Inter-satellite switching method and system for point-to-point voice communication of low-orbit satellite 5G network

Abstract

The invention discloses an inter-satellite switching method and system for low-orbit satellite 5G network point-to-point voice communication, and the method comprises the steps: building a point-to-point voice service session when a satellite terminal initiates a point-to-point voice service call, and recording the session information and IP addresses of two voice communication parties; when satellite switching occurs in a point-to-point voice service session, the satellite base station sends a satellite-borne UPF switching request to the AMF, and the AMF forwards the satellite-borne UPF switching request to the SMF; after the SMF queries the succeeding satellite-borne UPF, a point-to-point voice service session creation request is initiated to the succeeding satellite-borne UPF, and the original session information and the IP address are carried; and after the succeeding satellite-borne UPF completes session establishment, a point-to-point voice service session updating request is initiated to the IMS core network, and the succeeding satellite-borne UPF notifies the original satellite-borne UPF to delete original session information after receiving a reply, so that satellite-borne UPF switching is completed. According to the invention, the point-to-point voice service is not disconnected during satellite switching, and the stability and reliability of satellite voice communication are greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of 5G network communication technology, and in particular to an inter-satellite switching method and system for low-orbit satellite 5G network point-to-point voice communication. Background Art

[0002] 3GPP's Non Terrestrial Network (NTN) aims to combine satellite communications with terrestrial mobile communication networks to achieve seamless global coverage. NTN uses satellites as communication nodes to provide ground users with the ability to communicate in areas without traditional ground base station services.

[0003] In the NTN architecture, satellites can be divided into different orbit types, including geostationary orbit (GEO), medium earth orbit (MEO) and low earth orbit (LEO). Satellites in different orbits have different characteristics and advantages. GEO satellites are located at an altitude of about 36,000 kilometers above the equator, are relatively stationary relative to the earth, and can provide a larger coverage range, but have higher latency. MEO satellites are located at an altitude of about 10,000 kilometers, with latency and coverage between GEO and LEO. LEO satellites are located at an altitude of about 500 to 2,000 kilometers, have lower latency, and can provide high-speed data transmission, but have a relatively small coverage range. The current StarNet GW satellite constellation network and Starlink low-orbit satellite network are mainly based on LEO low-orbit satellites.

[0004] The solution of launching satellite base stations and core network user plane functions (UPF) into the sky together is referred to as the satellite-borne UPF solution. Under the satellite-borne UPF solution, there is a point-to-point voice communication service. The voice communication media stream between satellite users can be directly from the terminal to the satellite-borne base station, to the satellite-borne UPF, and then to the target satellite-borne UPF, and then connect to the target user terminal. In the prior art, the limited service time of low-orbit satellites leads to frequent satellite switching, and when switching, only Xn switching between base stations is performed, and the satellite-borne UPF is not switched. The satellite-borne UPF switching adopts the method of re-establishing the session, which causes the IP address to change and then causes the user's voice to drop. The current satellite-borne UPF switching will cause the voice service to drop, and this drop phenomenon seriously affects the continuity of the satellite voice communication service. When the user is making a voice call, a sudden drop in the line will cause great inconvenience to the user, reducing the reliability of the communication system and user satisfaction.

[0005] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0006] The main purpose of the present invention is to provide an inter-satellite switching method and system for point-to-point voice communication in a low-orbit satellite 5G network, aiming to solve the problem in the prior art that the current on-board UPF switching causes the voice service to be disconnected, affecting the continuity of the satellite voice communication service. When the user is making a voice call, the sudden disconnection will cause great inconvenience to the user, reducing the reliability of the communication system and the user satisfaction.

[0007] To achieve the above object, the present invention provides an inter-satellite handover method for point-to-point voice communication in a low-orbit satellite 5G network, and the inter-satellite handover method for point-to-point voice communication in a low-orbit satellite 5G network comprises the following steps:

[0008] When the satellite terminal initiates a point-to-point voice service call, a point-to-point voice service session is established, and the session information and IP addresses of both parties in the voice communication are recorded;

[0009] When a satellite handover occurs in a point-to-point voice service session, the satellite base station sends the onboard UPF handover request to the ground core network AMF, and the ground core network AMF forwards it to the ground core network SMF;

[0010] After the ground core network SMF queries the replaced satellite UPF, it initiates a point-to-point voice service session creation request to the replaced satellite UPF and carries the original session information and IP address;

[0011] When the successor satellite-borne UPF completes the session establishment, it initiates a point-to-point voice service session update request to the IMS core network. After receiving the response, the successor satellite-borne UPF notifies the original satellite-borne UPF to delete the original session information to complete the satellite-borne UPF switching.

[0012] Optionally, the inter-satellite handover method for point-to-point voice communication in the low-orbit satellite 5G network, when the satellite terminal initiates a point-to-point voice service call, establishes a point-to-point voice service session, and records the session information and IP addresses of both parties in the voice communication, specifically includes:

[0013] When the calling terminal is in an idle state, an RRC connection is established between the calling terminal and the satellite base station, and the satellite base station establishes an N2 connection with the ground core network AMF to complete the signaling plane connection from the calling terminal to the ground core network AMF;

[0014] The calling terminal sends a Service Request message to the satellite base station, which is then sent to the ground core network AMF and ground core network SMF via the satellite base station, requesting to establish a point-to-point voice service session;

[0015] The ground core network SMF sends a point-to-point voice service session dedicated bearer establishment request to the satellite UPF based on the user's subscription data, carrying the session information and the IP address assigned to the terminal. After the satellite UPF completes the session establishment, it replies to the ground core network SMF with a response message.

