User terminal paging methods for large-scale constellation-based integrated satellite-ground networks

Abstract

This invention discloses a paging method for user terminals in a large-scale satellite-terrestrial converged network, primarily addressing the problems of low paging success rate and high latency in existing technologies for independent terrestrial or satellite networks. The implementation scheme includes: in a satellite-terrestrial converged network scenario, when the calling party is a 5G network user and the called party is a satellite network user, the calling party queries the called party's control center in the terrestrial core network. The core network forwards the paging request to the control center, which then queries the called party's satellite location area, and a low-Earth orbit (LEO) satellite performs paging within that area. When the calling party is a satellite network user and the called party is a 5G network user, the paging request is forwarded via a LEO satellite to the satellite network's control center. The control center queries the called party's satellite location area identifier and forwards the paging request to the terrestrial core network, where a base station performs paging within the satellite location area. This invention reduces paging failures caused by network switching, improves paging success rate, and reduces paging latency and overhead, making it applicable to satellite-terrestrial converged network communication.

Description

Technical Field

[0001] This invention belongs to the field of communication technology, specifically relating to a user terminal paging method that can be used in satellite-ground converged networks. Background Technology

[0002] With the rapid development of technology, terrestrial communication systems have achieved remarkable success and are now steadily moving towards the 5G / 6G era, continuously expanding the boundaries and possibilities of communication. However, in the real world, many geographical areas still pose significant challenges to terrestrial communication, such as the vast and sparsely populated and harsh environments of the open ocean, polar regions, and deserts. In these areas, the deployment of cellular networks faces problems such as high costs and extreme implementation difficulties, making it difficult to meet basic communication coverage needs. Furthermore, 5G communication targets are concentrated in a limited space within 10km of the land surface, failing to realize the vision of seamless air, land, sea, and air coverage. Against this backdrop, a space-ground integrated network, combining satellite and terrestrial networks, is gradually becoming a key research direction in the field of future communication networks.

[0003] Given the enormous potential of satellite and terrestrial network convergence, many internationally renowned organizations have devoted themselves to related research and experimental work. For example, 3GPP began research on satellite-terrestrial converged networks as early as Release 14. In its TS22.261 standard document, it explored in depth the role of satellites in 5G systems and the significant advantages they exhibit compared to 5G systems. In the TR22.822 document, it focused on the relevant content of satellite access in 5G networks and clearly defined twelve user scenarios under satellite-terrestrial converged networks. TR38.811 focused on 5G New Radio for NTN networks, and detailed the deployment scheme and various parameters of satellite networks. TR38.821 further explored the new radio protocol NR in NTN networks and innovatively proposed five network architecture models for satellite-terrestrial converged networks.

[0004] By leveraging the extensive coverage of satellites and combining them with terrestrial mobile communication networks, service continuity and call quality can be efficiently guaranteed. However, how users can access the optimal network in real time according to network quality, and how to design the paging process between users on different networks under the satellite-terrestrial converged network, have become urgent problems to be solved.

[0005] The patent application document with application number CN202410568173.7 discloses a technical solution for location paging, the implementation steps of which are as follows: (1) The access satellite queries the local location relationship database for the satellite where the target user is located. If a valid entry exists, a new IP header is encapsulated outside the service message payload and forwarded according to the routing protocol; (2) If no valid entry exists, the access satellite floods the query message within a limited range. The limited range adopts the fixed TTL scheme. Each satellite maintains the mapping relationship within the TTL range. The mapping relationship of satellites within the range of 2*TTL can be obtained by querying; (3) The satellite that receives the query message queries the local location relationship database. If no mapping relationship exists, it continues to forward; if a mapping relationship exists, it encapsulates the registration message and sends it to the access satellite by unicast according to the routing protocol; (4) The access satellite maintains the local location relationship database according to the registration message information, encapsulates a new IP header outside the service message payload, and forwards it according to the routing protocol. This scheme relies on satellites to query the local location database to find the satellite where the target user is located. If there is no valid entry in the database, it needs to search within a limited range by flooding query messages, which can lead to low efficiency. Especially when there are many satellites or users are widely distributed, such flooding queries will consume a lot of network resources and may cause network congestion.

[0006] Patent application CN202180099412.3 discloses a blockchain-based paging technology method. The implementation steps are as follows: the Active Registration Area (AMF) queries the blockchain network for the UE's paging information; upon receiving the query request from the AMF, the blockchain node derives its current Active Registration Area (RA) and calculates one or more suitable paging routes from the AMF to the UE via a smart contract (SC); the AMF then paging the UE for downlink data based on the UE's paging information. While this method improves the security of paging data through the immutability of blockchain, the need for a large number of nodes to participate in verifying and recording transactions in a blockchain network, coupled with high computational and storage resources and specialized technical support and maintenance, leads to reduced efficiency and increased costs. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of the existing technology by proposing a user terminal paging method for large-scale constellation-based satellite-ground integrated networks, thereby reducing paging latency and overhead and improving network efficiency and service quality.

