Methods and apparatus for enhancing minimization of drive test measurement in wireless communication system

Abstract

The disclosure relates to a 5G or 6G communication system for supporting higher data transmission rates and satisfying various service requirements. A method performed by a base station of NTN in a wireless communication system is provided. The method comprising: receiving, from an AMF, a first message including first information indicating an area scope of an MDT and second information indicating a specific geographical area for the MDT, wherein the area scope of MDT is configured as a coverage of a cell, a tracking area code, or a PLMN; selecting at least one terminal whose location is within the specific geographical area based on the first information and the second information; and transmitting, to a terminal among the at least one terminal, a second message including configuration information for the MDT.

Description

METHODS AND APPARATUS FOR ENHANCING MINIMIZATION OF DRIVE TEST MEASUREMENT IN WIRELESS COMMUNICATION SYSTEM

[0001] The disclosure relates to operations of a user equipment (UE) and a base station (BS) in a wireless communication system, more particularly, relates to methods and apparatus for enhancing minimization of drive test (MDT) measurement.

[0002] 5thgeneration (5G) mobile communication technology defines a wide frequency band to enable fast transmission speeds and new services, and can be implemented not only in the sub-6 gigahertz (GHz) frequency band such as 3.5GHz, but also in the ultra-high frequency band referred to as millimeter wave (mmWave) bands such as 28GHz and 39GHz (above 6GHz) bands. In 6thgeneration (6G) mobile communication technology, referred to as beyond 5G, it is expected that it will be paramount to secure new frequency resources such as the sub-6GHz band, ultra-high frequency bands, and upper mid band (7-24GHz) to handle the rapidly increased data traffic due to the spread of artificial intelligence (AI) technology and the increase in streaming services, to improve user perceived performance, and to efficiently utilize all available frequency resources as needed. To this end, reallocation, reuse, or sharing of existing frequency bands from 2ndgeneration (2G) to 5G for 6G can be considered.

[0003] Since the introduction of 5G, the communications market has been increasingly interested in improving system operation efficiency, sustainability, and user experience. Accordingly, in addition to improving traditional communications performance such as data transmission speed and delay time, the introduction of new innovative technologies such as AI, reducing operating costs, improving energy efficiency, expanding service coverage, and introducing new services are becoming increasingly important.

[0004] Since the early stages of 5G mobile communication technology, a goal has been to support services and satisfy performance requirements for enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communications (mMTC), including beamforming and massive multiple-input multiple-output (MIMO) to mitigate path loss of radio waves in ultra-high frequency bands and increase the range of radio transmission, support for various numerologies (such as operation of multiple subcarrier intervals) and dynamic operation of slot formats for efficient use of ultra-high frequency resources, initial access technology to support multi-beam transmission and wideband, definition and operation of band-width part (BWP), new channel coding methods such as low density parity check (LDPC) codes for large-capacity data transmission and polar codes for reliable transmission of control information, layer 2 (L2) pre-processing, and networks that provide dedicated networks specialized for specific services. Standardization of slicing (network slicing) etc. has been progressing.

[0005] Furthermore, discussions have been held on improving and enhancing the initial 5G mobile communication technology in consideration of the services that 5G mobile communication technology was intended to support, including vehicle-to-everything (V2X) to help autonomous vehicles make decisions based on their own location and status information transmitted by the vehicle and to increase user convenience, new radio unlicensed (NR-U) for system operation that meets various regulatory requirements in unlicensed bands, NR terminal low power consumption technology (i.e., UE power saving), non-terrestrial network (NTN), which is direct terminal-satellite communication to secure coverage in areas where communication with terrestrial networks is impossible, positioning, NR support up to 71GHz, support of reduced capability NR devices for lower cost and complexity compared to general terminals, user equipment (UE) power saving enhancement for improved power management in preparation for the use of various terminal types, and sidelink. Standardization of the physical layer has been performed for technologies such as sidelink enhancement, duplex enhancements which study a new form of duplexing called subband non-overlapping full duplex (SBFD), network energy saving which secures the idle period in which the base station operates in maximum power saving mode to the maximum extent and reduces power consumption, and network controlled repeaters which have improved performance compared to existing repeaters by having the function of receiving and processing side control information from the network.

[0006] In addition, standardization of the wireless interface architecture / protocol layer for technologies such as the industrial Internet of things (IIoT) for supporting new services through linkage and convergence with other industries, integrated access and backhaul (IAB) that provides nodes for expanding network service areas by integrating wireless backhaul links and access links, mobility enhancement technology including conditional handover (CHO) and dual active protocol stack (DAPS) handover, 2-step random access channel (RACH) for NR that simplifies random access procedures, multicast and broadcast, standardization of support for multi universal subscriber identity module (USIM) devices that provide services to users using information of two or more subscriber identity modules (SIMs), sidelink relay that provides relay-related functions to support connections between terminals in long distances and between terminals and networks, small data transfer (SDT) which transmits small data or signaling in an inactive state without transitioning to a connected state, mobility enhancements including layer 1 (L1) / L2 triggered mobility (LTM) / subsequent conditional PSCell addition / change (SCPAC) / and conditional handover (CHO) with candidate SCGs, extended reality (XR) enhancement to support XR services in NR systems, etc. has also been performed, and standardization of system architecture / services such as 5G baseline architecture (e.g., service-based architecture, service-based interface) for grafting network functions virtualization (NFV) and software-defined networking (SDN) technologies, mobile edge computing (MEC) that provides services based on the location of the terminal, non-public networks (NPN) that can be used only by some permitted terminals for non-public purposes, disaster roaming that supports the use of communication services through other carriers' networks in the event of a communication disaster, proximity-based service via 5GS, and unmanned Standardization has also been made in the system architecture / service areas, including support of an unmanned aircraft system (UAS) to support remote identification, tracking, and authorization of uncrewed aerial vehicles (UAVs), structural enhancements to support XR and interactive media services, 5GS to support AI / machine learning (ML) services, and advanced mobile edge computing to provide edge computing services in roaming networks, etc. has also been performed.

