WO2025150624A1 - Method and device for selecting base station on basis of tracking area information in wireless communication system - Google Patents

Abstract

The objective of the present disclosure is to select a base station on the basis of tracking area information in a wireless communication system. A method performed by a network node may comprise the steps of: receiving a configuration request message from at least one base station; transmitting a configuration response message to the at least one base station; detecting downlink data for a terminal; and transmitting a message for paging the terminal to a first base station among the at least one base station.

Description

Method and device for selecting a base station based on tracking area information in a wireless communication system

The following description relates to a wireless communication system, and more particularly, to a device and method for selecting a base station based on tracking area (TA) information in a wireless communication system.

Wireless access systems are being widely deployed to provide various types of communication services such as voice and data. In general, wireless access systems are multiple access systems that can support communication with multiple users by sharing available system resources (bandwidth, transmission power, etc.). Examples of multiple access systems include CDMA (code division multiple access) systems, FDMA (frequency division multiple access) systems, TDMA (time division multiple access) systems, OFDMA (orthogonal frequency division multiple access) systems, and SC-FDMA (single carrier frequency division multiple access) systems.

In particular, as many communication devices require large communication capacity, enhanced mobile broadband (eMBB) communication technology is being proposed compared to the existing radio access technology (RAT). In addition, a communication system that considers reliability and latency-sensitive services/UE (user equipment) as well as mMTC (massive machine type communications) that connects a large number of devices and objects to provide various services anytime and anywhere is being proposed. Various technology configurations are being proposed for this.

The present disclosure relates to a device and method for selecting a base station based on tracking area (TA) information in a wireless communication system.

The present disclosure relates to a device and method for performing paging based on information about a supported TA of a base station in a wireless communication system.

The present disclosure relates to a device and method for selecting a base station for paging based on information about a supported TA of the base station in a wireless communication system.

The present disclosure relates to a device and method for obtaining valid time information for a support TA of a base station mounted on a satellite in a wireless communication system.

The present disclosure relates to a device and method for updating a TA list of a base station mounted on a satellite in a wireless communication system.

The present disclosure relates to a device and method for provisioning TA information to a base station or a network node in a wireless communication system.

The present disclosure relates to a device and method for obtaining time validity information for each supported TA of a base station based on TA information provisioned in advance in a wireless communication system.

The present disclosure relates to a device and method for selecting a base station for paging a terminal based on at least one of time validity information per supported TA of the base station and connection information between base stations in a wireless communication system.

The technical objectives to be achieved in the present disclosure are not limited to those mentioned above, and other technical tasks not mentioned can be considered by a person having ordinary skill in the art to which the technical configuration of the present disclosure is applied from the embodiments of the present disclosure described below.

As an example of the present disclosure, a method performed by a network node in a wireless communication system includes the steps of receiving a setup request message from at least one base station, transmitting a setup response message to the at least one base station, detecting downlink data for a terminal, and transmitting a message for paging for the terminal to a first base station of the at least one base station, wherein the at least one base station is mounted on at least one satellite, and the first base station is selected based on tracking area (TA) information of the at least one base station provisioned to the at least one base station or the network node, and the TA information of the at least one base station may include at least one of a TA supported by the at least one base station and information indicating a valid time of the TA.

As an example of the present disclosure, a method performed by a base station in a wireless communication system includes the steps of transmitting a setup request message to a network node, receiving a setup response message from the network node, and receiving a message for paging for a terminal, wherein the base station is mounted on a satellite, and the base station is selected as the base station for the paging based on TA information of at least one base station including the base station or the at least one base station provisioned to the network node, and the TA information of the at least one base station may include at least one of a TA supported by the at least one base station and information indicating a valid time of the TA.

As an example of the present disclosure, in a wireless communication system, a network node includes a transceiver, and a processor connected to the transceiver, wherein the processor controls to receive a setup request message from at least one base station, transmit a setup response message to the at least one base station, detect downlink data for a terminal, and transmit a message for paging for the terminal to a first base station among the at least one base station, wherein the at least one base station is mounted on at least one satellite, and the first base station is selected based on TA information of the at least one base station provisioned to the at least one base station or the network node, and the TA information of the at least one base station may include at least one of a TA supported by the at least one base station and information indicating a valid time of the TA.

As an example of the present disclosure, in a wireless communication system, a base station includes a transceiver, and a processor connected to the transceiver, wherein the processor controls to transmit a setup request message to a network node, receive a setup response message from the network node, and receive a message for paging for a terminal, wherein the base station is mounted on a satellite, and the base station is selected as a base station for the paging based on TA information of at least one base station including the base station or the at least one base station provisioned to the network node, and the TA information of the at least one base station may include at least one of a TA supported by the at least one base station and information indicating a valid time of the TA.

As an example of the present disclosure, a communication device includes at least one processor, and at least one computer memory coupled to the at least one processor and storing instructions that, when executed by the at least one processor, direct operations, including: receiving a setup request message from at least one base station, transmitting a setup response message to the at least one base station, detecting downlink data for a terminal, and transmitting a message for paging for the terminal to a first base station of the at least one base station, wherein the at least one base station is mounted on at least one satellite, and the first base station is selected based on tracking area (TA) information of the at least one base station provisioned to the at least one base station or the network node, and the TA information of the at least one base station may include at least one of a TA supported by the at least one base station and information indicating an effective time of the TA.

As an example of the present disclosure, a non-transitory computer-readable medium storing at least one instruction includes the at least one instruction executable by a processor, the at least one instruction controlling a device to receive a setup request message from at least one base station, transmit a setup response message to the at least one base station, detect downlink data for a terminal, and transmit a message for paging for the terminal to a first base station of the at least one base station, wherein the at least one base station is mounted on at least one satellite, and the first base station is selected based on TA information of the at least one base station provisioned to the at least one base station or the network node, and the TA information of the at least one base station may include at least one of a TA supported by the at least one base station and information indicating a valid time of the TA.

The following effects may be achieved by embodiments based on the present disclosure.

The present disclosure can prevent resource consumption by minimizing unnecessary signaling for obtaining information on a support TA of a base station mounted on a satellite in a wireless communication system.

The effects obtainable from the embodiments of the present disclosure are not limited to the effects mentioned above, and other effects not mentioned can be clearly derived and understood by a person having ordinary skill in the art to which the technical configuration of the present disclosure is applied from the description of the embodiments of the present disclosure below. That is, unintended effects resulting from implementing the configuration described in the present disclosure can also be derived by a person having ordinary skill in the art from the embodiments of the present disclosure.

The drawings attached below are intended to aid in understanding the present disclosure and may provide embodiments of the present disclosure together with detailed descriptions. However, the technical features of the present disclosure are not limited to specific drawings, and the features disclosed in each drawing may be combined with each other to form a new embodiment. Reference numerals in each drawing may mean structural elements.

Figure 1 illustrates an example of a communication system applicable to the present disclosure.

FIG. 2 illustrates an example of a user equipment (UE) applicable to the present disclosure.

FIG. 3 illustrates an example of functional separation of a next generation radio access network (NG-RAN) and a 5th generation core (5GC) applicable to the present disclosure.

FIG. 4 illustrates an example of a general architecture of a 5G (5th generation) system applicable to the present disclosure.

Figure 5 illustrates an example of the NG setup procedure.

Figure 6 illustrates an example of a RAN configuration update procedure.

Figure 7 illustrates an example of a list of supported TAs per base station in a transparent satellite-based system.

Figure 8 illustrates an example of a list of supported TAs per base station in a regenerative satellite-based system.

FIG. 9 illustrates an example of a paging message transmission procedure according to one embodiment of the present disclosure.

FIG. 10 illustrates an example of a paging message receiving procedure according to one embodiment of the present disclosure.

FIG. 11 illustrates examples of time-dependent support TAs of satellite base stations according to one embodiment of the present disclosure.

FIG. 12 illustrates an example of an Xn setup procedure between satellite base stations according to one embodiment of the present disclosure.

FIG. 13 illustrates an example of a configuration update procedure of satellite base stations according to one embodiment of the present disclosure.

FIG. 14 illustrates an example of a specific procedure for transmitting a paging message based on TA information according to one embodiment of the present disclosure.

FIG. 15 illustrates an example of a specific procedure for receiving a paging message according to one embodiment of the present disclosure.

FIG. 16 illustrates an example of a paging procedure based on TA information according to one embodiment of the present disclosure.

FIG. 17 illustrates an example of sharing satellite connection information according to one embodiment of the present disclosure.

The following embodiments are combinations of the components and features of the present disclosure in a given form. Each component or feature may be considered optional unless otherwise explicitly stated. Each component or feature may be implemented in a form that is not combined with other components or features. In addition, some components and/or features may be combined to form an embodiment of the present disclosure. The order of the operations described in the embodiments of the present disclosure may be changed. Some components or features of one embodiment may be included in another embodiment, or may be replaced with corresponding components or features of another embodiment.

In the description of the drawings, procedures or steps that may obscure the gist of the present disclosure are not described, and procedures or steps that can be understood by those skilled in the art are also not described.

Throughout the specification, when a part is said to "comprising" or "including" a component, this does not mean that other components are excluded, but rather that other components can be included, unless otherwise specifically stated. In addition, terms such as "... part," "... unit," "module," etc. described in the specification mean a unit that processes at least one function or operation, which may be implemented by hardware, software, or a combination of hardware and software. In addition, "a" or "an," "one," "the," and similar related words may be used in the context of describing the present disclosure (especially in the context of the claims below) to include both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context.

