occurs during the UE performs the next S-CPAC and accesses the new target SN, or a failure that occurs after executing the procedure of step 707d. The UE saves information related to the failure. The information related to the failure includes the information on the secondary cell group failure described in step 302, which will not be described again here.

[0309] Step 709: the UE sends SCG failure information to the MN. The information contained in the SCG failure information is the same as that described in step 302, and will not be described again here. The UE may send the SCG failure information in step 302 to the MN through an existing SCG failure information message or other RRC messages.

[0310] Step 710: the MN determines which node causes the failure. The determination method of the MN is the same as that in step 303 and will not be described again here. The MN can also further determine a type of the failure, and the specific determination method is the same as that in step 303 and will not be described again here.

[0311] If the failure is caused by the MN, the procedure ends and subsequent steps do not need to be performed.

[0312] The SCG failure that occurs in the following S-CPAC is not a failure caused by the MN, but is a problem caused by the source SN or the candidate target SN.

[0313] For the problem caused by the source SN, step 711 is performed.

[0314] For the problem caused by the target SN or the candidate target SN, corresponding to Mode 1 of the present disclosure (Mode 1 in step 304), step 713 is directly executed; and corresponding to Mode 2 of the present disclosure (Mode 2 in step 304), step 711, step 712 and step 713 are executed.

[0315] Steps 711-713 are the same as steps 611-613 and will not be described again here.

[0316] At this point, the description of the embodiment of the method for supporting self-configuration and self-optimization of the present disclosure is completed. Through the embodiment of the present disclosure, the robustness of PSCell changes during the enhanced mobility process, for example, in the S-CPAC, can be supported, and the cause of failure is correctly identified, in order to perform reasonable optimization, reduce occurrence of failures, ensure service continuity, and reduce labor costs of operators.

[0317] An example of Embodiment 3 of the Method 2 of the present disclosure that supports self-configuration and self-optimization is shown in Figure 8.

[0318] If an SN triggered an S-CPAC, the method includes steps 801-812b.

[0319] If an MN triggerd the S-CPAC, then step 801 and step 805a can be omitted.

[0320] Step 801: a source SN sends an SN change required message to the MN. The message is used for the source SN to trigger the S-CPAC. The message comprises third configuration information on successful PSCell change report and / or fourth configuration information on the successful PSCell change report. The message contains at least one of the following information:

[0321] - third configuration information on the successful PSCell change report. For details, please refer to step 400;

[0322] - fourth configuration information on the successful PSCell change report. For details, please refer to step 400;

[0323] -UE mobility information in the source PSCell;

[0324] -a C-RNTI of the UE in the source PSCell;

[0325] -list information of candidate PSCells, including information on one or more candidate PSCells for the S-CPAC proposed by the source SN. The list information of candidate PSCells includes one of the following information:

[0326] ■a cell identity, which is a cell identity of the candidate PSCell, and may be a Global Cell Identity (CGI), or other identity.

[0327] ■execution condition(s), which are execution condition(s) of the candidate PSCell. In the S-CPAC, the execution condition(s) are the initial S-CPAC execution condition(s).

[0328] -maximum number of PSCells that can be prepared by each candidate target SN.

[0329] Step 802: the MN sends an SN addition request message to the candidate target SN. The MN sends the message to the candidate target SN which the candidate PSCell belongs to, for indicating that the request is for the S-CPAC.

[0330] In this embodiment of the present disclosure, if the S-CPAC is triggered by the source SN, the MN determines the candidate PSCells according to the list information of candidate PSCells received in step 801. If the S-CPAC is triggered by the MN, the MN selects the candidate PSCells based on measurement result.

[0331] Step 803: the candidate target SN sends an SN addition request acknowledge message to the MN. The message includes first configuration information on the successful PSCell change report. The message contains at least one of the following information:

[0332] -first configuration information on the successful PSCell change report, the specific content of which is, please refer to step 401;

[0333] -mobility information of the UE in the target PSCell;

[0334] -a C-RNTI of the UE in the target PSCell.

[0335] Step 804: the MN sends an RRC reconfiguration message to the UE. The message contains at least one of the following information:

[0336] -first configuration information of the successful PSCell change report;

[0337] -second configuration information of the successful PSCell change report;

[0338] -third configuration information of the successful PSCell change report;

[0339] -fourth configuration information of the successful PSCell change report;

[0340] -information on whether the PSCell change is initiated by the MN or the SN;

[0341] -mobility information of the UE in the PCell of the MN;

[0342] -mobility information of the UE in the source PSCell;

[0343] -mobility information of the UE in the target PSCell;

[0344] -S-CPAC configuration, including at least one of the following information: S-CPAC candidate cell identity, S-CPAC execution condition(s) (including initial S-CPAC execution condition(s) and following S-CPAC execution condition(s)), and conditional RRC reconfiguration corresponding to the S-CPAC candidate cell(s).

[0345] In the embodiment of the present disclosure, the first configuration information on the successful PSCell change report may be received from the candidate target SN, and the second configuration information on the successful PSCell change report may be configured by the MN. The third configuration information on the successful PSCell change report and the fourth configuration information on the successful PSCell change report may be received from the source SN. For the specific content and function of those configuration information, please refer to the description in the Method 2 of self-configuration and self-optimization.

[0346] Step 805: the UE saves the received information and sends an RRC reconfiguration complete message to the MN. The RRC reconfiguration complete message may be an RRC Reconfiguration Complete *. The UE saves the configuration information on the successful PSCell change report.

[0347] The UE performs execution condition evaluation for target PSCell selection.

[0348] The UE determines whether to generate an SPR report based on the first configuration information on the successful PSCell change report and / or the second configuration information on the successful PSCell change report and / or the third configuration information on the successful PSCell change report and / or the fourth configuration information on the successful PSCell change report received in step 804. If the SPR report is generated, information on the successful PSCell change report being available will be sent to the MN.

[0349] Step 805a: the MN sends an SN change confirm message to the source SN.

[0350] If the S-CPAC is triggered by the source SN, the MN sends the SN change confirm message to the source SN after receiving the RRC reconfiguration complete message sent by the UE.

[0351] Step 806: the UE sends an RRC reconfiguration complete message to the MN. If the execution condition(s) of one candidate PSCell is satisfied, the UE sends the RRC reconfiguration complete message to the MN. The message contains information on the selected target PSCell. The message may also contain information on the successful PSCell change report being available. The RRC reconfiguration complete message may be an RRC Reconfiguration Complete **. If the target PSCell selected by the UE belongs to SN2, then SN2 is the target SN.

[0352] Step 807: the MN sends an SN reconfiguration complete message to the target SN. The message also contains mobility information of the UE in the Pcell of the MN and / or mobility information of the UE in the source PSCell. The message also contains a C-RNTI of the UE in the Pcell of the MN and / or a C-RNTI of the UE in the source PSCell.

[0353] In step 807a, the MN sends a message to the source SN. The message may be an SN release request message, or an SN modification request message, or a UE context release message, or other messages.

[0354] If the source SN is a candidate target SN of the S-CPAC, then the message is the SN modification request message.

[0355] Step 807b: the source SN sends a message to the MN. The message may be an SN release request acknowledge message, or an SN modification request acknowledge message, or other messages.

[0356] Step 808a: the MN sends a UE information request message to the UE, for requesting the UE to report the successful PSCell change report.

[0357] In step 808b, the UE sends a message to the MN. The message includes the successful PSCell change report. The content of the successful PSCell change report is the same as that in step 404 and will not be described again here. The message may be a UE information response message or other RRC message.