[0007] Currently, standardization is in progress for technologies such as beam prediction using AI / ML technology, channel state information (CSI) prediction to improve positioning accuracy, ultra-low-power terminal technology using low-power wake-up receivers, technology for transmitting long term evolution (LTE) broadcasts to 5G networks, MIMO transmission technology using multiple base stations, and ultra-low-power terminals (ambient IoT) that transmit data by obtaining power from an external source without a battery. At the radio interface architecture / protocol layer, standardization is in progress for technologies such as LTM scenario support and conditional LTM support between central units (CUs), simultaneous support for the same XR service between multiple devices, NTN coverage enhancement and evolution, AI / ML-based mobility support, and terminal-to-terminal connection relay across multiple hops between terminals and networks.

[0008] In addition, standardization of system architecture / service fields for satellite communication optimization methods, 5G system energy usage management and efficiency, SBI-based user plane evolution, ambient IoT technology, data service provision methods in IMS (IP multimedia subsystem), and avatar communication service persists. When such 5G mobile communication systems are commercialized, a vast increase in devices connected to the communication network will be realized, and accordingly, it is expected that the functions and performance of 5G mobile communication systems will be strengthened and integrated operation of connected devices will be required. To this end, new research will be additionally conducted on XR to efficiently support augmented reality (AR), virtual reality (VR), and mixed reality (MR), 5G performance improvement and complexity reduction using AI / ML, AI service support, metaverse service support, and drone communication.

[0009] The development of these 5G mobile communication systems is expected to serve as the basis for enhancing 5G performance and ultimately evolving into 6G. In the 6G era, eMBB, URLLC, and mMTC services, are expected to evolve into immersive communication (IC), hyper-reliable and low-latency communication (HRLLC), and massive communication (MC) services, respectively. In addition, new services such as AI and communication, integrated sensing and communication, and ubiquitous connectivity are expected to be additionally supported. For these 6G services, improved performance requirements compared to 5G are also essential, and standardization to define these is also in progress.

[0010] In this manner, to satisfy the expanded services and improved performance requirements of 6G, it is expected that it will be essential to optimize and improve system operation, such as introducing AI technology, improving energy efficiency, expanding coverage, and applying next-generation security technology, as well as developing sustainable communication technology, in addition to simply improving existing communication performance.

[0011] To this end, the latest AI technology is applied to all areas from the communication system design stage to development, management, and operation to improve communication performance and realize AI internalization technology that realizes network automation and efficiency, technology that improves user-perceived performance and network operation efficiency by improving power consumption of networks and terminals, technology that reduces power consumption in core base station components such as radio frequency (RF) and modems and in the channel coding and signal modulation and transmission / reception processes, multi-antenna transmission technology (e.g., extreme MIMO (X-MIMO)) that utilizes large antennas to overcome propagation path loss due to high frequency compared to the 3.5 GHz band of 5G communication and provide equivalent coverage, transmission / reception technology based on multiple base stations (e.g., distributed MIMO (D-MIMO)) to improve quality in cell edge areas, full-duplex communication (e.g., SBFD) technology to improve frequency efficiency and system network, next-generation encryption technology (e.g., post quantum cryptography (PQC)) and zero trust architecture (ZTA) technology to strengthen 6G communication security, and initial access delay and mobility. Research will be focused on technologies to minimize delay, design a hardware-friendly protocol structure for ultra-high-speed data processing, and expand the application of integrity protection technologies.

[0012] In addition, research will be conducted on the structure of mobile communication systems (prevention of redundant functions, simplification of functions, etc.), introduction of new planes for providing service providers, user privacy protection measures, realistic services, enhancement of network resiliency, network sharing technologies, improved security technologies (false base stations, lower layer protection, etc.), and intent-based network operation and management.

[0013] Recently, there has been growing interest in wireless communication methods that provide service to a terminal via a non-terrestrial network (NTN), beyond traditional terrestrial networks. In NTN, cells are not fixed but move over time, and a single cell may cover an area that spans multiple countries. In such environments, it is challenging to apply existing MDT (minimization of drive test) techniques, which are based on fixed cell locations. To efficiently collect MDT measurements in NTN, there is a need for an MDT configuration method that can adapt to the dynamic nature of NTN cells and their wide coverage.

[0014]

[0015] The disclosure relates to operations of a user equipment (UE) and a base station (BS) in a wireless communication system, more particularly, relates to methods and apparatus for enhancing minimization of drive test (MDT) measurement.

[0016] Accordingly, an aspect of the disclosure is to provide a method and apparatus for configuring information on a specific geographical area for the MDT.

[0017] In addition, an aspect of the disclosure is to provide a method and an apparatus for selecting UEs based on information on area scope of the MDT and the information on the specific geographical area for the MDT.

[0018] Furthermore, an aspect of the disclosure is to provide a method and an apparatus for providing, to the selected terminal, MDT configuration.

[0019] Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments.

[0020] Aspects of the disclosure are to address at least the above-mentioned problems and / or disadvantages and to provide at least the advantages described below.

[0021]

[0022] In accordance with embodiments of the disclosure, a method performed by a base station of NTN in a wireless communication system is provided. The method includes: receiving, from an access and mobility management (AMF), a first message including first information indicating an area scope of a minimization of drive test (MDT) and second information indicating a specific geographical area for the MDT, wherein the area scope of MDT is configured as a coverage of a cell, a tracking area code, or a public land mobile network (PLMN); selecting at least one terminal whose location is within the specific geographical area based on the first information and the second information; and transmitting, to a terminal among the at least one terminal, a second message including configuration information for the MDT.