[0016] The ground core network AMF replies to the satellite base station with a Service Request response message, notifying the calling terminal that the point-to-point voice service session has been established and is ready to start the call process;

[0017] The calling terminal initiates the call process and sends the SIP INVITE request to the IMS core network via the terrestrial 5G core network through a dedicated session;

[0018] The IMS core network processes the call request and sends it to the ground core network SMF. The ground core network SMF feeds back the connection status of the called terminal to the IMS core network. The IMS core network initiates a paging process to the ground core network AMF. The ground core network AMF initiates paging to the satellite base station. The satellite base station pages the called terminal.

[0019] The called terminal responds to the paging and establishes a session on the called side through the Service Request process. The ground core network SMF guides the satellite UPF to complete the establishment of the called session. The ground core network SMF records the session information and IP addresses of the calling terminal and the called terminal.

[0020] When the session is established, the called terminal answers the call and sends a SIP response to the onboard UPF to establish a point-to-point voice service session.

[0021] Optionally, the inter-satellite switching method for point-to-point voice communication in the low-orbit satellite 5G network, when satellite switching occurs in the point-to-point voice service session, the satellite base station sends the onboard UPF switching request to the ground core network AMF, and the ground core network AMF forwards it to the ground core network SMF, specifically including:

[0022] When the original satellite base station learns that a base station switch is required, it initiates a base station switch request to the new satellite base station;

[0023] After receiving the base station switching request from the original satellite base station, the new satellite base station processes the base station switching request and responds, indicating that it is ready to receive the switching operation;

[0024] The original satellite base station initiates an RRC connection reconfiguration operation to the first satellite terminal and the second satellite terminal respectively, wherein the connection reconfiguration operation is used to reconfigure wireless connection parameters of the terminals;

[0025] After successfully completing the RRC connection reconfiguration, the first satellite terminal and the second satellite terminal send an RRC connection application to the new satellite base station, and the first satellite terminal and the second satellite terminal respectively establish new connections with the new satellite base station to complete the handover from the original satellite base station to the new satellite base station;

[0026] After completing the connection switching with the satellite terminal, the new satellite base station initiates a satellite UPF switching request to the ground core network SMF through the N2 interface via the ground core network AMF.

[0027] Optionally, the inter-satellite handover method for point-to-point voice communication in the low-orbit satellite 5G network, after the ground core network SMF queries the replaced satellite-borne UPF, initiates a point-to-point voice service session creation request to the replaced satellite-borne UPF and carries the original session information and IP address, specifically including:

[0028] After receiving the onboard UPF switching request, the ground core network SMF queries the relevant network configuration to obtain the parameter information of the new onboard UPF, as well as the recorded point-to-point voice service session information and IP address;

[0029] After obtaining the parameter information of the new satellite-borne UPF, the ground core network SMF sends a point-to-point voice service session establishment message to the new satellite-borne UPF. The point-to-point voice service session establishment message carries the original session information and IP address.

[0030] Optionally, the inter-satellite switching method for point-to-point voice communication in the low-orbit satellite 5G network, when the replaced satellite-borne UPF completes the session establishment, initiates a point-to-point voice service session update request to the IMS core network, and the replaced satellite-borne UPF notifies the original satellite-borne UPF to delete the original session information after receiving the reply to complete the satellite-borne UPF switching, specifically including:

[0031] After receiving the point-to-point voice service session establishment message, the new satellite-borne UPF performs internal configuration and processing according to the information in the point-to-point voice service session establishment message to complete the session establishment operation, and replies to the ground core network SMF that the session establishment is complete, indicating that the new satellite-borne UPF is ready for data transmission;

[0032] After the ground core network SMF completes the session establishment with the new satellite-borne UPF, it initiates an IMS session update message to the IMS core network, notifying the IMS core network that the data transmission path in the network has changed and the session information needs to be updated;

[0033] After receiving the IMS session update message from the ground core network SMF, the IMS core network performs corresponding updates on its own session configuration, and then replies to the ground core network SMF to indicate that the IMS core network has completed the session update;

[0034] After ensuring that the IMS core network and the new satellite-based UPF are ready, the ground core network SMF initiates a deletion request to the original satellite-based UPF to delete the original session information in order to clean up the network resources that are no longer in use;

[0035] After receiving the deletion request, the original onboard UPF deletes the original session information as required and replies to the ground core network SMF that the deletion operation has been completed;

[0036] After receiving the deletion reply from the original satellite UPF, the ground core network SMF replies to the original satellite base station through the ground core network AMF with the satellite UPF switching request response, notifying the original satellite base station that the entire base station switching process has been completed and the network has switched to a new configuration state.

[0037] Optionally, in the inter-satellite switching method for point-to-point voice communication in the low-orbit satellite 5G network, the RRC connection is a signaling connection between the satellite terminal and the network, which is used to transmit control plane information.