[0358] In the embodiment of the present disclosure, step 808 (including 808a and 808b) and step 807 and step 807a have no absolute order. Step 808 may be performed first and then step 807 and step 807a may be performed. Step 807 and step 807a may be performed first and then step 808 may be performed. Or step 807 may be performed first, and then step 808 may be performed and next step 807a may be performed. That is, according to embodiments of the present disclosure, step 808 (including 808a and 808b) and step 807 and step 807a may be performed in any order as desired.

[0359] The MN decides whether the successful PSCell change report is generated due to the configuration of the MN, the configuration of the source SN or the configuration of the target SN, and thus the MN decides which node the SPR is sent to. If it is generated by the configuration of the target SN, the MN sends the successful PSCell change report to the target SN. If it is generated by the configuration of the source SN, the MN sends the successful PSCell change report to the source SN. If it is generated by the MN, the MN performs corresponding optimization. The method of determining which node the SPR is sent to is described in step 405, and will not be described again here.

[0360] The MN sends the information on the successful PSCell change report to the source SN or the target SN through an Access and Mobility Indication message or a newly defined message. The MN may also send through an SN reconfiguration complete message. The MN may also send the successful PSCell change report to the source SN through a UE context release message or an SN modification request message or an SN release request message.

[0361] In the S-CPAC, after the UE successfully accesses the target PSCell, when executing the next S-CPAC, the UE selects the target PSCell according to the saved configuration information received in step 804, and determines whether to generate the SPR report. That is, steps 809-812b are performed.

[0362] Step 809 is the same as step 806, except that SN2 is the current source SN of the UE, the target PSCell selected by the UE belongs to SN3, and SN3 is the target SN of the UE.

[0363] Step 810: the MN sends an SN reconfiguration complete message to the target SN. At this time, the target SN of the UE is SN3. For details, please refer to step 807, which will not be described again here.

[0364] Step 811a: the MN sends a message to the source SN. At this time, the source SN is SN2. The message may be an SN release request message, or an SN modification request message, or a UE context release message, or other messages. If the source SN is a candidate target SN of the S-CPAC, the message is the SN modification request message.

[0365] Step 811b: the source SN sends a message to the MN. At this time, the source SN is SN2. The message may be an SN release request acknowledge message, or an SN modification request acknowledge message, or other messages.

[0366] Steps 812a-812b are the same as steps 808a-808b, and the UE sends the successful PSCell change report to the MN at the request of the MN. For specific description, please see steps 808a-808b, which will not be described again here.

[0367] In the embodiment of the present disclosure, step 812 (including 812a and 812b) and step 810 and step 811a have no absolute order. Step 812 may be performed first and then step 810 and step 811a may be performed. Step 810 and step 811a may be performed first and then step 812 may be performed. Or step 810 may be performed first, and then step 812 may be performed and next step 811a may be performed. That is, according to the embodiment of the present disclosure, step 812 (including 812a and 812b) and step 810 and step 811a may be performed in any order as desired.

[0368] The MN decides to which node the successful PSCell change report is sent. For the method of determining which node the SPR is sent to, please see step 405, which will not be described again here. In the embodiment of the present disclosure, at this time, the source SN is SN2 and the target SN is SN3.

[0369] At this point, the description of the embodiment of Method 2 of supporting self-configuration and self-optimization of the present disclosure is completed. Through the embodiment of the present disclosure, it can support reasonably configuring and processing the successful PSCell change report in the enhanced mobility process, for example, in the S-CPAC, correctly identifying potential failures, in order to enhance the robustness of PSCell changes for reasonable optimization, reduce the occurrence of failures, ensure service continuity, and reduce labor costs of operators.

[0370] An example of Embodiment 4 of Method 3 of supporting self-configuration and self-optimization of the present disclosure is shown in Figure 9.

[0371] The specific steps are as follows:

[0372] Completing the S-CPCA configuration for the UE, the UE performs execution condition evaluation. If at least one candidate PSCell fulfills the execution conditions, step 901 is executed.

[0373] Step 901: the UE sends an RRC reconfiguration complete message to the MN. The message contains information on the selected target PSCell, such as a PSCell identity, which may be a conditional reconfiguration identity, or a PCI, or a CGI, or other cell identity. The message may be an RRC reconfiguration complete message, or other messages.

[0374] Step 902: the MN sends an SN reconfiguration complete message to the target SN.

[0375] If the target PSCell selected by the UE is a cell of SN2, then the target SN is SN2.

[0376] The message contains SCG history information of the UE. The message may be the SN reconfiguration complete message, or other messages. For the information contained in the message, please refer to step 502, which will not be described again here. For example, if the source PSCell in the source SN (SN1) is PSCell1, then the SCG history information will include information such as an identity of PSCell1 and the time the UE stays in PSCell1.

[0377] The target secondary node (SN2) receives and saves the SCG history information of the UE. The information may be used to detect whether there is a ping-pong handover of the PSCell. Based on the history information, the target SN can determine the PSCell that the UE has accessed and the time of staying in the PSCell, thereby detecting whether the UE has a ping-pong handover of the PSCell. For example, if the UE stays in a certain PSCell a very short time, SN2 may not configure the cell as a candidate cell, thereby avoiding unnecessary PSCell change to the cell. Optionally, the target SN can avoid a ping-pong handover of the PSCell by adjusting or deleting a candidate PSCell configured by it.

[0378] In the S-CPAC, after the UE successfully accesses the target PSCell, the UE continues to evaluate the execution conditions based on the saved S-CPAC configuration. If at least one candidate PSCell fulfills the execution conditions, step 903 will be performed.

[0379] Step 903: the UE sends an RRC reconfiguration complete message to the MN. The message contains information on the selected new target PSCell, such as a PSCell identity, which may be a conditional reconfiguration identity, or a PCI, or a CGI, or other cell identity. The message may be an RRC reconfiguration complete message, or other messages.

[0380] Step 904: the MN sends an SN reconfiguration complete message to the target SN.

[0381] If the target PSCell selected by the UE is a cell of SN3, then the target SN is SN3.

[0382] The message contains the SCG history information of the UE. The message may be an SN reconfiguration complete message, or other messages. For the information contained in the message, please refer to step 502, which will not be described again here.

[0383] For example, before accessing SN3, the UE accessed SN1 and SN2. If the accessed cell of SN1 is PSCell1 and the accessed cell of SN2 is PSCell2, then the SCG history information will sequentially include: information on PSCell2 and information on PSCell1. The information includes a PSCell identity, a time the UE stays in a PSCell and other information.

[0384] The target secondary node (SN3) receives and saves the SCG history information of the UE. The information is used to detect whether there is a ping-pong handover of the PSCell. Based on the history information, the target SN can determine a PSCell that the UE has accessed and the time the UE stays in the PSCell, thereby detecting whether the UE has a ping-pong handover of the PSCell. Optionally, the target SN can avoid a PSCell ping-pong handover by adjusting or deleting the candidate PSCell configured by it.

[0385] An example of Method 4 of the present disclosure that supports self-configuration and self-optimization is shown in Figure 10. Based on the method, selection of candidate PSCells can be optimized. The specific steps are described as follows:

[0386] The SCG status of the PSCell includes an activated status and a deactivated status. The SCG status may be changed. In embodiments of the present disclosure, the master node, the secondary node and the UE can trigger adjustment of the SCG status.

[0387] Step 1001: the master node saves or records information on the SCG status of the visited PSCells by the UE. In the embodiment of the present disclosure, the visited PSCells by the UE is the PSCells that the UE has recently visited, including the PSCell currently serving the UE.

[0388] The SCG status information may include an SCG status, a time duration in the SCG status, and / or a time of SCG status change, and may also include other information. The SCG status comprises an SCG deactivated status and / or an SCG activated status. Information on the SCG deactivated status comprises an SCG deactivated status and / or a time duration of the SCG deactivated status.