[0008] The technical approach to achieving the above objectives is as follows: First, some functions of the core network are ported to medium-Earth orbit (MEO) satellites, which, together with ground stations, serve as the control center for the satellite network, responsible for managing low-Earth orbit (LEO) satellites and information on users accessing LEO satellites. After users register their information with both the terrestrial and space-based core networks, when a 5G network user initiates a call, the information of the called satellite network user can be found in the terrestrial core network; similarly, when a satellite network user initiates a call, the information of the called 5G network user can be found in the satellite network. Paging between users of different networks avoids cross-network information exchange, thereby reducing paging latency and overhead.

[0009] Based on the above ideas, the present invention includes technical solutions for different scenarios:

[0010] Technical Solution 1: A paging method for user terminals in a large-scale constellation-based satellite-ground integrated network scenario where the calling party is a 5G network user and the called party is a satellite network user, characterized by including:

[0011] Some functions of the core network are migrated to medium-Earth orbit satellites, and the medium-Earth orbit satellites and ground stations are used together as the control center of the satellite network. The Access and Mobility Management Function Module (AMF) is deployed in the core network, the Access and Mobility Management Function Module (AMF-M) is deployed in the medium-Earth orbit satellites, and the Access and Mobility Management Function Module (AMF-G) is deployed in the ground stations.

[0012] A registered 5G network user initiates a call, and the call request is accessed through the base station to the terrestrial network and forwarded to the first access and mobility management function module A1;

[0013] After receiving a call request, the first access and mobility management function module A1 queries the second access and mobility management function module A2, which stores the called user information, and sends the call request to A2.

[0014] The second access and mobility management module A2 forwards the call request to the low-Earth orbit satellite associated with the called party's satellite network user, and the low-Earth orbit satellite then paging the satellite network user.

[0015] The called party's satellite network user responds to the call request and returns the paging response to the calling party's 5G network user via the network.

[0016] Technical Solution 2: A paging method for user terminals in a large-scale constellation-based satellite-ground converged network scenario where the calling party is a satellite network user and the called party is a 5G network user, characterized by including:

[0017] Some functions of the core network are migrated to medium-Earth orbit satellites, and the medium-Earth orbit satellites and ground stations are used together as the control center of the satellite network. The first access and mobility management function module A1 is deployed in the core network, and the second access and mobility management function module A2 is deployed in the control center.

[0018] A registered satellite network user initiates a call. The call request accesses the satellite network via a low-Earth orbit satellite. The low-Earth orbit satellite selects its own control center based on the principles of minimum hop count and shortest distance, and forwards the call request to the second access and mobility management function module A2 of that control center.

[0019] After receiving a call request, the second access and mobility management module A2 queries the called user's information in the satellite network's control center and sends the call request to the ground core network.

[0020] The terrestrial core network forwards the call request to the base station associated with the called party's 5G network user, and the base station then pages the 5G network user.

[0021] The called party's 5G network user responds to the call request and returns the paging response to the calling party's satellite network user via the network.

[0022] Furthermore, the access and mobility management function module is used to manage information about low-Earth orbit satellites and their access users, including:

[0023] Registration management: Allows user devices to register with the satellite network;

[0024] Connection Management: Ensures the establishment and maintenance of satellite network connections by initializing communication links, continuously monitoring their status, and managing handover when users move;

[0025] Business request processing: Responding to service requests initiated by users;

[0026] Paging: Locating user equipment in a satellite network;

[0027] User mobility management: Tracking user location by enforcing mobility restrictions, managing time subscriptions and notifications, handling in-system mobility updates and handovers between base stations;

[0028] Location reporting: Allows user devices to report their location information to the satellite network;

[0029] Session management: Establishing, maintaining, and releasing user sessions;

[0030] NAS Short Message Service: This service enables users to send and receive messages through the SMS service system by transmitting short messages between the user device and the access and mobility management module A2.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] First, the space-ground converged network architecture proposed in this invention breaks through the geographical limitations of ground station construction by distributing access and mobility management functions across medium-Earth orbit satellites, ground stations, and the ground core network. This solves the problems of high paging latency and high transmission overhead caused by the difficulty of ground station construction. Simultaneously, this architecture avoids the extremely high costs associated with centrally deploying functional modules on giant low-Earth orbit satellite constellations, reduces the burden on the ground core network, effectively lowers paging latency and overhead, and significantly improves service quality and communication efficiency.