In this specification, embodiments of the present disclosure have been described with a focus on data transmission and reception relationships between a base station and a mobile station. Here, the base station is meant as a terminal node of a network that directly communicates with a mobile station. A specific operation described as being performed by the base station in this document may in some cases be performed by an upper node of the base station.

That is, in a network consisting of a plurality of network nodes including a base station, various operations performed for communication with a mobile station may be performed by the base station or other network nodes other than the base station. In this case, the 'base station' may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), a gNode B (gNB), an ng-eNB, an advanced base station (ABS), or an access point.

Additionally, in the embodiments of the present disclosure, the term terminal may be replaced with terms such as user equipment (UE), mobile station (MS), subscriber station (SS), mobile subscriber station (MSS), mobile terminal, or advanced mobile station (AMS).

In addition, the transmitter refers to a fixed and/or mobile node that provides data service or voice service, and the receiver refers to a fixed and/or mobile node that receives data service or voice service. Accordingly, in the case of uplink, a mobile station can be a transmitter and a base station can be a receiver. Similarly, in the case of downlink, a mobile station can be a receiver and a base station can be a transmitter.

Embodiments of the present disclosure may be supported by standard documents disclosed in at least one of wireless access systems, namely IEEE 802.xx system, 3rd Generation Partnership Project (3GPP) system, 3GPP Long Term Evolution (LTE) system, 3GPP ^5th generation (5G) NR (New Radio) system and 3GPP2 system, and in particular, embodiments of the present disclosure may be supported by 3GPP TS (technical specification) 38.211, 3GPP TS 38.212, 3GPP TS 38.213, 3GPP TS 38.321 and 3GPP TS 38.331 documents.

In addition, the embodiments of the present disclosure may be applied to other wireless access systems and are not limited to the above-described system. For example, they may be applied to systems applied after the 3GPP 5G NR system and are not limited to a specific system.

That is, obvious steps or parts that are not described in the embodiments of the present disclosure can be described by referring to the above documents. In addition, all terms disclosed in this document can be described by the above standard documents.

Hereinafter, preferred embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. The detailed description set forth below together with the accompanying drawings is intended to explain exemplary embodiments of the present disclosure and is not intended to represent the only embodiments in which the technical configuration of the present disclosure may be implemented.

Additionally, specific terms used in the embodiments of the present disclosure are provided to aid in understanding of the present disclosure, and the use of such specific terms may be changed to other forms without departing from the technical spirit of the present disclosure.

The following technology can be applied to various wireless access systems such as CDMA (code division multiple access), FDMA (frequency division multiple access), TDMA (time division multiple access), OFDMA (orthogonal frequency division multiple access), and SC-FDMA (single carrier frequency division multiple access).

For the sake of clarity, the following description is based on a 3GPP communication system (e.g., LTE, NR, etc.), but the technical spirit of the present invention is not limited thereto. LTE may refer to technology after 3GPP TS 36.xxx Release 8. Specifically, LTE technology after 3GPP TS 36.xxx Release 10 may be referred to as LTE-A, and LTE technology after 3GPP TS 36.xxx Release 13 may be referred to as LTE-A pro. 3GPP NR may refer to technology after TS 38.xxx Release 15. 3GPP 6G may refer to technology after TS Release 17 and/or Release 18. “xxx” refers to a standard document detail number. LTE/NR/6G may be collectively referred to as a 3GPP system.

For background technology, terms, abbreviations, etc. used in this disclosure, reference may be made to matters described in standard documents published prior to the present invention. For example, reference may be made to standard documents 36.xxx and 38.xxx.

For terms, abbreviations, and other background technologies that may be used in this document, refer to the following standard documents published prior to this document. In particular, terms, abbreviations, and other background technologies related to LTE/EPS (Evolved Packet System) refer to the 36.xxx series, 23.xxx series, and 24.xxx series, and terms, abbreviations, and other background technologies related to NR (new radio)/5GS (5G system) refer to the 38.xxx series, 23.xxx series, and 24.xxx series.

Below, this specification is described based on the terms defined above.

The three key requirement areas for 5G include (1) Enhanced Mobile Broadband (eMBB), (2) Massive Machine Type Communication (mMTC), and (3) Ultra-reliable and Low Latency Communications (URLLC).

Some use cases may require multiple areas to optimize, while others may focus on just one Key Performance Indicator (KPI). 5G supports these diverse use cases in a flexible and reliable way.

Communication system applicable to the present disclosure

Although not limited thereto, the various descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts of the present disclosure disclosed in this document may be applied to various fields requiring wireless communication/connectivity (e.g., 5G) between devices.

Hereinafter, more specific examples will be provided with reference to the drawings. In the drawings/descriptions below, the same drawing symbols may illustrate identical or corresponding hardware blocks, software blocks, or functional blocks, unless otherwise described.

Figure 1 illustrates an example of a communication system applied to the present disclosure.

Referring to FIG. 1, a communication system (100) applied to the present disclosure includes a wireless device, a base station, and a network. Here, the wireless device means a device that performs communication using a wireless access technology (e.g., 5G NR, LTE) and may be referred to as a communication/wireless/5G device. Although not limited thereto, the wireless device may include a robot (100a), a vehicle (100b-1, 100b-2), an XR (extended reality) device (100c), a hand-held device (100d), a home appliance (100e), an IoT (Internet of Thing) device (100f), and an AI (artificial intelligence) device/server (100g). For example, the vehicle may include a vehicle equipped with a wireless communication function, an autonomous vehicle, a vehicle capable of performing vehicle-to-vehicle communication, etc. Here, the vehicles (100b-1, 100b-2) may include unmanned aerial vehicles (UAVs) (e.g., drones). The XR devices (100c) include augmented reality (AR)/virtual reality (VR)/mixed reality (MR) devices, and may be implemented in the form of a head-mounted device (HMD), a head-up display (HUD) equipped in a vehicle, a television, a smartphone, a computer, a wearable device, a home appliance, digital signage, a vehicle, a robot, etc. The portable devices (100d) may include a smartphone, a smart pad, a wearable device (e.g., a smart watch, smart glasses), a computer (e.g., a laptop, etc.), etc. The home appliances (100e) may include a TV, a refrigerator, a washing machine, etc. The IoT devices (100f) may include sensors, smart meters, etc. For example, the base station (120) and network (130) may also be implemented as wireless devices, and a specific wireless device (120a) may act as a base station/network node to other wireless devices.

Wireless devices (100a to 100f) can be connected to a network (130) via a base station (120). AI technology can be applied to the wireless devices (100a to 100f), and the wireless devices (100a to 100f) can be connected to an AI server (100g) via a network (130). The network (130) can be configured using a 3G network, a 4G (e.g., LTE) network, a 5G (e.g., NR) network, etc. The wireless devices (100a to 100f) can communicate with each other via the base station (120)/network (130), but can also communicate directly (e.g., sidelink communication) without going through the base station (120)/network (130). For example, vehicles (100b-1, 100b-2) can communicate directly (e.g., V2V (vehicle to vehicle)/V2X (vehicle to everything) communication). Additionally, an IoT device (100f) (e.g., a sensor) can communicate directly with another IoT device (e.g., a sensor) or another wireless device (100a to 100f).

Wireless communication/connection (150a, 150b, 150c) can be established between wireless devices (100a to 100f)/base stations (120), and base stations (120)/base stations (120). Here, the wireless communication/connection can be established through various wireless access technologies (e.g., 5G NR) such as uplink/downlink communication (150a), sidelink communication (150b) (or, D2D communication), and communication between base stations (150c) (e.g., relay, IAB (integrated access backhaul)). Through the wireless communication/connection (150a, 150b, 150c), the wireless device and base station/wireless device, and the base station and base station can transmit/receive wireless signals to each other. For example, the wireless communication/connection (150a, 150b, 150c) can transmit/receive signals through various physical channels. To this end, based on various proposals of the present disclosure, at least some of various configuration information setting processes for transmitting/receiving wireless signals, various signal processing processes (e.g., channel encoding/decoding, modulation/demodulation, resource mapping/demapping, etc.), resource allocation processes, etc. may be performed.

Figure 2 illustrates an example of a UE applicable to the present disclosure.

Referring to FIG. 2, the UE (200) may include a processor (202), a memory (204), a transceiver (206), one or more antennas (208), a power management module (241), a battery (242), a display (243), a keypad (244), a SIM (Subscriber Identification Module) card (245), a speaker (246), and a microphone (247).

The processor (202) may be configured to implement the descriptions, functions, procedures, suggestions, methods and/or flowcharts disclosed herein. The processor (202) may be configured to control one or more other components of the UE (200) to implement the descriptions, functions, procedures, suggestions, methods and/or flowcharts disclosed herein. A layer of a radio interface protocol may be implemented in the processor (202). The processor (202) may include an ASIC, other chipset, logic circuitry and/or data processing devices. The processor (202) may be an application processor. The processor (202) may include at least one of a DSP, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), and a modem (modulator and demodulator).