[0038] Optionally, in the inter-satellite switching method for point-to-point voice communication in the low-orbit satellite 5G network, the RRC connection is also used to manage wireless resources between the terminal and the base station, including the establishment, reconfiguration and release operations of the wireless bearer.

[0039] Optionally, the inter-satellite switching method for point-to-point voice communication in a low-orbit satellite 5G network, the inter-satellite switching method for point-to-point voice communication in a low-orbit satellite 5G network further includes:

[0040] In a satellite communication scenario, when a satellite base station is switched, an RRC connection is established between the satellite terminal and the new satellite base station to achieve normal communication under the new satellite coverage.

[0041] Optionally, in the inter-satellite switching method for point-to-point voice communication in the low-orbit satellite 5G network, the session information includes: user identification information, IP address allocation information, QoS parameters, security context information and service flow information.

[0042] In addition, to achieve the above-mentioned purpose, the present invention also provides an inter-satellite switching system for point-to-point voice communication in a low-orbit satellite 5G network, wherein the inter-satellite switching system for point-to-point voice communication in a low-orbit satellite 5G network includes: a calling terminal, a called terminal, an original satellite base station, a new satellite base station, a first satellite terminal, a second satellite terminal, a ground core network AMF, a ground core network SMF, an original satellite-borne UPF, a new satellite-borne UPF and an IMS core network;

[0043] When a point-to-point voice service call is initiated, a point-to-point voice service session is established between the calling terminal and the called terminal, and the session information and IP addresses of both parties in the voice communication are recorded;

[0044] When a satellite handover occurs in a point-to-point voice service session, the original satellite base station initiates an RRC connection to the first satellite terminal and the second satellite terminal respectively, and the first satellite terminal and the second satellite terminal establish new connections with the new satellite base station respectively. The original satellite base station sends the satellite UPF handover request to the ground core network AMF, and the ground core network AMF forwards it to the ground core network SMF;

[0045] After the ground core network SMF queries the new satellite-borne UPF that takes over, it initiates a point-to-point voice service session creation request to the new satellite-borne UPF and carries the original session information and IP address;

[0046] When the new satellite UPF completes the session establishment, it initiates a point-to-point voice service session update request to the IMS core network. After receiving the response, the new satellite UPF notifies the original satellite UPF to delete the original session information to complete the satellite UPF switching.

[0047] In the present invention, when the satellite terminal initiates a point-to-point voice service call, a point-to-point voice service session is established, and the session information and IP addresses of both parties in the voice communication are recorded; when the point-to-point voice service session is switched by satellite, the satellite base station sends the satellite UPF switching request to the ground core network AMF, and the ground core network AMF forwards it to the ground core network SMF; after the ground core network SMF inquires about the replaced satellite UPF, it initiates a point-to-point voice service session creation request to the replaced satellite UPF and carries the original session information and IP address; when the replaced satellite UPF completes the session establishment, it initiates a point-to-point voice service session update request to the IMS core network, and the replaced satellite UPF notifies the original satellite UPF to delete the original session information after receiving the reply, so as to complete the satellite UPF switching. The present invention realizes that the point-to-point voice service does not drop the line during the satellite switching, greatly improves the stability and reliability of satellite voice communication, provides users with better communication services, and at the same time reduces the communication interruption and poor user experience caused by frequent disconnection, which is of great significance to promoting the development of satellite communication technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a schematic diagram of a point-to-point voice communication service in an existing satellite-borne UPF solution;

[0049] Figure 2 It is a flow chart of a preferred embodiment of the inter-satellite handover method for point-to-point voice communication in a low-orbit satellite 5G network of the present invention;

[0050] Figure 3 It is a schematic diagram of a process in which a satellite terminal initiates a point-to-point voice service call in a preferred embodiment of the inter-satellite handover method for point-to-point voice communication in a low-orbit satellite 5G network of the present invention;

[0051] Figure 4It is a flow chart of a satellite switching process that occurs when a point-to-point voice service is communicating in a preferred embodiment of the inter-satellite switching method for point-to-point voice communication in a low-orbit satellite 5G network of the present invention. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solution and advantages of the present invention clearer and more specific, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0053] The solution of launching the satellite base station and the core network user plane element (UPF) into the sky together is referred to as the satellite-borne UPF solution. Under the satellite-borne UPF solution, there is a point-to-point voice communication service. The voice communication media flow between satellite users can go directly from the terminal to the satellite-borne base station, to the satellite-borne UPF, and then to the target satellite-borne UPF, and then connect to the target user terminal. The signaling control flow still goes through the ground IMS core network. The advantage of this method is that it can reduce the path of the voice media flow to go around the ground core network and then go up to the sky, thereby reducing the round-trip distance and delay between the ground and the sky, and improving the quality and efficiency of voice communication. Figure 1 As shown, the red line is the media flow of the point-to-point voice communication service, which is directly transmitted only through the satellite base station and the onboard UPF, greatly reducing the communication delay.