[0389] The UE may execute the PSCell change and / or addition multiple times, the UE may have multiple visited PSCells as well as the current PSCell. Thus, the master node may save the SCG status information of recently visited PSCells (or accessed PSCells) by the UE and / or the current source PSCell. In the embodiment of the present disclosure, the SCG status information comprises SCG deactivated status information, for example including an SCG deactivated status and / or a time duration of the SCG deactivated status. Optionally, the master node can store information on visited PSCells by the UE in the time order of visiting the PSCells, with the most recently visited PSCell placed at the most front.

[0390] In the embodiment of the present disclosure, the SCG status information may be saved in history information on the visited PSCells by the UE.

[0391] The master node saves or records the history information on visited PSCells by the UE. The history information on visited PSCells by the UE may also be SCG UE history information. The history information on visited PSCells by the UE includes a list of visited PSCells by the UE. The list of visited PSCells by the UE contains information on PSCells recently visited by the UE. The information on PSCell includes a PSCell identity, a time the UE stays in the PSCell, a status of the PSCell, a deactivation time of the PSCell, a time duration of the deactivated status of the PSCell, an activation time of the PSCell, and / or a time duration of the activated status of the PSCell.

[0392] Optionally, the master node can optimize selection of the candidate PSCell or the target PSCell based on the stored SCG status information. Optionally, candidate cells of existing candidate PSCells can be changed or deleted.

[0393] In the embodiment of the present disclosure, when the SCG status of the serving PSCell is changed, the master node and / or the secondary node need to update and store the SCG status information on the PSCell. The adjustment of the SCG status can be triggered by the master node or the secondary node or the UE. The following describes the SCG status change procedure triggered by different nodes respectively.

[0394] SCG Status Change Procedure Triggered by Master Node

[0395] If the master node determines that the SCG status needs to be adjusted, the master node sends a message containing an SCG status request to the source secondary node, the SCG status request can be activation of the SCG or deactivation of the SCG. The basis for the master node to determine adjustment of the SCG status may optionally be one or more of a load condition, a volume of transmitted traffic, a resource condition or other factors.

[0396] The message may be an SN modification request message, or other messages. The message contains at least the following information:

[0397] -SCG status request (or SCG activation request). The request may be activation of the SCG, or deactivation of the SCG.

[0398] The source secondary node sends a feedback message containing acceptance of the adjusted SCG status to the master node. The message may be an SN modification request acknowledge message, or other messages. The message contains at least the following information:

[0399] -an SCG status, or an SCG activation status. The status may be SCG activated, or SCG deactivated.

[0400] Optionally, the source secondary node can record or store SCG status information on the source PSCell. The SCG status information may include one or more of an SCG status, a time duration of the status, and a time of status change, or other information. The recording may further comprise recording SCG deactivated status information, e.g. a time duration of deactivated status.

[0401] The master node sends the received SCG status to the UE.

[0402] The master node may record or store the SCG status information on the source PSCell. The SCG status information may include one or more of an SCG status, a time duration of the status, and a time of status change, or other information. The recording may further comprise recording SCG deactivated status information, e.g. a time duration of deactivation status.

[0403] SCG Status Change Triggered by Source Secondary Node

[0404] If the source secondary node determines that the SCG status needs to be adjusted, the source secondary node sends a message to the master node. The message includes an SCG status request, and the SCG status request can be activation of the SCG or deactivation of the SCG. The basis for the source secondary node to determine the SCG status change may optionally be one or more of a volume of transmitted traffic, a resource condition, or other factors.

[0405] The message may be an SN modification required message, or other messages. The message includes at least the following information:

[0406] -SCG status request (or SCG activation request). The request may be activation of the SCG, or deactivation of the SCG.

[0407] The master node determines the information sent to the UE based on the received SCG status request. If the received SCG status request is an SCG deactivation status request, the master node sends the requested SCG status to the UE, otherwise there is no need to send the requested SCG status to the UE. The message of the requested SCG status sent to the UE may be an RRC reconfiguration message, or other message. The UE determines whether to perform SCG activation or SCG deactivation based on whether the received message contains the SCG status. If the SCG status is included in the received message, the SCG deactivation is performed, otherwise the SCG activation is performed.

[0408] After receiving a feedback message from the UE, the master node sends a message to the source secondary node to feed back the SCG status request sent by the source secondary node. In the embodiment of the present disclosure, the feedback message of the UE received by the master node may be an RRC reconfiguration complete message, or other messages. The message sent by the master node to the source secondary node may be an SN modification confirm message.

[0409] Optionally, the master node and / or the source secondary node may record or store the SCG status information on the source PSCell. The SCG status information may include one or more of an SCG status, a time duration of the status, and a time of status change, or other information. The recording may further comprise recording SCG deactivated status information, e.g. a time duration of deactivated status.

[0410] SCG Status Change Triggered by UE

[0411] If the SCG status is deactivated, when uplink data arrives on the SCG bearer, the UE sends a message to the master node, indicating that there is uplink data to be transmitted through the SCG bearer. The UE can also send a message to the master node, indicating SCG deactivation preference, if the network configures that the UE can send the information.

[0412] The message may be a UE assistance information (UEAssistanceInformation) message, or other messages. The message contains at least one of the following information:

[0413] -SCG-deactivation preference, which may also be referred to as SCG-deactivation tendency. The SCG-deactivation preference is used to indicate whether the UE tends to or prefers to select the SCG deactivation. The SCG-deactivation preference includes two options: SCG-deactivation preference, no preference;

[0414] -uplink data, which is used to indicate whether there is uplink data. If the uplink data is included in the message, it is used for the UE to indicate that there is uplink data on the deactivated SCG.

[0415] The master node determines whether the SCG status needs to be adjusted based on the information contained in the received message from the UE. If the SCG status needs to be adjusted, the master node will send a message to the source secondary node to request an SCG status. The source secondary node sends a feedback message to the master node, the message containing acceptance of the adjusted SCG status. The master node sends the received SCG status to the UE. In the embodiment of the present disclosure, the message transmission between the master node and the source secondary node and the behavior description of the master node and the source secondary node are the same as those in the adjustment procedure of the SCG status triggered by the master node, and will not be described again here.

[0416] When there is a need to perform a PSCell change, such as a PSCell change triggered by the MN or the SN, step 1002 is performed. The SN at this time is also the source SN. In this method, the above-mentioned SN is also the source SN. The PSCell change may be a general PSCell change, a conditional handover with SCG, a CPC, or an S-CPAC.

[0417] Step 1002: the master node sends a message to the target secondary node, and the message contains SCG status information on the visited PSCell by the UE. The SCG status information on the PSCell visited by the UE is the same as that described in step 1001, and will not be described again here.

[0418] The master node may send the SCG status information on the recently visited PSCell by the UE stored in the master node to the target secondary node.

[0419] The master node may also receive the SCG status information on the PSCell visited by the UE from the source secondary node by sending a message to the source secondary node to request the source secondary node for the SCG status information on the PSCell recently visited by the UE stored in the source secondary node.

[0420] When the UE selects the target PSCell, or the network selects the target PSCell for the UE, or the UE completes the PSCell change and accesses to the target PSCell, the master node sends the stored SCG status information on the recently visited PSCell to the target secondary node. The information may be used to optimize selection of candidate PSCell or target PSCell. Optionally, candidate cell of the existing candidate PSCells can be adjusted or deleted.