The memory (204) is operatively coupled with the processor (202) and can store various information for operating the processor (202). The memory (204) can include ROM, RAM, flash memory, memory cards, storage media, and/or other storage devices. When the implementation is implemented in software, the techniques described herein can be implemented using modules (e.g., procedures, functions, etc.) that perform the descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts disclosed herein. The modules can be stored in the memory (204) and executed by the processor (202). The memory (204) can be implemented within the processor (202) or external to the processor (202), in which case it can be communicatively coupled with the processor (202) via various methods known in the art.

A transceiver (206) is operatively coupled to the processor (202) and can transmit and/or receive wireless signals. The transceiver (206) can include a transmitter and a receiver. The transceiver (206) can include baseband circuitry for processing radio frequency signals. The transceiver (206) can control one or more antennas (208) to transmit and/or receive wireless signals.

The power management module (241) can manage power of the processor (202) and/or the transceiver (206). The battery (242) can supply power to the power management module (241).

The display (243) can output the result processed by the processor (202). The keypad (244) can receive input to be used by the processor (202). The keypad (244) can be displayed on the display (243).

A SIM card (245) is an integrated circuit for securely storing an International Mobile Subscriber Identity (IMSI) and associated keys, and can be used to identify and authenticate subscribers in mobile phone devices such as mobile phones or computers. Contact information can also be stored on many SIM cards.

The speaker (246) can output sound-related results processed by the processor (202). The microphone (247) can receive sound-related input to be used by the processor (202).

In an implementation of the present specification, a UE may operate as a transmitter in uplink and as a receiver in downlink. In an implementation of the present specification, a base station may operate as a receiver in UL and as a transmitter in DL. In the present specification, a base station may be referred to as a Node B, an eNode B (eNB), a gNB, and may not be limited to a specific form.

In addition, for example, the UE may be implemented in various forms depending on the use case/service. The UE may be composed of various components, devices/parts, and/or modules. For example, each UE may include a communication device, a control device, a memory device, and additional components. The communication device may include a communication circuit and a transceiver. For example, the communication circuit may include one or more processors and/or one or more memories. For example, the transceiver may include one or more transceivers and/or one or more antennas. The control device is electrically connected to the communication device, the memory device, and the additional components, and may control the overall operation of each UE. For example, the control device may control the electrical/mechanical operation of each UE based on a program/code/command/information stored in the memory device. The control device may transmit information stored in the memory device to an external device (e.g., another communication device) via the communication device via a wireless/wired interface, or may store information received from an external device (e.g., another communication device) via the communication device via a wireless/wired interface in the memory device.

The additional components may be configured in various ways depending on the type of the UE. For example, the additional components may include at least one of a power unit/battery, an input/output (I/O) device (e.g., an audio I/O port, a video I/O port), a driving device, and a computing device. In addition, the UE is not limited thereto, and may be implemented in the form of a robot (100a in FIG. 1), a vehicle (100b-1 and 100b-2 in FIG. 1), an XR device (100c in FIG. 1), a portable device (100d in FIG. 1), a home appliance (100e in FIG. 1), an IoT device (100f in FIG. 1), a digital broadcasting terminal, a hologram device, a public safety device, an MTC device, a medical device, a fintech device (or a financial device), a security device, a climate/environmental device, an AI server/device (100g in FIG. 1), a base station (120 in FIG. 1), or a network node. UE can be used in mobile or fixed locations depending on the use case/service.

The various components, devices/parts and/or modules of the UE may all be connected to each other via wired interfaces, or at least some of them may be connected wirelessly via communication devices. In addition, each component, device/part and/or module of the UE may further include one or more elements. For example, the control device may be configured by a set of one or more processors. For example, the control device may be configured by a set of a communication control processor, an application processor (AP), an electronic control unit (ECU), a graphic processing unit and a memory control processor. As another example, the memory device may be configured by a RAM, a DRAM (Dynamic RAM), a ROM, a flash memory, a volatile memory, a nonvolatile memory and/or a combination thereof.

5G system architecture applicable to the present disclosure

The 5G system is an advanced technology from the 4th generation LTE mobile communication technology. It supports new radio access technology (RAT: Radio Access Technology), extended LTE (eLTE) as an extended technology of LTE (Long Term Evolution), and non-3GPP (e.g., WLAN) access through the evolution or clean-state structure of the existing mobile communication network structure.

5G systems are defined as service-based, and the interaction between network functions (NF) within the architecture for 5G systems can be expressed in two ways as follows.

- Reference point representation: Represents the interaction between NF services within NFs described by a point-to-point reference point (e.g., N11) between two NFs (e.g., AMF and SMF).

- Service-based representation: Network functions (e.g., AMF) within the Control Plane (CP) allow other authorized network functions to access their services. This representation also includes point-to-point reference points, if required.

5GC (5G Core) may include various components, some of which include access and mobility management function (AMF), session management function (SMF), policy control function (PCF), user plane function (UPF), application function (AF), unified data management (UDM), and non-3GPP interworking function (N3IWF).

The UE connects to the data network via the UPF through the next generation radio access network (NG-RAN) including the gNB. The UE can receive data services via untrusted non-3GPP access, for example, a wireless local area network (WLAN). To connect the non-3GPP access to the core network, an N3IWF can be deployed.

The N3IWF performs the function of managing interworking between non-3GPP access and 5G system. When UE is connected to non-3GPP access (e.g. WiFi, also known as IEEE 802.11), UE can be connected to 5G system through N3IWF. N3IWF performs control signaling with AMF and connects to UPF through N3 interface for data transmission.

AMF can manage access and mobility in 5G systems. AMF can perform the function of managing NAS (non-access stratum) security. AMF can perform the function of handling mobility in idle state.

UPF performs the function of a gateway for transmitting and receiving user data. UPF node can perform all or part of the user plane functions of S-GW (serving gateway) and P-GW (packet data network gateway) of 4th generation mobile communication.

The UPF acts as an interface between the next generation RAN (NG-RAN) and the core network, and is an element that maintains the data path between the gNB and the SMF. In addition, the UPF acts as a mobility anchor point when the UE moves across the area served by the gNB. The UPF can perform the function of handling PDUs. For mobility within the NG-RAN (e.g., NG-RAN defined after 3GPP Release-15), the UPF can route packets. In addition, the UPF can also act as an anchor point for mobility with other 3GPP networks (e.g., RAN defined before 3GPP Release-15), such as UTRAN (UMTS (universal mobile telecommunications system) terrestrial radio access network)), E-UTRAN (evolved-UTRAN) or GERAN (GSM (global system for mobile communication)/EDGE (enhanced data rates for global evolution) radio access network). A UPF may correspond to the termination point of a data interface toward a data network.

PCF is a node that controls the operator's policy. AF is a server that provides various services to UE. UDM is a server that manages subscriber information, such as the HSS (home subscriber server) of 4th generation mobile communication. UDM (460) stores and manages subscriber information in a unified data repository (UDR).

SMF can perform the function of allocating IP (Internet protocol) address of UE. And, SMF can control PDU (protocol data unit) session.

For convenience of explanation below, the drawing symbols for AMF, SMF, PCF, UPF, AF, UDM, N3IWF, gNB, or UE may be omitted, and operation may be performed by referring to the matters described in standard documents published before this document.

FIG. 3 illustrates an example of functional separation of NG-RAN and 5GC (5th generation core) applicable to the present disclosure.

Referring to Fig. 3, the UE is connected to a data network (DN) through a next-generation RAN. A control plane function (CPF) node performs all or part of the functions of a mobility management entity (MME) of 4th generation mobile communication, and all or part of the control plane functions of a serving gateway (S-GW) and a PDN gateway (P-GW). The CPF node includes an AMF and an SMF.

The UPF node functions as a gateway through which user data is transmitted and received.

The authentication server function (AUSF) authenticates and manages the UE. The Network Slice Selection Function (NSSF) is a node for network slicing as described below.

The network exposure function (NEF) provides a mechanism to securely expose services and features of the 5G core.

The reference points shown in Fig. 3 are as follows. N1 represents a reference point between the UE and the AMF. N2 represents a reference point between the (R)AN and the AMF. N3 represents a reference point between the (R)AN and the UPF. N4 represents a reference point between the SMF and the UPF. N5 represents a reference point between the PCF and the AF. N6 represents a reference point between the UPF and the DN. N7 represents a reference point between the SMF and the PCF. N8 represents a reference point between the UDM and the AMF. N9 represents a reference point between the UPFs. N10 represents a reference point between the UDM and the SMF. N11 represents a reference point between the AMF and the SMF. N12 represents a reference point between the AMF and the AUSF. N13 represents a reference point between the UDM and the AUSF. N14 represents a reference point between the AMFs. N15 represents a reference point between a PCF and an AMF in a non-roaming scenario, and a reference point between an AMF and a PCF of a visited network in a roaming scenario. N16 represents a reference point between SMFs. N22 represents a reference point between an AMF and an NSSF. N30 represents a reference point between a PCF and an NEF. N33 may represent a reference point between an AF and an NEF, and the entities and interfaces described above may be configured with reference to those described in standard documents published before this document. N58 represents a reference point between an AMF and an NSSAAF. N59 represents a reference point between a UDM and an NSSAAF. N80 represents a reference point between an AMF and an NSACF. N81 represents a reference point between an SMF and an NSACF.