[0033] Secondly, based on the dual user registration mechanism, this invention designs a paging scheme between terrestrial network users and satellite network users, which can realize a complete user paging process in a space-ground integrated network. Since this method allows users to directly query the called user information in the local database without cross-network information interaction, it can quickly complete the delivery and return of signaling, significantly reducing paging latency and overhead. Attached Figure Description

[0034] Figure 1 This is a scene diagram of the satellite-ground fusion network of the present invention;

[0035] Figure 2 This is a diagram of the satellite-ground fusion network protocol architecture of the present invention;

[0036] Figure 3 This is a flowchart illustrating the implementation of a 5G network user calling a satellite network user according to the present invention.

[0037] Figure 4 This is a flowchart illustrating the implementation of a satellite network user calling a 5G network user according to the present invention.

[0038] Figure 5 This is a diagram of the satellite-ground fusion network architecture of the present invention;

[0039] Figure 6 This is a flowchart illustrating how a 5G network user initiates a call and accesses the terrestrial network according to the present invention.

[0040] Figure 7 This is a flowchart illustrating how the control center of this invention queries and pages the called user via a low-orbit satellite.

[0041] Figure 8 This is a flowchart illustrating the process of a called satellite network user responding to a call request according to the present invention.

[0042] Figure 9 This is a flowchart illustrating how a satellite network user initiates a call and accesses the satellite network according to the present invention.

[0043] Figure 10 This is a flowchart illustrating how the present invention queries the called user's information and initiates a paging process at the satellite network control center;

[0044] Figure 11This is a flowchart illustrating the response of a 5G network user to a call request according to the present invention. Detailed Implementation

[0045] The embodiments and effects of the present invention will be further described in detail below with reference to the accompanying drawings.

[0046] Reference Figure 1 The implementation scenarios of this invention include: user segment, ground segment, and space segment, wherein:

[0047] The user segment includes various types of users, such as those on land and in the air. The user terminals are for pure 5G network user terminals, pure satellite network user terminals, and dual-mode user terminals. They can be directly connected to the satellite network or the 5G network.

[0048] The ground segment includes a network management center, a satellite management center, a 5G core network, and ground stations. The ground stations can communicate directly with the satellites via a power supply link and can serve as a control center to manage low-orbit satellites and manage user information accessing the satellites. They are equipped with a base station center module, an access and mobility management module, and a session management module.

[0049] The space segment employs a network of multiple medium-Earth orbit (MEO) and low-Earth orbit (LEO) satellites, forming a multi-layered constellation structure combining MEO and LEO. The LEO constellation utilizes a mixed layout of polar and inclined orbits, while the multiple MEO satellites provide full coverage of the LEO satellites. Each LEO satellite is responsible for user access and also supports data forwarding. To reduce the satellite communication system's dependence on the terrestrial core network, access and mobility management functions are extended to the space-based system. Each MEO satellite is equipped with a SAMF unit, similar to the terrestrial core network's Access and Mobility Management (AMF) function, responsible for user and LEO satellite location information registration, updating, and storage, as well as satellite authentication and security management, and maintaining the user-satellite association.

[0050] These medium-Earth orbit satellites and ground stations together serve as the control center of the satellite network, responsible for managing low-Earth orbit satellites and information on users accessing low-Earth orbit satellites.

[0051] Reference Figure 2 In this example, the user UE, LEO satellite, LEO satellite relay station, MEO satellite, MEO satellite relay station, ground station GS, and 5G / 6G core network each have their own protocol modules, among which:

[0052] The protocol modules of the user UE include: Non-access stratum session management protocol NAS-SM, Non-access stratum mobility management protocol NAS-MM, Radio resource control protocol RRC, Packet data convergence protocol PDCP, Radio link layer control protocol RLC, Media access control protocol MAC, and New Radio physical layer protocol NR-PHY.

[0053] The protocol modules of the LEO satellite and the LEO satellite relay station both include: a satellite-borne base station central unit (gNB-CU), a packet data aggregation protocol (PDCP), a radio link layer control protocol (RLC), a media access control protocol (MAC), a new radio physical layer protocol (NR-PHY), an inter-satellite link next-generation application protocol (ISL-NGAP), a flow control transmission protocol (ISL-SCTP), an inter-satellite link physical layer (ISL-L1), an inter-satellite link physical layer (ISL-L2), an inter-satellite link physical layer (ISL-L3), a location management flow control transmission protocol (LM-SCTP), a location management physical layer (LM-L3), and a location management radio interface (LM SRI).

