CN114466378A

CN114466378A - Base station and method supporting self-configuration and self-optimization

Info

Publication number: CN114466378A
Application number: CN202110044496.2A
Authority: CN
Inventors: 许丽香; 汪巍崴; 王弘
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2020-10-21
Filing date: 2021-01-13
Publication date: 2022-05-10

Abstract

The application relates to a base station and a method supporting self-configuration self-optimization. A method performed by a destination base station in a mobile communication system includes: receiving a radio link failure, RLF, report for a user equipment, UE, from a source base station or a third base station; detecting a cause of failure occurrence based on the UE RLF report; based on the reason for the detected failure occurrence, a message is sent to the source base station.

Description

Base station and method supporting self-configuration and self-optimization

Technical Field

The present application relates to wireless communication technology, and more particularly, to a base station and method for supporting self-configuration and self-optimization.

Background

In order to meet the increasing demand for wireless data communication services since the deployment of 4G communication systems, efforts have been made to develop improved 5G or quasi-5G communication systems. Accordingly, the 5G or quasi-5G communication system is also referred to as a "super 4G network" or a "post-LTE system".

Wireless communication is one of the most successful innovations in modern history. Recently, the number of subscribers to wireless communication services has exceeded 50 billion and is continuing to grow rapidly. Due to the increasing popularity of smart phones and other mobile data devices (e.g., tablet computers, notebook computers, netbooks, e-book readers, and machine type devices) among consumers and businesses, the demand for wireless data services is growing rapidly. To meet the high-speed growth of mobile data services and support new applications and deployments, it is important to improve radio interface efficiency and coverage.

Disclosure of Invention

For an enhanced mobility scheme, how to support mobility robustness in a handover process is a problem to be solved at present.

The method supporting self-configuration and self-optimization can support the enhanced switching robustness in the moving process, correctly identify the reasons of failure occurrence, reasonably optimize, reduce the failure occurrence, ensure the service continuity and reduce the labor cost of operators.

According to an aspect of the present application, there is provided a method performed by a destination base station in a mobile communication system, the method including: receiving a radio link failure, RLF, report for a user equipment, UE, from a source base station or a third base station; detecting a cause of failure occurrence based on the UE RLF report; based on the reason for the detected failure occurrence, a message is sent to the source base station.

Optionally, the message sent to the source base station comprises a type of handover report, wherein the type of handover report comprises at least one of too early handover, too late handover, handover to a wrong cell, CHO handover, too late CHO execution, too early CHO handover, too early CHO execution, CHO to a wrong cell, CHO execution to a wrong cell, and improper CHO candidate cell configuration.

Optionally, based on the UE RLF report, the reason for the occurrence of the detection failure includes at least one or more of: if there is a recent CHO execution before the failure occurs and the cell where the UE first attempts Radio Resource Control (RRC) re-establishment or the cell where the UE attempts RRC connection establishment or the cell where the UE successfully establishes RRC connection after the failure occurs is the cell serving the UE when the last handover occurs, the reason for the failure occurrence is too early CHO execution; if the latest CHO execution is performed before the failure occurs, and the cell for which the UE tries RRC reestablishment for the first time after the failure occurs or the cell for which the CHO recovers success or the cell for which the UE tries RRC connection establishment or the cell for which the UE successfully establishes RRC connection is not the cell serving the UE when the latest switching occurs or the cell serving the UE when the RLF occurs or the target cell for the CHO switching execution, the reason for the failure occurrence is that the CHO is executed to the wrong cell or the CHO is executed to the wrong cell; the reason for the failure occurrence is too late CHO or too late CHO execution if it is determined from the UE RLF report that no CHO execution is contained or the UE RLF report does not contain the time from CHO execution to failure occurrence or the time from CHO execution to failure occurrence is greater than a configured threshold that there is no recent CHO execution before failure occurrence; if the latest CHO execution occurs before the failure occurs, and the cell for which the UE first attempts RRC reestablishment or the cell for which the CHO recovers successfully or the cell for which the UE attempts RRC connection establishment or the cell for which the UE successfully establishes RRC connection after the failure occurs is not the cell serving the UE when the latest handover occurs or the cell serving the UE when the RLF occurs or the cell to which the CHO handover is executed, and the cell for which the UE first attempts RRC reestablishment or the cell for which the CHO recovers successfully or the cell for which the UE attempts RRC connection establishment or the cell for which the UE successfully establishes RRC connection after the failure occurs is not in the CHO candidate cell list, the reason for the failure occurrence is improper CHO candidate cell configuration.

Optionally, the method further comprises: receiving, from the source base station, a message including a Conditional Handover (CHO) candidate cell list, a CHO execution condition, CHO configuration information, and/or a time from the CHO configuration to a closest or immediate handover command, wherein the CHO candidate cell list contains all candidate cells for the CHO handover. Optionally, the message sent to the source base station further includes a CHO candidate cell list containing all candidate cells for the CHO handover.

According to another aspect of the present application, there is provided a method performed by a source base station in a mobile communication system, the method including: sending a Radio Link Failure (RLF) report of User Equipment (UE) to a target base station; a message is received from the destination base station containing a reason for the occurrence of the failure detected by the destination base station based on the UE RLF report.

Optionally, the message received from the destination base station comprises a type of handover report, wherein the type of handover report comprises at least one of too early handover, too late handover, handover to a wrong cell, CHO handover, too late CHO execution, too early CHO handover, too early CHO execution, CHO to wrong cell, CHO execution to wrong cell, and unsuitable CHO candidate cell configuration.

Optionally, based on the UE RLF report, the reason for the occurrence of the detection failure includes at least one or more of: if the most recent CHO execution occurs before the failure occurs, and the cell in which the UE first attempts RRC reestablishment after the failure occurs, or the cell in which the UE attempts RRC connection establishment, or the cell in which the UE successfully establishes RRC connection is the cell serving the UE when the latest handover occurs, the reason for the failure occurrence is too early CHO execution; if the latest CHO execution is performed before the failure occurs, and the cell for which the UE tries RRC reestablishment for the first time after the failure occurs or the cell for which the CHO recovers success or the cell for which the UE tries RRC connection establishment or the cell for which the UE successfully establishes RRC connection is not the cell serving the UE when the latest switching occurs or the cell serving the UE when the RLF occurs or the target cell for the CHO switching execution, the reason for the failure occurrence is that the CHO is executed to the wrong cell or the CHO is executed to the wrong cell; the reason for the failure occurrence is too late CHO or too late CHO execution if it is determined from the UE RLF report that no CHO execution is contained or the UE RLF report does not contain the time from CHO execution to failure occurrence or the time from CHO execution to failure occurrence is greater than a configured threshold that there is no recent CHO execution before failure occurrence; if the latest CHO execution is carried out before the failure occurs, the cell for which the UE tries RRC reestablishment for the first time after the failure occurs, or the cell for which the CHO restores or the cell for which the UE tries RRC connection establishment or the cell for which the UE succeeds in establishing RRC connection are not the cell serving the UE when the latest handover occurs or the cell serving the UE when RLF occurs or the cell to which the CHO handover is carried out, and the cell for which the UE tries RRC reestablishment for the first time after the failure occurs, or the cell for which the CHO restores or the cell for which the UE tries RRC connection establishment or the cell for which the UE succeeds in establishing RRC connection is not in the CHO candidate cell list, the reason for the failure occurrence is improper CHO candidate cell configuration.

Optionally, the method further comprises: and transmitting a CHO candidate cell list and/or a CHO executing condition to the destination base station, wherein the CHO candidate cell list contains all candidate cells for the CHO switching.

Optionally, the message received from the destination base station further comprises a CHO candidate cell list containing all candidate cells for the CHO handover.

According to still another aspect of the present application, there is provided a method performed by a source base station in a mobile communication system, the method including: receiving a Radio Link Failure (RLF) report of User Equipment (UE); the reason for the failure occurrence is confirmed based on the UE RLF report.

Optionally, the RLF report of the UE is received by the source base station through the third base station, through the destination base station, or directly from the UE.