The radio interface protocol is based on the 3GPP radio access network standard. The radio interface protocol is divided horizontally into the physical layer, data link layer, and network layer, and vertically into the user plane for data information transmission and the control plane for control signal transmission.

Protocol layers can be divided into L1 (layer-1), L2 (layer-2), and L3 (layer-3) based on the three lower layers of the open systems interconnection (OSI) standard model, which is widely known in communication systems.

Below, the present disclosure describes each layer of the wireless protocol. FIG. 4 illustrates an example of a general architecture of a 5G (5th generation) system applicable to the present disclosure.

Referring to FIG. 4, the AS (access stratum) layer may include a physical (PHY) layer, a medium access control layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a radio resource control (RRC) layer, and operations based on each layer may be performed by referring to matters described in standard documents published prior to this document.

Specific embodiments of the present disclosure

The present disclosure relates to a base station selection based on tracking area (TA) information in a wireless communication system. Specifically, the present disclosure relates to a device and method for obtaining time validity information per supported TA of at least one satellite base station based on TA information provisioned in advance to a base station or a network node, and selecting a base station for paging of a terminal based on the time validity information per supported TA. In the present disclosure, the satellite base station may include at least one of an NG-RAN node, a gNB, and an eNB mounted on a satellite.

Currently, in 3GPP Release 19, research is being conducted to support satellite communications as a study item called FS_5GSAT_ARCH_Ph3 (study on integration of satellite components in the 5G architecture Phase III). Specifically, referring to TR 23.700-29, a method to support regenerative-based satellite access is being studied, as shown in [Table 1].

As shown in [Table 1], solutions to the impact of 5GS/EPS to support regeneration-based satellite access where eNB and/or gNB are mounted on the satellite will be discussed.

When an NG-RAN node (e.g., an eNB and/or gNB) is initially connected to an AMF, a NG setup procedure as illustrated in Fig. 5 is performed. The NG-RAN node and the AMF may perform the NG setup procedure to exchange application level data required for interoperability over the NG-C interface. The NG setup procedure is the first NGAP (Next Generation Application Protocol) procedure triggered after a transport network layer (TNL) association is activated, and uses signaling that is not related to the UE.

FIG. 5 illustrates an example of an NG setup procedure. Referring to FIG. 5, at step S501, the NG-RAN node (520) transmits an NG setup request (NG SETUP REQUEST) message to the AMF (510), and at step S503, receives an NG setup response (NG SETUP RESPONSE) message from the AMF (510). The NG-RAN node (520) can transmit application layer information for an NG-C interface instance using the NG setup request message. The NG setup request message is configured as shown in [Table 2].

As shown in [Table 2], the NG setup request message includes a supported TA list including TACs corresponding to TAs supported by the NG-RAN node (520).

Additionally, the list of supported TAs can be updated by a RAN configuration update procedure. The NG-RAN node and AMF can perform the RAN configuration update procedure to exchange application level configuration data required for interoperability over the NG-C interface. The RAN configuration update procedure does not affect the context related to existing UEs and uses non-UE related signaling.

Fig. 6 illustrates an example of a conventional RAN configuration update procedure. Referring to Fig. 6, at step S601, the NG-RAN node (620) transmits an NG configuration update (NG CONFIGURATION UPDATE) message to the AMF (610), and at step S603, receives an NG configuration update acknowledgment (NG CONFIGURATION UPDATE ACKNOWLEDGE) message from the AMF (610). The NG configuration update message is structured as shown in [Table 3].

As shown in [Table 3], the NG configuration update message includes a support TA list including TACs corresponding to the TAs supported by the NG-RAN node (620). When the NG configuration update message includes a support TA list, the AMF (610) can update the support TA list for the NG-RAN node (620) and the support slice list for each TA, and use them for subsequent registration area management of the terminal.

Fig. 7 illustrates an example of a list of supported TAs per base station in a transparent satellite-based system. Referring to Fig. 7, in a transparent satellite-based system, the supported TAs of a gNB (720) are fixed. In other words, although the area covered by the satellite (730) in a transparent satellite-based system changes, the gNB (720) is fixed on the ground, so the list of supported TAs of a gNB (720) is fixed unless the network configuration changes. Accordingly, when paging is required for a terminal, the AMF (710) can request paging to a gNB (720) supporting the corresponding TA.

FIG. 8 illustrates an example of a list of supported TAs per base station in a regenerative satellite-based system. Referring to FIG. 8, in a regenerative satellite-based system, since gNBs (820-1, 820-2) are mounted on a satellite, the supported TAs of gNBs (820-1, 820-2) may change according to movement of the satellite. For example, the first satellite gNB (820-1) may support TA1, TA2, TA4, TA5, and TA7 at time T1, and may be moved to support TA1 and TA4 at time T2. In addition, the second satellite gNB (820-2) may support TA3 and TA6 at time T1, and may be moved to support TA2, TA3, TA5, TA6, and TA7 at time T2. In this case, when paging for a terminal is required, AMF (810) must identify a gNB supporting the corresponding TA among multiple gNBs (820-1, 820-2) and request paging to the identified gNB.

As described above, the supported TA list of a satellite gNB changes due to movement of the satellite gNB. Therefore, for accurate paging, the changed supported TA list of each satellite gNB needs to be transmitted to the AMF whenever the supported TA of each satellite gNB changes. However, if the supported TA list is transmitted whenever the supported TA of each satellite gNB changes, a lot of signaling is required between the satellite gNBs and the AMF. To minimize signaling, there is a method of transmitting the supported TA lists of all satellite gNBs to the AMF at once. However, if such a method is used, there still exists a problem that the TA that changes due to movement of the satellite gNB cannot be clearly notified.

Meanwhile, the satellite base station moves along a fixed orbit. Therefore, the time-based TA area supported by the satellite base station can be determined based on the orbit of the satellite base station. However, the network node can only check the area information covered by the satellite based on the satellite coverage availability information proposed in Release 18, and does not know which satellite covers each area.

Accordingly, the present disclosure proposes a technique for obtaining time validity information of support TAs for each satellite base station that changes according to movement of satellite base stations based on TA information provisioned to a satellite base station or network node using O&M, and selecting a base station for paging based on the obtained time validity information of support TAs for each satellite base station.

Hereinafter, for convenience of explanation, the present disclosure will describe components and interfaces of 5GS (5G system) as an example, but can be equally applied to EPS (evolved packet system). For example, the network node of the present disclosure includes AMF or MME, and the satellite base station includes an NG-RAN node, gNB, or eNB mounted on a satellite. In addition, the interface between the satellite base stations includes an Xn interface or an S1 interface, and a configuration update for the network node means an NG-RAN node configuration update or an eNB configuration update. In addition, the interface between the satellite base stations in the present disclosure can be implemented through an ISL (inter satellite link). In addition, the satellite base stations can be connected in multi-hops through one or more ISLs and one or more other satellite base stations. Therefore, the satellite base stations connected through an ISL include both satellite base stations connected in multi-hops through a plurality of ISLs and one or more satellite base stations. The satellite of the present disclosure includes a low earth orbit (LEO) satellite or a medium earth orbit (MEO) satellite.

FIG. 9 illustrates an example of a paging message transmission procedure according to one embodiment of the present disclosure. FIG. 9 illustrates a method performed by a network node. The network node may be an AMF or an MME.

Referring to FIG. 9, in step S901, the network node receives a setup request message. In other words, the network node receives a setup request message from the satellite base station. The setup request message may be a message for exchanging application level data required for interoperability on an interface between the network node and the satellite base station. For example, the setup request message may be an NG setup request message. If TA information is provisioned to the satellite base station, the setup request message may include a list of supported TAs of at least one satellite base station. In this case, the list of supported TAs of at least one satellite base station may include TA information of at least one satellite base station provisioned to the satellite base station. The TA information of at least one satellite base station may include at least one of a supported TA of at least one satellite base station and time validity information per supported TA of at least one satellite base station. The time validity information per supported TA is information indicating a valid time for a tracking area code (TAC) per supported TA, and indicates at least some time intervals during which the corresponding supported TA is supported by the corresponding satellite base station among preconfigured time intervals. If TA information is provisioned to the network node, the setup request message may not include a list of supported TAs of at least one satellite base station.

At step S903, the network node transmits a setup response message. In other words, the network node transmits a setup response message to the satellite base station as a response to the setup request message.

In step S905, the network node transmits a paging message. In other words, the network node detects downlink data for the terminal and transmits a message for paging the terminal to a specific satellite base station. To this end, the network node can identify a TA for which paging should be performed for downlink data, and select a satellite base station supporting the identified TA as a base station for paging. At this time, the satellite base station supporting the identified TA can be identified based on TA information of at least one satellite base station provisioned to the network node or the satellite base station. When the TA information is provisioned to the satellite base station, the network node can obtain changed TA information of at least one satellite base station through a configuration update procedure.

FIG. 10 illustrates an example of a paging message receiving procedure according to one embodiment of the present disclosure. FIG. 10 illustrates a method performed by a satellite base station. The satellite base station may be an NG-RAN node, gNB, or eNB mounted on a satellite.