[0054] The disadvantages of the prior art are as follows:

[0055] (1) Problems caused by the limited service time of low-orbit satellites: Low-orbit satellites usually operate in orbits of several hundred to two thousand kilometers above the ground. Due to their relatively low orbital altitude, the satellites operate very fast. Taking a common low-orbit satellite as an example, it may take only tens of minutes to one or two hours to orbit the earth. This results in the communication service time provided by each low-orbit satellite to the ground terminal being limited. A specific area on the ground may only be within the coverage of a certain satellite for a relatively short period of time. When the satellite continues to operate and leaves the area, subsequent satellite relay services are required to ensure continuous communication of the ground terminal.

[0056] (2) Limitations of the current satellite switching method: In the prior art, only Xn switching between base stations is performed when the satellite is switched. Xn switching mainly refers to switching between satellite base stations. When a satellite switch occurs, the communication connection is simply switched from the current satellite base station to the new satellite base station. However, this switching method does not take into account the switching of the satellite UPF. The satellite UPF is responsible for handling the transmission of user data in the communication system. Under the existing switching method, although the satellite base station has changed, the satellite UPF is still on the previous satellite. This means that when user data is transmitted, it still needs to detour through the satellite UPF of the previous satellite, and then be transmitted to the satellite base station of the target satellite and the target user terminal. This increases the path length of data transmission, which not only increases the round-trip distance between the earth and the sky, but also introduces additional delays, reducing communication efficiency.

[0057] (3) Current onboard UPF switching will cause voice service disconnection: In the onboard UPF switching of the prior art, the method of re-establishing the session is adopted. In this method, the ground core network SMF (session management function) controls the onboard UPF to re-establish the session. In the process of re-establishing the session, the IP address will change with the new session. For voice communication services, the change of IP address will cause the interruption of communication connection. Because in the process of voice communication, the communicating parties transmit data based on a specific IP address. When the IP address changes, the communication connection cannot adapt to this change in time, resulting in user voice disconnection. This disconnection phenomenon seriously affects the continuity of satellite voice communication services. When users are making voice calls, sudden disconnection will cause great inconvenience to users, reducing the reliability of the communication system and user satisfaction.

[0058] In the prior art, the limited service time of low-orbit satellites leads to frequent satellite switching, and during switching, only Xn switching is performed between base stations without switching the onboard UPF. Moreover, the onboard UPF switching adopts the method of re-establishing the session, which causes the IP address to change and thus causes the user's voice to be disconnected.

[0059] In order to solve the above problems, the present invention proposes a brand-new solution. First, the ground core network SMF is innovated so that when the point-to-point voice service is established, the session information and IP addresses of both parties in the voice communication are recorded. When the point-to-point voice service undergoes satellite switching, the Xn switching process of the satellite base station is innovated. After the base station completes the switching, the satellite base station simultaneously initiates the satellite-borne UPF switching process. The satellite-borne UPF switching request is sent by the satellite base station to the ground core network AMF, and then forwarded to the SMF. After the SMF queries the successor satellite-borne UPF, it initiates a point-to-point voice service session creation request to it and carries the original session information and IP address. After the satellite-borne UPF to be replaced completes the session establishment, it initiates a point-to-point voice service session update request to the ground IMS core network. After receiving the reply, it notifies the original satellite-borne UPF to delete the original session information, thereby completing the satellite-borne UPF switching.

[0060] Through the method of the present invention, point-to-point voice services are realized without disconnection during satellite switching, which greatly improves the stability and reliability of satellite voice communications and provides users with better communication services. At the same time, it reduces the problems of communication interruption and poor user experience caused by frequent disconnection, which is of great significance for promoting the development of satellite communication technology.

[0061] The inter-satellite handover method for point-to-point voice communication in a low-orbit satellite 5G network described in a preferred embodiment of the present invention is as follows: Figure 2 As shown, the inter-satellite switching method for point-to-point voice communication in the low-orbit satellite 5G network includes the following steps:

[0062] Step S10: When the satellite terminal initiates a point-to-point voice service call, a point-to-point voice service session is established, and session information and IP addresses of both parties in the voice communication are recorded;

[0063] Step S20: When a satellite handover occurs in a point-to-point voice service session, the satellite base station sends a satellite UPF handover request to the ground core network AMF, and the ground core network AMF forwards it to the ground core network SMF;

[0064] Step S30: After the ground core network SMF queries the replaced satellite-borne UPF, it initiates a point-to-point voice service session creation request to the replaced satellite-borne UPF and carries the original session information and IP address;

[0065] Step S40: After the replacement satellite-borne UPF completes the session establishment, it initiates a point-to-point voice service session update request to the IMS core network. After receiving the reply, the replacement satellite-borne UPF notifies the original satellite-borne UPF to delete the original session information to complete the satellite-borne UPF switching.

[0066] The present invention is mainly divided into two major steps. The first is that when the satellite terminal initiates a point-to-point voice service call, through the Service Request process (the Service Request process refers to the process of requesting service initiated by the satellite terminal to the network when there is a business demand when the satellite terminal has established a connection with the network and is in an idle state, and is used to request the establishment or recovery of a bearer session for communication of a specific business), the SMF will guide the satellite-borne UPF to establish a point-to-point voice service session for the calling user, and at the same time, the SMF will also guide the satellite-borne UPF to establish a point-to-point voice service session for the called user. At this time, the SMF also needs to innovate and record the session information at both ends and the IP address assigned to the user terminal; the second is that when the point-to-point voice service is communicating, a satellite switch occurs. At this time, the Xn switch of the satellite base station is first performed. After the Xn switch of the satellite base station is completed, the satellite base station is innovated, and the satellite UPF switching process is continued to be initiated to the ground core network to complete the switch of the satellite UPF. Through these two steps, the optimized switching of the inter-satellite switching of the low-orbit satellite 5G network point-to-point voice communication is completed without disconnection.