[0023] In accordance with embodiments of the disclosure, a method performed by a terminal in a wireless communication system is provided. The method includes: receiving, from a base station of non-terrestrial network (NTN), a message including configuration information for a minimization of drive test (MDT); and performing a measurement for the MDT based on the configuration information, wherein the terminal is selected based on first information indicating an area scope of the MDT and second information indicating a specific geographical area for the MDT, wherein the area scope of MDT is configured as a coverage of a cell, a tracking area code, or a public land mobile network (PLMN), and wherein a location of the terminal is within the specific geographical area.

[0024] In accordance with embodiments of the disclosure, a base station of NTN in a wireless communication system is provided. The base station includes: a transceiver; a processor communicatively coupled to the transceiver; and memory, communicatively coupled to the processor, storing instructions executable by the processor to cause the base station to: receive, from an access and mobility management function (AMF), a first message including first information indicating an area scope of a minimization of drive test (MDT) and second information indicating a specific geographical area for the MDT, wherein the area scope of MDT is configured as a coverage of a cell, a tracking area code, or a public land mobile network (PLMN), select at least one terminal whose location is within the specific geographical area based on the first information and the second information, and transmit, to a terminal among the at least one terminal, a second message including configuration information for the MDT.

[0025] In accordance with embodiments of the disclosure, a terminal in a wireless communication system is provided. The terminal includes: a transceiver; a processor communicatively coupled to the transceiver; and memory, communicatively coupled to the processor, storing instructions executable by the processor to cause the terminal to: receive, from a base station of non-terrestrial network (NTN), a message including configuration information for a minimization of drive test (MDT), and perform a measurement for the MDT based on the configuration information, wherein the terminal is selected based on first information indicating an area scope of the MDT and second information indicating a specific geographical area for the MDT, wherein the area scope of MDT is configured as a coverage of a cell, a tracking area code, or a public land mobile network (PLMN), and wherein a location of the terminal is within the specific geographical area.

[0026] According to various embodiments of the disclosure, there is provided a method for enhancing minimization of drive test, MDT, measurement performed by a first node, including receiving configuration information for the MDT from an Operation Administration and Maintenance node, wherein the configuration information for the MDT includes an MDT area scope, NTN auxiliary information; selecting, by the first node, a corresponding UE to configure MDT measurement according to the NTN auxiliary information; and transmitting, by the first node, the configuration information for the MDT to a second node, the configuration information for the MDT including the MDT area scope.

[0027] In some embodiments, the NTN auxiliary information includes at least one of the following: mapped cell ID, fixed routing identification, and geographical area scope.

[0028] In some embodiments, the NTN auxiliary information further includes indication information indicating that the MDT measurement is only for NTN cells or only for cells included in the MDT area scope.

[0029] In some embodiments, the first node may be an eNB of a 4G system, a core network of a 4G system, a gNB or eNB of a 5G system, a core network of a 5G system, and a base station or core network in other systems.

[0030] In some embodiments, the second node may be at least one of an eNB of a 4G system, a gNB or eNB of a 5G system, and a base station or UE in other systems.

[0031] In some embodiments, when the first node selects the UE for MDT measurement, it not only needs to refer to the MDT area scope but also to the NTN auxiliary information to select the UE.

[0032] In some embodiments, the configuration information for the MDT transmitted to the second node is a UE-specific message.

[0033] According to various embodiments of the disclosure, there is provided a first node, including: a transceiver configured to transmit and receive signals; and a controller coupled with the transceiver and configured to perform the aforementioned method.

[0034] According to various embodiments of the disclosure, there is provided a second node, including: a transceiver configured to transmit and receive signals; and a controller coupled with the transceiver and configured to perform the aforementioned method.

[0035] A method and apparatus for enhancing minimization of drive test measurement is presented in the disclosure.

[0036]

[0037] According to an embodiment of the disclosure, an operator may obtain MDT measurement associated with a PLMN the operator providing in the NTN wireless communication system by configuring a specific geographical area for the MDT to the base station.

[0038] Furthermore, according to an embodiment of the disclosure, a base station may select at least one UE for the MDT performed in the specific geographical area, by using information on area scope of the MDT and the information on the geographical area.

[0039] In addition, according to an embodiment of the disclosure, a terminal may reduce battery consumption by being configured to perform measurement in an area associated with the PLMN.

[0040] Through the enhancing method for the minimization of drive test, the first node can refer to the NTN auxiliary information when selecting the UE. This makes the selection of the UE more accurate, reduces unnecessary configuration processes for the UE, and reduces the complexity of the UE.

[0041] The effects obtainable in the disclosure are not limited to the above-mentioned effects, and other effects not mentioned herein will be clearly understood from the following description by those skilled in the art to which the disclosure belongs.

[0042]

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the disclosure, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the disclosure and do not limit the disclosure. In the drawings:

[0044] Figure 1 illustrates an exemplary system architecture of SAE according to an embodiment of the disclosure;

[0045] Figure 2 illustrates an exemplary system architecture according to an embodiment of the disclosure;

[0046] Figure 3 illustrates a schematic diagram of method for configuring MDT measurement, according to an embodiment of the disclosure;

[0047] Figure 4 illustrates a schematic diagram of method for selecting a suitable UE for MDT measurement in NTN communication system, according to an embodiment of the disclosure; and

[0048] Figure 5 illustrates a block diagram of a configuration of a node according to an embodiment of the disclosure.

[0049]

[0050] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the disclosure as defined by the claims and their equivalents. This description includes various specific details to assist in that understanding but are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications can be made to the various embodiments described herein without departing from the scope and spirit of the disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.

[0051] The terms and phrases used in the following description and claims are not limited to their dictionary meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of various embodiments of the disclosure is provided for illustration purpose only and not for the purpose of limiting the disclosure as defined by the appended claims and their equivalents.