Optionally, the cause of the occurrence of the acknowledgement failure comprises at least one or more of the following, based on the UE RLF report: if the most recent CHO execution occurs before the failure occurs, and the cell in which the UE first attempts RRC reestablishment after the failure occurs, or the cell in which the UE attempts RRC connection establishment, or the cell in which the UE successfully establishes RRC connection is the cell serving the UE when the latest handover occurs, the reason for the failure occurrence is too early CHO execution; if the latest CHO execution is performed before the failure occurs, and the cell for which the UE tries RRC reestablishment for the first time after the failure occurs or the cell for which the CHO recovers success or the cell for which the UE tries RRC connection establishment or the cell for which the UE successfully establishes RRC connection is not the cell serving the UE when the latest switching occurs or the cell serving the UE when the RLF occurs or the target cell for the CHO switching execution, the reason for the failure occurrence is that the CHO is executed to the wrong cell or the CHO is executed to the wrong cell; the reason for the failure occurrence is too late CHO or too late CHO execution if it is determined from the UE RLF report that no CHO execution is contained or the UE RLF report does not contain the time from CHO execution to failure occurrence or the time from CHO execution to failure occurrence is greater than a configured threshold that there is no recent CHO execution before failure occurrence; if the latest CHO execution occurs before the failure occurs, and the cell for which the UE first attempts RRC reestablishment or the cell for which the CHO recovers successfully or the cell for which the UE attempts RRC connection establishment or the cell for which the UE successfully establishes RRC connection after the failure occurs is not the cell serving the UE when the latest handover occurs or the cell serving the UE when the RLF occurs or the cell to which the CHO handover is executed, and the cell for which the UE first attempts RRC reestablishment or the cell for which the CHO recovers successfully or the cell for which the UE attempts RRC connection establishment or the cell for which the UE successfully establishes RRC connection after the failure occurs is not in the CHO candidate cell list, the reason for the failure occurrence is improper CHO candidate cell configuration.

Optionally, the method further comprises: transmitting to the destination base station a list of CHO candidate cells comprising all candidate cells for a CHO handover, a CHO execution condition, CHO configuration information and/or a time from the CHO configuration to the closest or immediate handover command.

Optionally, the method further comprises: and sending a switching request message to the target base station.

Optionally, the method further comprises: sending an RRC reconfiguration message containing CHO configuration information to the UE, and receiving a UE RLF report from the UE.

According to yet another aspect of the present application, there is provided a method performed by a destination base station in a mobile communication system, the method including: receiving a message from a source base station; receiving a successful handover report from the UE; and sending the access and movement indication message to the source base station.

Optionally, the message received from the source base station comprises information of a CHO candidate cell list and/or CHO execution conditions. The message also contains CHO configuration information and/or the time from the CHO configuration to the nearest or immediate handover command. The CHO configuration is a CHO configuration sent by the source base station to the UE. The handover command is the handover command message closest/next to the CHO configuration for triggering the usual handover.

Optionally, the successful handover report contains at least one or more of the following information: the identification of the source cell, the global cell identification of the cell sent by the last RRC reconfiguration message, also contains the Tracking Area Code (TAC) of the cell; the primary cell identity of the target cell may also include the TAC or TAI of the cell; a cell radio network temporary identity (C-RNTI); the type of failure; measurement results of the UE.

Optionally, the access and mobility indication message sent by the destination base station to the source base station contains a successful handover report. The message may also contain a handover type, a CHO candidate cell list, CHO execution conditions, CHO configuration information, and/or time from CHO configuration to the nearest or immediate handover command.

According to still another aspect of the present application, there is provided a destination base station in a mobile communication system, including: a transceiver to transmit/receive signals to/from other network entities; and a controller controlling an overall operation of the destination base station, wherein the destination base station is configured to perform the above-described method performed by the destination base station.

According to still another aspect of the present application, there is provided a source base station in a mobile communication system, including: a transceiver to transmit/receive signals to/from other network entities; and a controller controlling an overall operation of the source base station, wherein the source base station is configured to perform the method performed by the source base station.

By the method and the base station supporting the self-configuration and self-optimization, the enhanced robustness of switching in the moving process can be supported, and the reason of failure occurrence can be correctly identified, so that reasonable optimization is carried out, the failure occurrence is reduced, the service continuity is ensured, and the labor cost of operators is reduced.

Drawings

The foregoing and additional aspects and advantages of the present application will become more apparent and readily appreciated from the following description, taken in conjunction with the accompanying drawings, wherein:

fig. 1 is an exemplary system architecture for System Architecture Evolution (SAE).

Fig. 2 is an exemplary system architecture according to various embodiments of the present disclosure.

FIG. 3 is a flowchart illustrating a first method of supporting self-configuration self-optimization in accordance with an exemplary embodiment of the present invention.

Fig. 4 shows a flowchart of a second method for supporting self-configuration self-optimization according to an exemplary embodiment of the present invention.

Fig. 5 shows a flowchart of a third method of supporting self-configuration self-optimization according to an exemplary embodiment of the present invention.

Fig. 6 is a diagram illustrating an embodiment of a first method for supporting self-configuration self-optimization according to an exemplary embodiment of the present invention.

Fig. 7 is a diagram illustrating another embodiment of a method for supporting self-configuration self-optimization according to an exemplary embodiment of the present invention.

Fig. 8 is a diagram illustrating an embodiment of a second method for supporting self-configuration self-optimization according to an exemplary embodiment of the present invention.

Fig. 9 is a schematic diagram illustrating another embodiment of a second method for supporting self-configuration self-optimization according to an exemplary embodiment of the present invention.

Fig. 10 is a schematic diagram illustrating a further embodiment of a second method for supporting self-configuration self-optimization according to an exemplary embodiment of the present invention.

FIG. 11 shows a schematic diagram of one embodiment of a method III for supporting self-configuring self-optimization, in accordance with an illustrative embodiment of the present invention.

Fig. 12 shows a schematic diagram of another embodiment of a method three of supporting self-configuration self-optimization according to an exemplary embodiment of the present invention.

FIG. 13 illustrates a flowchart of method four for supporting self-configuration self-optimization in accordance with an exemplary embodiment of the present invention.

Fig. 14 illustrates a block diagram of a destination base station according to an exemplary embodiment of the present invention.

Fig. 15 shows a block diagram of a source base station according to an exemplary embodiment of the present invention.

Detailed Description

Figures 1 through 15, discussed below, and the various embodiments used 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 system or device.

Fig. 1 is an exemplary system architecture 100 for System Architecture Evolution (SAE). A 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 that includes macro base stations (eNodeB/NodeB) that provide access to a radio network interface for UEs. A Mobility Management Entity (MME)103 is responsible for managing mobility context, session context and security information of the UE. Serving Gateway (SGW)104 mainly provides the functions of the user plane, and MME 103 and SGW 104 may be in the same physical entity. A packet data network gateway (PGW)105 is responsible for charging, lawful interception, etc., and may also be in the same physical entity as the SGW 104. A Policy and Charging Rules Function (PCRF)106 provides quality of service (QoS) policy and charging criteria. The general packet radio service support node (SGSN)108 is a network node device in the Universal Mobile Telecommunications System (UMTS) that provides routing for the transmission of data. The Home Subscriber Server (HSS)109 is the home subsystem of the UE and is responsible for protecting user information including the current location of the user equipment, the address of the serving node, user security information, the packet data context of the user equipment, etc.

Fig. 2 is an exemplary system architecture 200 in accordance with various embodiments of the present disclosure. Other embodiments of the system architecture 200 can be used without departing from the scope of this disclosure.

A User Equipment (UE)201 is a terminal device for receiving data. The next generation radio access network (NG-RAN)202 is a radio access network comprising base stations (the gbb or enbs connected to the 5G core network 5GC, also called NG-gbb) providing access to radio network interfaces for UEs. An access control and mobility management function (AMF)203 is responsible for managing the mobility context of the UE, and security information. A user plane functional entity (UPF)204 mainly provides the functions of the user plane. The session management function entity SMF205 is responsible for session management. The Data Network (DN)206 contains services such as the operator, access to the internet, and services for third parties.

In order to improve the reliability of handover when a UE moves between two base stations, Conditional Handover (CHO) is defined in 3GPP release 16. Improper setup or triggering of the CHO procedure may also result in Radio Link Failure (RLF) or handover failure (HOF). How to identify the type of failure for reasonable optimization is a problem that needs to be solved at present.

Exemplary embodiments of the present disclosure are further described below in conjunction with the appended drawings.

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

Fig. 3 illustrates a flowchart of a method of supporting self-configuration self-optimization (hereinafter, referred to as method one) according to an exemplary embodiment of the present invention. The embodiment is particularly suitable for the scene that the radio connection failure happens soon after the CHO switching is successful.