[0067] Specifically, Figure 3 As shown in the figure, the specific process of the first major step includes:

[0068] Step S101: When the calling terminal is in an idle state, an RRC connection is established between the calling terminal and the satellite base station, and the satellite base station establishes an N2 connection with the terrestrial core network AMF to complete the signaling plane connection from the calling terminal to the terrestrial core network AMF.

[0069] Step S102: The calling terminal sends a Service Request message to the satellite base station, which is then sent to the ground core network AMF and the ground core network SMF via the satellite base station, requesting to establish a point-to-point voice service session.

[0070] Step S103: The ground core network SMF sends a point-to-point voice service session dedicated bearer establishment request to the satellite UPF based on the user's contract data, carrying session information (session information includes user identification information, IP address allocation information, QoS parameters, security context information and service flow information) and the IP address assigned to the terminal. After the satellite UPF completes the session establishment, it replies with a response message to the ground core network SMF.

[0071] Step S104: The ground core network AMF replies a Service Request response message to the satellite base station, notifying the calling terminal that the point-to-point voice service session has been established and is ready to start the call process.

[0072] Step S105: The calling terminal initiates a call process and sends a SIP INVITE request to the IMS core network via the terrestrial 5G core network through a dedicated session.

[0073] Step S106: The IMS core network processes the call request and sends the call request to the terrestrial core network SMF. The terrestrial core network SMF feeds back the connection status of the called terminal to the IMS core network. The IMS core network initiates a paging process to the terrestrial core network AMF. The terrestrial core network AMF initiates paging to the satellite base station, and the satellite base station pages the called terminal.

[0074] Step S107: The called terminal responds to the paging and establishes a session on the called side through the Service Request process. The ground core network SMF guides the satellite UPF to complete the establishment of the called session. The ground core network SMF records the session information and IP addresses of the calling terminal and the called terminal.

[0075] Step S108: After the session is established, the called terminal answers the call and sends a SIP response to the satellite UPF to establish a point-to-point voice service session.

[0076] The key innovation of the first major step is that SMF needs to record the session information and IP addresses of the caller and the called party. The purpose is to establish a completely replicated identical session at the relay satellite base station and the onboard UPF when switching between satellites, so that the terminal will not perceive the change in network routing, thereby ensuring the continuity of voice services.

[0077] Specifically, Figure 4 As shown in the figure, the specific process of the second major step includes:

[0078] Step S201: When the original satellite base station learns that base station switching is required, it initiates a base station switching request to a new satellite base station.

[0079] Step S202: After receiving the base station switching request from the original satellite base station, the new satellite base station processes the base station switching request and responds, indicating that it is ready to receive the switching operation.

[0080] Step S203: The original satellite base station initiates an RRC (Radio Resource Control) connection reconfiguration operation to the first satellite terminal and the second satellite terminal respectively, wherein the connection reconfiguration operation is used to reconfigure the wireless connection parameters of the terminals.

[0081] Step S204: The first satellite terminal (i.e. Figure 4 Satellite terminal 1 in the satellite terminal) and the second satellite terminal (i.e. Figure 4 The satellite terminal 2 in the figure sends an RRC connection application to the new satellite base station after successfully completing the RRC connection reconfiguration. Through this application, the first satellite terminal and the second satellite terminal respectively establish new connections with the new satellite base station to complete the switching from the original satellite base station to the new satellite base station.

[0082] Step S205: After the new satellite base station completes the connection switching with the satellite terminal, in order to ensure smooth data transmission, it initiates a satellite UPF switching request to the ground core network SMF through the N2 interface via the ground core network AMF. This step is to update the data transmission path in the network.

[0083] Step S206: After receiving the satellite UPF switching request, the ground core network SMF queries the relevant network configuration to obtain parameter information of the new satellite UPF, as well as the recorded point-to-point voice service session information and IP address.

[0084] Step S207: After obtaining the parameter information of the new satellite-borne UPF, the ground core network SMF sends a point-to-point voice service session establishment message to the new satellite-borne UPF. The point-to-point voice service session establishment message carries the original session information and IP address to ensure the continuity of the service during the switching process.

[0085] Step S208: After the new satellite-borne UPF receives the point-to-point voice service session establishment message, it performs internal configuration and processing according to the information in the point-to-point voice service session establishment message to complete the session establishment operation, and replies to the ground core network SMF that the session establishment is complete, indicating that the new satellite-borne UPF is ready for data transmission.

[0086] Step S209: After the new satellite-borne UPF completes the session establishment, the ground core network SMF initiates an IMS session update message to the IMS core network, notifying the IMS core network that the data transmission path in the network has changed and the session information needs to be updated.