[0054] The protocol modules of the medium-orbit satellite MEO and the medium-orbit satellite MEO relay station both include: a satellite-borne base station centralization unit gNB-CU-CP, an access and mobility management submodule AMF, a non-access stratum mobility management protocol NAS-MM, a radio resource control protocol RRC, an inter-satellite link next-generation application protocol ISL-NGAP, a location management flow control transmission protocol LM-SCTP, a location management physical layer LM-L1, a location management physical layer LM-L2, a location management physical layer LM-L3, a flow control transmission protocol SCTP, an Internet Protocol (IP) protocol, and a satellite ground radio interface 5G SRI.

[0055] The protocol modules of the ground station include: base station centralization unit gNB-CU-CP, access and mobility management submodule AMF, non-access stratum mobility management protocol NAS-MM, radio resource control protocol RRC, Internet Protocol (IP), satellite terrestrial radio interface 5G SRI, physical layer L1, and physical layer L2.

[0056] The protocol modules of the core network include: Non-Access Stratum Session Management Protocol (NAS-SM), Flow Control Transmission Protocol (SCTP), Internet Protocol (IP), Physical Layer L1, and Physical Layer L2.

[0057] Based on the above scenarios and protocol system modules, the present invention provides the following two embodiments:

[0058] Example 1: A paging method for user terminals in a large-scale constellation-oriented satellite-ground converged network scenario where the calling party is a 5G network user and the called party is a satellite network user.

[0059] refer to Figure 3 The implementation steps for this example are as follows:

[0060] Step 1: Construct a space-ground integrated network architecture.

[0061] refer to Figure 5The space-ground integrated network architecture includes space-based and ground-based components as well as user equipment (UE).

[0062] The space-based component includes low-Earth orbit (LEO) satellites, medium-Earth orbit (MEO) satellites, and ground stations. The LEO satellites carry an onboard base station module (RAN-L) and a user plane function module (UPF-L). The MEO satellites carry an access and mobility management module (AMF-M) and a session management function module (SMF-M). The ground stations carry an access and mobility management module (AMF-G) and a session management function module (SMF-G). Modules AMF-M and AMF-G together form the space-based access and mobility management module (AMF-C), and modules SMF-M and SMF-G together form the space-based session management function module (SMF-C). The space-based access and mobility management module (AMF-C) has functions such as registration management, connection management, service request processing, paging, user mobility management, location reporting, session management, and NAS short message service. Medium-Earth orbit (MEO) satellites and ground stations work together as a space-based control center to manage and control low-Earth orbit (LEO) satellites. The onboard base station module RAN-L of the LEO satellites is connected to the access and mobility management module and session management module of the space-based control center through the LEO satellite user plane function module UPF-L.

[0063] The ground-based component includes the Access and Mobility Management Function Module (AMF), Authentication Server Function Module (AUSF), Unified Data Management Function Module (UDM), Policy Control Function Module (PCF), Network Service Presentation Function Module (NEF), Network Function Registration Function Module (NRF), User Plane Function Module (UPF), Session Management Function Module (SMF), as well as the terrestrial base station RAN-gNB and the operator's data network. The terrestrial base station RAN-gNB is connected to the AMF, AUSF, SMF, AF, and other modules in the ground-based core network through the user plane function module UPF of the core network.

[0064] The user UE can access space-based or ground-based networks through the onboard base station module RAN-L of a low-orbit satellite or the ground base station RAN-gNB.

[0065] Step 2: Registered 5G network users initiate a call and access the terrestrial network through the base station.

[0066] Reference Figure 6 The implementation of this step includes:

[0067] 2.1) When a registered 5G network user initiates a call, the NAS-MM protocol module creates a paging request message, which includes the user identifier and satellite location area identifier;

[0068] 2.2) The user selects the base station RAN with the strongest signal to access the network and establishes a Radio Resource Control (RRC) connection:

[0069] When a user is idle, after receiving system information broadcast by the base station through the NR-PHY protocol module, the user initiates a call and triggers a Radio Resource Control (RRC) connection establishment request. The RRC protocol layer encrypts and protects the integrity of the request through the PDCP protocol layer, then processes it in segments through the RLC protocol layer, and finally the MAC layer schedules resources and sends the request to the base station gNB through the common control channel.

[0070] After receiving the request, the gNB base station performs an access control check: if the cell allows user access, it initiates the Radio Resource Control (RRC) connection establishment procedure and sends configuration parameters to the user; otherwise, it rejects the user's access.