Step 301, in response to the source base station deciding to initiate a CHO handover, the destination base station receives a message from the source base station including a CHO candidate cell list and/or CHO execution conditions. The message also contains CHO configuration information and/or the time from the CHO configuration to the nearest or immediate handover command. The CHO configuration is a CHO configuration sent by the source base station to the UE. The handover command is the handover command message closest/next to the CHO configuration for triggering the usual (normal) handover. The message may be a handover request message, an early state transfer message, a Sequence Number (SN) state transfer message, a newly defined message, or other existing message. The message may be sent to the destination base station by the source base station in the handover preparation stage, or sent to the destination base station after the source base station receives the handover success message, or sent to the destination base station at other times, which is not limited in the present invention. The destination base station may receive the above-mentioned information from the source base station through the same message or a different message. The destination base station saves the received information. The CHO candidate cell list contains all candidate cells of this CHO handover decided by the source base station, including all candidate cells on the destination base station receiving the message and candidate cells on other potential destination base stations. The information of each candidate cell comprises a global cell identity. The CHO execution condition may be one or more, and is the same as the CHO execution condition that the source base station transmits to the UE through the RRC reconfiguration message. The source base station sends the CHO candidate cell list, the CHO executing condition, the CHO configuration information and/or the time from the CHO configuration to the nearest or immediate switching command to the target base station through an interface message between the base stations, or the source base station sends the CHO candidate cell list, the CHO executing condition, the CHO configuration information and/or the time from the CHO configuration to the nearest or immediate switching command to the target base station through an interface message from the source base station to the core network and an interface message from the core network to the target base station. The source-to-destination transparent transmitter, which may be a handover requirement message from the source base station to the core network and a handover request from the core network to the destination base station, transmits the CHO candidate cell list, the CHO execution condition, the CHO configuration information, and/or the time from the CHO configuration to the closest or immediate handover command to the destination base station.

In step 302, the destination base station receives a Radio Link Failure (RLF) report of the UE from the third base station or the source base station. The radio link failure report contains at least one or more of the following information:

-the identity of the previous primary cell, the global cell identity of the cell sent by the last RRC reconfiguration message, also containing the Tracking Area Code (TAC) of said cell;

-a failed primary cell identity, a global cell identity of a cell where RLF failure occurred or a destination cell when handover failed, also containing TAC of said cell;

-cell identity of the destination cell for which CHO execution failed, also containing the TAC of said cell. The cell identity of the destination cell for which the CHO execution failed may also be indicated by the above failed primary cell identity;

-a cell radio network temporary identity (C-RNTI), a C-RNTI for a cell in case of RLF failure or a C-RNTI for a source cell in case of handover failure;

-reconnect cell identity, global cell identity of cell successfully accessed by UE after failure, also containing TAC of said cell;

time from failure to successful network access

-re-establishing the cell identity of the cell, the cell identity of the cell for which the UE initiated the RRC re-establishment;

-time to failure occurrence from reception of RRC reconfiguration message containing handover command; for CHO, this time represents the time from the receipt of an RRC reconfiguration message containing the CHO configuration to the occurrence of a failure, or represents the time from the start of CHO execution to the occurrence of a failure. The time may be two for the case where the UE receives the CHO configuration followed by the old (legacy) handover command, respectively, the time from the CHO configuration to the failure and the time from the old handover command to the failure.

-the time from the reception of the RRC reconfiguration message containing the CHO configuration to the occurrence of the failure, this information being represented by defining a new information element or by said information element from the reception of the RRC reconfiguration message containing the handover command to the occurrence of the failure at the time of the CHO;

-time from receipt of the RRC reconfiguration message containing the CHO configuration to receipt of the old handover command;

-time from failure occurrence to occurrence of UE RLF reporting;

types of connection failures, including radio link failures, handover failures. CHO handover failure may also be included;

-a cell identity of a CHO recovery cell, a global cell identity of a CHO recovery cell, and may also contain a TAC of said cell;

-the cell identity of the successful cell is restored by CHO, the global cell identity of the successful cell is restored by CHO, and may also contain the TAC of said cell;

-cell identity of CHO recovery failed cell, global cell identity of CHO recovery failed cell, which may also contain TAC of said cell;

-an indication of CHO recovery, which indication information may be used to indicate that the CHO recovery was successful or that the CHO recovery was not successful;

-an indication that the CHO condition is met or not met. Information of which CHO event was or was not satisfied may also be included.

CHO starts executing until failure occurs. If the time from the reception of the RRC reconfiguration message containing the handover command to the occurrence of the failure for the CHO means the time from the reception of the RRC reconfiguration message containing the CHO configuration to the occurrence of the failure, it is necessary to increase the time from the start of the CHO execution to the occurrence of the failure;

-time from reception of the RRC reconfiguration message containing the CHO configuration to start execution by the CHO; the base station may not separately contain the information element, and the base station calculates the time from the reception of the RRC reconfiguration message containing the CHO configuration to the start of the CHO execution according to the time difference between the time from the reception of the RRC reconfiguration message containing the CHO configuration to the occurrence of the failure and the time from the start of the CHO execution to the occurrence of the failure;

-an indication of a CHO configuration;

-an indication of CHO execution, which indication information may be used to indicate that CHO execution or not;

-from the receipt of the CHO configuration to the immediately following RRC reconfiguration message containing the handover command;

-event or condition satisfying CHO enforcement;

-time from CHO handover failure to immediate CHO recovery failure;

-from the CHO configuration to the immediate time of receipt of the RRC reconfiguration message containing the handover command;

-an indication of CHO failure and CHO recovery failure or an indication of a secondary failure;

-measurement results of the UE. The measurement results include measurement results for a serving cell, a CHO candidate cell, and/or a neighboring cell. For the cell satisfying the execution condition, the information further includes indication information that the execution condition is satisfied. The measurement result includes a measurement result during handover trigger, a measurement result received by a CHO configuration, a measurement result during CHO execution, a measurement result during handover execution, a measurement result during failure occurrence, a measurement result after handover execution, and/or a measurement result during handover success.

The UE may also maintain two RLF reports for two consecutive failures, e.g., a CHO handover failure followed by a CHO recovery failure or a CHO handover failure followed by a HOF. The failed primary cell identities are cell identities of cells that have failed for the first and second times, or cell identities of handover destination cells for which handover failed. For example, when a failure occurs in CHO execution to cell a and a failure occurs in UE performing CHO recovery in cell B, the primary cell id that has failed contained in the first RLF report is the id of cell a, and the primary cell id that has failed contained in the second RLF report is the id of cell B. The above time relating to the failure is also calculated in accordance with the times at which two failures occur, respectively. The time from the reception of the RRC reconfiguration message containing the handover command to the occurrence of the failure contained in the first RLF report is the time from the reception of the RRC reconfiguration message containing the handover command to the CHO execution failure. The time from the reception of the RRC reconfiguration message containing the handover command to the occurrence of the failure contained in the second RLF report is the time from the reception of the RRC reconfiguration message containing the handover command to the CHO recovery failure. For the time from CHO handover execution to failure, the time from CHO handover execution to execution failure is contained in the first RLF report, and the time from CHO handover execution to CHO recovery failure is contained in the second RLF report. The RLF report may be one but contains information of two failures, e.g. cell identity of the cell that failed twice, time from receiving RRC reconfiguration message containing handover command to failure occurrence of the two, time from CHO handover execution to failure of the two.

According to one embodiment, the UE RLF report is received from the UE by the source base station or the third base station.

According to one embodiment, the method of the present invention may detect, by the destination base station, a cause of the failure occurrence, for example, based on one or more of a CHO candidate cell list, a CHO execution condition, and/or an RLF; according to another embodiment, the source base station may detect the cause of the failure, for example, based on one or more of a CHO candidate cell list, CHO execution conditions, and/or RLF. According to another embodiment, the source base station may determine the reason for the occurrence of the failure based on the CHO candidate cell list, the CHO execution condition, and/or the RLF. The destination base station and the source base station may also take into account other factors without affecting the main content of the invention.

The reason for the failure may be one or more of too early CHO execution, CHO to wrong cell or CHO execution to wrong cell, too late CHO or too late CHO execution, improper CHO candidate cell configuration.

Too early CHO executions: if the failure occurs before the latest CHO execution, for example, according to the indication of the CHO execution or according to the fact that the time from the start of the CHO execution to the occurrence of the failure is less than a configured threshold, it is determined that the latest CHO execution precedes the failure, and the cell in which the UE first attempts the RRC reestablishment after the failure occurs or the cell in which the UE attempts the RRC connection establishment or the cell in which the UE successfully establishes the RRC connection is the cell serving the UE when the latest handover occurs, the reason for the failure occurrence is too early CHO execution. It should be noted that the cell serving the UE at the time of the last handover occurrence is also the source cell at the time of the last handover occurrence.

CHO to wrong cell or CHO implementation to wrong cell: if the failure occurs before the latest CHO execution, for example, according to the indication of the CHO execution or according to the fact that the time from the start of the CHO execution to the occurrence of the failure is less than a configured threshold, it is determined that the latest CHO execution precedes the failure, and the cell where the UE first attempts the RRC reestablishment after the failure occurs or the cell where the CHO recovers or the cell where the UE attempts the RRC connection establishment or the cell where the UE successfully establishes the RRC connection is not the cell serving the UE when the latest handover occurs or the cell serving the UE when the RLF occurs or the target cell of the CHO handover execution, the reason for the failure occurrence is that the CHO is executed to the wrong cell or the CHO is executed to the wrong cell. It should be noted that the cell serving the UE when the last handover occurred is also the source cell when the last handover occurred.