Referring to FIG. 10, in step S1001, the satellite base station transmits a setup request message. In other words, the satellite base station transmits a setup request message to the network node. The setup request message may be a message for exchanging application level data required for interoperability on an interface between the satellite base station and the network node. For example, the setup request message may be an NG setup request message. If TA information is provisioned to the satellite base station, the setup request message may include a list of supported TAs of at least one satellite base station. In this case, the list of supported TAs of at least one satellite base station may include TA information of at least one satellite base station provisioned to the satellite base station. The TA information of at least one satellite base station may include at least one of a supported TA of at least one satellite base station and time validity information per supported TA of at least one satellite base station. The time validity information per supported TA is information indicating a valid time for a tracking area code (TAC) per supported TA, and indicates at least some time intervals during which the corresponding supported TA is supported by the corresponding satellite base station among preconfigured time intervals. If TA information is provisioned to the network node, the setup request message may not include a list of supported TAs of at least one satellite base station.

At step S1003, the satellite base station receives a setup response message. In other words, the satellite base station receives a setup response message from the network node as a response to the setup request message.

In step S1005, the satellite base station receives a paging message. In other words, the satellite base station receives a paging message for a TA supported by the satellite base station from a network node. Upon receiving the paging message, the satellite base station may perform paging for a terminal within a cell belonging to the corresponding TA. The satellite base station may be selected as a base station for paging for a terminal based on TA information provisioned to the network node or the satellite base station. When the TA information is provisioned to the satellite base station, the satellite base station may transmit changed TA information of at least one satellite base station to the network node through a configuration update procedure.

As described with reference to FIGS. 9 and 10, TA information may be provisioned to a satellite base station or a network node. Depending on which entity, the satellite base station or the network node, the transmission and reception signaling and/or the transmission and reception information between the satellite base station and the network node may vary.

A method for provisioning TA information to satellite base stations

TA information can be provisioned to a satellite base station. In other words, by using O&M (operation & maintenance), the orbit of the satellite and the coverage information according to the orbit are provisioned to the base station mounted on the satellite, and the TA information of at least one satellite base station is determined by the orbit and coverage information of the satellite. The satellite base station provides a network node with a support TA list including time validity information for each supported TA of the satellite base station based on the provisioned TA information. The support TA list is provided using an NG setup request message or a RAN configuration update message. For example, the NG setup request message or the RAN configuration update message may include a support TA list including time validity information for each supported TA of the satellite base station. At this time, the time validity information may be expressed in various forms or formats. For example, the time validity information may be expressed in a UTC (coordinated universal time) format, a format having a time stamp value and a duration from the time stamp value, and a format indicating periodicity.

In one embodiment, each of the satellite base stations may be provisioned with TA information indicating the TAs that the satellite base station covers or supports on a time-by-time basis. In this case, each of the satellite base stations exchanges and stores information about the TAs covered on a time-by-time basis, i.e., time validity information for each supported TA, with neighboring base stations via the ISL.

Each satellite base station can be directly connected to a network node through a ground gateway. At this time, each satellite base station can transmit TA information of the corresponding satellite base station and TA information of adjacent satellite base stations to the network node during a preset time period through an NG setting procedure. The network node stores TA information of the corresponding satellite base station and TA information of adjacent satellite base stations received from a directly connected satellite base station.

When each satellite base station needs to update the TA information provided to the network node, it can transmit the TA information of the satellite base station and the TA information of the adjacent satellite base station for a certain period of time thereafter to the network node through a configuration update procedure. In this case, the network node can update the TA information by deleting the previously stored TA information and storing the TA information received through the configuration update procedure.

In addition, when downlink data for a terminal is generated, the network node may select a satellite base station that currently supports a TA requiring paging based on the TA information of each satellite base station and the connection information of the satellite base stations, and attempt paging by transmitting a paging message to the selected satellite base station. At this time, the satellite base station that has received the paging message checks whether the TA requiring paging is an area served by itself or an area served by a neighboring satellite base station connected via ISL. If the TA requiring paging is an area served by itself, the satellite base station performs paging based on the paging support information provided by the network node. On the other hand, if the TA requiring paging is an area served by a neighboring satellite base station connected via ISL, the satellite base station transmits the paging message to the neighboring satellite base station.

FIG. 11 illustrates examples of time-dependent support TAs of satellite base stations according to one embodiment of the present disclosure.

Referring to FIG. 11, in a regenerative satellite-based system, the supported TAs of each of the satellite base stations (1120-1, 1120-1) may vary over time due to the movement of the corresponding satellite. Specifically, the first satellite base station (1120-1) supports TA1, TA2, TA4, TA5, and TA7 during the time interval corresponding to T1 to T2, supports TA1 and TA4 during the time interval corresponding to T2 to T3, and does not support TA1 to TA8 during the time interval corresponding to T3 to T4. Additionally, the second satellite base station (1120-2) supports TA3 and TA6 during the time interval corresponding to T1 to T2, supports TA2, TA3, TA5, TA6, and TA7 during the time interval corresponding to T2 to T3, and supports TA1, TA2, TA4, TA5, and TA7 during the time interval corresponding to T3 to T4.

Therefore, the support TA list of each of the first satellite base station (1120-1) and the second satellite base station (1120-2) can be configured as follows.

- List of supported TAs of the first satellite base station (1120-1): TA2 (T1~T2), TA5 (T1~T2), TA1 (T1~T3), TA4 (T1~T3), TA7 (T1~T2)

- List of supported TAs of the 2nd satellite base station (1120-2): TA3 (T1~T3), TA6 (T1~T3), TA2 (T2~T4), TA5 (T2~T4), TA7 (T2~T4), TA1 (T3~T4), TA4 (T3~T4)

As described above, TA3 and TA6 can be covered during some time intervals corresponding to T1 to T2 and some time intervals corresponding to T2 to T3 among the time intervals T1 to T4, which are preset by the second satellite base station (1120-2). Accordingly, if the support TA list of the second satellite base station (1120-2) includes information indicating that TA3 and TA6 are valid during the time intervals corresponding to T1 to T3, i.e., time validity information for TA3 and TA6, the network node can know that TA3 and TA6 are not covered by the second satellite base station (1120-2) after time point T3. Accordingly, the network node can control so that paging for TA3 or TA6 that occurs after time point T3 is not transmitted to the second satellite base station (1120-2).

Satellite base stations can share time availability information for each supported TA through ISL. At this time, the time availability information for each supported TA of each satellite base station is shared using a procedure for exchanging configuration data required for the interface between satellite base stations (e.g., Xn setup procedure).

FIG. 12 illustrates an example of an Xn setup procedure between satellite base stations according to one embodiment of the present disclosure.

Referring to FIG. 12, in step S1201, a first satellite base station (satellite NG-RAN node ₁ ) (1220-1) transmits an Xn setup request (XN SETUP REQUEST) message to a second satellite base station (satellite NG-RAN node ₂ ) (1220-2). The Xn setup request message includes TA information of the first satellite base station (1220-1). The TA information of the first satellite base station (1220-1) includes a support TA list including at least one tracking area identity (TAI) corresponding to at least one TA supported by the first satellite base station (1220-1) and time validity information of at least one TA. The time validity information of at least one TA indicates at least a part of time intervals during which at least one TA among preset time intervals is supported by the corresponding satellite base station.

At step S1203, the second satellite base station (1220-2) transmits an Xn setup response (XN SETUP RESPONSE) message to the first satellite base station (1220-1). The Xn setup response message includes TA information of the second satellite base station (1220-2). The TA information of the second satellite base station (1220-2) includes a supported TA list including at least one TAI corresponding to at least one TA supported by the second satellite base station (1220-2) and time validity information of at least one TA.

As described with reference to FIG. 12, each of the Xn setup request message and the Xn setup response message may include time validity information of at least one TA as a new IE.

In addition, as described with reference to FIG. 12, each of the Xn setup request message and the Xn setup response message includes TA information of the satellite base station for a preset time interval. Therefore, when the preset time interval has elapsed, the satellite base stations can share TA information of the satellite base station for a time interval after the preset time interval by using a procedure for updating the configuration for the base station.

FIG. 13 illustrates an example of a configuration update procedure of satellite base stations according to one embodiment of the present disclosure.

Referring to FIG. 13, in step S1301, the first satellite base station (satellite NG-RAN node ₁ ) (1320-1) transmits a base station configuration update (NG-RAN NODE CONFIGURATION UPDATE) message to the second satellite base station (satellite NG-RAN node ₂ ) (1320-2). The base station configuration update message includes TA information of the first satellite base station (1320-1). At this time, time validity information of at least one TA included in the TA information of the first satellite base station (1320-1) indicates at least a part of a time interval during which at least one TA among other time intervals after a preset time interval is supported by the first satellite base station (1320-1).

At step S1303, the second satellite base station (1320-2) transmits a base station configuration update acknowledgement (NG-RAN NODE CONFIGURATION UPDATE ACKNOWLEDGE) message to the first satellite base station (1320-1). The second satellite base station (1320-2) may obtain and store TA information of the first satellite base station (1320-2) for another time interval after a preset time interval based on the base station configuration update message, and then transmit an acknowledgement message for the base station configuration update message to the first satellite base station (1320-1).

As described with reference to FIG. 13, the base station configuration update message may include time validity information of at least one TA as a new IE.