[0087] Step S210: After receiving the IMS session update message from the ground core network SMF, the IMS core network performs corresponding update operations on its own session configuration, and after completion, replies to the ground core network SMF, indicating that the IMS core network has completed the session update.

[0088] Step S211: After ensuring that the IMS core network and the new satellite-based UPF are ready, the ground core network SMF initiates a deletion request to the original satellite-based UPF to delete the original session information in order to clean up network resources that are no longer in use.

[0089] Step S212: After receiving the deletion request, the original satellite-borne UPF deletes the original session information as required and replies to the ground core network SMF that the deletion operation has been completed.

[0090] Step S213: After receiving the deletion reply from the original satellite UPF, the ground core network SMF replies to the satellite UPF switching request response to the original satellite base station through the ground core network AMF, notifying the original satellite base station that the entire base station switching process has been completed and the network has switched to a new configuration state.

[0091] In the process of the second major step, the innovative part is that after the new satellite base station completes the base station switching, it is necessary to add a satellite-borne UPF switching process and complete the copy switching of the point-to-point voice service session at the same time to ensure that the parameters of the original session and the new session are consistent. The terminal is unaware of the changes in the network, so that the point-to-point voice service will not be disconnected.

[0092] Among them, the RRC connection is a signaling connection between the satellite terminal and the network, which is used to transmit control plane information. It is mainly responsible for managing the wireless resources between the terminal and the base station, including the establishment, reconfiguration and release of wireless bearers. Through the RRC connection, the terminal can obtain network configuration information, such as cell selection, switching and other related parameters, which is an important link in realizing communication between the terminal and the network. In the satellite communication scenario, when the satellite base station is switched, an RRC connection is established between the satellite terminal and the new satellite base station, so that normal communication can be achieved under the new satellite coverage.

[0093] In the process of satellite base station switching, in order to ensure the effective use of resources and avoid conflicts, when the new satellite base station and the onboard UPF session are established, it is necessary to notify the deletion of the original session. Because the original session is based on the old satellite base station and the old onboard UPF, the old session is no longer necessary. If the old session is not deleted, it may lead to a waste of network resources. And if two sessions exist at the same time, it may cause confusion in data transmission.

[0094] The innovative features of the present invention are as follows:

[0095] (1) The SMF network element of the satellite ground 5G core network has been innovated, and a new capability has been added to save point-to-point voice service session information. This allows the SMF to send the original session parameters to the new satellite base station and the new satellite UPF when the satellite-borne UPF is switched, guiding the new satellite base station and the new satellite UPF to establish the same session as the original one.

[0096] (2) The switching process of the satellite base station is innovated. After the existing satellite base station switching is completed, the onboard UPF switching will not be performed. The present invention adds a satellite-borne UPF switching process, which is initiated by the satellite base station after the base station switching is completed, and the satellite-borne UPF switching process is initiated to the ground core network AMF. The ground core network AMF then forwards it to the SMF, and the SMF executes the satellite-borne UPF switching.

[0097] (3) During the satellite UPF switching process, point-to-point voice service replication switching will be performed, that is, the original satellite UPF session on the secondary point-to-point voice service will be copied to the new satellite UPF. This operation is guided by the SMF to perform the two satellite UPFs.

[0098] (4) The SMF network element of the satellite ground 5G core network has been innovated, and a new process has been added to notify the original satellite base station and onboard UPF to delete the original point-to-point voice service session, reducing the waste of network resources and ensuring that only one session provides services to users at the same time.

[0099] Through the method of the present invention, point-to-point voice services are realized without disconnection during satellite switching, which greatly improves the stability and reliability of satellite voice communications and provides users with better communication services. At the same time, it reduces the problems of communication interruption and poor user experience caused by frequent disconnection, which is of great significance for promoting the development of satellite communication technology.

[0100] Furthermore, if Figure 3 and Figure 4 As shown, based on the above-mentioned inter-satellite switching method for point-to-point voice communication in a low-orbit satellite 5G network, the present invention also provides an inter-satellite switching system for point-to-point voice communication in a low-orbit satellite 5G network, wherein the inter-satellite switching system for point-to-point voice communication in a low-orbit satellite 5G network includes: a calling terminal, a called terminal, an original satellite base station, a new satellite base station, a first satellite terminal (i.e. Figure 4 Satellite terminal 1), the second satellite terminal (i.e. Figure 4 Satellite terminal 2), ground core network AMF, ground core network SMF, original satellite-borne UPF, new satellite-borne UPF and IMS core network.

[0101] When a point-to-point voice service call is initiated, a point-to-point voice service session is established between the calling terminal and the called terminal, and the session information and IP addresses of both parties in the voice communication are recorded; when a satellite handover occurs in the point-to-point voice service session, the original satellite base station initiates an RRC connection to the first satellite terminal and the second satellite terminal respectively, and the first satellite terminal and the second satellite terminal establish new connections with the new satellite base station respectively, and the original satellite base station sends a satellite UPF handover request to the ground core network AMF, and the ground core network AMF forwards it to the ground core network SMF; after the ground core network SMF queries the new satellite UPF that takes over, it initiates a point-to-point voice service session creation request to the new satellite UPF and carries the original session information and IP address; when the new satellite UPF completes the session establishment, it initiates a point-to-point voice service session update request to the IMS core network, and after receiving the reply, the new satellite UPF notifies the original satellite UPF to delete the original session information to complete the satellite UPF handover.