Too late CHO or too late CHO execution: if no recent CHO execution occurred before the failure occurred, the reason for the failure occurred was too late CHO or too late CHO execution, determined based on, for example, the UE RLF report not containing an indication of CHO execution or an indication of CHO execution being that CHO was not executed or the UE RLF report not containing a time from CHO execution to failure occurrence or the time from CHO execution to failure occurrence being greater than a configured threshold.

Inappropriate CHO candidate cell configuration: if the occurrence of a failure is preceded by a most recent CHO execution, e.g., determined based on an indication of CHO execution or based on CHO execution starting until the time at which the failure occurred being less than a configured threshold, and the cell that the UE tries RRC reestablishment for the first time after the failure occurs or the cell that the CHO recovers successfully or the cell that the UE tries RRC connection establishment or the cell that the UE successfully establishes RRC connection is not the cell that serves the UE when the last handover occurs, or the cell that serves the UE when the RLF occurs or the target cell for CHO handover execution, and after the failure occurs, the cell for which the UE tries RRC reestablishment for the first time or the cell for which the CHO recovers successfully or the cell for which the UE tries RRC connection establishment or the cell for which the UE successfully establishes RRC connection is not in the CHO candidate cell list, the reason for the failure occurrence is improper CHO candidate cell configuration. The improper CHO candidate cell configuration may be used alone as a failure reason or a handover report type, or it may be further determined whether the improper CHO candidate cell configuration is determined when the failure reason or the handover report type is from CHO to a wrong cell or from CHO execution to a wrong cell. After detecting that the cell is wrongly executed by the CHO or the cell is wrongly executed by the CHO, the target base station judges improper CHO candidate cell configuration according to the cell which is firstly tried by the UE to be reestablished by the RRC after the failure occurs, the cell which is recovered by the CHO or the cell which is successfully recovered by the CHO or the cell which is tried to be established by the UE to be established by the RRC connection or the cell which is successfully established by the UE to be not in the CHO candidate cell list.

For consecutive failures, the base station may check the reason for the occurrence of the failure according to the information of the first failure and/or the information of the second failure. The base station may check the reason for the occurrence of the failure in the above-described manner. The base station causing the problem is optimized by using the information of two failures to avoid further occurrence of the problem.

Step 303, the destination base station sends a message to the source base station. The message may contain a CHO candidate cell list, CHO execution conditions, CHO configuration information, and/or time from CHO configuration to the nearest or immediate handover command. The information is received from the source base station in step 301. The CHO candidate cell list includes all candidate cells of the current CHO handover. The message may also contain a ue rlf report. The message may also contain the type of handover report, which indicates the reason for the failure to occur. The type of handover report includes at least one of too early handover, too late handover, handover to a wrong cell, CHO handover, too late CHO execution, too early CHO handover, too early CHO execution, CHO to wrong cell, CHO execution to wrong cell, and improper CHO candidate cell configuration. The message may further include a cell identity of the source cell, a cell identity of the destination cell, and/or a cell identity of a cell in which the UE is successfully reconnected after the RRC connection reestablishment cell or failure occurs, or a cell in which the CHO successfully recovers. The message may also contain an indication of the type of handover. The handover types include normal handover, CHO handover, Dual Active Protocol Stack (DAPS) handover, and the like. The message may also contain the cell identity of the CHO recovery failed cell. The message may also contain an indication of a secondary failure. The message may also contain a CHO configuration indication. The message may also contain an unsuitable CHO candidate cell configuration. An unsuitable CHO candidate cell configuration is included when the type of handover report is CHO to the wrong cell or CHO executed to the wrong cell. The inappropriate CHO candidate cell configuration includes cells that satisfy CHO execution conditions but are not in the CHO candidate cell list, cells that are suitable but not in the CHO candidate cell list, and/or cells that are in the CHO candidate cell list but are not suitable in the CHO candidate cell list. And the target base station judges improper CHO candidate cell configuration according to the measurement report of the UE, the CHO execution condition and the cell identifier contained in the RLF report. The cell identities contained in the RLF report may be one or more cell identities as described in step 302. For cells of good quality, but not in the candidate cell list, e.g. based on measurements in the UE measurement reports, the cells need to be included in the candidate cell list. Or for cells in the UE measurement report that are of poor quality but in the candidate cell list, the cells are not suitable for inclusion in the candidate cell list. Among these, the benefits of the CHO candidate cell list, CHO execution conditions, CHO configuration information, and/or the time from CHO configuration to the closest or immediate handover command being sent from the source base station to the destination base station and back to the source base station by the destination base station are: for the case where a radio connection failure occurs immediately after a successful CHO handover, the source base station has released the context of the UE, and the source base station has no knowledge of the candidate cell list for the last CHO handover, the CHO execution conditions, the CHO configuration information, and/or the time from the CHO configuration to the closest or immediate handover command. The source base station needs to further determine whether the failure is caused by unreasonable configuration of candidate cells or the failure is caused by unreasonable configuration of CHO execution conditions according to the CHO candidate cell list. For example, when the UE successfully completes a CHO handover from the source base station to the destination base station, the UE fails RLF at the destination base station, and the UE succeeds in RRC reestablishment or succeeds in RRC connection establishment at the third base station, if a cell that succeeds in RRC reestablishment or succeeds in RRC connection establishment at the third base station is not in the candidate cell list, the reason for the failure includes that the candidate cell is not configured reasonably, and may also include that the CHO execution condition is configured unreasonably; if the cell in which the RRC reestablishment is successful or the RRC connection establishment is successful at the third base station is in the candidate cell list, the reason for the failure is that the CHO execution condition configuration is not reasonable. After determining the cause of the failure, the source base station may further perform optimization of the CHO handover by using the CHO execution condition and/or the candidate cell list, so as to avoid the subsequent CHO handover failure.

According to one embodiment, the reason for the failure occurrence is detected by the destination base station, in which case the message may contain the reason for the failure occurrence detected by the destination base station. According to one embodiment, the cause of the occurrence of the failure is confirmed by the source base station, in which case the source base station confirms and optimizes the cause of the occurrence of the failure according to the type of handover report received, the UE RLF report, the CHO candidate cell list, the CHO execution conditions, the CHO configuration information, and/or the time from the CHO configuration to the closest or immediate handover command. The method for the source base station to determine the reason for the failure occurrence is the same as the method described in step 302, and the source base station may also consider other information to determine the reason for the failure occurrence and perform optimization. According to one embodiment, the reason for the occurrence of the failure detected by the destination base station is one or more of too late CHO, too late CHO execution, too early CHO handover, too early CHO execution, CHO to wrong cell, CHO execution to wrong cell, in which case the message may contain the reason for the occurrence of the failure detected by the destination base station, such as but not limited to a determination by the source base station that the CHO candidate cell configuration is not reasonable and/or the CHO execution condition configuration is not reasonable, the source base station determining whether the CHO candidate cell configuration is reasonable and/or the CHO execution condition configuration is not reasonable according to one or more of the type of handover report received, the UE RLF report, the CHO candidate cell list, the CHO execution condition, the CHO configuration information and/or the time from the CHO configuration to the closest or immediate handover command, and optimizing. The method for the source base station to determine that the CHO candidate cell configuration is unreasonable is the same as that described in step 302, and is not repeated here.

According to one embodiment, if the source base station receives two UE RLF reports or receives an indication of a secondary failure or receives information of a secondary failure, the source base station may determine that handover to an RRC connection re-establishment cell should be performed or handover to a cell where UE reconnection succeeds after failure occurs, instead of performing handover to a target cell or a CHO recovery failure cell, according to the received cell identity of the source cell, the cell identity of the target cell, the cell identity of the RRC connection re-establishment cell, or the cell where UE reconnection succeeds after failure occurs, and/or the cell identity of the CHO recovery failure cell, thereby optimizing a corresponding CHO handover condition.

According to one embodiment, the source base station may determine to reasonably optimize the CHO if the source base station receives a handover too early, a handover too late or a handover to a wrong cell and receives a CHO configuration indication.

The first method of the present invention to support self-configuration self-optimization is shown in an exemplary manner above. Although the method is described from the perspective of the destination base station, it will be understood by those skilled in the art that the source base station can perform corresponding operations, and the description of the present invention is not repeated in order to avoid redundancy. By the aid of the first method, the enhanced robustness of switching in the moving process can be supported, the reason of failure occurrence is correctly identified, reasonable optimization is conducted, failure occurrence is reduced, service continuity is guaranteed, and labor cost of operators is reduced.