In the description with reference to FIGS. 12 and 13, the satellite base stations shared TA information of each satellite base station through a setup procedure and/or a base station configuration update procedure. According to one embodiment, the satellite base stations may share additional information through the setup procedure and/or the base station configuration update procedure. For example, each satellite base station may further share, with an adjacent satellite base station, at least one of information about a network node to which each satellite base station is connected and information about a time when each satellite base station can be directly connected to the network node by using the setup procedure and/or the base station configuration update procedure. Here, the information about the time when the satellite base station can be directly connected to the network node indicates a time when the satellite base station is directly connected to the network node through a ground gateway without going through an adjacent satellite base station connected via an ISL. The information shared in this way can be transmitted to the network node, so that the network node can use it to select a satellite base station for paging.

FIG. 14 illustrates an example of a specific procedure for transmitting a paging message based on TA information according to one embodiment of the present disclosure. FIG. 14 illustrates a method performed by a network node. The network node may be an AMF or an MME.

Referring to FIG. 14, in step S1401, the network node receives TA information of satellite base stations. In other words, the network node receives a setup request message including TA information of the satellite base station from the satellite base station, and stores the TA information of the received satellite base station. At this time, if the satellite base station is connected to at least one adjacent satellite base station, the setup request message may further include TA information of at least one adjacent satellite base station connected to the satellite base station. If there is no adjacent satellite base station connected to the satellite base station for a certain period of time, the setup request message may not include TA information of the adjacent satellite base station. Here, the setup request message may be an NG setup request message. In addition, at least one adjacent satellite base station includes a satellite base station connected to the satellite base station that transmitted the setup request message to the network node by ISL. The TA information of at least one adjacent satellite base station included in the NG setup request message may be information acquired by the satellite base station through the Xn setup procedure and/or the base station configuration update procedure as described with reference to FIG. 12 and/or FIG. 13.

According to one embodiment, the NG setup request message may further include at least one of: availability and usage time of ISL with a neighboring satellite base station; identification information of a neighboring satellite base station connected to the satellite base station (e.g., global gNB-ID); time information when the satellite base station and the neighboring satellite base station are connectable via ISL; information about a network node to which the neighboring satellite base station is connected; time information when the neighboring satellite base station is directly connectable to the network node; and time validity information about TAs supported by the neighboring satellite base station during a time when the neighboring satellite base station is not directly connected to the network node. This is to enable the network node to determine at least one of the connection relationship between satellite base stations via ISL and the ISL usage time information of the satellite base stations.

At step S1403, the network node checks whether downlink data is detected. In other words, the network node checks whether downlink data to be transmitted to the terminal is generated.

If downlink data is detected, at step S1405, the network node selects a paging base station based on TA information. If downlink data to be transmitted to a terminal is generated, the network node checks the TA where the terminal is located, and selects a satellite base station supporting the TA where the terminal is located at the current time based on the TA information of the satellite base stations as a satellite base station for paging. At this time, at least one other information included in the NG setup request message may be further used to select a satellite base station for paging. For example, the network node selects a satellite base station supporting a TA in which a terminal is located at the current time based on at least one of TA information of the satellite base station, TA information of at least one neighboring satellite base station, whether ISL is used with the neighboring satellite base station, identification information of the neighboring satellite base station connected to the satellite base station (e.g., global gNB-ID), time information when the satellite base station and the neighboring satellite base station can be connected via ISL, information about the network node to which the neighboring satellite base station is connected, time information when the neighboring satellite base station can be directly connected to the network node, and time validity information about TAs supported by the neighboring satellite base station during a time when the neighboring satellite base station is not directly connected to the network node. At this time, the selected satellite base station may be a satellite base station directly connected to the network node, or a neighboring satellite base station connected to the satellite base station directly connected to the network node via ISL. The network node may determine whether to use ISL for transmitting a paging message based on whether the selected satellite base station is a satellite base station directly connected to the network.

In step S1407, the network node transmits a paging message. In other words, the network node transmits a paging message to the selected satellite base station. If the selected satellite base station is a base station directly connected to the network node, the network node may transmit the paging message to the selected satellite base station. On the other hand, if the selected satellite base station is a satellite base station directly connected to the network node and an adjacent satellite base station connected via ISL, the network node may determine that the use of ISL is required, and may transmit a paging message to the satellite base station directly connected to the network node while requesting that the adjacent satellite base station connected via ISL transmit the paging message. According to one embodiment, the paging message may include a TAI of a TA requiring paging, i.e., a TA where the terminal is located. Alternatively, the network node may transmit information indicating a TA where the terminal is located and a paging message to the satellite base station directly connected to the network node without directly determining whether the use of ISL is required. In this case, the satellite base station that received the paging message from the network node can determine that the TA where the terminal is located is a TA serviced by an adjacent satellite base station connected to an ISL, and can transmit the paging message to the adjacent satellite base station.

If downlink data is not detected, in step S1409, the network node checks whether a configuration update message is received. In other words, the network node checks whether a configuration update message including TA information of the satellite base station and TA information of at least one neighboring satellite base station is received. The configuration update message may be a RAN configuration update message including TA information of the satellite base station and TA information of at least one neighboring satellite base station for a time period after a preset time. According to one embodiment, the configuration update message may be received when an update of the TA information of the satellite base station and the TA information of at least one neighboring satellite base station is required. For example, when a preset time elapses, when a new TA is added to the satellite base station through O&M, when the satellite base station is connected to a new neighboring satellite base station through ISL, or when an ISL connection between the satellite base station and the neighboring satellite base station is released, the configuration update message may be received from the satellite base station.

When a configuration update message is received, in step S1411, the network node updates the TA information and transmits a configuration update response message. The network node acquires and stores TA information of the satellite base station and TA information of at least one satellite base station from the configuration update message, and transmits a configuration response message, which is a response message to the configuration update message, to the satellite base station. At this time, the TA information of the satellite base station and the TA information of the at least one satellite base station that have been previously stored may be deleted, and the TA information of the satellite base station and the TA information of the at least one satellite base station acquired from the configuration update message may be stored.

FIG. 15 illustrates an example of a specific procedure for receiving a paging message according to one embodiment of the present disclosure. FIG. 15 illustrates a method performed by a satellite base station. The satellite base station may be an NG-RAN node, gNB, or eNB mounted on a satellite.

Referring to FIG. 15, in step S1501, the satellite base station exchanges TA information with the neighboring satellite base station. That is, the satellite base station transmits TA information of the satellite base station to the neighboring satellite base station, and receives TA information of the neighboring satellite base station from the neighboring satellite base station. For example, the satellite base station can exchange and share TA information with the neighboring base station by using the Xn setting procedure and/or the base station configuration update procedure set with reference to FIG. 12 and/or FIG. 13. According to one embodiment, there may be no neighboring base station connected or connectable to the satellite base station for a certain period of time, in which case step S1501 may be omitted.

In step S1503, the satellite base station transmits TA information of the satellite base station to the network node. In other words, the satellite base station transmits a setup request message including TA information of the corresponding satellite base station to the network node. If TA information of an adjacent satellite base station is obtained through step S1501, the setup request message may further include TA information of the adjacent satellite base station obtained through step S1501. Here, the setup request message may be an NG setup request message.

At step S1505, the satellite base station checks whether a paging message is received. In other words, the satellite base station checks whether a paging message indicating that there is downlink data to be transmitted from the network node to the terminal is received.

If the paging message is not received, in step S1507, the satellite base station determines whether TA information update is necessary. The satellite base station determines that TA information update is necessary if a TA information update trigger event occurs. The TA information update trigger event may include at least one of an event in which a preset time elapses, an event in which a new TA is added to the satellite base station through O&M, an event in which the satellite base station is connected to a new neighboring satellite base station through ISL, or an event in which an ISL connection between the satellite base station and the neighboring satellite base station is released.

If TA information update is required, in step S1509, the satellite base station transmits a configuration update message including the updated TA information. The satellite base station updates at least one of the TA information of the satellite base station or the TA information of an adjacent satellite base station, and transmits a configuration update message including the updated TA information to the network node. Here, the TA information may be updated based on a generated TA information update trigger event. For example, if the generated TA information update trigger event is an event in which a preset time elapses, at least one of the TA information of the satellite base station or the TA information of the adjacent satellite base station may be updated with TA information for a time period after the preset time period. Alternatively, if the generated TA information update trigger event is an event in which a new TA is added to the satellite base station through O&M, the TA information of the satellite base station may be updated to include TAI and time validity information of the new TA. Alternatively, if the trigger event for the TA information update is an event in which the satellite base station is connected to a new neighboring satellite base station via an ISL, the TA information of at least one neighboring satellite base station may be updated to include the TA information of the new neighboring satellite base station. Alternatively, if the trigger event for the TA information update is an event in which the ISL connection between the satellite base station and the neighboring satellite base station is released, the TA information of the released neighboring satellite base station may be removed from the TA information of at least one neighboring satellite base station.

At step S1511, the satellite base station receives a response message. In other words, the satellite base station receives a response message to the configuration update message from the network node.

At step S1519, the satellite base station checks whether the connection with the network node is released. If the connection with the network node is not released, the satellite base station may re-perform step S1505.