[0102] In summary, the present invention provides an inter-satellite switching method and system for point-to-point voice communication in a low-orbit satellite 5G network, the method comprising: when a satellite terminal initiates a point-to-point voice service call, a point-to-point voice service session is established, and the session information and IP addresses of both parties in the voice communication are recorded; when a satellite switching occurs in the point-to-point voice service session, the satellite base station sends a satellite UPF switching request to the ground core network AMF, and the ground core network AMF forwards it to the ground core network SMF; after the ground core network SMF queries the successor satellite UPF, it initiates a point-to-point voice service session creation request to the successor satellite UPF and carries the original session information and IP address; when the successor satellite UPF completes the session establishment, it initiates a point-to-point voice service session update request to the IMS core network, and after receiving the reply, the successor satellite UPF notifies the original satellite UPF to delete the original session information to complete the satellite UPF switching. The present invention realizes point-to-point voice services without disconnection during satellite switching, greatly improves the stability and reliability of satellite voice communications, provides users with better communication services, and reduces communication interruptions and poor user experience caused by frequent disconnections, which is of great significance for promoting the development of satellite communication technology.

[0103] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the existence of other identical elements in the process, method, article or terminal including the element.

[0104] Of course, those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing related hardware (such as a processor, a controller, etc.) through a computer program, and the program can be stored in a computer-readable storage medium that can be read by a computer, and the program can include the processes of the above-mentioned method embodiments when executed. The computer-readable storage medium can be a memory, a disk, an optical disk, etc.

[0105] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for inter-satellite handover of point-to-point voice communication in a low-orbit satellite 5G network, characterized in that: The inter-satellite handover method for point-to-point voice communication in the low-orbit satellite 5G network includes: When the satellite terminal initiates a point-to-point voice service call, a point-to-point voice service session is established, and the session information and IP addresses of both parties in the voice communication are recorded; When a satellite handover occurs in a point-to-point voice service session, the satellite base station sends the onboard UPF handover request to the ground core network AMF, and the ground core network AMF forwards it to the ground core network SMF; After the ground core network SMF queries the replaced satellite UPF, it initiates a point-to-point voice service session creation request to the replaced satellite UPF and carries the original session information and IP address; When the successor satellite-borne UPF completes the session establishment, it initiates a point-to-point voice service session update request to the IMS core network. After receiving the response, the successor satellite-borne UPF notifies the original satellite-borne UPF to delete the original session information to complete the satellite-borne UPF switching.

2. The inter-satellite handover method for low-orbit satellite 5G network point-to-point voice communication according to claim 1 is characterized in that: When the satellite terminal initiates a point-to-point voice service call, a point-to-point voice service session is established, and the session information and IP addresses of both parties in the voice communication are recorded, specifically including: When the calling terminal is in an idle state, an RRC connection is established between the calling terminal and the satellite base station, and the satellite base station establishes an N2 connection with the ground core network AMF to complete the signaling plane connection from the calling terminal to the ground core network AMF; The calling terminal sends a Service Request message to the satellite base station, which is then sent to the ground core network AMF and ground core network SMF via the satellite base station, requesting to establish a point-to-point voice service session; The ground core network SMF sends a point-to-point voice service session dedicated bearer establishment request to the satellite UPF based on the user's subscription data, carrying the session information and the IP address assigned to the terminal. After the satellite UPF completes the session establishment, it replies to the ground core network SMF with a response message. The ground core network AMF replies to the satellite base station with a Service Request response message, notifying the calling terminal that the point-to-point voice service session has been established and is ready to start the call process; The calling terminal initiates the call process and sends the SIP INVITE request to the IMS core network via the terrestrial 5G core network through a dedicated session; The IMS core network processes the call request and sends it to the ground core network SMF. The ground core network SMF feeds back the connection status of the called terminal to the IMS core network. The IMS core network initiates a paging process to the ground core network AMF. The ground core network AMF initiates paging to the satellite base station. The satellite base station pages the called terminal. The called terminal responds to the paging and establishes a session on the called side through the Service Request process. The ground core network SMF guides the satellite UPF to complete the establishment of the called session. The ground core network SMF records the session information and IP addresses of the calling terminal and the called terminal. When the session is established, the called terminal answers the call and sends a SIP response to the onboard UPF to establish a point-to-point voice service session.

3. The inter-satellite handover method for point-to-point voice communication in a low-orbit satellite 5G network according to claim 1 is characterized in that: When a satellite handover occurs in a point-to-point voice service session, the satellite base station sends a satellite-borne UPF handover request to the ground core network AMF, and the ground core network AMF forwards it to the ground core network SMF, specifically including: When the original satellite base station learns that a base station switch is required, it initiates a base station switch request to the new satellite base station; After receiving the base station switching request from the original satellite base station, the new satellite base station processes the base station switching request and responds, indicating that it is ready to receive the switching operation; The original satellite base station initiates an RRC connection reconfiguration operation to the first satellite terminal and the second satellite terminal respectively, wherein the connection reconfiguration operation is used to reconfigure wireless connection parameters of the terminals; After successfully completing the RRC connection reconfiguration, the first satellite terminal and the second satellite terminal send an RRC connection application to the new satellite base station, and the first satellite terminal and the second satellite terminal respectively establish new connections with the new satellite base station to complete the handover from the original satellite base station to the new satellite base station; After completing the connection switching with the satellite terminal, the new satellite base station initiates a satellite UPF switching request to the ground core network SMF through the N2 interface via the ground core network AMF.