Fig. 4 shows a flowchart of a method of supporting self-configuration self-optimization (hereinafter, referred to as method two) according to an exemplary embodiment of the present invention. The embodiment is particularly suitable for the situations that CHO execution failure, CHO execution failure followed by CHO recovery failure, UE receives CHO configuration followed by handover failure, and/or UE successfully accesses a target base station or other base stations after RLF failure occurs in a source base station.

Step 401, the source base station sends a handover request message to the destination base station to request the CHO. And the source base station receives the switching request confirmation message of the target base station. The handover request message may comprise CHO candidate cell list CHO execution conditions, CHO configuration information and/or time from CHO configuration to the closest or immediate handover command. Optionally, the source base station sends an RRC reconfiguration message including the CHO to the UE. The method can be used for the failure of the UE when the source base station has not yet sent the RRC reconfiguration message to the UE or the failure of the UE after the source base station sends the RRC reconfiguration message to the UE. It is therefore an optional step for the source base station to send an RRC reconfiguration message containing CHO to the UE.

The source base station receives the RLF report of the UE from the destination base station, the third base station, or directly. According to one embodiment, the RLF report of the UE is received by the destination base station or a third base station from the UE. According to another embodiment, the RLF report of the UE is received by the source base station directly from the UE. The content of the UE RLF report is the same as that described in step 302, and is not described herein again.

The source base station detects the cause of the failure occurrence. The method for detecting the source base station is the same as that described in step 302, and is not described herein again.

Therefore, the method II for supporting self-configuration and self-optimization is completed, the robustness of switching in the enhanced moving process can be supported, the reason of failure occurrence can be correctly identified, reasonable optimization is carried out, the failure occurrence is reduced, the service continuity is ensured, and the labor cost of operators is reduced.

Fig. 5 shows a flowchart of a method of supporting self-configuration self-optimization (hereinafter, referred to as method three) according to an exemplary embodiment of the present invention. The embodiment is particularly suitable for the situations that the CHO fails to execute, the CHO fails to execute and is followed by the CHO fails to recover, and/or the UE receives the CHO configuration and is followed by the switching failure and then the UE successfully accesses the source base station.

Step 501, the source base station sends a handover request message to the destination base station to request the CHO. The handover request message may include a CHO candidate cell list, CHO execution conditions, CHO configuration information, and/or time from CHO configuration to the nearest or immediate handover command. And the source base station receives the switching request confirmation message of the target base station.

Step 502, the source base station sends an RRC reconfiguration message containing CHO configuration information to the UE.

In step 503, the source base station receives an RLF report of the UE from the UE. After the RRC of the source base station is successfully reestablished or the RRC connection is successfully reconnected, the source base station requests the UE to report an RLF report, and the UE sends the RLF report to the source base station.

The content of the UE RLF report is the same as that described in step 302, and is not described herein again.

Therefore, the method III for supporting self-configuration and self-optimization is completed, the robustness of switching in the enhanced moving process can be supported, the reason of failure occurrence can be correctly identified, reasonable optimization is carried out, the failure occurrence is reduced, the service continuity is ensured, and the labor cost of operators is reduced.

Thus, the method for supporting self-configuration and self-optimization of the invention is completed. The method can support the enhanced switching robustness in the moving process, correctly identify the reason of failure occurrence, reasonably optimize, reduce the failure occurrence, ensure the service continuity and reduce the labor cost of operators.

Fig. 6 is a diagram illustrating an embodiment of a first method for supporting self-configuration self-optimization according to an exemplary embodiment of the present invention. Fig. 6 omits and simplifies detailed description of steps irrelevant to the present invention.

In step 600, the source base station decides to initiate a CHO handover.

Step 601a, the source base station sends a switching request message to the destination base station. The handover request message includes a CHO candidate cell list, CHO execution conditions, CHO configuration information, and/or time from CHO configuration to the nearest or immediate handover command. The CHO candidate cell list includes all candidate cells determined by the source base station for the current CHO handover, and includes all candidate cells on the destination base station receiving the handover request message and candidate cells on other potential destination base stations. The information of each candidate cell comprises a global cell identity. The CHO execution condition may be one or more, and is the same as the CHO execution condition transmitted to the UE by the source base station through RRC reconfiguration. In the method of this embodiment, the CHO candidate cell list, CHO execution conditions, CHO configuration information, and/or the time from the CHO configuration to the closest or immediate handover command may be sent to the destination base station through this step, step 603, step 605b, or step 605 c.

Step 601b, the target base station receives the switching request message. The destination base station maintains the received list of CHO candidate cells and, the CHO execution conditions, the CHO configuration information, and/or the time from the CHO configuration to the closest or immediate handover command. The target base station sends a switching request confirmation message to the source base station.

The above steps 601a and 601b are required to be performed for each handover candidate cell.

Step 602, the source base station sends an RRC reconfiguration message to the UE. The message contains a CHO configuration and/or CHO enforcement conditions. The CHO execution condition is the same as the CHO execution condition sent to the destination base station in step 601 a. And the UE sends an RRC reconfiguration complete message to the source base station.

Step 603, the source base station sends an early state transition message to the destination base station. The message may contain a CHO candidate cell list, CHO execution conditions, CHO configuration information, and/or time from CHO configuration to the nearest or immediate handover command. The CHO candidate cell list and/or CHO execution conditions are the same as those sent to the UE in step 602. The CHO candidate cell list, CHO execution conditions, CHO configuration information, and/or the meaning of the time from the CHO configuration to the closest or immediate handover command are the same as described in step 601a and will not be described again here. The destination base station saves the received information.

Step 604, after receiving the CHO configuration, the UE maintains the connection with the source base station. The UE starts evaluating the execution conditions of each candidate cell. If at least one candidate cell meets the CHO execution condition, the UE departs from the source cell, synchronizes to the selected candidate cell by applying the corresponding configuration of the selected candidate cell, sends an RRC reconfiguration completion message to the target base station, and completes the RRC switching process or the CHO execution process

Step 605a, the destination base station sends a handover success message to the source base station.

Step 605b, the source base station sends an SN status transfer message to the destination base station. The message may contain a CHO candidate cell list, CHO execution conditions, CHO configuration information, and/or time from CHO configuration to the nearest or immediate handover command. The CHO candidate cell list and/or CHO execution conditions are the same as those sent to the UE in step 602. The CHO candidate cell list, CHO execution conditions, CHO configuration information, and/or the meaning of the time from the CHO configuration to the closest or immediate handover command are the same as described in step 601a and will not be described again here. The destination base station saves the received information.

In step 605c, a new message may be defined or other existing message may be used to send the CHO candidate cell list, CHO execution conditions, CHO configuration information, and/or the time from CHO configuration to the nearest or immediate handover command to the destination base station. The CHO candidate cell list and/or CHO execution conditions are the same as those sent to the UE in step 602. The CHO candidate cell list, CHO execution conditions, CHO configuration information, and/or the meaning of the time from the CHO configuration to the closest or immediate handover command are the same as described in step 601a and will not be described again here. The destination base station saves the received information. If the source base station transmits the above information to the destination base station through step 601a or step 605b, this step may not be performed. In the method of the present invention, the CHO candidate cell list, CHO execution conditions, CHO configuration information, and/or the time from the CHO configuration to the closest or immediate handover command may be sent to the destination base station by different messages. For example, the time from the CHO configuration to the closest or immediate handover command is sent to the destination base station through the handover request message, and other new messages are sent to the destination base station through this step.

In step 606, the UE experiences a radio connection failure. The UE saves the RLF report information. The RLF report contains the same contents as those described in step 302, and is not described herein again.

Step 607, the UE and the third base station RRC reestablish successfully, or the UE and the third base station RRC connection establish successfully. The RRC reestablishment complete or RRC setup complete message contains indication information that the UE has an RLF report.

Step 608, the third base station sends a UE information request message to the UE requesting an RLF report.

Step 609, the UE sends a UE information response message to the third base station. The message includes an RLF report. The RLF report contains the same contents as those described in step 302, and is not described here again.

In step 610, the third base station sends a failure indication message to the base station that last served the UE. According to one embodiment, the third base station determines the base station that last served the UE from the RLF report. For the case of RLF failure, the last base station serving the UE is the base station of the failed primary cell. For the case of handover failure, the last base station serving the UE is the source base station that triggered the last handover, i.e. the base station where the previous primary cell was. In this embodiment, the last base station serving the UE is the destination base station of the last successful handover. Since the destination base station will no longer have the role of the destination base station for the UE after step 610, the destination base station is called the second base station after step 610 of this embodiment.

The specific determination method for the reason for the failure detection of the second base station is the same as that in step 302, and is not described herein again. According to the method in step 302, in this embodiment, the failure occurs before the latest CHO execution, for example, according to the indication of the CHO execution or according to the fact that the time from the start of the CHO execution to the occurrence of the failure is less than a configured threshold, and the cell where the UE first attempts RRC re-establishment after the failure occurs or the cell where the UE successfully establishes RRC connection is not the cell serving the UE when the latest handover occurs, nor the cell serving the UE when the RLF occurs or the target cell of the CHO handover execution. The reason for the failure of the UE is that CHO goes to the wrong cell or CHO executes to the wrong cell.