[0052] It is to be understood that the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Thus, for example, reference to "a component surface" includes reference to one or more of such surfaces.

[0053] The terms "include" or "may include" refer to the presence of corresponding disclosed functions, operations, or components that may be used in various embodiments of the disclosure, and do not limit the presence of one or more additional functions, operations, or features. Furthermore, the terms "include" or "have" may be construed to indicate certain characteristics, numbers, steps, operations, constituent elements, components, or combinations thereof, but should not be construed to exclude one or more other characteristics, numbers, steps, operations, constituent elements, components, or combinations thereof.

[0054] The term "or" as used in various embodiments of the disclosure includes any of the listed terms and all combinations thereof. For example, "A or B" may include A, may include B, or may include both A and B.

[0055] Unless defined differently, all terms (including technical terms or scientific terms) used in this disclosure have the same meaning as understood by those skilled in the art to which this disclosure belongs. Common terms as defined in dictionaries are interpreted to have meanings consistent with the context in the relevant technical field, and should not be interpreted ideally or overly formally unless expressly so defined in this disclosure.

[0056] Figures 1 through 5, discussed below, and the various embodiments used to describe the principles of the 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 disclosure may be implemented in any suitably arranged system or device.

[0057] Reference throughout this specification to "one embodiment," "an embodiment," "one example," or "an example" means that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the disclosure. Thus, appearances of the phrases "in one embodiment," "in an embodiment," "one example," or "example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures or characteristics may be combined in any suitable combinations and / or subcombinations in one or more embodiments or examples. In addition, those of ordinary skill in the art will appreciate that the drawings provided herein are for illustrative purposes and that the drawings are not necessarily drawn to scale. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0058]

[0059] Figure 1 illustrates an exemplary system architecture 100 of system architecture evolution (SAE) according to an embodiment of the disclosure

[0060] User equipment (UE) 101 is a terminal device for receiving data. An evolved universal terrestrial radio access network (E-UTRAN) 102 is a radio access network, which includes a macro base station (eNodeB / NodeB) that provides UE with interfaces to access the radio network. A mobility management entity (MME) 103 is responsible for managing mobility context, session context and security information of the UE. A serving gateway (SGW) 104 mainly provides functions of user plane, and the MME 103 and the SGW 104 may be in the same physical entity. A packet data network gateway (PGW) 105 is responsible for functions of charging, lawful interception, etc., and may be in the same physical entity as the SGW 104. A policy and charging rules function entity (PCRF) 106 provides quality of service (QoS) policies and charging criteria. A general packet radio service support node (SGSN) 108 is a network node device that provides routing for data transmission in a universal mobile telecommunications system (UMTS). A home subscriber server (HSS)109 is a home subsystem of the UE, and is responsible for protecting user information including a current location of the user equipment, an address of a serving node, user security information, and packet data context of the user equipment, etc.

[0061]

[0062] Figure 2 illustrates an exemplary system architecture 200 according to an embodiment of the disclosure. Other embodiments of the system architecture 200 can be used without departing from the scope of the disclosure.

[0063] User equipment (UE) 201 is a terminal device for receiving data. A next generation radio access network (NG-RAN) 202 is a radio access network, which includes a base station (a gNB or an eNB connected to 5G core network 5GC, and the eNB connected to the 5GC is also called ng-gNB) that provides UE with interfaces to access the radio network. An access control and mobility management function entity (AMF) 203 is responsible for managing mobility context and security information of the UE. A user plane function entity (UPF) 204 mainly provides functions of user plane. A session management function entity SMF 205 is responsible for session management. A data network (DN) 206 includes, for example, services of operators, access of Internet and service of third parties. The interface between AMF and NG-RAN is called NG-C interface, or NG interface, or N2 interface. The interface between UPF and NG-RAN is called NG-U interface, or N3 interface, and the signaling between UE and AMF is called non-access stratum signaling (NAS), also called N1 interface. The interface between base stations is called Xn interface.

[0064] Minimization of drive test (MDT) is that an operation administration and maintenance (OAM) node of an operator configures a base station or user equipment to perform some measurement, and transmit the measurement result(s) to measurement center node, such as trace collection entity (TCE) node, to reduce the burden of manual test. MDT measurements should support real-time and non-real-time measurements. The core network or OAM node transmits an MDT activation message to the access network node, and the message carries specific MDT measurement configuration, such as measurement type, measurement period, threshold, reporting period or threshold, etc. Some MDT measurement types require the UE to perform measurements. For these measurement types, the access network node transmits a radio resource control (RRC) message to the UE, configures the UE to perform MDT measurements, and the UE reports the measurement results to the access network node. Some MDT measurement types require the base station to perform measurements. For these measurement types, the base station performs MDT measurements based on specific configuration information. The access network transmits the measurement results, including the measurement results performed by the UE and the measurement results performed by the base station, to the measurement center node.

[0065] According to the way to initiate the MDT, MDT can be divided into management-based MDT and signaling-based MDT. Management-based MDT refers to the access network entity receiving an MDT activation message from an OAM node, and signaling-based MDT refers to the access network entity receiving an MDT activation message from a core network entity, such as a mobility management entity.

[0066] According to the status of a UE, the MDT measurement performed by the UE in RRC connected state is called immediate MDT, and the MDT measurement performed by the UE in RRC idle state or RRC inactive state is called logged MDT.

[0067] In satellite communications, the base station can be deployed on the satellite, which is called a bent pipe mode, or the base station can be deployed on the ground and forward data to the UE through the satellite, which is called a transparent transmission mode. Typically, the coverage of cells in satellite communications is large, possibly up to hundreds of kilometers. The current way to configure the MDT is not suitable for the users served by the satellite cell. The disclosure proposes an enhanced MDT configuration mechanism, which adopts the minimum configuration process and reduces the impact on the UE.