4. The inter-satellite handover method for point-to-point voice communication in a low-orbit satellite 5G network according to claim 3 is characterized in that: After the ground core network SMF queries the replaced satellite-borne UPF, it initiates a point-to-point voice service session creation request to the replaced satellite-borne UPF and carries the original session information and IP address, specifically including: After receiving the onboard UPF switching request, the ground core network SMF queries the relevant network configuration to obtain the parameter information of the new onboard UPF, as well as the recorded point-to-point voice service session information and IP address; After obtaining the parameter information of the new satellite-borne UPF, the ground core network SMF sends a point-to-point voice service session establishment message to the new satellite-borne UPF. The point-to-point voice service session establishment message carries the original session information and IP address.

5. The inter-satellite handover method for point-to-point voice communication in a low-orbit satellite 5G network according to claim 4 is characterized in that: When the replaced satellite-borne UPF completes the session establishment, it initiates a point-to-point voice service session update request to the IMS core network. After receiving the reply, the replaced satellite-borne UPF notifies the original satellite-borne UPF to delete the original session information to complete the satellite-borne UPF switching, which specifically includes: After receiving the point-to-point voice service session establishment message, the new satellite-borne UPF performs internal configuration and processing according to the information in the point-to-point voice service session establishment message to complete the session establishment operation, and replies to the ground core network SMF that the session establishment is complete, indicating that the new satellite-borne UPF is ready for data transmission; After the ground core network SMF completes the session establishment with the new satellite UPF, it initiates an IMS session update message to the IMS core network, notifying the IMS core network that the data transmission path in the network has changed and the session information needs to be updated; After receiving the IMS session update message from the ground core network SMF, the IMS core network performs corresponding updates on its own session configuration, and then replies to the ground core network SMF to indicate that the IMS core network has completed the session update; After ensuring that the IMS core network and the new satellite-based UPF are ready, the ground core network SMF initiates a deletion request to the original satellite-based UPF to delete the original session information in order to clean up the network resources that are no longer in use; After receiving the deletion request, the original onboard UPF deletes the original session information as required and replies to the ground core network SMF that the deletion operation has been completed; After receiving the deletion reply from the original satellite UPF, the ground core network SMF replies to the original satellite base station through the ground core network AMF with the satellite UPF switching request response, notifying the original satellite base station that the entire base station switching process has been completed and the network has switched to a new configuration state.

6. The inter-satellite handover method for point-to-point voice communication in a low-orbit satellite 5G network according to claim 3 is characterized in that: The RRC connection is a signaling connection between the satellite terminal and the network, used to transmit control plane information.

7. The inter-satellite handover method for low-orbit satellite 5G network point-to-point voice communication according to claim 6 is characterized in that: The RRC connection is also used to manage radio resources between the terminal and the base station, including the establishment, reconfiguration and release operations of radio bearers.

8. The inter-satellite handover method for low-orbit satellite 5G network point-to-point voice communication according to claim 3 is characterized in that: The inter-satellite handover method for point-to-point voice communication in the low-orbit satellite 5G network also includes: In a satellite communication scenario, when a satellite base station is switched, an RRC connection is established between the satellite terminal and the new satellite base station to achieve normal communication under the new satellite coverage.

9. The inter-satellite handover method for low-orbit satellite 5G network point-to-point voice communication according to claim 1, characterized in that: The session information includes: user identification information, IP address allocation information, QoS parameters, security context information and service flow information.

10. An inter-satellite switching system for point-to-point voice communication in a low-orbit satellite 5G network, characterized in that: The inter-satellite switching system for point-to-point voice communication in the low-orbit satellite 5G network includes: a calling terminal, a called terminal, an original satellite base station, a new satellite base station, a first satellite terminal, a second satellite terminal, a ground core network AMF, a ground core network SMF, an original satellite-borne UPF, a new satellite-borne UPF and an IMS core network; When a point-to-point voice service call is initiated, a point-to-point voice service session is established between the calling terminal and the called terminal, and the session information and IP addresses of both parties in the voice communication are recorded; When a satellite handover occurs in a point-to-point voice service session, the original satellite base station initiates an RRC connection to the first satellite terminal and the second satellite terminal respectively, and the first satellite terminal and the second satellite terminal establish new connections with the new satellite base station respectively. The original satellite base station sends the satellite UPF handover request to the ground core network AMF, and the ground core network AMF forwards it to the ground core network SMF; After the ground core network SMF queries the new satellite-borne UPF that takes over, it initiates a point-to-point voice service session creation request to the new satellite-borne UPF and carries the original session information and IP address; When the new satellite UPF completes the session establishment, it initiates a point-to-point voice service session update request to the IMS core network. After receiving the response, the new satellite UPF notifies the original satellite UPF to delete the original session information to complete the satellite UPF switching.

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