The second base station may further determine whether the CHO candidate cell is not properly configured, and send information that the CHO candidate cell is not properly configured to the source base station triggering the last handover through the handover report in step 611. The specific determination method is the same as that in step 302, and is not described herein again. Or whether the CHO candidate cell configuration is not reasonable is determined in step 611 by the source base station triggering the last handover according to one or more of the type of handover report received, the UE RLF report, the CHO candidate cell list, the CHO execution conditions, the CHO configuration information, and/or the time from the CHO configuration to the closest or immediate handover command. The specific determination method is the same as that in step 302 and step 303, and is not described herein again.

In step 611, the second base station sends a handover report message to the source base station that triggered the last handover. The content of the message is the same as that of step 303, and is not described herein again. In this embodiment, the type of handover report may be CHO to the wrong cell or CHO performed to the wrong cell.

The source base station confirms the reason of the failure according to the received message, and the specific method is the same as that in step 303, which is not described herein again.

Therefore, the description of an embodiment of the first method for supporting self-configuration and self-optimization according to the present invention is completed, and the method can support the enhanced robustness of handover in the moving process, correctly identify the reason of failure occurrence, so as to perform reasonable optimization, reduce the failure occurrence, ensure the service continuity, and reduce the labor cost of operators.

Fig. 7 is a diagram illustrating another embodiment of a method for supporting self-configuration self-optimization according to an exemplary embodiment of the present invention. Fig. 7 omits and simplifies detailed description of steps irrelevant to the present invention.

Steps 700 to 706 are the same as steps 600 to 606, and are not described herein again.

And step 707, successfully reestablishing the RRC between the UE and the source base station. Or the UE successfully establishes the RRC connection at the source base station. The RRC reestablishment complete or RRC setup complete message contains indication information that the UE has an RLF report. After the UE CHO handover is successful, the source base station will no longer be the role of the source base station for the UE, so in this embodiment, the source base station is also referred to as the first base station, i.e. the source base station of the last CHO handover.

In step 708, the first base station sends a UE information request message to the UE requesting an RLF report.

In step 709, the UE sends a UE information response message to the first base station. The message includes an RLF report. The RLF report contains the same contents as in step 302, and is not described herein again.

In step 710, the first base station sends a failure indication message to the last base station serving the UE. From the RLF report, the first base station determines the last base station serving the UE. For the case of RLF failure, the last base station serving the UE is the base station of the failed primary cell. For the case of handover failure, the last base station serving the UE is the source base station that triggered the last handover, i.e. the base station where the previous primary cell was. In this embodiment, the last base station serving the UE is the destination base station of the last successful handover. Since the destination base station will no longer be the destination base station to the UE after step 710, the destination base station is called the second base station after step 670 of this embodiment.

The specific determination method for the reason for the failure detection of the second base station is the same as that in step 302, and is not described herein again. According to the method in step 302, in this embodiment, the failure occurs before the latest CHO execution, for example, according to the indication of the CHO execution or according to the time from the start of the CHO execution until the failure occurs is less than a configured threshold, and after the failure occurs, the cell where the UE first attempts RRC reestablishment or the cell where the UE attempts RRC connection establishment or the cell where the UE successfully establishes RRC connection is the cell serving the UE when the latest handover occurs, the reason for the failure occurrence is too early CHO execution.

Step 711, the second base station sends a handover report message to the source base station that triggered the last handover. The content of the message is the same as that of step 303, and is not described herein again. In this embodiment, the type of handover report may be too early CHO execution.

Therefore, the description of another embodiment of the first method supporting self-configuration and self-optimization according to the present invention is completed, and the method can support the enhanced robustness of handover in the moving process, correctly identify the reason of failure occurrence, so as to perform reasonable optimization, reduce the occurrence of failure, ensure service continuity, and reduce the labor cost of operators.

Fig. 8 is a diagram illustrating an embodiment of a second method for supporting self-configuration self-optimization according to an exemplary embodiment of the present invention. Fig. 8 omits and simplifies a detailed description of steps not relevant to the present invention.

Steps 800 to 803 are the same as steps 600 to 603, and are not described herein again.

Step 804, after receiving the CHO configuration, the UE maintains the connection with the source base station. The UE starts evaluating the execution conditions of each candidate cell. If at least one candidate cell meets the CHO execution condition, the UE departs from the source cell, the UE executes synchronization to the selected candidate cell by applying the corresponding configuration of the selected candidate cell, and the failure of the synchronization process causes the failure of the CHO switching execution.

Since the destination base station will no longer be the role of the destination base station for the UE after step 804, the destination base station is called the second base station after step 804 of this embodiment

The UE saves the RLF report information. The RLF report contains the same contents as those described in step 302, and is not described herein again.

Step 805, the UE and the third base station are successfully reestablished, or the UE and the third base station are successfully established in RRC connection, or the UE is successfully recovered in the third base station CHO. The RRC reestablishment complete or RRC establishment complete or RRC reconfiguration complete message includes indication information that the UE has an RLF report. The embodiment is also applicable to the case where the cell in which the RRC reestablishment is successful or the RRC connection is successfully established or the CHO recovery is successful is another cell other than the CHO execution candidate cell on the second base station. In this case, steps 805 to 807 are procedures between the second base station and the UE. Step 808 is a procedure between the second base station and the source base station.

In step 806, the third base station sends a UE information request message to the UE requesting an RLF report.

In step 807, the UE sends a UE information response message to the third base station. The message includes an RLF report. The RLF report contains the same contents as in step 302, and is not described in detail here.

Step 808, the third base station sends a failure indication message to the base station that last served the UE. From the RLF report, the third base station determines the base station that last served the UE. For the case of RLF failure, the last base station serving the UE is the base station of the failed primary cell. For the case of handover failure, the last base station serving the UE is the source base station that triggered the last handover, i.e. the base station where the previous primary cell was. In this embodiment, the last base station serving the UE is the source base station triggering the latest handover, i.e. the base station where the previous primary cell is located.

The source base station detects the reason for the failure, and the specific determination method is the same as that in step 302, and is not described herein again. According to the method in step 302, in this embodiment, the failure occurs before the latest CHO execution, for example, according to the indication of the CHO execution or according to the time from the start of the CHO execution until the failure occurs is less than a configured threshold, and the cell where the UE first attempts RRC re-establishment after the failure occurs or the cell where the UE successfully establishes RRC connection is not the cell serving the UE when the latest handover occurs, nor the cell serving the UE when the RLF occurs or the target cell of the CHO handover execution. The reason for the failure of the UE is that CHO goes to the wrong cell or CHO executes to the wrong cell.

The source base station may further determine whether the CHO candidate cell is unreasonable in configuration, and the specific determination method is the same as that in step 302, which is not described herein again.

And the source base station performs corresponding optimization according to the reason of the failure detection.

Therefore, the description of an embodiment of the method two for supporting self-configuration and self-optimization according to the present invention is completed, and the method can support the enhanced robustness of handover in the moving process, correctly identify the reason of failure occurrence, so as to perform reasonable optimization, reduce the failure occurrence, ensure the service continuity, and reduce the labor cost of operators.

Fig. 9 is a schematic diagram illustrating another embodiment of a second method for supporting self-configuration self-optimization according to an exemplary embodiment of the present invention. Fig. 9 omits and simplifies detailed description of steps irrelevant to the present invention.

Steps 900 to 901b are the same as steps 600 to 601b, and are not described again here.

Step 903, the source base station sends an RRC reconfiguration message to the UE. The message includes a CHO candidate cell, CHO execution conditions, and/or CHO configuration information. The embodiment includes a scenario in which the source base station sends the RRC reconfiguration message to the UE or a scenario in which the source base station has not yet sent the RRC reconfiguration message to the UE, and is applicable to both scenarios. Step 903 may also be performed correspondingly to a scenario including that the source base station sends the RRC reconfiguration message to the UE, and step 903 is the same as step 603, which is not described herein again.

In step 904, the UE does not receive the RRC reconfiguration message, or the UE receives the RRC reconfiguration message but no candidate cell meets the CHO execution condition so that the CHO is not executed, and the UE fails in radio connection. The UE saves the RLF report information. The RLF report includes the same contents as in step 302, and is not described herein again.

Step 905, the UE and the target base station are successfully reestablished, or the UE is successfully established in the target base station RRC connection. The RRC reestablishment complete or RRC setup complete message contains indication information that the UE has an RLF report.

Step 906, the destination base station sends a UE information request message to the UE requesting an RLF report.