Meanwhile, if a paging message is received as a result of the verification in step S1505, in step S1513, the satellite base station verifies whether the received paging message is a paging message of the satellite base station. The satellite base station can verify whether the received paging message is a paging message of the satellite base station based on the TAI included in the paging message. In other words, the satellite base station can verify whether the corresponding TA is a TA currently supported by the satellite base station or a TA supported by an adjacent satellite base station based on the TAI included in the paging message. If the corresponding TA is a TA currently supported by the satellite base station, the satellite base station can determine the received paging message as a paging message of the satellite base station. If the corresponding TA is a TA currently supported by the adjacent satellite base station, the satellite base station can determine the received paging message as a paging message of the adjacent satellite base station.

If it is a paging message from a satellite base station, in step S1515, the satellite base station performs paging. If the corresponding TA is a TA currently supported by the satellite base station, the satellite base station can perform paging based on paging assistance information provided from the network node through the paging message.

If it is not a paging message from a satellite base station, in step S1517, the satellite base station transmits the paging message to the neighboring satellite base station. If the TA is a TA currently supported by the neighboring satellite base station, the satellite base station can transmit the paging message to the neighboring satellite base station supporting the TA. At this time, the paging message can be transmitted to the neighboring satellite base station through ISL.

FIG. 16 illustrates an example of a paging procedure based on TA information according to one embodiment of the present disclosure.

Referring to FIG. 16, in step S1601, each of the satellite base stations (1620-1 to 1620-3) transmits an NG setup request message to the AMF (1610). When each of the satellite base stations (1620-1 to 1620-3) is connected to the AMF, the NG setup request message including TA information of the corresponding satellite base station transmits to the AMF (1610). The NG setup request message may further include TA information of at least one neighboring satellite base station connected to the corresponding satellite base station among the satellite base stations (1620-1 to 1620-3). At this time, the TA information of the corresponding satellite base station and the TA information of the at least one neighboring satellite base station each include a support TA list including a support TA and time validity information for a TAC of the support TA during a preconfigured time interval. At this time, the TA information of at least one neighboring satellite base station can be obtained from at least one neighboring satellite base station connected via an ISL. For example, each of the satellite base stations (1620-1 to 1620-3) can obtain TA information of at least one neighboring satellite base station by performing an Xn setup procedure and/or an NG-RAN node configuration update procedure with at least one neighboring satellite base station connected via an ISL.

According to one embodiment, the NG setup request message may further include at least one of: availability and usage time of ISL with a neighboring satellite base station; identification information of a neighboring satellite base station connected to the satellite base station (e.g., global gNB-ID); time information when the satellite base station and the neighboring satellite base station are connectable via ISL; information about an AMF connected to the neighboring satellite base station; time information when the neighboring satellite base station is directly connectable to the AMF; and time validity information about TAs supported by the neighboring satellite base station during a time when the neighboring satellite base station is not directly connected to the AMF. This is to enable the AMF to determine at least one of a connection relationship between satellite base stations via ISL and ISL usage time information of the satellite base stations.

In step S1603, the AMF (1610) transmits an NG setup response message to each of the satellite base stations (1620-1 to 1620-3). In other words, when the AMF (1610) receives an NG setup request message from each of the satellite base stations (1620-1 to 1620-3), the AMF (1610) may transmit an NG setup response message to each of the satellite base stations (1620-1 to 1620-3) in response thereto. In addition, the AMF (1610) may store TA information of each of the satellite base stations (1620-1 to 1620-3) and TA information of a satellite base station connectable via ISL based on the NG setup request message received from each of the satellite base stations (1620-1 to 1620-3).

In step S1605, AMF (1610) attempts to page UE (1630) by transmitting a paging message to satellite base station (1610-2). Specifically, when the occurrence of downlink data to UE (1630) is detected, AMF (1610) selects a satellite base station supporting TA that requires paging at the current time based on TA information of each of satellite base stations (1610-1 to 1610-3) acquired through steps S1601 and S1603 and TA information of at least one neighboring satellite base station of each of satellite base stations (1610-1 to 1610-3), and transmits a paging message to the selected base station.

In step S1607, the satellite base station (1610-2) transmits a paging message to the UE (1630). Here, the satellite base station (1610-2), which has received the paging message from the AMF (1610), checks whether the TA requiring paging is a TA supported by the satellite base station (1610-2) at the current time or a TA supported by an adjacent satellite base station connected to the satellite base station (1610-2) via ISL. If the TA requiring paging is a TA supported by the satellite base station (1610-2) at the current time, the satellite base station (1610-2) transmits a paging message to the UE (1630) based on the paging support information included in the paging message. If the TA requiring paging is not a TA supported by the satellite base station (1610-2) at the current point in time, but is a TA supported by an adjacent satellite base station connected to the satellite base station (1610-2) via ISL, the satellite base station (1610-2) transmits a paging message to the adjacent satellite base station supporting the TA. In this case, the paging message can be transmitted to the UE (1630) by the adjacent satellite base station.

At step S1609, a UE triggered service request procedure may be performed by the UE (1630) transmitting a service request signal to the AMF (1610). At this time, the UE triggered service request procedure may be performed as defined in section 4.2.3.2 of TS 23.502.

In step S1611, each of the satellite base stations (1620-1 to 1620-3) transmits a RAN configuration update message to the AMF (1610). The RAN configuration update message includes TA information of the corresponding satellite base station and TA information of at least one neighboring satellite base station. The RAN configuration update message may be transmitted when it is necessary to update the TA information transmitted from each of the satellite base stations (1620-1 to 1620-3) to the AMF (1610). For example, each of the satellite base stations (1620-1 to 1620-3) may transmit the RAN configuration update message to the AMF (1610) when a preset time elapses, when a new TA supported by the satellite base station is added through O&M, when a new neighboring satellite base station is connected through ISL, or when a connection with a neighboring satellite base station previously connected through ISL is released. The TA information of the satellite base station included in the RAN configuration update message and the TA information of at least one adjacent satellite base station may include TA information for a certain period of time from the time of transmitting the RAN configuration update message.

In step S1613, the AMF (1610) transmits a RAN configuration response message to the satellite base stations (1620-1 to 1620-3). In other words, when the AMF (1610) receives a RAN configuration update message from the satellite base stations (1620-1 to 1620-3), the AMF (1610) may transmit a RAN configuration response message to each of the satellite base stations (1620-1 to 1620-3) in response thereto. At this time, the AMF (1610) updates the TA information by deleting the TA information of the satellite base station and the TA information of at least one satellite base station that have been previously stored, and storing the TA information of the satellite base station and the TA information of at least one satellite base station included in the RAN configuration update message.

A method for provisioning TA information to network nodes

TA information can be provisioned to the network node. In other words, satellite coverage availability information including at least one of orbital information of each satellite base station, information about the time interval covered by each TA by the satellite base stations, and information about the satellite base stations covering each TA can be provisioned to the network node. The information provisioned to the network node is not limited thereto. For example, various types of information necessary to obtain TA information of the satellite base stations and connection information between the satellite base stations can be provisioned to the network node. Accordingly, the network node can obtain TA information of all satellite base stations covering or supporting an area served by the network node, and through this, can obtain TA information of at least one satellite base station currently connected to the network node. Provisioning of the TA information can be performed through O&M (operation & maintenance) or by receiving information from AF or NF.

When TA information is provisioned to a network node, the satellite base station may transmit the orbital information of the satellite base station to the network node. For example, the satellite base station may transmit the orbital information of the satellite base station to the network node using the NG setup procedure, the RAN configuration update procedure, or a new procedure.

When TA information is provisioned to a network node, the satellite base station does not transmit the TA information of the satellite base station to the network node. For example, an NG setup request message or a RAN configuration update message transmitted from the satellite base station to the network node does not include the TA information of the satellite base station. However, the satellite base station may instruct the network node to use the provisioned TA information by transmitting a separate indication to the network node. According to one embodiment, the satellite base station may transmit a TA list including all TAs supported by the satellite base station regardless of time to the network node. In this case, the TA list does not include time validity information of the TA.

A satellite base station can transmit information about its connection to neighboring satellite base stations to the network node. For example, if a satellite base station is connected to a neighboring satellite base station via an ISL, it can transmit a list of connected base stations to the AMF, indicating neighboring satellite base stations that are currently connected to the satellite base station via the ISL, using an NG setup request message or a RAN configuration update message.

FIG. 17 illustrates an example of sharing satellite connection information according to one embodiment of the present disclosure.

Referring to FIG. 17, in step S1701, a satellite NG-RAN node (1720) transmits an NG SETUP REQUEST message to an AMF (1710). The NG SETUP REQUEST message includes a connected RAN node list. The connected RAN node list may include identification information (e.g., Global RAN Node ID) of neighboring satellite base stations currently connected to the satellite base station. According to one embodiment, the NG SETUP REQUEST message may further include time information at which an ISL exists for each neighboring satellite base station. The time information at which an ISL exists for each neighboring satellite base station may indicate a time period during which a satellite base station and a neighboring satellite base station can be connected via an ISL.

At step S1703, AMF (1710) transmits an NG SETUP RESPONSE message to satellite base station (1720). AMF (1710) can obtain and store at least one of a list of connected base stations and time information at which ISL exists for each adjacent satellite base station from the NG SETUP REQUEST message.

In one embodiment, when a satellite base station is connected to a new neighboring satellite base station through an ISL, or when an ISL with an existing neighboring satellite base station is released or disconnected, the satellite base station may update the connected satellite base station list and provide the updated connected satellite base station list to the network node. At this time, the updated connected satellite base station list may be transmitted to the network node using a RAN Configuration Update message.