[0068] The exemplary embodiments of the disclosure are further described below in conjunction with the accompanying drawings.

[0069] The text and drawings are provided as examples only to assist in understanding the disclosure. They should not be construed as limiting the scope of the disclosure in any way. Although certain embodiments and examples have been provided, it will be apparent to those skilled in the art, based upon this disclosure, that changes can be made to the embodiments and examples shown without departing from the scope of the disclosure.

[0070]

[0071] Figure 3 illustrates a schematic diagram of method for configuring MDT measurement, according to an embodiment of the disclosure.

[0072] Applicable to signaling-based MDT configuration and management-based MDT configuration, 301 is an operation administration and maintenance (OAM), and the OAM node 301 transmits a first message to the first node 302, and the first message can be an MDT activation request message. The first node 302 can be an eNB of a 4G system, a core network of a 4G system, a gNB or eNB of a 5G system, a core network of a 5G system, or a base station or core network in other systems. The second node 303 may be an eNB of a 4G system, a gNB or eNB of a 5G system, a base station in other systems, or a UE.

[0073] The first message, i.e, the MDT activation request message includes configuration information for MDT. The configuration information for MDT mainly includes: MDT Area Scope, reporting mechanism configuration, Trace Reference (TR), IP address of MDT measurement center node (such as TCE), job type, MDT data anonymity, etc. The above job type can be configured into different types, for example four types are currently defined: Immediate MDT only, Logged MDT only, Trace only, as well as Immediate MDT and Trace. Definition of more types or simplification of the types is not excluded. The MDT area scope configures which scope of UEs can be selected as a UE(s) for MDT measurements. The MDT area scope can be configured as the coverage of a cell, or the coverage of a Tracking Area Code (TAC), or the entire Public Land Mobile Network (PLMN). UEs within the scope can be selected by the first node as UEs for MDT. For satellite cells, the minimum coverage is the coverage of one cell. For satellite communications, the satellites may be moving. There are multiple satellites providing coverage for the same geographical area at different points in time. The cell identities provided by multiple satellites can be different. Therefore, the MDT area scope can include the cell identities of all satellite cells serving the same geographical area at different times. TR uniquely identifies an MDT process. During an MDT process, the base station may select multiple users for MDT measurements.

[0074] Currently, the minimum MDT area scope can be defined as the coverage of one cell. In a wide coverage cell in satellite communications, even if it is one cell, its coverage area is still very large, such as tens or hundreds of kilometers. The coverage of a big cell can even reach another country. If the OAM node of the operator wants to collect measurement results for a specific geographical area, or for the coverage area belonging to another country, the OAM node does not care whether there is a coverage vulnerability, the current possible method is to configure the UE with a smaller MDT area scope. For example, the MDT area scope includes a geographical area scope, and the UE only measures the signal quality in the geographical area scope. However, the UE needs to determine whether its current location belongs to the geographical area. However, the UE needs to determine whether its current location belongs to the geographical area. The operation on the UE side is complex and consumes more power, so it requires upgrading on the UE. Therefore, the disclosure provides a network-side solution that has no impact on the UE and does not require upgrading on the UE. In order to have no impact on the UE, the MDT area scope still adopts the previous definition. Through network enhancement, a suitable UE is selected for MDT measurement, reducing unnecessary MDT configuration processes for the UE, reducing the determination process of the UE, and saving UE's power consumption. By transmitting Non-Terrestrial Network (NTN) auxiliary information to the first node by the OAM node, so that when the first node selects the UE, the corresponding UE can be more accurately selected. If the first message includes the NTN auxiliary information, when the first node selects the UE for MDT measurement, the first node may not only refer to the MDT area scope, but also refer to the NTN auxiliary information to select the UE.

[0075]

[0076] NTN auxiliary information includes one or more of the following information:

[0077] ■ Mapped cell ID, which corresponds to a specific geographical area. The first node or the OAM node is configured with the geographical area corresponding to the mapped cell ID. In order to narrow the area scope of MDT measurement, the OAM can separately transmit the mapped cell ID, or a mapped cell ID list, the first node can be configured with the mapped cell where the UE is located from the saved UE context, and the first node can only select the UEs whose current locations are within the mapped cell to perform MDT measurement.

[0078] ■ Fixed routing identity, which corresponds to a specific geographical area. The first node or the OAM node is configured with the geographical area corresponding to the fixed routing identity. In order to narrow the selection scope of MDT measurement users, the OAM can separately transmit the mapped cell ID, or a mapped cell ID list, the first node can be configured with the fixed routing identity where the UE is located from the saved UE context, and the first node can only select the UEs whose current locations are at the fixed routing identity to perform MDT measurement.

[0079] ■ Geographical area scope, which is a specific set of geographical location configuration information, for example, including longitude and latitude information. The first node can be configured with the location information of the UE and select only UEs whose current locations are within the geographical area scope to perform MDT measurements.

[0080] ■ Indication information, which indicates that MDT measurement is only for NTN cells. When the serving cell of the UE is not an NTN cell, MDT measurement is not performed. Or the indication information may indicate MDT measurement is performed only on cells indicated by cell identities in the MDT area scope.

[0081]

[0082] The first node 302 transmits a second message to the second node 303, where the second message is a UE-specific message, and the message includes the configuration information for the MDT. The configuration information for MDT mainly includes: MDT Area Scope, reporting mechanism configuration, Trace Reference (TR), MDT measurement center node (such as TCE) related information. In this step, in order to reduce the impact on the second node, the second message can be an existing message. For example, if the first node is a base station, the second node is a UE, and the MDT configuration is a logged MDT configuration, then the second message is an RRC message carrying configuration message for logged measurement; if the first node is a base station, the second node is a UE, and the MDT configuration is an immediate MDT configuration, then the second message is an RRC configuration request message; if the first node is a core network and the second node is a base station, the second message is a trace activation message, etc.