In step 907, the UE sends a UE information response message to the destination base station. The message includes an RLF report. The RLF report contains the same contents as in step 302, and is not described herein again.

Step 908, the destination base station sends a failure indication message to the source base station. From the RLF report, the destination base station determines the base station that last served the UE. For the case of RLF failure, the last base station serving the UE is the base station of the failed primary cell. For the case of handover failure, the last base station serving the UE is the source base station that triggered the last handover, i.e. the base station where the previous primary cell was. In this embodiment, the last base station serving the UE is the source base station triggering the latest handover, i.e. the base station where the previous primary cell is located.

The source base station detects the reason for the failure, and the specific determination method is the same as that in step 302, and is not described herein again. According to the method in step 302, in this embodiment, no recent CHO execution occurred before the failure occurred, it is determined that no recent CHO execution occurred before the failure occurred, according to, for example, whether the UE RLF report does not contain an indication of CHO execution or an indication of CHO execution, or whether the UE RLF report does not contain a time from CHO execution to failure occurrence or whether the time from CHO execution to failure occurrence is greater than a configured threshold, and the reason for the failure occurrence is too late CHO or too late CHO execution.

And the source base station carries out corresponding optimization according to the reason of the failure detection.

Therefore, the description of another embodiment of the method two for supporting self-configuration and self-optimization according to the present invention is completed, and the method can support the enhanced robustness of handover in the moving process, correctly identify the reason of failure occurrence, so as to perform reasonable optimization, reduce the failure occurrence, ensure the service continuity, and reduce the labor cost of operators.

Fig. 10 is a schematic diagram illustrating a further embodiment of a second method for supporting self-configuration self-optimization according to an exemplary embodiment of the present invention. Fig. 10 omits and simplifies detailed description of steps irrelevant to the present invention.

Steps 1000 to 1004 are the same as steps 800 to 804, and are not described herein again.

Step 1005, the UE reselects the cell, where the reselected cell is a cell in the CHO candidate cell list, and the UE performs CHO recovery. The CHO recovery failed.

The UE saves the RLF report. The RLF report may be one but contains information of two failures, for example, contains cell identities of two failed cells, that is, cell identity of cell failing in CHO handover execution and cell identity of cell failing in CHO recovery, and may further contain time from receiving RRC reconfiguration to CHO handover execution failure and time from receiving RRC reconfiguration to CHO recovery failure, and may further contain time from CHO handover execution to execution failure and time from CHO handover execution to CHO recovery failure. The RLF report may be two RLF reports, corresponding to two pieces of failure information. The contents of the two RLF reports are specifically the same as those in step 302, and are not described herein again.

Steps 1006 to 1008 are the same as steps 805 to 807, and are not described again.

In step 1009, the third base station sends a failure indication message to the source base station. From the RLF report, the third base station determines the base station that last served the UE. For the case of RLF failure, the base station that last served the UE is the base station of the failed primary cell. For the case of handover failure, the last base station serving the UE is the source base station that triggered the last handover, i.e. the base station where the previous primary cell was. In this embodiment, the last base station serving the UE is the source base station triggering the latest handover, i.e. the base station where the previous primary cell is located.

The source base station detects the reason of the failure, and the specific determination method is the same as that in step 302, and is not described herein again. According to the method in step 302, in this embodiment, the failure occurs before the latest CHO execution, for example, according to the indication of the CHO execution or according to the fact that the time from the start of the CHO execution to the occurrence of the failure is less than a configured threshold, and the cell where the UE first attempts RRC re-establishment after the failure occurs or the cell where the UE successfully establishes RRC connection is not the cell serving the UE when the latest handover occurs, nor the cell serving the UE when the RLF occurs or the target cell of the CHO handover execution. The reason for the failure of the UE is the CHO to the wrong cell or the CHO execution to the wrong cell.

The source base station may further determine whether the result is due to an unreasonable CHO candidate cell configuration. The specific determination method is the same as that in step 302, and is not described herein again.

Therefore, the description of another embodiment of the method two for supporting self-configuration and self-optimization according to the present invention is completed, and the method can support the enhanced robustness of handover in the moving process, correctly identify the reason of failure occurrence, so as to perform reasonable optimization, reduce the occurrence of failure, ensure service continuity, and reduce the labor cost of operators.

FIG. 11 shows a schematic diagram of one embodiment of a method III for supporting self-configuring self-optimization, in accordance with an illustrative embodiment of the present invention. Fig. 11 omits and simplifies detailed description of steps irrelevant to the present invention.

Steps 1101 to 1104 are the same as steps 801 to 804, and are not described again here.

In step 1105, the UE and the source base station are successfully reestablished, or the UE is successfully established in the RRC connection of the source base station. The RRC reestablishment complete or RRC setup complete message contains indication information that the UE has an RLF report.

In step 1106, the source base station sends a UE information request message to the UE requesting an RLF report.

Step 1107, the UE sends a UE information response message to the source base station. The message includes an RLF report. The RLF report contains the same contents as in step 302, and is not described herein again.

The source base station detects the reason for the failure, and the specific determination method is the same as that in step 302, and is not described herein again. According to the method in step 302, in this embodiment, the failure occurs before the latest CHO execution, for example, according to the indication of the CHO execution or according to the time from the start of the CHO execution until the failure occurs is less than a configured threshold, and after the failure occurs, the cell where the UE first attempts RRC reestablishment or the cell where the UE attempts RRC connection establishment or the cell where the UE successfully establishes RRC connection is the cell serving the UE when the latest handover occurs, the reason for the failure occurrence is too early CHO execution.

Therefore, the description of an embodiment of the method supporting self-configuration and self-optimization according to the present invention is completed, and the method can support the enhanced robustness of handover in the moving process, correctly identify the reason of failure occurrence, so as to perform reasonable optimization, reduce the failure occurrence, ensure the service continuity, and reduce the labor cost of operators.

Fig. 12 shows a schematic diagram of another embodiment of a method three of supporting self-configuration self-optimization according to an exemplary embodiment of the present invention. Fig. 12 omits and simplifies detailed description of steps irrelevant to the present invention.

Steps 1200 to 1205 are the same as steps 1000 to 1005 and are not described again.

In step 1206, the UE is successfully reestablished with the source base station RRC, or the UE is successfully established in the source base station RRC connection. The RRC reestablishment complete or RRC setup complete message contains indication information that the UE has an RLF report.

Step 1207, the source base station sends a UE information request message to the UE requesting an RLF report.

In step 1207, the UE sends a UE information response message to the source base station. The message includes an RLF report. The RLF report may be one RLF report but includes information of two failures, or two RLF reports, and the specific content is the same as that described in step 302 and step 1005, and is not described herein again.

Therefore, the description of another embodiment of the third method for supporting self-configuration and self-optimization according to the present invention is completed, and the method can support the enhanced robustness of handover in the moving process, correctly identify the reason of failure occurrence, so as to perform reasonable optimization, reduce the occurrence of failure, ensure service continuity, and reduce the labor cost of operators.

Step 1301, the destination base station receives a message from the source base station. The message contains information of the CHO candidate cell list and/or CHO execution conditions. The message also contains CHO configuration information and/or the time from the CHO configuration to the nearest or immediate handover command. The CHO configuration is a CHO configuration sent by the source base station to the UE. The handover command is the handover command message closest/next to the CHO configuration for triggering the usual handover. The message may be a handover request message, an early state transfer message, a Sequence Number (SN) state transfer message, a newly defined message, or other existing message. The message may be sent to the destination base station by the source base station in the handover preparation stage, or sent to the destination base station after the source base station receives the handover success message, or sent to the destination base station at other times, which is not limited in the present invention. The destination base station may receive the above-mentioned information from the source base station through the same message or a different message. The destination base station saves the received information. The CHO candidate cell list contains all candidate cells of this CHO handover decided by the source base station, including all candidate cells on the destination base station receiving the message and candidate cells on other potential destination base stations. The information of each candidate cell comprises a global cell identity. The CHO execution condition may be one or more, and is the same as the CHO execution condition that the source base station transmits to the UE through the RRC reconfiguration message. The source base station sends the information to the destination base station through an interface message between the base stations or sends the information to the destination base station through the core network, and the specific manner is the same as that in step 301, and is not described herein again.

In step 1302, the destination base station receives a successful handover report from the UE. The successful handover report may be one or more. And the target base station receives a successful switching report from the UE after the UE is successfully switched to the target base station. After the UE is successfully switched to the target base station, the UE can inform the target base station that the UE has the successful switching report information through an RRC reconfiguration completion message or other messages. The target base station requests a successful switching report of the UE, and the UE sends the successful switching report to the target base station. The successful handover report contains at least one or more of the following information:

-an identity of the source cell, a global cell identity of the cell to which the last RRC reconfiguration message was sent, also containing a Tracking Area Code (TAC) of said cell;

-a primary cell identity of a destination cell, which may also contain the TAC or TAI of said cell;

-a cell radio network temporary identity (C-RNTI), a C-RNTI for a source cell;

type of failure, e.g. whether beam detects failure or other failure;

The destination base station may use the received information for optimization, e.g., to optimize dedicated RACH resources or beam resources.