As described above, by provisioning TA information to the network node and receiving connection information of the satellite base station and the adjacent satellite base station from the satellite base station, the network node can know TA information of all satellite base stations covering the area served by the network node. For example, even if a specific satellite base station is not directly connected to the network node via the ground gateway, but is connected to a satellite base station directly connected to the network node via ISL, the network node can know TA information of the specific satellite base station. That is, the network node can know time validity information of at least one TA of a satellite base station directly connected via the ground gateway and time validity information of at least one TA of a satellite base station indirectly connected via ISL. In other words, the network node can know satellite base stations supporting TAs in the area served by the network node and valid time information of each of the satellite base stations supporting the corresponding TA based on the provisioned TA information.

Accordingly, the network node can select a satellite base station for paging to the terminal based on the provisioned TA information and the connection information of the satellite base station and the adjacent satellite base station. In other words, the network node can select a satellite base station for paging based on the satellite base stations supporting TAs within the area served by the network node and the valid time information during which each of the satellite base stations supports the corresponding TA. The network node can transmit a paging message to the selected satellite base station. For example, the network node can transmit a paging message to the selected satellite base station as described in step S1605 of FIG. 16. At this time, the paging message can include identification information of the selected satellite base station.

Accordingly, the satellite base station that receives the paging message can transmit the paging message to the terminal or forward it to an adjacent satellite base station as described in step S1607. For example, if the identification information of the selected satellite base station included in the paging message is identical to the identification information of the satellite base station that received the paging message, the satellite base station that received the paging message can transmit the paging message to the terminal. On the other hand, if the identification information of the selected satellite base station included in the paging message is different from the identification information of the satellite base station that received the paging message, the satellite base station that received the paging message can forward the paging message to an adjacent satellite base station that has the corresponding identification information.

As described above, the TA information provisioned to a network node can be used for other operations as well as paging operations. For example, the TA information provisioned to a network node can be used to select a target network node for handover of a terminal.

In the present disclosure, the network node can know which satellite base station supports each TA at which point in time based on the TA information provisioned to the satellite base station or the network node. Therefore, the network node can select the satellite base station to perform paging based on the TA information when paging a terminal. Accordingly, the satellite base station does not need to transmit information about the changed TA to the network node every time the TA being served is changed, thereby preventing unnecessary signaling from occurring and minimizing resource consumption.

It is obvious that the examples of the proposed methods described above can also be included as one of the implementation methods of the present disclosure, and thus can be considered as a kind of proposed methods. In addition, the proposed methods described above can be implemented independently, but can also be implemented in the form of a combination (or merge) of some of the proposed methods. Information on whether the proposed methods are applied (or information on the rules of the proposed methods) can be defined as a rule so that the base station notifies the terminal through a predefined signal (e.g., a physical layer signal or a higher layer signal).

The present disclosure may be embodied in other specific forms without departing from the technical ideas and essential features described in the present disclosure. Accordingly, the above detailed description should not be construed as limiting in all aspects but should be considered as illustrative. The scope of the present disclosure should be determined by a reasonable interpretation of the appended claims, and all changes within the equivalent scope of the present disclosure are included in the scope of the present disclosure. In addition, claims that do not have an explicit citation relationship in the patent claims may be combined to form an embodiment or may be included as a new claim by a post-filing amendment.

Embodiments of the present disclosure can be applied to various wireless access systems. As examples of various wireless access systems, there are 3GPP (3rd Generation Partnership Project) or 3GPP2 systems.

The embodiments of the present disclosure can be applied not only to the various wireless access systems described above, but also to all technical fields that apply the various wireless access systems described above. Furthermore, the proposed method can also be applied to mmWave and THz communication systems that utilize ultra-high frequency bands.

Additionally, embodiments of the present disclosure can be applied to various applications such as autonomous vehicles and drones.

Claims (16)

A method performed by a network node in a wireless communication system, A step of receiving a setup request message from at least one base station; A step of transmitting a setup response message to at least one base station; A step of detecting downlink data for a terminal; and A step of transmitting a message for paging for the terminal to a first base station among at least one of the base stations, At least one of the above base stations is mounted on at least one satellite, The first base station is selected based on tracking area (TA) information of the at least one base station provisioned to the at least one base station or the network node, A method wherein the TA information of the at least one base station includes at least one of information indicating a TA supported by the at least one base station and an effective time of the TA. In claim 1, A method wherein the TA information of said at least one base station is determined based on orbit and coverage information of said at least one satellite provisioned to said at least one base station or said network node. In claim 1, The above setup request message includes TA information provisioned to the base station that transmitted the above setup request message, A method in which the TA information provisioned to the base station that transmitted the above-mentioned setup request message includes at least one of the TA information of the base station that transmitted the above-mentioned setup request message and the TA information of at least one adjacent base station connected to the base station that transmitted the above-mentioned setup request message. In claim 3, Further comprising the step of receiving a configuration update message from at least one base station, A method wherein the above configuration update message includes changed TA information of at least one base station. In claim 4, A method wherein the above configuration update message is received when a preset time has elapsed, when a new TA is added to the at least one base station, when the at least one base station is connected to a new neighboring base station, or when the at least one base station and the at least one neighboring base station are disconnected. In claim 1, The above setup request message includes a list of connected base stations indicating identification information of adjacent base stations connected to the base station that transmitted the above setup request message. A method wherein the first base station is selected further based on the list of connected base stations. In claim 6, Further comprising the step of receiving a configuration update message from at least one base station, A method wherein the above configuration update message includes a list of connected base stations indicating identification information of adjacent base stations connected to the base station that transmitted the above configuration update message. In a method performed by a base station in a wireless communication system, A step of sending a setup request message to a network node; A step of receiving a setup response message from the above network node; and A step of receiving a message for paging to a terminal, The above base station is mounted on a satellite, The base station is selected as the base station for the paging based on TA information of at least one base station including the base station or at least one base station provisioned to the network node, A method wherein the TA information of the at least one base station includes at least one of information indicating a TA supported by the at least one base station and an effective time of the TA. In claim 8, A step of transmitting TA information of the base station to an adjacent base station; and Further comprising a step of receiving TA information of the adjacent base station from the adjacent base station, A method wherein the above setup request message includes TA information of the base station and TA information of the adjacent base station. In claim 8, If a trigger event for updating TA information occurs, the method further includes a step of transmitting a configuration update message including changed TA information to the network node. A method wherein the trigger event for updating the TA information includes at least one of a preset time-lapse event, an event in which a new TA is added to the base station, an event in which a new neighboring base station is connected to the base station, or an event in which the base station and at least one neighboring base station are disconnected. In claim 10, The above setup request message includes a list of connected base stations indicating identification information of adjacent base stations connected to the base station, A method wherein the above base station is selected as the base station for the paging based further on the list of the above connected base stations. In claim 11, A step of updating a list of base stations connected to the base station when the connection between the base station and at least one adjacent base station is released or a new adjacent base station is connected to the base station; and A method further comprising the step of transmitting a configuration update message including the updated connected base station list to the network node. In a network node in a wireless communication system, Transmitter and receiver; and comprising a processor connected to the above transceiver, The above processor, Receive a setup request message from at least one base station, Transmitting a setup response message to at least one of the above base stations, Detect downlink data for the terminal, Controlling to transmit a message for paging for the terminal to the first base station among the at least one base station, At least one of the above base stations is mounted on at least one satellite, The first base station is selected based on TA information of the at least one base station or the at least one base station provisioned to the network node, A network node wherein the TA information of the at least one base station includes at least one of information indicating a TA supported by the at least one base station and an effective time of the TA. In a wireless communication system, at a base station, Transmitter and receiver; and comprising a processor connected to the above transceiver, The above processor, Send a setup request message to the network node, Receive a setup response message from the above network node, Controls receiving messages for paging to the terminal, The above base station is mounted on a satellite, The base station is selected as the base station for the paging based on TA information of at least one base station including the base station or at least one base station provisioned to the network node, A base station, wherein the TA information of the at least one base station includes at least one of information indicating a TA supported by the at least one base station and an effective time of the TA. In communication devices, At least one processor; At least one computer memory coupled to said at least one processor and storing instructions that direct operations when executed by said at least one processor, The above actions are, A step of receiving a setup request message from at least one base station; A step of transmitting a setup response message to at least one base station; A step of detecting downlink data for a terminal; and A step of transmitting a message for paging for the terminal to a first base station among at least one of the base stations, At least one of the above base stations is mounted on at least one satellite, The first base station is selected based on tracking area (TA) information of the at least one base station provisioned to the at least one base station or the network node, A communication device, wherein the TA information of the at least one base station includes at least one of information indicating a TA supported by the at least one base station and an effective time of the TA. In a non-transitory computer-readable medium storing at least one instruction, comprising at least one instruction executable by the processor; At least one of the above commands causes the device to: Receive a setup request message from at least one base station, Transmitting a setup response message to at least one of the above base stations, Detect downlink data for the terminal, Controlling to transmit a message for paging for the terminal to the first base station among the at least one base station, At least one of the above base stations is mounted on at least one satellite, The first base station is selected based on TA information of the at least one base station or the at least one base station provisioned to the network node, A computer-readable medium comprising at least one of TA information of said at least one base station and information indicating a TA supported by said at least one base station and an effective time of said TA.