[0083]

[0084] Figure 4 illustrates a method of MDT enhancement, more particularly, a schematic diagram of method for selecting a suitable UE for MDT measurement in NTN communication system, according to an embodiment of the disclosure. This embodiment describes configuring the UE to perform logged MDT measurement under a non-separated base station architecture. In order to select a suitable UE for MDT measurement, reduce unnecessary MDT configuration processes for the UE, reduce the determination process of the UE, and save UE power consumption, the OAM node also transmits NTN auxiliary information to the first node, so that when the first node selects the UE, it can select the corresponding UE more accurately. If the first message includes the NTN auxiliary information, when selecting the UE for MDT measurement, the first node may not only refer to the MDT area scope, but also refer to the NTN auxiliary information to select the UE.

[0085]

[0086] Step 401: the OAM node transmits an MDT activation request message to the base station.

[0087] The first message, i.e., the MDT activation request message includes configuration information for the MDT. The configuration information for MDT mainly includes: MDT Area Scope, reporting mechanism configuration, Trace Reference (TR), IP address of MDT measurement center node (such as TCE), job type, MDT data anonymity, etc. The above job type can be configured into different types, for example four types are currently defined: Immediate MDT only, Logged MDT only, Trace only, as well as Immediate MDT and Trace. Definition of more types or simplification of the types is not excluded. The MDT area scope configures which scope of UEs can be selected as a UE(s) for MDT measurements. The MDT area scope can be configured as the coverage of a cell, or the coverage of a TAC, or the entire PLMN. UEs within the scope can be selected by the first node as UEs for MDT. For satellite cells, the minimum MDT area scope is the coverage of a cell. Due to the movement of satellites, multiple satellite cells provide coverage for the same geographical area at different points in time. Cell IDs broadcast by the multiple satellite cells providing coverage can be different, so the MDT area scope can contain the cell IDs of all satellite cells serving the same geographical area at different times. TR uniquely identifies an MDT process. During an MDT process, the base station may select multiple users for MDT measurements.

[0088] The message also includes NTN auxiliary information, and the NTN auxiliary information includes one or more of the following information:

[0089] ■ Mapped cell ID, which corresponds to a specific geographical area. The first node or the OAM node is configured with the geographical area corresponding to the mapped cell ID. In order to narrow the selection scope of MDT measurement user, the OAM can separately transmit the mapped cell ID, or a mapped cell ID list, the first node can be configured with the mapped cell where the UE is located from the saved UE context, and the first node can only select the UEs whose current locations are within the mapped cell to perform MDT measurement.

[0090] ■ Fixed routing identity, which corresponds to a specific geographical area. The first node or the OAM node is configured with the geographical area corresponding to the fixed routing identity. In order to narrow the selection scope of MDT measurement users, the OAM can separately transmit the mapped cell ID, or a mapped cell ID list, the first node can be configured with the fixed routing identity where the UE is located from the saved UE context, and the first node can only select the UEs whose current locations are at the fixed routing identity to perform MDT measurement.

[0091] ■ Geographical area scope, which is a specific set of geographical location configuration information, for example, including longitude and latitude information. Based on the existing information, the first node can be configured with the location information of the UE which is saved in the context of the UE, and select only UEs whose current locations are within the geographical area scope to perform MDT measurements.

[0092] ■ Indication information, which indicates that MDT measurement is only for NTN cells. When the serving cell of the UE is not an NTN cell, MDT measurement is not performed. Or the indication information may indicate MDT measurement is performed only on cells indicated by cell identities in the MDT area scope.

[0093] ■ Any combination of cell identity or routing area identity and geographical area scope or mapped cell ID. The cell identity includes the unique identification of the cell, or frequency plus physical layer identity, the routing area identity corresponds to a specific geographical area, and the cell identity and routing area identity are broadcast in the broadcast information of the cell. The geographical area scope is a set of specific geographical location configuration information, for example including maximum and minimum longitude, maximum and minimum latitude information, or a reference location and radius information. The mapped cell ID corresponds to a specific geographical area, and the corresponding relationship is configured in the UE in advance.

[0094] The base station can know the location information of the UE from the saved UE context. The base station can only select the current serving cell as the cell indicated by the cell identity, or when the current serving cell is located in the routing area indicated by the routing area identity, and the UE is located in the geographical area scope or the geographical area corresponding to the mapped cell ID. The base station can only select this kind of UE for MDT measurement.

[0095]

[0096] Step 402: The base station transmits configuration message for logged measurement to the UE.

[0097] The message includes configuration information of MDT, including Trace Reference, Trace Session Reference (TRSR), MDT measurement center node ID, MDT area scope, operator ID list, period of logged measurement logs, whether the type of MDT measurement or MDT report is periodically reported or event triggered. The UE performs MDT measurements according to the measurement configuration information, and saves the measurement results in the MDT measurement results or MDT measurement logs.

[0098] If the cell identity contained in the MDT area scope is the cell identity corresponding to a certain satellite, the UE can know the geographical area scope served by the cell from the broadcast information of the cell, and also know that the cell is a satellite cell, then the UE obtains the geographical area scope corresponding to the cell. According to the NTN neighbor cell information in the broadcast information (the neighbor cell information including the cell ID of the neighbor cell and the geographical area scope corresponding to the cell), or when the geographical area is covered by another satellite cell, it is known from the broadcast information of the new satellite cell (the broadcast information including the cell ID and the geographical area scope corresponding to the cell) that the new satellite cell covers the same geographical area, and then the UE considers that the new satellite cell is still in the MDT measurement scope. Although the new cell ID is not within the MDT area scope, the UE continues to perform MDT measurement.

[0099] If the cell identity contained in the MDT area scope is a cell identity list corresponding to a group of satellites, the UE performs MDT measurements on the cells corresponding to the cell identity list.