[0421] The message may be an SN reconfiguration complete message, or an SN addition request message, or an SN modification request message, or other messages. The message contains SCG status information on one or more visited PSCells by the UE, and the multiple pieces of the SCG status information is sorted according to the time when the UE visited the PSCell, and the most recently visited one is placed at the most front. The SCG status information comprises at least one of:

[0422] (1) a cell identity, which is a cell identity of the PSCell identity, that is, a cell identity of the PSCell that the UE has visited. The identity may be a CGI, or other cell identity;

[0423] (2) SCG status information including at least one of the following information:

[0424] -SCG deactivated status;

[0425] -a time duration of SCG deactivated status;

[0426] -SCG activated status;

[0427] -a time duration of SCG activated status

[0428] -SCG activation time;

[0429] -SCG deactivation time.

[0430] At this point, the Method 4 of supporting self-configuration and self-optimization of the present disclosure is completed. Through the method of the present disclosure, it can be supported that selection of target PSCell or candidate PSCell are reasonably optimized, in order to ensure service continuity and effective utilization of resources, and reduce labor costs of operators.

[0431] An example of Embodiment 5 of the Method 4 of the present disclosure that supports self-configuration and self-optimization is shown in Figure 11.

[0432] A UE is in dual connectivity mode and is connected to an MN and a source SN (S-SN) at the same time.

[0433] According to the description in Method 4, the master node, the source secondary node and the UE can trigger adjustment of the SCG status. According to an embodiment of the disclosure,

[0434] For a procedure of SCG status change triggered by the source secondary node, please see steps 1101-1104;

[0435] For a procedure of SCG status change triggered by the master node, please see steps 1106-1110;

[0436] For a procedure of SCG status change triggered by the UE, please see steps 1105-1110.

[0437] In the embodiment of the present disclosure, the adjustment of the SCG status may be triggered multiple times, and may be triggered by the master node and / or the source secondary node and / or the UE. There is no order of precedence for the three procedures.

[0438] Step 1101: the source secondary node sends a message to the master node for sending an SCG status request. The message may be an SN modification required message, or other messages.

[0439] When the source SN decides to adjust the SCG status, the source SN sends an SCG status request to the MN. The message includes at least the following information:

[0440] SCG status request (or SCG activation request). The request may be activation of the SCG, or deactivation of the SCG.

[0441] Step 1102: the master node sends a message to the UE. The message may be an RRC reconfiguration message, or other messages.

[0442] When the master node receives the SCG status request sent by the source SN, it determines information to be sent to the UE based on the received SCG status request. If the received SCG status request is an SCG deactivated status request, the master node sends the requested SCG status to the UE, otherwise there is no need to send the requested SCG status to the UE. The message contains at least the following information:

[0443] an SCG status, which may be a deactivated status.

[0444] Step 1103: the UE sends a message to the master node. The message may be an RRC reconfiguration complete message, or other messages. The message may indicate that the UE completes the reconfiguration, including completing activation or deactivation of the SCG. The UE determines whether to perform SCG activation or deactivation based on whether the message received from the master node contains the SCG status. If the SCG status is included in the received message, the SCG deactivation is performed, otherwise SCG activation is performed.

[0445] At this time, the master node may record or store the SCG status information on the source PSCell, which may include one or more of an SCG status, a time duration of the status, and a time of status change or other information. The recording may further comprise recording SCG deactivated status information, e.g. a time duration of deactivated status. In the embodiment of the present disclosure, the master node will save the SCG status of multiple PSCells (including the visited PSCell by the UE and the current source PSCell) in the time order in which the UE visited the PSCells.

[0446] Step 1104: the master node sends a message to the source secondary node. The message may be an SN modification confirm message, or other message.

[0447] After receiving a feedback message from the UE, the master node sends a message to the source secondary node to feed back the SCG status request sent by the source secondary node. The message sent by the master node to the source secondary node may be an SN modification confirm message.

[0448] Optionally, the source secondary node can record or store the SCG status information. The SCG status information may include one or more of an SCG status, a time duration of the status, and a time of status change, or other information. The recording may further comprise recording the SCG deactivation status information, e.g. a time duration of deactivated status.

[0449] Step 1105: the UE sends a message to the master node to provide information for the SCG status change. The message may be a UE assistance information (UEAssistanceInformation) message, or other message. The message contains at least one of the following information:

[0450] (1) SCG-deactivation preference, which may also be referred to as an SCG-deactivation tendency. The SCG deactivation preference is used to indicate whether the UE prefers to or tends to select the SCG deactivation. The SCG-deactivation preference includes two options: SCG deactivation preference, no preference;

[0451] (2) uplink data, which is used to indicate whether there is uplink data. If the uplink data is included in the message, it is used for the UE to indicate that there is uplink data on the deactivated SCG.

[0452] Step 1106: the master node sends a message to the source secondary node, and the message includes the SCG status request. The message may be an SN modification request message, or other messages. When the MN decides to adjust the SCG status, it sends an SCG status request to the source SN. The message contains at least the following information:

[0453] an SCG status request (or SCG activation request). The request may be activation of the SCG, or deactivation of the SCG.

[0454] In the embodiment of the present disclosure, the MN decides to adjust the SCG status, which can be determined based on one or more of a load condition, a volume of transmitted traffic, a resource condition, or other factors. It may also be determined based on the UE information received in step 1105.

[0455] Step 1107: the source secondary node sends a message to the master node. The message includes the SCG status accepted by the secondary node. The message may be an SN modification request acknowledge message, or other messages. The message contains at least the following information:

[0456] an SCG status, or an SCG activation status. The status may be SCG activated, or SCG deactivated.

[0457] Optionally, the source secondary node can record or store the SCG status information. The SCG status information may include one or more of an SCG status, a time duration of the status, and a time of status change, or other information. The recording may further comprise recording the SCG deactivation status information, e.g. a time duration of deactivated status.

[0458] Steps 1108-1109: the master node sends the received SCG status to the UE. In the embodiment of the present disclosure, steps 1108-1109 are the same as steps 1102-1103 and will not be described again here.

[0459] Step 1110: the master node sends a message to the source secondary node. Optionally, after receiving the message sent by the UE, the master node sends the message to the source secondary node. The message is used to indicate that the UE completes SCG configuration, which may include completing SCG status change.

[0460] PSCell change procedure, which may be a PSCell change triggered by the MN or source SN, or a UE selecting the target PSCell to perform PSCell change under the CPC or the S-CAPC.

[0461] Step 1111: the UE sends a message to the master node. The message may be an RRC reconfiguration complete message, or other messages. The message may contain at least one of the following information:

[0462] (1) a cell identity, which is a cell identity of the target PSCell. The identity may be a CGI, or a PCI, or other cell identity.

[0463] (2) an SN RRC response including an RRC reconfiguration complete message sent by the UE to the SN.

[0464] Step 1112: the master node sends a message to the target SN (T-SN). The master node sends the SCG status information to the target SN.

[0465] The message may be an SN reconfiguration complete message, or an SN addition request message, or an SN modification request message, or other messages. In the embodiment of the present disclosure, the SCG status information may be stored by the master node, or may be requested and acquired by the master node from the source secondary node. The message contains at least one of the following information:

[0466] (1) SCG status information on one or more visited PSCells by the UE. The multiple pieces of SCG status information are sorted according to the time when the UE visited the PSCell. The status information includes at least one of the following information:

[0467] -a cell identity, which is a cell identity of the PSCell, that is, a cell identity of the visited PSCells by the UE. The identity may be a CGI, or other cell identity;

[0468] -SCG status information, containing at least one of the following information:

[0469] -　■SCG deactivated status;

[0470] - 　■ a time duration of SCG deactivated status.

[0471] (2)an RRC reconfiguration complete message, which is the RRC reconfiguration complete message sent by the UE to the SN.

[0472] Optionally, the target SN uses the received SCG status information to optimize selection of candidate PSCell or target PSCell. Optionally, candidate cell of the existing candidate PSCell can be adjusted or deleted.