[0071] After receiving the configuration parameters, the user sets the corresponding parameters and establishes a Radio Resource Control (RRC) connection, while setting the current cell as the primary serving cell. After completing these settings, the user sends an RRC connection establishment completion message to the base station, successfully establishing a communication link between the user and the base station.

[0072] 2.3) The base station RAN forwards the call request to the user plane function module UPF of the ground core network. The UPF of the ground core network forwards the call request to the session management function module SMF and informs that the protocol data unit (PDU) has arrived.

[0073] 2.4) The Session Management Function (SMF) module of the terrestrial core network returns response signaling to the User Plane Function (UPF) module and sends session messages to the Local Access and Mobility Management (AMF) module;

[0074] 2.5) Access and Mobility Management Function Module (AMF) and Response Session Management Function Module (SMF) of the Terrestrial Core Network.

[0075] Step 3: The ground core network queries the called user's control center and forwards the call request.

[0076] 3.1) When the core network’s Access and Mobility Management Function Module (AMF) receives a call request, it accesses a database that stores the mapping relationship between user identifiers and control center identifiers. It then searches the database based on the called user identifier to determine the control center of the called user and, in turn, the space-based access and mobility management function module (AMF-C) where the called user information is located.

[0077] 3.2) The core network forwards the call request to the called user's control center.

[0078] Step 4: The called user management center queries the low-Earth orbit satellite associated with the called user, and the low-Earth orbit satellite pages the called user.

[0079] Reference Figure 7 The implementation of this step includes:

[0080] 4.1) The called user management center queries the low-orbit satellite identifier and satellite location area information associated with the called user;

[0081] 4.2) The control center sends a paging signal to the low-Earth orbit satellite, which then pages the satellite network users within its location area.

[0082] Calculate the distance and azimuth between the user terminal and the paging satellite;

[0083] Based on the geometric relationship between the user and the satellite and the signal propagation characteristics, the probability beam for successful paging is calculated;

[0084] These calculated probability beams are grouped, and paging signals are sent to users within the grouped beams.

[0085] Step 5: The called satellite network user responds to the call request and returns the paging response to the calling 5G network user via the network.

[0086] Reference Figure 8 The implementation of this step includes:

[0087] 5.1) The called user responds to the paging request from the LEO satellite and sends a service request to the LEO satellite;

[0088] 5.2) The LEO satellite sends a session request to the AMF (Access and Mobility Management Function) module of the ground core network;

[0089] 5.3) The Terrestrial Core Network Access and Mobility Management Function Module (AMF) sends a session request to the Terrestrial Core Network Session Management Function Module (SMF);

[0090] 5.4) The terrestrial core network session management function module (SMF) sends a session update request to the user plane function module (UPF);

[0091] 5.5) The User Plane Function Module (UPF) responds to the session update request and forwards the paging response to the base station associated with the calling user;

[0092] 5.6) The base station forwards the paging response to the calling 5G network user;

[0093] 5.7) The calling 5G network user receives the paging response, confirms the call establishment, sends data packets, and the paging is completed.

[0094] Example 2: A paging method for user terminals in a large-scale constellation-oriented satellite-ground converged network scenario where the calling party is a satellite network user and the called party is a 5G network user.

[0095] refer to Figure 4 The implementation steps of this example include the following:

[0096] Step A: Construct a space-ground integrated network architecture.

[0097] This step is implemented in the same way as step 1 in Example 1.

[0098] Step B: Registered satellite network users initiate a call and access the satellite network via low-Earth orbit satellites.

[0099] Reference Figure 9 The implementation of this step includes:

[0100] B1) Registered satellite network users generate paging requests and send them to the associated low-Earth orbit satellites. The request message includes the user identifier and the satellite location area identifier.

[0101] B2) The NR-PHY protocol layer of the low-Earth orbit satellite first receives the paging request signal from the user equipment (UE) and performs demodulation and decoding to extract the paging request message. Subsequently, the MAC protocol layer further decodes these signals and passes the paging request message to the RLC protocol layer. The RLC layer is responsible for reassembling the message to ensure its integrity and accuracy. Next, the PDCP protocol layer decrypts and verifies the integrity of the reassembled message to recover the original paging request message. Finally, the onboard base station central unit gNB-CU receives the paging request message transmitted by the PDCP protocol layer and forwards it to the user plane function module UPF-L.