[0100] If the cell identity contained in the MDT area scope is the cell identity corresponding to a certain satellite, and the configuration information for the MDT includes indication information indicating that measurements are only performed on that cell, the UE only performs MDT measurements on the cell corresponding to the cell identity.

[0101] The message also includes NTN-related information, or NTN auxiliary information, which is used to reduce the measurement of the satellite cell by the UE and save the energy of the UE. The NTN-related information includes one or more of the following information:

[0102] ■ Mapped cell ID, which corresponds to a specific geographical area. The UE can know the specific location corresponding to the mapped cell from the saved UE context or the pre-configured information. When the UE has the position measurement or the global satellite navigation system, the UE can determine whether it is currently located in the geographical area corresponding to the mapped cell ID.

[0103] If the UE is configured with tracking MDT measurement, when the UE in idle mode or the UE in inactive mode moves out of the geographical area corresponding to the mapped cell ID, the UE can stop the MDT measurement, regardless of whether the current serving cell is included in the cell indicated by the cell identity list included in the MDT area scope or whether the routing area of the current serving cell is located in the routing area indicated by the routing area identity list included in the MDT area scope. When the UE in idle mode or the UE in inactive mode is located in the geographical area corresponding to the mapped cell, in the cell indicated by the cell identity list included in the MDT area scope, or in the routing area indicated by the routing area identity list included in the MDT area scope, the UE performs MDT measurement and logs the MDT measurement results. The purpose of this is to enable the UE to only perform the necessary MDT measurement and save power for the UE as much as possible.

[0104] ■ Fixed routing identity, which corresponds to a specific geographical area. The first node or the OAM node is configured the geographical area corresponding to the fixed routing identity. In order to narrow the selection range of MDT measurement users, the OAM can separately transmit a mapped cell ID or a mapped cell ID list. The first node can be configured with the fixed routing identity where the UE is located from the saved UE context, and the first node can only select the UE whose current position is in the fixed routing identity to perform MDT measurement.

[0105] ■ Geographical area scope, which is a set of specific geographical location configuration information, such as including longitude and latitude information, or including a reference location and radius information. When the UE has the position measurement or the global satellite navigation system, the UE can determine whether its current location is within the geographical area scope included in the NTN auxiliary information.

[0106] If the UE is configured with tracking MDT measurement, when the UE in the idle mode or the UE in the inactive mode moves out of the geographical area corresponding to the geographical area scope contained in the NTN auxiliary information, the UE can stop the MDT measurement, regardless of whether the current serving cell is contained in the cell identity list contained in the MDT area scope or whether the routing area of the current serving cell is located in the routing area indicated in the routing area identity list contained in the MDT area scope. When the UE in idle mode or the UE in inactive mode is located in the geographical area corresponding to the geographical area scope contained in the NTN auxiliary information, in the cell indicated by the cell identity list contained in the MDT area scope, or in the routing area indicated by the routing area identity list contained in the MDT area scope, the UE performs MDT measurement and logs the MDT measurement results. The purpose of this is to enable the UE to only make the necessary MDT measurement and save power for the UE as much as possible.

[0107] ■ Any combination of cell identity or routing area identity and geographical area scope or mapped cell ID. The cell identity includes the unique identification of the cell, or frequency plus physical layer identity, the routing area identity corresponds to a specific geographical area, and the cell identity and routing area are broadcast in the broadcast information of the cell. The geographical area scope is a set of specific geographical location configuration information, such as maximum and minimum longitude, maximum and minimum latitude information, or a reference location and radius information. The mapped cell ID corresponds to a specific geographical area, and the corresponding relationship is configured in the UE in advance.

[0108] When the UE has the position measurement or the global satellite navigation system, the UE can determine whether its current location is in the geographical area scope contained in the NTN auxiliary information or the geographical area scope indicated by the mapped cell ID.

[0109] If the UE is configured with tracking MDT measurement, when the UE in idle mode or inactive mode moves out of the geographical area scope or the geographical area corresponding to the mapped cell ID, the UE stops the MDT measurement. When UE in the idle mode or UE in the inactive mode is located in the geographical area scope or the geographical area corresponding to the mapped cell ID, and the current serving cell is the cell indicated by the cell identity, or the current serving cell is located in the routing area indicated by the routing area identity, the UE performs MDT measurement and logs the MDT measurement result. The purpose of this is to enable the UE to only make the necessary MDT measurement and save power for the UE as much as possible.

[0110] ■ Indication information which indicates that MDT measurement is only for NTN cell, and when the serving cell of UE is not NTN cell, the MDT measurement will not be performed, or indicates that MDT measurement is only made for the cell indicated by the cell identity in the MDT area scope.

[0111]

[0112] Step 403: The UE enters the RRC idle mode or inactive mode and performs MDT measurement. When the UE re-enters the RRC connection, the UE transmits an RRC re-establishment request message, a resume request message, or an RRC setup request message, which may also be other messages. The RRC message includes a service operator identity PLMN ID selected by the UE, information of a registered core network Access and Mobility Management Function(AMF) entity, a non-access stratum message, and a temporary identity allocated by the core network for the UE. The RRC message may also include indication information indicating that the UE saves MDT measurement results (or measurement logs, which can be interchangeably used with "measurement results" too below) for the NTN. According to the indication information, if the base station has a connection with the node for collecting MDT logs of the NTN, the base station can transmit an RRC message to the UE requesting the UE to transmit the MDT measurement results to the base station, and the base station forwards the MDT measurement results to the node for collecting the MDT logs. If there is no connection, the base station does not request MDT measurement results from the UE.