[0473] At this point, the description of the embodiment of the Method 4 of supporting self-configuration and self-optimization of the present disclosure is completed. Through the embodiment of the present disclosure, the reasonable optimization of selecting the target PSCell or the candidate PSCell can be supported during the enhanced mobility process, ensuring service continuity and effective utilization of resources and reducing labor costs of operators.

[0474] An example of Method 5 for supporting self-configuration and self-optimization of the present invention is shown in Figure 12. The method is used in a scenario of a failure occurring during an S-CPAC triggered by an MN. The method comprises the following steps:

[0475] Step 1201, the MN receives SCG failure information from a UE. The SCG failure message comprises the same information as in step 302, and will not be described here.

[0476] Step 1202, the MN performs initial analysis. The MN determines a type of a PSCell change or addition.

[0477] For the S-CPAC triggered by the MN, the MN performs cause analysis. Performing the cause analysis includes determining that it is a too early CPC / CPA execution, a too late CPC / CPA execution, a CPC execution to a wrong PSCell. The specific determining method is the same as that in step 303, and will not be repeated here. Performing the cause analysis further includes determining whether the failure is caused by unreasonable configuration of candidate PSCells or unreasonable configuration of execution conditions, and may further include deciding which node causes the failure and / or which node needs relevant optimization. The MN knows that the S-CPAC is triggered by the MN according to the saved information or the SCG failure information received from the UE. For example, the MN knows that the S-CPAC is triggered by the MN according to the indication information on the S-CPAC being triggered by the MN or the S-CPAC being triggered by the SN included in the SCG failure information. Performing the cause analysis in the present invention can also be referred to as perform root cause analysis.

[0478] If the suitable PSCell is not one of the candidate PSCells recommended by the MN, or is one of the candidate PSCells recommended by MN but is not one of the candidate PSCells selected by the candidate or target SN, it is a failure caused by improper configuration of the candidate PSCells, otherwise it is a failure caused by improper execution conditions. The MN knows the suitable PSCell according to a measurement report received from the UE, or the MN knows the suitable PSCell according to the measurement report received from the UE and the information saved by the MN, the same below.

[0479] For an initial S-CPAC of the S-CPAC initiated by the MN, if the suitable PSCell is one of the candidate PSCells recommended by the MN but not one of the candidate PSCells selected by the candidate or the target SN, step 1203 is performed, otherwise, the MN performs relevant optimization. If the suitable PSCell is not recommended by the MN or the configuration of execution conditions is unreasonable, the MN needs to perform corresponding optimization. Here, the initial S-CPAC of the S-CPAC initiated by the MN means that the SCG failure is a failure caused by the initial S-CPAC or a failure related to the initial S-CPAC.

[0480] For a following S-CPAC of the S-CPAC initiated by the MN, if the suitable PSCell is not recommended by the MN, then the MN performs relevant optimization, otherwise, step 1203 is performed. If the suitable PSCell is one of the candidate PSCells recommended by the MN, but not one of the candidate PSCells selected by the candidate or the target SN, or the configuration of execution conditions is unreasonable, it is a failure caused by the candidate or the target SN, and the target or the candidate SN needs to perform relevant optimization, and step 1203 is executed. Here, the following S-CPAC of the S-CPAC initiated by the MN means that the SCG failure is caused by the following S-CPAC or related to the following S-CPAC.

[0481] If the MN performs related optimization, step 1203 does not need to be performed.

[0482] The MN knows whether it is the initial S-CPAC or the following S-CPAC according to the saved information or the indication information on the initial S-CPAC failure or the following S-CPAC failure in the SCG failure information received from the UE.

[0483] Step 1203, the MN sends a message to the node that needs to perform relevant optimization. For the S-CPAC triggered by the MN, the MN sends the message to the candidate or target SN, and the candidate or target SN performs relevant optimization. The candidate SN also includes the source SN of the following S-CPAC. The information included in the message is the same as that in step 304, and will not be described here. The message may be an SCG failure information report or other messages, and the present invention does not limit this. If the MN only determines which node causes the failure, the source SN, the target SN or the candidate target SN determines the type of failure after receiving the message from the MN. The specific determination method is the same as that in step 304, so the details are not repeated here.

[0484] At this point, the Method 5 for supporting self-configuration and self-optimization of the present invention is completed, which can support the robustness of the PSCell change in the enhanced mobility process, for example, in the S-CPAC, and correctly identify the cause of the failure, so as to carry out reasonable optimization, reduce the occurrence of failure, ensure service continuity, and reduce the labor cost of operators.

[0485] An example of Method of the present invention for supporting self-configuration and self-optimization is shown in Figure 13. This method is used in the scenario of a failure occurring in the process of an S-CPAC triggered by an MN. The method comprises the following steps:

[0486] Step 1301, the MN receives SCG failure information from a UE. The SCG failure message includes the same information as that in step 302, and will not be described here.

[0487] Step 1302, the MN performs initial analysis. The MN determines a type of a PSCell change or addition.

[0488] For the S-CPAC triggered by the MN, due to the failure caused by the initial S-CPAC, the MN performs cause analysis. The failure caused by the initial S-CPAC can also be said to be a failure related to the initial S-CPAC. Performing the cause analysis is the same as that in step 1202. The MN knows that the S-CPAC is triggered by the MN according to the saved information or the SCG failure information received from the UE. For example, the MN knows that the S-CPAC is triggered by the MN according to the indication information on the S-CPAC being triggered by the MN or the S-CPAC being triggered by the SN included in the SCG failure information. The MN knows whether it is the initial S-CPAC or the following S-CPAC according to the saved information or the indication information on the initial S-CPAC failure or the following S-CPAC failure in the SCG failure information received from the UE. If the suitable PSCell is one of the candidate PSCells recommended by the MN, but is not one of the candidate PSCells selected by the candidate or target SN, the MN sends a message to the node that needs to perform relevant optimization, otherwise, the MN performs relevant optimization. The MN sends a message to the node that needs to perform relevant optimization, which is exactly the same as that described in step 1203, and will not be repeated here. If the suitable PSCell is not recommended by the MN or the configuration of execution conditions is unreasonable, the MN needs to perform corresponding optimization.

[0489] For the S-CPAC triggered by the MN, due to the failure caused by the following S-CPAC, the MN sends a message to a source SN of the corresponding CPC, and the source SN performs the cause analysis. Performing the cause analysis is the same as that in step 1202. The source SN is a source SN corresponding to the following CPC. The message sent to the source SN by the MN comprises an MN UE XnAP ID, an SN UE XnAP ID, SCG failure information, S-CPAC configuration, SN mobility information, a source PSCell identity, and / or an identity of the failed PSCell. The SCG failure information is SCG failure information received from the UE. The S-CPAC configuration may be all or part of configuration information on the S-CPAC received by the MN from the source SN during the S-CPAC preparation procedure. The SN mobility information is information related to the PSCell change received by the MN from the source SN, and is used to analyze the situation that causes the wrong PSCell change. The message sent by the MN to the source SN can be the SCG failure information report or other messages.

[0490] For the S-CPAC triggered by the MN, due to the failure caused by the following S-CPAC, if the suitable PSCell is not recommended by the MN, the MN needs to perform relevant optimization, and the source SN indicates to the MN that the cause of the SCG failure occurs in the MN, otherwise the source SN indicates to the MN that the cause of the SCG failure occurs in other nodes. If the suitable PSCell is one of the candidate PSCells recommended by the MN, but is not one of the candidate PSCells selected by the candidate or the target SN, or the configuration of the execution conditions is unreasonable, the failure is caused by the candidate or the target SN, and the cause of the SCG failure occurs in other nodes, and the target or the candidate SN needs to perform relevant optimization. The message sent by the source SN to the MN includes information on the MN UE XnAP ID, the SN UE XnAP ID, whether the cause of the SCG failure occurs in the MN or other candidate or target SNs. Here, the failure caused by the following S-CPAC can also be said to be the failure related to the following S-CPAC. The MN receives the message from the source SN. If the cause of the SCG failure occurs in the MN, the MN performs corresponding optimization. If the cause of the SCG failure occurs in other node (candidate or target SN), the MN sends a message to the candidate or target SN. The information included in the message is the same as that in step 304, which will not be described here. The message may be an SCG failure information report or other messages, and the present invention does not limit this.