[0102] B3) The User Plane Function Module (UPF-L) forwards the paging request to the Session Management Function Module (SMF-L), informing the PDU of its arrival;

[0103] B4) Session Management Function Module SMF-L returns paging response signaling to User Plane Function UPF-L module;

[0104] B5) Low-Earth orbit satellites select a control center based on the principles of minimum hop count and shortest distance via the NGAP protocol module:

[0105] B51) Initialize the hop count from the low-Earth orbit satellite to each medium-Earth orbit satellite and ground station to 0. Starting from the low-Earth orbit satellite, query the routing table and count the hop count from the low-Earth orbit satellite to all medium-Earth orbit satellites and ground stations.

[0106] B52) Select the control center based on the minimum hop count of the ground station or medium-Earth orbit satellite:

[0107] If only one ground station or medium-Earth orbit satellite has the minimum hop count, then that ground station or medium-Earth orbit satellite is directly selected as the control center for the low-Earth orbit satellite.

[0108] If multiple ground stations or medium-Earth orbit satellites have the same minimum hop count, the low-Earth orbit satellite further calculates its distance to these medium-Earth orbit satellites and ground stations to determine the optimal control center.

[0109] B53) Initialize the distance from the low-Earth orbit satellite to each medium-Earth orbit satellite and ground station to 0. Calculate the distance from the low-Earth orbit satellite to all medium-Earth orbit satellites and ground stations based on the latitude and longitude information of the low-Earth orbit satellite, medium-Earth orbit satellite, and ground station, and select the medium-Earth orbit satellite or ground station with the shortest distance as the control center of the low-Earth orbit satellite.

[0110] B6) The Session Management Function Module (SMF-L) sends a session message to the Space-Based Access and Mobility Management Function Module (AMF-C);

[0111] B7) Space-based access and mobility management function AMF-C responds to low-Earth orbit satellite session management function SMF-L.

[0112] Step C: The low-orbit satellite control center queries the called user information and forwards the call request to the ground core network.

[0113] Reference Figure 10 The implementation of this step includes:

[0114] C1) When the Space-Based Access and Mobility Management Function (AMF-C) receives a paging request, it queries the called user information at the control center in the satellite network:

[0115] C11) Check if the called user information exists in the AMF-C module of the current control center's space-based access and mobility management function:

[0116] If it exists, directly obtain the satellite location area identifier of the called user;

[0117] Otherwise, proceed to step C12);

[0118] C12) Polling query in the control center of the satellite network:

[0119] If the current control center is a medium-Earth orbit satellite, then query other medium-Earth orbit satellites one by one in numerical order. If the called user information is still not found, then continue to query the ground station.

[0120] If the current control center is a ground station, then query other ground stations one by one in numerical order. If the called user information is still not found, then continue to query medium-orbit satellites.

[0121] C2) The Space-based Access and Mobility Management Function Module (AMF-C) sends a paging request to the terrestrial core network.

[0122] Step D: The ground core network queries the base station associated with the called user, and the base station then paging the called user.

[0123] D1) Count the number of times a user stays in each paging cell and calculate the probability of a user staying in each paging cell;

[0124] D2) Group cells according to dwell probability and paging delay limit:

[0125] The paging cells are arranged in descending order of user dwell probability, and divided into multiple groups according to a preset paging latency limit:

[0126] The implementation of this step includes:

[0127] Each location area is set to contain N paging cells, and the paging delay is limited to D, meaning that a maximum of D searches are allowed, and the search time for each search is normalized to 1.

[0128] Based on the latency constraint D, the N paging cells in the location area are divided into D paging groups, and within each paging group, the cells are arranged from high to low according to their dwell probability.

[0129] D3) The base station will page the packets in the order of the packets, prioritizing the packets with higher dwell probability. If no user response is received, the base station will continue to page the packets with lower dwell probability until all packets have been paged or a user response has been received.

[0130] In step E, the called 5G network user responds to the call request and returns the paging response to the calling satellite network user via the network.

[0131] Reference Figure 11 The implementation of this step includes:

[0132] E1) The called 5G network user responds to the paging request and sends a service request to the base station;

[0133] E2) The base station sends a session request to the Space-Based Access and Mobility Management Function Module (AMF-C);

[0134] E3) The space-based access and mobility management function module AMF-C sends a session request to the low-Earth orbit satellite session management function module SMF-L;

[0135] E4) The Session Management Function Module (SMF-L) of the low-Earth orbit satellite sends a session update request to the User Plane Function Module (UPF-L) of the low-Earth orbit satellite.

[0136] E5) The User Plane Function Module (UPF-L) of the low-Earth orbit satellite responds to the session update request and sends a paging response to the calling user on the satellite network;

[0137] E6) The calling user receives the paging response, confirms the call establishment, and sends a data packet to complete the paging.