[0113]

[0114] Figure 5 illustrates a block diagram of a configuration of a node according to an embodiment of the disclosure

[0115] The node 500 may include any one of a first node, a second node, and a third node. The first node can be an eNB of a 4G system, a core network of a 4G system, a gNB or eNB of a 5G system, a core network of a 5G system, or a base station or core network in other systems. The second node 303 may be an eNB of a 4G system, a gNB or eNB of a 5G system, a base station in other systems, or a UE. The second node 303 may be an eNB of a 4G system, a gNB or eNB of a 5G system, a base station in other systems, or a UE. The third node may be network node other than first node and second node, including core network or core network or UE.

[0116] Referring to Figure 5, the node 500 according to various embodiments of the disclosure may include a transceiver 501 and a controller(or processor) 502. For example, the transceiver 501 can be configured to transmit and receive signals. For example, the controller 502 may be coupled to the transceiver 501 and configured to perform the aforementioned methods.

[0117] Although the nodes are illustrated as having separate functional blocks for convenience of explanation, the configuration of the nodes is not limited thereto. For example, a node may include a communication unit consisting of a transceiver and a controller. The node may communicate with at least one network node by means of the communication unit.

[0118] According to an embodiment of the disclosure, at least a part of a node (e.g., modules or functions thereof) or a method (e.g., operations or steps) may be implemented as instructions stored in a computer-readable storage medium (e.g., a memory), e.g., in the form of a program module. The instructions, when executed by a processor or controller, may enable the processor or controller to perform the corresponding functions. The computer-readable media may include, for example, hard disks, floppy disks, magnetic media, optical recording media, DVDs, magneto-optical media. The instruction may include code created by a compiler or code executable by an interpreter. A module or UE according to various embodiments of the disclosure may include at least one or more of the above-described components, may omit some of them, or further include other additional components. Operations performed by modules, programming modules, or other components according to various embodiments of the disclosure may be executed sequentially, in parallel, repeatedly, or heuristically, or at least some operations may be executed in a different order or omitted, or other operations may be added.

[0119] What has been described above is only an exemplary embodiment of the disclosure, and is not intended to limit the scope of protection of the disclosure, which is determined by the appended claims.

Claims

1.A method performed by a base station of non-terrestrial network (NTN) in a wireless communication system, the method comprising:receiving, from an access and mobility management (AMF), a first message including first information indicating an area scope of a minimization of drive test (MDT) and second information indicating a specific geographical area for the MDT, wherein the area scope of MDT is configured as a coverage of a cell, a tracking area code, or a public land mobile network (PLMN);selecting at least one terminal whose location is within the specific geographical area based on the first information and the second information; andtransmitting, to a terminal among the at least one terminal, a second message including configuration information for the MDT.2.The method of claim 1,wherein the second information indicates cell identities of satellite cells serving the specific geographical area at different times, andwherein the first message further includes information on a mode of the MDT indicating a logged MDT.3.The method of claim 1, further comprising:transmitting, to the terminal, a request message requesting a logged measurement report for the MDT; andreceiving, from the terminal, a response message including the logged measurement report.4.A method performed by a terminal in a wireless communication system, the method comprising:receiving, from a base station of non-terrestrial network (NTN), a message including configuration information for a minimization of drive test (MDT); andperforming a measurement for the MDT based on the configuration information,wherein the terminal is selected based on first information indicating an area scope of the MDT and second information indicating a specific geographical area for the MDT,wherein the area scope of MDT is configured as a coverage of a cell, a tracking area code, or a public land mobile network (PLMN), andwherein a location of the terminal is within the specific geographical area.5.The method of claim 4,wherein the second information indicates cell identities of satellite cells serving the specific geographical area at different times, andwherein the message further includes information on a mode of the MDT indicating a logged MDT.6.The method of claim 4, further comprising:receiving, from the base station, a request message requesting a logged measurement report for the MDT; andtransmitting, to the base station, a response message including the logged measurement report of the measurement.7.A base station of non-terrestrial network (NTN) in a wireless communication system, the base station comprising:a transceiver;a processor communicatively coupled to the transceiver; andmemory, communicatively coupled to the processor, storing instructions executable by the processor to cause the base station to:receive, from an access and mobility management function (AMF), a first message including first information indicating an area scope of a minimization of drive test (MDT) and second information indicating a specific geographical area for the MDT, wherein the area scope of MDT is configured as a coverage of a cell, a tracking area code, or a public land mobile network (PLMN),select at least one terminal whose location is within the specific geographical area based on the first information and the second information, andtransmit, to a terminal among the at least one terminal, a second message including configuration information for the MDT.8.The base station of claim 7,wherein the second information indicates cell identities of satellite cells serving the specific geographical area at different times, andwherein the first message further includes information on a mode of the MDT indicating a logged MDT.9.The base station of claim 7,wherein the instructions executable by the processor further cause the base station to:transmit, to the terminal, a request message requesting a logged measurement report for the MDT; andreceive, from the terminal, a response message including the logged measurement report.10.A terminal in a wireless communication system, the terminal comprising:a transceiver;a processor communicatively coupled to the transceiver; andmemory, communicatively coupled to the processor, storing instructions executable by the processor to cause the terminal to:receive, from a base station of non-terrestrial network (NTN), a message including configuration information for a minimization of drive test (MDT), andperform a measurement for the MDT based on the configuration information,wherein the terminal is selected based on first information indicating an area scope of the MDT and second information indicating a specific geographical area for the MDT,wherein the area scope of MDT is configured as a coverage of a cell, a tracking area code, or a public land mobile network (PLMN), andwherein a location of the terminal is within the specific geographical area.11.The terminal of claim 10,wherein the second information indicates cell identities of satellite cells serving the specific geographical area at different times, andwherein the message further includes information on a mode of the MDT indicating a logged MDT.12.The terminal of claim 10,wherein the instructions executable by the processor further cause the terminal to:receive, from the base station, a request message requesting a logged measurement report for the MDT, andtransmit, to the base station, a response message including the logged measurement report of the measurement.

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