[0491] For the S-CPAC triggered by the MN, due to the failure caused by the following S-CPAC, another method is as follows: if the suitable PSCell is not recommended by the source SN, the source SN needs to perform relevant optimization, otherwise, the source SN indicates to the MN that the SCG failure occurs in other nodes. The source SN sends a message to indicate to the MN that the SCG failure occurred in other nodes. If the suitable PSCell is one of the candidate PSCells recommended by the source SN, but is not one of the candidate PSCells selected by the candidate or target SN, or the configuration of the execution condition is unreasonable, the failure is brought by the candidate or target SN, the SCG failure occurs in other nodes, and the target or candidate SN needs to perform relevant optimization. The message sent by the source SN to the MN includes an MN UE XnAP ID and an SN UE XnAP ID. Here, the failure caused by the following S-CPAC can also be said to be the failure related to the following S-CPAC. The MN receives the message from the source SN, and sends the message to the candidate or target SN. The information included in the message is the same as that in step 304, which is not repeated here. The message may be an SCG failure information report or other messages, and the present invention does not limit this.

[0492] At this point, the Method 6 for supporting self-configuration and self-optimization of the present invention is completed, which can support the robustness of the PSCell change in the enhanced mobility procedure, for example, in the S-CPAC, and correctly identify a cause of a failure, so as to make reasonable optimization, reduce occurrence of a failure, ensure service continuity, and reduce labor cost of operators.

[0493] An example of Method 7 for supporting self-configuration and self-optimization of the present invention is shown in Figure 14. The method is used in the scenario of a failure occurring during an S-CPAC triggered by an SN. The method comprises the following steps:

[0494] Step 1401: an MN receives SCG failure information from an UE. The SCG failure message includes the same information as in step 302, and will not be described here.

[0495] Step 1402: the MN performs initial analysis. The MN determines a type of PSCell change or addition.

[0496] For the S-CPAC triggered by the SN, the MN sends a message to the SN that initiated the S-CPAC. The MN knows that the S-CPAC is triggered by the SN based on the saved information or the SCG failure information received from the UE. For example, the MN knows that the S-CPAC is triggered by the SN according to the indication information on the S-CPAC being triggered by the MN or the S-CPAC being triggered by the SN included in the SCG failure information. The SN initiating the S-CPAC is the source SN of the initial S-CPAC. The message includes one or more of the following information elements:

[0497] - a cell identity of source PSCell;

[0498] - a cell identity of target PSCell or a cell identity of failed PSCell;

[0499] - a cell identity of suitable PSCell;

[0500] - SCG failure information received from a UE;

[0501] - a list of candidate PSCells recommended by the MN or initial SN; each candidate PSCell includes a cell identity, which may be a global cell identity, and the global cell identity may also include a tracking area code (TAC);

[0502] - initial S-CPAC execution conditions. There are one or more execution conditions for each candidate PSCell;

[0503] - following S-CPAC execution conditions. There are one or more execution conditions for each candidate PSCell;

[0504] - a list of candidate PSCells selected by a target SN or a candidate target SN; each candidate PSCell includes a cell identity, which may be a global cell identity, and the global cell identifier may also include a tracking area code (TAC). The message may include a list of candidate PSCells selected by the target SN or a candidate target SN, or indication information on whether it is selected by the target SN or the candidate target SN included in the list of candidate PSCells recommended by the MN or the source SN. The target SN or the candidate target SN knows which cells in the list of candidate PSCells recommended by the MN or the source SN are selected by the target SN or the candidate target SN and which cells in the list of candidate PSCells recommended by the MN or the source SN are not selected by the target SN or the candidate target SN, according to the indication information in the list of candidate PSCells recommended by the MN or the source SN;

[0505] - a list of PSCells which are not selected by the target SN or the candidate target SN in a candidate PSCell list recommended by the MN or initial SN;

[0506] - maximum number of prepared PSCells;

[0507] - estimated reachability;

[0508] - SCG failure time.

[0509] The message may be an SCG failure information report or other messages.

[0510] Step 1403: the SN initiating the S-CPAC performs cause analysis. Performing the cause analysis is the same as step 1202.

[0511] If the suitable PSCell is not one of the candidate PSCells recommended by the SN that initiated the S-CPAC, or is one of the candidate PSCells recommended by the SN that initiated the S-CPAC but is not one of the candidate PSCells selected by the candidate or target SN, the failure is caused by improper configuration of the candidate PSCells, otherwise the failure is caused by improper execution conditions. The SN initiating the S-CPAC knows the suitable PSCell according to the measurement report received from the UE, or the MN knows the suitable PSCell according to the measurement report received from the UE and sends it to the SN of the S-CPAC through the SCG failure information report message or other messages.

[0512] For the initial S-CPAC of the S-CPAC initiated by the SN, if the suitable PSCell is one of the candidate PSCells recommended by the SN initiating the S-CPAC but is not one of the candidate PSCells selected by the candidate or target SN, the SN initiating the S-CPAC indicates to the MN that the cause of the failure of the SCG is on other nodes, otherwise, the SN initiating the S-CPAC performs corresponding optimization. After receiving the message from the SN that initiated the S-CPAC, the MN sends the SCG failure information report to the candidate or target SN, and the message includes the same information as that in step 304, and the candidate or target SN performs corresponding optimization.

[0513] For the following S-CPAC of the S-CPAC initiated by the SN, if the suitable PSCell is not recommended by the SN initiating the S-CPAC, the SN initiating the S-CPAC performs relevant optimization; otherwise, the SN initiating the S-CPAC indicates to the MN that the cause of the SCG failure is on other nodes. If the suitable PSCell is one of the candidate PSCells recommended by the SN that initiated the S-CPAC, but is not one of the candidate PSCells selected by the candidate or target SN, or the configuration of execution conditions is unreasonable, the failure is brought by the candidate or target SN, and the target or candidate SN needs to perform relevant optimization. After receiving the message from the SN that initiated the S-CPAC, the MN sends the SCG failure information report to the candidate or target SN, and the message includes the same information as that in step 304, and the candidate or target SN performs corresponding optimization. Here, the following S-CPAC of the S-CPAC initiated by the SN means that the SCG failure is a failure caused by or related to the following S-CPAC.

[0514] The SN that initiated the S-CPAC knows whether it is the initial S-CPAC or the following S-CPAC according to the saved information or the indication information on the initial S-CPAC failure or the following S-CPAC failure in the SCG failure information received from the UE.

[0515] The candidate SN also includes the source SN of the following S-CPAC.

[0516] At this point, the Method 7 for supporting self-configuration and self-optimization of the present invention is completed, which can support the robustness of the PSCell change in the enhanced mobility process, for example, in the S-CPAC, and correctly identify a cause of a failure, so as to carry out reasonable optimization, reduce occurrence of failures, ensure service continuity, and reduce labor cost of operators.

[0517] An example of Method 8 of the present invention for supporting self-configuration and self-optimization is shown in Figure 15. This method is used in the scenario of a failure occurring during an S-CPAC triggered by an SN. The method comprises the following steps:

[0518] Step 1501: an MN receives SCG failure information from a UE. The SCG failure message includes the same information as that in step 302, and will not be described here.

