Method and system for storing and forwarding user plane data

Abstract

This disclosure provides a user plane data storage and forwarding method and system, belonging to the field of wireless communication technology. The method includes: during the session establishment process, the PCF receives a session policy request corresponding to the terminal, and returns a session policy response including a data storage and forwarding policy to the SMF based on the IoT latency tolerance service subscribed to by the terminal; the SMF selects an anchor UPF and a relay UPF according to the data storage and forwarding policy, and establishes a session corresponding to the terminal based on the data storage and forwarding policy; if the connection between the satellite and the ground gateway station is lost, the session resources corresponding to the terminal are maintained, and if the target user plane data arrives at the first UPF, the first UPF stores the target user plane data; if the connection between the satellite and the ground gateway station is restored, the session connection corresponding to the terminal is restored, and the first UPF forwards the target user plane data to the second UPF. Based on the technical solution provided by the embodiments of this disclosure, the problem of important data loss caused by the disconnection of the satellite and ground gateway station connection can be solved.

Description

Technical Field

[0001] This disclosure belongs to the field of wireless communication technology, specifically relating to a method and system for storing and forwarding user plane data. Background Technology

[0002] With the development of wireless communication technology, in order to improve the application scenarios of communication, ground terminals can now use satellites as base stations to establish connections, and satellites can establish connections with ground gateways to access the core network.

[0003] The current 3GPP (3rd Generation Partnership Project) standard only considers using satellites as 5G NR (New Radio) access or as backhaul links. That is, satellites can transmit data uploaded by terminals back to the ground server in real time, and can also transmit data from the server back to the ground terminal in real time.

[0004] However, in reality, due to various reasons, the connection between satellites and ground gateways may be interrupted, causing mobile network services to be interrupted along with the connection, and data transmission may not continue. For services with high latency tolerance, this may result in the loss of important data. Summary of the Invention

[0005] The purpose of this disclosure is to provide a method and system for storing and forwarding user plane data, which can solve the problem of important data loss caused by the disconnection of the connection between the satellite and the ground gateway station.

[0006] To solve the above-mentioned technical problems, this disclosure is implemented as follows:

[0007] In a first aspect, embodiments of this disclosure provide a method for storing and forwarding user plane data, applied in an air-space-ground scenario. The method includes: during the session establishment process, the PCF (Policy Control Function) receives a session policy request corresponding to the terminal sent by the SMF (Session Management Function), and returns a session policy response including a data storage and forwarding policy to the SMF based on the IoT latency tolerance service subscribed to by the terminal; the SMF selects an anchor point UPF (User Plane Function) based on the data storage and forwarding policy. The system handles user plane functions and relay UPFs, and establishes a session corresponding to the terminal based on session policy responses. The anchor UPF is a ground UPF, and the relay UPF is a satellite UPF. If the connection between the satellite and the ground gateway is lost, the session resources corresponding to the terminal are maintained. When the target user plane data arrives at the first UPF, the first UPF stores the target user plane data, which is the user plane data corresponding to the terminal. If the connection between the satellite and the ground gateway is restored, the session connection corresponding to the terminal is restored, and the first UPF forwards the stored target user plane data to the second UPF. Here, the first UPF is the anchor UPF, and the second UPF is the relay UPF.

[0008] Optionally, the data storage and forwarding strategy includes at least one of the following: land-to-non-land identifier, access aircraft parameters, uplink / downlink identifier, duration threshold, and data storage volume threshold.

[0009] Optionally, the SMF selects the anchor UPF according to the data storage forwarding strategy, including: the SMF selects the UPF from the ground UPFs as the anchor UPF based on the uplink and downlink identifiers in the data storage forwarding strategy, and whether the UPF needs to support the store-and-forward function; wherein, if the uplink and downlink identifiers indicate uplink and downlink, or downlink, then the anchor UPF supports the store-and-forward function; if the uplink and downlink identifiers indicate uplink, then the anchor UPF does not need to support the store-and-forward function.

[0010] Optionally, the SMF selects a relay UPF based on the data storage and forwarding strategy, including: the SMF selects a UPF in the satellite where the terminal's access base station is located that supports store-and-forward functionality as the relay UPF based on the uplink and downlink identifiers and access aircraft parameters in the data storage and forwarding strategy; wherein, if the uplink and downlink identifiers indicate uplink and downlink, or uplink, then the relay UPF supports store-and-forward functionality; if the uplink and downlink identifiers indicate downlink, then the satellite UPF is not selected, and the terminal's access base station is the base station in the satellite.