Step 1303, the destination base station sends an access and movement indication message to the source base station. The message contains a successful handover report. The message may also contain a handover type, a CHO candidate cell list, CHO execution conditions, CHO configuration information, and/or time from CHO configuration to the nearest or immediate handover command. The CHO candidate cell list, CHO execution conditions, CHO configuration information, and/or time information from CHO configuration to the nearest or immediate handover command are received from the source base station in step 1301. The CHO candidate cell list includes all candidate cells of the current CHO handover. The handover types include normal handover, CHO handover, DAPS handover, and the like.

And the source base station analyzes whether the mobile configuration needs to be adjusted or not according to the received information. The source base station performs reasonable optimization of the mobility or handover parameters, if needed.

The method four of the present invention supporting self-configuration self-optimization is shown above in an exemplary manner. By the fourth method, the robustness of the switching in the moving process can be supported, the failure occurring in the successful switching is analyzed, and the reason of the failure occurrence is correctly identified, so that the reasonable optimization is carried out, the failure occurrence is reduced, and the robustness in the UE moving process is ensured.

Referring to fig. 14, a destination base station 1400 may include a controller 1401 and a transceiver 1406. The controller 1401 may be defined as a circuit application specific integrated circuit or at least one processor according to an embodiment of the present invention. The controller 1401 may control the overall operation of the destination base station and control the destination base station to implement various methods proposed in the present invention.

The transceiver 1406 may transmit/receive signals to/from other network entities (such as but not limited to a source base station, a third base station, user equipment) over a wired or wireless link. For example, the transceiver 1406 may transmit signals to and receive signals from user equipment.

Referring to fig. 15, a source base station 1500 may include a controller 1501 and a transceiver 1506. According to an embodiment of the invention, the controller 1501 may be defined as a circuit application specific integrated circuit or at least one processor. The controller 1501 may control the overall operation of the source base station and control the source base station to implement various methods proposed in the present invention.

The transceiver 1506 may transmit/receive signals to/from other network entities (such as, but not limited to, a destination base station, a third base station, a user equipment) over a wired or wireless link. For example, the transceiver 1506 may transmit signals to and receive signals from user devices.

Those of skill in the art would understand that the various illustrative logical blocks, modules, circuits, and steps described in this application 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 implementation decisions should not be interpreted as causing a departure from the scope of the present application.

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.

The steps of a method or algorithm described in this application 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 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.

In one or more exemplary designs, the functions may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on 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. A storage media may be any available media that can be accessed by a general purpose or special purpose computer.

The examples of the present application are merely for ease of description and to aid in a comprehensive understanding of the present disclosure, and are not intended to limit the scope of the present disclosure. Therefore, it should be understood that all modifications and changes or forms of modifications and changes derived from the technical idea of the present disclosure other than the embodiments disclosed herein fall within the scope of the present disclosure.

Claims

1. A method performed by a destination base station in a mobile communication system, the method comprising:

receiving a radio link failure, RLF, report for a user equipment, UE, from a source base station or a third base station;

detecting a cause of failure occurrence based on the UE RLF report;

based on the reason for the detected failure occurrence, a message is sent to the source base station.

2. The method of claim 1, wherein the message transmitted to the source base station includes a type of handover report,

wherein the type of handover report comprises at least one of too early handover, too late handover, handover to a wrong cell, conditional handover CHO handover, too late CHO execution, too early CHO handover, too early CHO execution, CHO to wrong cell, CHO execution to wrong cell, and improper CHO candidate cell configuration.

3. The method of claim 1, wherein, based on the UE RLF report, the reason for the occurrence of the detection failure comprises at least one or more of:

if the latest Conditional Handover (CHO) is executed before the failure occurs, and the cell in which the UE tries RRC reestablishment for the first time after the failure occurs, or the cell in which the UE tries RRC connection establishment, or the cell in which the UE successfully establishes RRC connection is the cell serving the UE when the latest handover occurs, the reason for the failure occurrence is too early CHO execution;

if the latest CHO execution is performed before the failure occurs, and the cell for which the UE tries RRC reestablishment for the first time after the failure occurs or the cell for which the CHO recovers success or the cell for which the UE tries RRC connection establishment or the cell for which the UE successfully establishes RRC connection is not the cell serving the UE when the latest switching occurs or the cell serving the UE when the RLF occurs or the target cell for the CHO switching execution, the reason for the failure occurrence is that the CHO is executed to the wrong cell or the CHO is executed to the wrong cell;

the reason for the failure occurrence is too late CHO or too late CHO execution if it is determined from the UE RLF report that no CHO execution is contained or the UE RLF report does not contain the time from CHO execution to failure occurrence or the time from CHO execution to failure occurrence is greater than a configured threshold that there is no recent CHO execution before failure occurrence;

if the latest CHO execution occurs before the failure occurs, and the cell for which the UE first attempts RRC reestablishment or the cell for which the CHO recovers successfully or the cell for which the UE attempts RRC connection establishment or the cell for which the UE successfully establishes RRC connection after the failure occurs is not the cell serving the UE when the latest handover occurs or the cell serving the UE when the RLF occurs or the cell to which the CHO handover is executed, and the cell for which the UE first attempts RRC reestablishment or the cell for which the CHO recovers successfully or the cell for which the UE attempts RRC connection establishment or the cell for which the UE successfully establishes RRC connection after the failure occurs is not in the CHO candidate cell list, the reason for the failure occurrence is improper CHO candidate cell configuration.

4. The method of claim 1, wherein the method further comprises:

receiving, from a source base station, a list of CHO candidate cells comprising a conditional handover CHO and/or CHO execution conditions, wherein,

the CHO candidate cell list contains all candidate cells for a CHO handover.

5. The method of claim 4, wherein the message sent to the source base station further comprises a CHO candidate cell list containing all candidate cells for a CHO handover.

6. A method performed by a source base station in a mobile communication system, the method comprising:

sending a Radio Link Failure (RLF) report of User Equipment (UE) to a target base station;

a message is received from the destination base station containing a reason for the occurrence of the failure detected by the destination base station based on the UE RLF report.

7. The method of claim 6, wherein the message received from the destination base station includes a type of handover report,

8. The method of claim 6, wherein, based on the UE RLF report, the reason for the occurrence of the detection failure comprises at least one or more of:

if the most recent CHO execution occurs before the failure occurs, and the cell in which the UE tries RRC reestablishment for the first time after the failure occurs, or the cell in which the UE tries RRC connection establishment, or the cell in which the UE successfully establishes RRC connection is the cell serving the UE when the most recent handover occurs, the reason for the failure occurrence is too early CHO execution;

9. The method of claim 6, wherein the method further comprises:

transmitting a list of CHO candidate cells including a conditional handover and/or CHO execution conditions to a destination base station, wherein,

the CHO candidate cell list contains all candidate cells for a CHO handover.

10. The method of claim 9, wherein the message received from the destination base station further comprises a CHO candidate cell list containing all candidate cells for a CHO handover.

11. A method performed by a source base station in a mobile communication system, the method comprising:

receiving a Radio Link Failure (RLF) report of User Equipment (UE);

the reason for the failure occurrence is confirmed based on the UE RLF report.

12. The method of claim 11, wherein the RLF report for the UE is received by the source base station through the third base station, through the destination base station, or directly from the UE.

13. The method of claim 11, wherein the cause of the occurrence of the acknowledgement failure based on the UE RLF report includes at least one or more of:

if the latest CHO execution is performed before the failure occurs, and the cell for which the UE tries RRC reestablishment for the first time after the failure occurs, or the cell for which the CHO recovers successfully, or the cell for which the UE tries RRC connection establishment, or the cell for which the UE successfully establishes RRC connection is not the cell serving the UE when the latest handover occurs, or the cell serving the UE when the RLF occurs, or the target cell for the CHO handover execution, the reason for the failure occurrence is that the CHO is performed to the wrong cell or the CHO is performed to the wrong cell;

14. A destination base station in a mobile communication system, comprising:

a transceiver to transmit/receive signals to/from other network entities; and

a controller for controlling the overall operation of the destination base station,

wherein the destination base station is configured to perform the method of any of claims 1-5.

15. A source base station in a mobile communication system, comprising:

a transceiver to transmit/receive signals to/from other network entities; and

a controller controlling an overall operation of the source base station,

wherein the source base station is configured to perform the method of any of claims 6-13.