[0519] Step 1502: the MN performs initial analysis. The MN determines a type of a PSCell change or addition.

[0520] For the S-CPAC triggered by the SN, due to the failure caused by the initial S-CPAC, the MN sends a message to the SN that initiated the S-CPAC, and the SN that initiated the S-CPAC performs cause analysis; due to the failure caused by the following S-CPAC, the MN sends a message to the source SN of the corresponding following CPC procedure, and the corresponding source SN performs the cause analysis. The failure caused by the initial S-CPAC can also be said to be the failure related to the initial S-CPAC. Performing the cause analysis is the same as step 1202. The MN knows that the S-CPAC is triggered by the SN based on the saved information or the SCG failure information received from the UE. For example, the MN knows that the S-CPAC is triggered by the SN according to the indication information on the S-CPAC being triggered by the MN or the S-CPAC being triggered by the SN included in the SCG failure information. The MN knows whether it is the initial S-CPAC or the following S-CPAC according to the saved information or indication information on the initial S-CPAC failure or the following S-CPAC failure in the SCG failure information received from the UE.

[0521] The message sent by the MN to the SN initiating the S-CPAC or the source SN of the following CPC procedure includes the same information as that in step 1402, and will not be repeated here.

[0522] The SN initiating the S-CPAC receives the message from the MN, and the behavior of the SN initiating the S-CPAC is the same as that described in step 1403, which is not repeated here.

[0523] The source SN of the following S-CPAC receives the message from the MN and performs the cause analysis. If the suitable PSCell is not recommended by the source SN, the source SN performs relevant optimization, otherwise, the source SN indicates to the MN that the cause of the SCG failure is on other nodes, and the MN sends an SCG failure information report message to the candidate or target SN. Sending a message by the MN to a node that needs to perform relevant optimization or sending an SCG failure information report message by the MN to a candidate or target SN is the same as that described in step 1203, and will not be repeated here. If the suitable PSCell is one of the candidate PSCells recommended by the source SN, but is not one of the candidate PSCells selected by the candidate or the target SN, or the configuration of the execution conditions is unreasonable, the candidate or the target SN needs to perform corresponding optimization.

[0524] For the S-CPAC triggered by the SN, due to the failure caused by the following S-CPAC, the MN sends a message to the source SN of the corresponding CPC, and the source SN performs the cause analysis. The source SN is the source SN corresponding to the following CPC. The message sent by the MN to the source SN includes the same information as that in step 1302. The message sent by the MN to the source SN can be an SCG failure information report or other messages.

[0525] For the S-CPAC triggered by the SN, due to the failure caused by the following S-CPAC, another method is as follows: if the suitable PSCell is not recommended by the SN that initiated the S-CPAC, then the SN that initiated the S-CPAC performs relevant optimization, and the source SN indicates to the MN that the cause of the SCG failure occurred in the SN that initiated the S-CPAC, otherwise, the source SN indicates to the MN that the cause of the SCG failure occurred in the candidate or target SN. If the suitable PSCell is one of the candidate PSCells recommended by the SN that initiated the S-CPAC, but is not one of the candidate PSCells selected by the candidate or the target SN, or the configuration of the execution conditions is unreasonable, the failure is brought by the candidate or the target SN, and the cause of the SCG failure occurred in the candidate or the target SN, and the target or the candidate SN needs to perform relevant optimization. The message sent by the source SN to the MN includes an MN UE XnAP ID, an SN UE XnAP ID, and information on whether the cause of the SCG failure occurred in the SN that initiated the S-CPAC or other candidate or target SN. Here, the failure caused by the following S-CPAC can also be said to be the failure related to the following S-CPAC. The MN receives the message from the source SN. If the cause of the SCG failure occurred in the SN that initiated the S-CPAC, the MN sends a message to the SN that initiated the S-CPAC. If the cause of the SCG failure occurred in other nodes (candidate or target SN), the MN sends a message to the candidate or target SN. The information included in the message is the same as that in step 304, so it will not be repeated here. The message may be an SCG failure information report or other messages, and the present invention does not limit this.

[0526] At this point, the Method 8 for supporting self-configuration and self-optimization of the present invention is completed, which can support the robustness of the PSCell change in the enhanced mobility procedure, for example, in the S-CPAC, and correctly identify a cause of a failure, so as to carry out reasonable optimization, reduce occurrence of failures, ensure service continuity, and reduce labor cost of operators.

[0527] It should be noted that the following S-CPAC in the present invention can also be referred to as the following CPC or the following CPC of the S-CPAC procedure, and the following S-CPAC can also be referred to as the subsequent CPC or the subsequent CPC of the S-CPAC procedure. The source SN of the following S-CPAC can also be referred to as the source SN of the following CPC or the source SN corresponding to the following CPC of the S-CPAC procedure, both of which refer to the source SN of the following CPC in the S-CPAC procedure.

[0528] The methods in Figure 12 and Figure 14 can be used in combination. For example, after receiving the SCG failure message from the UE and performing the initial analysis, the behavior of the MN can be steps 1202 and 1203 in Figure 12 or steps 1403 and 1404 in Figure 14 for different scenarios.

[0529] The methods in Figure 12 and Figure 15 can be used in combination. For example, after receiving the SCG failure message from the UE and performing the initial analysis, the behavior of the MN can be steps 1202 and 1203 in Figure 12 or step 1502 in Figure 15 for different scenarios.

[0530] The methods in Figure 13 and Figure 14 can be used in combination. For example, after receiving the SCG failure message from the UE and performing the initial analysis, the behavior of the MN can be step 1302 in Figure 13 or steps 1403 and 1404 in Figure 14 for different scenarios.

[0531] The methods in Figure 13 and Figure 15 can be used in combination. For example, after receiving the SCG failure message from the UE and performing the initial analysis, the behavior of the MN can be step 1302 in Figure 13 or step 1502 in Figure 15 for different scenarios.

[0532] Figure 16 is a block diagram of a network node in a network according to the present disclosure.

[0533] Network nodes in the network can be used to implement the MN, SN, S-SN, T-SN, other candidate T-SNs, etc. in the present disclosure. Referring to Figure 16, a network node according to the present disclosure includes a transceiver 1610, a controller 1620 and a memory 1630. The transceiver 1610, controller 1620, and memory 1630 are configured to perform the operations of the methods and / or embodiments of the present disclosure. Although the transceiver 1610, the controller 1620, and the memory 1630 are shown as separate entities, they may be implemented as a single entity, such as a single chip. The transceiver 1610, the controller 1620, and the memory 1630 may be electrically connected or coupled to each other. The transceiver 1610 may transmit signals to and receive signals from other network nodes, such as UEs, MNs, SNs, S-SNs, T-SNs, candidate T-SNs, or core network nodes. The controller 1620 may include one or more processing units, and may control the network node to perform operations and / or functions according to one of the above embodiments. The memory 1630 may store instructions for implementing the operations and / or functions of one of the above embodiments.

[0534] Figure 17 is a block diagram of a user equipment UE according to the present disclosure.

[0535] Referring to Figure 17, the UE according to the present disclosure includes a transceiver 1710, a controller 1720, and a memory 1730. The transceiver 1710, controller 1720, and memory 1730 are configured to perform the operations of methods and / or embodiments of the present disclosure. Although the transceiver1710, the controller 1720, and the memory 1730 are shown as separate entities, they may be implemented as a single entity, such as a single chip. The transceiver 1710, the controller 1720, and the memory 1730 may be electrically connected or coupled to each other. The transceiver 1710 may transmit signals to and receive signals from other network nodes, such as UEs, MNs, SNs, S-SNs, T-SNs, candidate T-SNs, or core network nodes. The controller 1720 may include one or more processing units, and may control the UE to perform operations and / or functions according to one of the above-described embodiments. The memory 1730 may store instructions for implementing the operations and / or functions of one of the above-described embodiments.