[0138] The above descriptions are merely two examples of the paging process designed by this invention for satellite-terrestrial converged network scenarios, aiming to solve the problems of excessive paging latency and high overhead caused by cross-network interaction information, ensuring fast and efficient paging between different network users in satellite-terrestrial converged networks, and improving network efficiency and service quality. However, they do not constitute any limitation on this invention. Obviously, those skilled in the art, after understanding the content and principles of this invention, may make various modifications and changes in form and details without departing from the principles and structure of this invention. For example, in addition to the usage scenarios of the above embodiments, this invention can also be applied to scenarios where 5G network users call 5G network users or satellite network users call satellite network users. However, these modifications and changes based on the ideas of this invention are still within the scope of protection of the claims of this invention.

[0139] It should be noted that the step numbers in the specification and claims of this invention are only for the purpose of clearly describing the embodiments of this invention and facilitating understanding, and their order is not limited.

Claims

1. A user terminal paging method for a large-scale constellation-based satellite-ground integrated network in a scenario where the calling party is a 5G network user and the called party is a satellite network user, characterized in that... include: The core network's functions are partially migrated to medium-Earth orbit (MEO) satellites, utilizing both MEO satellites and ground stations as the control center for the satellite network. An Access and Mobility Management (AMF) module is deployed in the core network, and a Space-based Access and Mobility Management (AMF-C) module is deployed in the control center. This migration of core network functions to MEO satellites includes: 2a) Migrate the User Data Plane Function Module (UPF), Session Management Function Module (SMF), and Access and Mobility Management Function Module (AMF) of the traditional terrestrial 5G core network to the satellite network; 2b) User Data Plane Functional Module (UPF-L) is deployed on low-Earth orbit satellites for route lookup and data forwarding; The control center is equipped with a space-based session management function module (SMF-C) for establishing, modifying, and releasing user terminal sessions; and a space-based access and mobility management function module (AMF-C) for managing information about low-Earth orbit satellites and their access users. Registered 5G network users initiate calls and send call requests, which are then accessed through base stations to the terrestrial network and forwarded to the Access and Mobility Management Function (AMF) module of the core network. After receiving a call request, the Access and Mobility Management Function Module (AMF) of the core network queries the Space-based Access and Mobility Management Function Module (AMF-C) that stores the called user information, and sends the call request to the AMF-C. The Space-Based Access and Mobility Management Function Module (AMF-C) forwards the call request to the low-Earth orbit (LEO) satellite associated with the called party's satellite network user, which then paging the satellite network user. The called party's satellite network user responds to the call request and returns the paging response to the calling party's 5G network user via the network.

2. The method according to claim 1, characterized in that, The Space-Based Access and Mobility Management Function Module (AMF-C) mentioned in step 2b) manages information about low-Earth orbit satellites and their access users, including: Registration management: Allows user devices to register with the satellite network; Connection Management: Ensures the establishment and maintenance of satellite network connections by initializing communication links, continuously monitoring their status, and managing handover when users move; Business request processing: Responding to service requests initiated by users; Paging: Locating user equipment in a satellite network; User mobility management: Tracking user location by enforcing mobility restrictions, managing time subscriptions and notifications, handling in-system mobility updates and handovers between base stations; Location reporting: Allows user devices to report their location information to the satellite network; Session management: Establishing, maintaining, and releasing user sessions; NAS Short Message Service: Short messages are transmitted between the user equipment and the space-based access and mobility management function module AMF-C, enabling users to send and receive messages through the SMS service system.

3. The method according to claim 1, characterized in that, The registered 5G network user initiates the call, including: (4a) After the user is in an idle state and updates the system information, he initiates a call to trigger a Radio Resource Control (RRC) connection establishment request and sends the request to the base station gNB through the common control channel. (4b) After receiving the request, the base station gNB performs an access control check: if the cell allows the user to access, it initiates the Radio Resource Control (RRC) connection establishment process and sends configuration parameters to the user; otherwise, it rejects the user's access. (4c) After receiving the configuration parameters, the user sets the corresponding parameters and establishes a Radio Resource Control (RRC) connection, and sets the current cell as the primary serving cell. After completing these settings, the user sends an RRC connection establishment completion message to the base station, and successfully establishes a communication link between the user and the base station.

4. The method according to claim 1, characterized in that, After receiving a call request, the Access and Mobility Management (AMF) module of the core network queries the control center that stores the called user information, including: The core network's Access and Mobility Management Function (AMF) module accesses and stores a database containing the mapping relationship between user identifiers and control center identifiers. It then retrieves information from this database based on the called user's identifier to determine the called user's control center, and subsequently, to identify the space-based Access and Mobility Management Function (AMF-C) module where the called user's information is located.