[0011] Optionally, establishing a session corresponding to the terminal based on the session policy response includes: the SMF sending an N4 session establishment request to the relay UPF and the anchor UPF respectively based on the session policy response; the N4 session establishment request includes at least one of the following: PDU session identifier, N9 core network tunnel information, store-and-forward indication information, uplink / downlink identifier, duration threshold, and stored data volume threshold; the SMF receiving the N4 session establishment response sent by the relay UPF and the anchor UPF; the SMF returning session information to the AMF (access and mobility management function), the session information including: PDU session identifier, N3 core network tunnel information, store-and-forward indication information, and stored data duration threshold; the AMF sending a PDU session request to the access base station so that the base station can determine whether to establish a PDU session corresponding to the terminal, the PDU session request including session information, and the access base station being a base station in the satellite.

[0012] Optionally, if the connection between the satellite and the ground gateway station is lost, the session resources corresponding to the terminal are maintained, including: if the connection between the satellite and the ground gateway station is lost, the target network element starts a timer according to a duration threshold, and if the connection loss duration does not exceed the duration threshold, the session, resources and context corresponding to the target network element and the terminal are maintained; wherein, the target network element includes at least one of the following: access base station, AMF, SMF, PCF, anchor UPF and relay UPF.

[0013] Optionally, after the first UPF stores the target user plane data, the method further includes: if the connection disconnection duration does not exceed the duration threshold, and the user plane data corresponding to the terminal stored in the first UPF exceeds the storage data volume threshold, then the first UPF discards the subsequently received user plane data packets corresponding to the terminal.

[0014] Optionally, if the connection between the satellite and the ground gateway station is restored, the session connection corresponding to the terminal is restored, and the first UPF forwards the stored target user plane data to the second UPF, including: if the connection disconnection duration does not exceed the duration threshold and the connection between the satellite and the ground gateway station is restored, the target network element restores the connection of the session corresponding to the terminal based on the maintained resources, and the first UPF uses the maintained N9 core network tunnel information to forward the stored target user plane data to the second UPF.

[0015] Optionally, after the first UPF stores the target user plane data, the method further includes: if the connection disconnection duration exceeds a duration threshold, the first UPF deletes the stored user plane data corresponding to the terminal, and the target network element releases the session, resources, and context corresponding to the terminal.

[0016] Optionally, when target user plane data arrives at the first UPF, the first UPF stores the target user plane data, including: when an uplink data packet from the N3 tunnel arrives at the anchor UPF, the anchor UPF stores the uplink data packet from the N3 tunnel, and the uplink data packet from the N3 tunnel is the target user plane data; or, when a downlink data packet from the N6 tunnel arrives at the relay UPF, the relay UPF stores the downlink data packet from the N6 tunnel, and the downlink data packet from the N6 tunnel is the target user plane data.

[0017] Optionally, the first UPF forwards target user plane data to the second UPF, including: the anchor UPF forwarding the stored N3 tunnel uplink data packets to the relay UPF; or, the relay UPF forwarding the stored N6 tunnel downlink data packets to the anchor UPF.

[0018] Secondly, embodiments of this disclosure provide a user plane data storage and forwarding system, which includes: a PCF, an SMF, a UPF, and a terrestrial UPF; the PCF is used to receive a session policy request corresponding to the terminal sent by the SMF during the session establishment process, and return a session policy response including a data storage and forwarding policy to the SMF according to the IoT latency tolerance service subscribed to by the terminal; the SMF is used to select an anchor UPF and a relay UPF according to the data storage and forwarding policy, and establish a session corresponding to the terminal based on the session policy response; the anchor UPF is a terrestrial UPF, and the relay UPF is a satellite UPF; each network element in the storage and forwarding system uses... If the connection between the satellite and the ground gateway station is lost, the session resources corresponding to the terminal are maintained; the first UPF is used to store the target user plane data when the target user plane data arrives at the first UPF, and the target user plane data is the user plane data corresponding to the terminal; wherein, the first UPF is an anchor UPF and the second UPF is a relay UPF; the network elements in the storage and forwarding system are also used to restore the session connection corresponding to the terminal if the connection between the satellite and the ground gateway station is restored; the first UPF is also used to forward the target user plane data to the second UPF after the session connection corresponding to the terminal is restored.