[0536] Those skilled in the art will appreciate that the above illustrative embodiments are described herein and are not intended to be limiting. It should be understood that any two or more of the embodiments disclosed herein may be combined in any combination. Additionally, other embodiments may be utilized, and other changes may be made, without departing from the spirit and scope of the subject matter presented herein. It will be readily understood that the aspects of the disclosure of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are contemplated herein.

[0537] Those of skill in the art will appreciate that the various illustrative logical blocks, modules, circuits, and steps described herein may be implemented as hardware, software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such design decisions should not be interpreted as causing a departure from the scope of the present application.

[0538] The various illustrative logical blocks, modules, and circuits described herein may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0539] The steps of a method or algorithm described herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.

[0540] In one or more exemplary designs, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. Storage media may be any available media that can be accessed by a general purpose or special purpose computer.

[0541] The above descriptions are only exemplary embodiments of the present application and are not intended to limit the scope of protection of the present application, which is determined by the appended claims.

Claims

1.A method performed by a first base station operating as a secondary node (SN) in a dual connectivity of a user equipment (UE) in a communication system, the method comprising:initiating a subsequent conditional primary secondary cell group (SCG) cell (PSCell) addition or change (SCPAC);receiving, from a second base station operating as a mater node (MN) in the dual connectivity, a message for reporting information on an SCG failure; andperforming an analysis of a cause for the SCG failure,wherein in case that a time duration from execution of the SCPAC to the SCG failure is larger than a configured threshold or the time duration is not reported by the UE, and there is a suitable PSCell different from a PSCell where the UE stayed when the SCG failure occurred, the cause for the SCG failure is a Too Late SCPAC execution.2.The method of claim 1, further comprising:for an initial failure of the SCPAC,in case that the suitable PSCell is one of candidate PSCells determined by the first base station and is not one of candidate PSCells selected by a candidate or target SN, transmitting, to the second base station, information indicating that the cause for the SCG failure is associated with other nodes; andin case that the suitable PSCell is not one of the candidate PSCells determined by the first base station or is one of the candidate PSCells selected by the candidate or target SN, performing an optimization for mobility robustness.3.The method of claim 1, further comprising:for a following failure of the SCPAC,in case that the suitable PSCell is not one of candidate PSCells determined by the first base station, performing an optimization for mobility robustness; andin case that the suitable PSCell is one of the candidate PSCells determined by the first base station, transmitting, to the second base station, information indicating that the cause for the SCG failure is associated with other nodes.4.The method of claim 1, wherein the first base station is a source SN of the SCPAC.5.A method performed by a second base station operating as a master node (MN) in a dual connectivity of a user equipment (UE) in a communication system, the method comprising:receiving, from the UE, information on a secondary cell group (SCG) failure;performing an initial analysis for the SCG failure and determining a type of primary SCG cell (PSCell) addition or change;in case that the type of PSCell addition or change is a subsequent conditional PSCell addition or change (SCPAC) imitated by a first base station operating as a secondary node (SN) in the dual connectivity, transmitting, to the first base station, a message for reporting the information on the SCG failure, which triggers an analysis of a cause for the SCG failure,wherein in case that a time duration from execution of the SCPAC to the SCG failure is larger than a configured threshold or the time duration is not reported by the UE, and there is a suitable PSCell different from a PSCell where the UE stayed when the SCG failure occurred, the cause for the SCG failure is a Too Late SCPAC execution.6.The method of claim 5, further comprising:for an initial failure of the SCPAC, in case that the suitable PSCell is one of candidate PSCells determined by the first base station and is not one of candidate PSCells selected by a candidate or target SN,receiving, from the first base station, information indicating that the cause for the SCG failure is associated with other nodes; andtransmitting, to the candidate or target SN, the message for reporting the information on the SCG failure.7.The method of claim 5, further comprising:for a following failure of the SCPAC, in case that the suitable PSCell is one of the candidate PSCells determined by the first base station,receiving, from the first base station, information indicating that the cause for the SCG failure is associated with other nodes; andtransmitting, to the candidate or target SN, the message for reporting the information on the SCG failure.8.The method of claim 5, wherein the first base station is a source SN of the SCPAC.9.A first base station operating as a secondary node (SN) in a dual connectivity of a user equipment (UE) in a communication system, the first base station comprising:a transceiver; anda controller configured to:initiate a subsequent conditional primary secondary cell group (SCG) cell (PSCell) addition or change (SCPAC),receive, from a second base station operating as a mater node (MN) in the dual connectivity via the transceiver, a message for reporting information on an SCG failure, andperform an analysis of a cause for the SCG failure,wherein in case that a time duration from execution of the SCPAC to the SCG failure is larger than a configured threshold or the time duration is not reported by the UE, and there is a suitable PSCell different from a PSCell where the UE stayed when the SCG failure occurred, the cause for the SCG failure is a Too Late SCPAC execution.10.The first base station of claim 9, wherein the controller is further configured to:for an initial failure of the SCPAC,in case that the suitable PSCell is one of candidate PSCells determined by the first base station and is not one of candidate PSCells selected by a candidate or target SN, transmit, to the second base station via the transceiver, information indicating that the cause for the SCG failure is associated with other nodes, andin case that the suitable PSCell is not one of the candidate PSCells determined by the first base station or is one of the candidate PSCells selected by the candidate or target SN, perform an optimization for mobility robustness.11.The first base station of claim 9, wherein the controller is further configured to:for a following failure of the SCPAC,in case that the suitable PSCell is not one of candidate PSCells determined by the first base station, perform an optimization for mobility robustness, andin case that the suitable PSCell is one of the candidate PSCells determined by the first base station, transmit, to the second base station via the transceiver, information indicating that the cause for the SCG failure is associated with other nodes.12.The first base station of claim 9, wherein the first base station is a source SN of the SCPAC.13.A second base station operating as a master node (MN) in a dual connectivity of a user equipment (UE) in a communication system, the second base station comprising:a transceiver; anda controller configured to:receive, from the UE, secondary cell group (SCG) failure information,perform an initial analysis for an SCG failure and determining a type of primary SCG cell (PSCell) addition or change, andin case that the type of PSCell addition or change is a subsequent conditional PSCell addition or change (SCPAC) imitated by a first base station operating as a secondary node (SN) in the dual connectivity, transmit, to the first base station via the transceiver, a message for reporting the information on the SCG failure, which triggers an analysis of a cause for the SCG failure,wherein in case that a time duration from execution of the SCPAC to the SCG failure is larger than a configured threshold or the time duration is not reported by the UE, and there is a suitable PSCell different from a PSCell where the UE stayed when the SCG failure occurred, the cause for the SCG failure is a Too Late SCPAC execution.14.The second base station of claim 13, wherein the controller is further configured to:for an initial failure of the SCPAC, in case that the suitable PSCell is one of candidate PSCells determined by the first base station and is not one of candidate PSCells selected by a candidate or target SN,receive, from the first base station via the transceiver, information indicating that the cause for the SCG failure is associated with other nodes, andtransmit, to the candidate or target SN via the transceiver, the message for reporting the information on the SCG failure.15.The second base station of claim 13, wherein the controller is further configured to:for a following failure of the SCPAC, in case that the suitable PSCell is one of the candidate PSCells determined by the first base station,receive, from the first base station via the transceiver, information indicating that the cause for the SCG failure is associated with other nodes, andtransmit, to the candidate or target SN via the transceiver, the message for reporting the information on the SCG failure.

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