5. The method according to claim 1, characterized in that, The low-orbit satellite paging satellite network users includes: (6a) Calculate the distance and azimuth between the user terminal and the paging satellite; (6b) Calculate the probability beam that may be successfully paging based on the geometric relationship between the user and the satellite and the signal propagation characteristics; (6c) Group these calculated probability beams and send paging signals to users within the grouped beams.

6. A user terminal paging method for a large-scale constellation-based satellite-ground converged network in a scenario where the calling party is a satellite network user and the called party is a 5G network user, characterized in that... include: The core network's functions are partially migrated to medium-Earth orbit (MEO) satellites, utilizing both MEO satellites and ground stations as the control center for the satellite network. An Access and Mobility Management (AMF) module is deployed in the core network, and a Space-based Access and Mobility Management (AMF-C) module is deployed in the control center. This migration of core network functions to MEO satellites includes: 2a) Migrate the User Data Plane Function Module (UPF), Session Management Function Module (SMF), and Access and Mobility Management Function Module (AMF) of the traditional terrestrial 5G core network to the satellite network; 2b) User Data Plane Functional Module (UPF-L) is deployed on low-Earth orbit satellites for route lookup and data forwarding; The control center is equipped with a space-based session management function module (SMF-C) for establishing, modifying, and releasing user terminal sessions; and a space-based access and mobility management function module (AMF-C) for managing information about low-Earth orbit satellites and their access users. A registered satellite network user initiates a call and sends a call request. This call request accesses the satellite network via a low-Earth orbit (LEO) satellite. The LEO satellite selects its own control center based on the principles of minimum hop count and shortest distance, and forwards the call request to the Space-Based Access and Mobility Management Function (AMF-C) module of that control center. The selection of its control center based on the minimum hop count principle by the LEO satellite includes: (8a) Initialize the hop count from the low-Earth orbit satellite to each medium-Earth orbit satellite and ground station to 0. Starting from the low-Earth orbit satellite, query the routing table and count the hop count from the low-Earth orbit satellite to all medium-Earth orbit satellites and ground stations. (8b) Select the control center based on the minimum hop count of the ground station or medium-Earth orbit satellite: If only one ground station or medium-Earth orbit satellite has the minimum hop count, then that ground station or medium-Earth orbit satellite is directly selected as the control center for the low-Earth orbit satellite. If multiple ground stations or medium-Earth orbit satellites have the same minimum hop count, the low-Earth orbit satellite further calculates its distance to these medium-Earth orbit satellites and ground stations to determine the optimal control center. The low-orbit satellites select their control centers based on the shortest distance principle, including: (8c) Initialize the distance from the low-Earth orbit satellite to each medium-Earth orbit satellite and ground station to 0. Calculate the distance from the low-Earth orbit satellite to all medium-Earth orbit satellites and ground stations based on the latitude and longitude information of the low-Earth orbit satellite, medium-Earth orbit satellite and ground station. (8d) Select the shortest distance medium-Earth orbit satellite or ground station as the control center for the low-Earth orbit satellite; After receiving a call request, the Space-Based Access and Mobility Management Function Module (AMF-C) queries the called user's information in the satellite network's control center and sends the call request to the ground core network. The terrestrial core network forwards the call request to the base station associated with the called party's 5G network user, and the base station then pages the 5G network user. The called party's 5G network user responds to the call request and returns the paging response to the calling party's satellite network user via the network.

7. The method according to claim 6, characterized in that, After receiving a call request, the AMF-C (Space-based Access and Mobility Management Function Module) queries the called user's information in the satellite network's control center, including: (9a) Check if the called user information exists in the AMF-C module of the current control center's space-based access and mobility management function: If it exists, then directly obtain the satellite location area identifier of the called user; Otherwise, proceed to step (9b); (9b) Polling query in the control center of the satellite network: If the current control center is a medium-Earth orbit satellite, then query other medium-Earth orbit satellites one by one in numerical order. If the called user information is still not found, then continue to query the ground station. If the current control center is a ground station, then other ground stations will be queried one by one according to their numbers. If the called user information is still not found, then the query will continue to be performed on medium-orbit satellites.

8. The method according to claim 6, characterized in that, The base station pagees 5G network users, including: (10a) Count the number of times a user stays in each paging cell and calculate the probability of a user staying in each paging cell; (10b) Group cells according to dwell probability and paging delay limit; (10c) The base station will page the packets in the order of the packets, prioritizing the packets with higher dwell probability. If no user response is received, the base station will continue to page the packets with lower dwell probability until all packets have been paged or a user response has been received.

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