[0019] Thirdly, this disclosure provides a UPF, which includes a data storage module and a data forwarding module. The data storage module is used to store target user plane data, which is the user plane data corresponding to the terminal, when the connection between the satellite and the ground gateway station is lost and the target user plane data arrives at the UPF. The data forwarding module is used to forward the target user plane data in the data storage module when the connection between the satellite and the ground gateway station is restored.

[0020] Fourthly, embodiments of this disclosure provide a UPF, which includes a processor, a memory, and a program or instructions stored in the memory and executable on the processor, wherein when the program or instructions are executed by the processor, they implement the steps of the user plane data storage and forwarding method as described in the first aspect.

[0021] In this embodiment of the disclosure, in a space-air-ground scenario, during the session establishment process, after the PCF receives the session policy request corresponding to the terminal sent by the SMF, the PCF can determine the data storage and forwarding policy based on the IoT latency tolerance service subscribed to by the terminal, and return this data storage and forwarding policy to the SMF in the session policy response. When the SMF selects a UPF based on the session policy response, it can select a ground UPF as the anchor UPF and a satellite UPF as the relay UPF based on the data storage and forwarding policy. Then, it can establish the session corresponding to the terminal based on the session policy response. Therefore, after the session is successfully established, if each network element corresponding to the terminal senses that the connection between the satellite and the ground gateway station is disconnected, each network element can continue to maintain the session resources corresponding to the terminal. When the user plane data of the terminal arrives at the first UPF, the first UPF can temporarily store the user plane data of the terminal. If each network element senses that the connection between the satellite and the ground gateway station is restored, it can restore the session connection corresponding to the terminal based on the previously maintained session resources. Then, the first UPF can forward the user plane data of the terminal stored when the connection was disconnected to the second UPF. For example, data uploaded by the terminal can be temporarily cached by the satellite UPF, and then forwarded to the ground after the connection is restored. Alternatively, data transmitted to the terminal can be temporarily cached by the ground UPF, and then uploaded to the satellite and forwarded to the terminal after the connection is restored. In other words, the interruption of mobile network services can be avoided when the connection between the satellite and the ground gateway is interrupted, the transmission of user plane data can be maintained, and the loss of important data can be avoided. Thus, it can provide a highly continuous transmission service for IoT services with massive amounts of data. Attached Figure Description

[0022] Figure 1 This disclosure provides a network schematic diagram of user plane data storage and forwarding in an air-space-ground scenario.

[0023] Figure 2 A schematic diagram of a user plane data storage and forwarding system provided in an embodiment of this disclosure;

[0024] Figure 3 This is one of the flowcharts illustrating the method for storing and forwarding user plane data provided in this embodiment of the disclosure;

[0025] Figure 4 A second schematic flowchart illustrating the method for storing and forwarding user plane data provided in this embodiment of the disclosure;

[0026] Figure 5 The third schematic flowchart of the user plane data storage and forwarding method provided in the embodiments of this disclosure;

[0027] Figure 6 This disclosure provides a message flow diagram for establishing a user plane data storage and forwarding session in an air-space-ground scenario.

[0028] Figure 7 This is one of the possible structural diagrams of a UPF provided in the embodiments of this disclosure;

[0029] Figure 8 This is a second possible structural schematic diagram of a UPF provided in an embodiment of this disclosure;

[0030] Figure 9 This is a hardware schematic diagram of a network element provided in an embodiment of this disclosure. Detailed Implementation

[0031] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0032] The terms "first," "second," etc., used in this disclosure and in the claims are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this disclosure can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0033] It is worth noting that the technologies described in this disclosure are not limited to LTE (Long Term Evolution) / LTE-A (LTE-Advanced) systems, but can also be used in other wireless communication systems, such as CDMA (Code Division Multiple Access), TDMA (Time Division Multiple Access), FDMA (Frequency Division Multiple Access), OFDMA (Orthogonal Frequency Division Multiple Access), SC-FDMA (Single-carrier Frequency-Division Multiple Access), and other systems. The terms "system" and "network" in this application are often used interchangeably, and the described technologies can be used with the systems and radio technologies mentioned above, as well as with other systems and radio technologies. However, the following description describes NR systems for illustrative purposes, and NR terminology is used in most of the following description, although these technologies can also be applied to applications other than NR systems, such as 6G (6th Generation) communication systems.

[0034] The method for storing and forwarding user plane data provided in this disclosure will be described in detail below with reference to the accompanying drawings, through specific embodiments and application scenarios.

[0035] Figure 1 This is a network diagram illustrating user plane data storage and forwarding in a space-air-ground scenario, as provided in an embodiment of this disclosure. Figure 1 As shown in the network diagram, the ground UE 100 accesses the base station 102 in satellite 101. Satellite 101 includes a UPF 103. Satellite 101 establishes a connection with ground gateway station 104. The base station 102 of satellite 101 is connected to ground AMF 105 through ground gateway station 104. Ground AMF 105 is connected to ground PCF 107. Satellite UPF 103 is connected to ground SMF 106 through ground gateway station 104. Ground SMF 106 is connected to ground UPF 108. Ground UPF 108 is connected to enterprise server 109 through N6 interface. Ground UPF is connected to satellite UPF 103 through ground gateway station 104 via N9 channel.

[0036] In this embodiment of the disclosure, the UPF supports data storage and forwarding functions for uplink and downlink traffic, supports receiving storage and forwarding instructions indicated by the SMF, supports starting internal data storage and starting a storage and forwarding timer after the user plane tunnel link is disconnected, while maintaining the N4 session state, supports forwarding the stored data in order after the link is restored, and supports releasing related resources after the timer expires.

[0037] SMF supports receiving data storage forwarding policies issued by PCF, selecting UPFs that support data storage forwarding functions and issuing corresponding instructions, sending data storage forwarding parameters to AMF, maintaining user information and session information and starting a store-and-forward timer after disconnecting from the UPF, and releasing related resources after the timer expires.

[0038] PCF supports the distribution of data storage and forwarding policies to corresponding terminals, and its backend storage supports adding, deleting, modifying, and querying data storage and forwarding policies.

[0039] AMF supports receiving data storage and forwarding parameters and instructions issued by SMF and forwarding them to the base station. It supports maintaining user information and base station link-related information and starting a store-and-forward timer after the connection with the base station is lost. It also supports releasing related resources after the timer expires.

[0040] The base station supports receiving data storage and forwarding parameters sent by the SMF through the AMF, and supports maintaining user information and AMF link-related information and starting a store-and-forward timer after the link with the AMF is disconnected. It also supports releasing related resources after the timer expires.

[0041] Figure 2This illustration shows a user plane data storage and forwarding system 200 provided in an embodiment of the present disclosure. The storage and forwarding system 200 includes: PCF 201, SMF 202, satellite UPF 203, and ground UPF 204. PCF 201 is used to receive a session policy request corresponding to a terminal sent by SMF 202 during the session establishment process, and to return a session policy response including a data storage and forwarding policy to SMF 202 based on the IoT latency tolerance service subscribed to by the terminal. 202 is used to select the anchor UPF and relay UPF according to the data storage and forwarding strategy, and to establish a session corresponding to the terminal based on the session policy response; the anchor UPF is a ground UPF, and the relay UPF is a satellite UPF; each network element in the storage and forwarding system is used to maintain the session resources corresponding to the terminal if the connection between the satellite and the ground gateway station is lost; the first UPF is used to store the target user plane data when the target user plane data arrives at the first UPF, and the target user plane data is the user plane data corresponding to the terminal; wherein, the first UPF is an anchor UPF, and the second UPF is a relay UPF; the first UPF is a relay UPF, and the second UPF is an anchor UPF; each network element in the storage and forwarding system is also used to restore the session connection corresponding to the terminal if the connection between the satellite and the ground gateway station is restored; the first UPF is also used to forward the target user plane data to the second UPF after the session connection corresponding to the terminal is restored.

[0042] This disclosure provides a user plane data storage and forwarding system. In a space-air-ground scenario, during the session establishment process, after the PCF receives a session policy request from the SMF corresponding to the terminal, the PCF can determine a data storage and forwarding policy based on the IoT latency tolerance service subscribed to by the terminal. This data storage and forwarding policy is then included in the session policy response and returned to the SMF. When the SMF selects a UPF based on the session policy response, it can select a terrestrial UPF as the anchor UPF and a satellite UPF as the relay UPF based on the data storage and forwarding policy. Then, a session corresponding to the terminal can be established based on the session policy response. Therefore, after successful session establishment, if the network elements corresponding to the terminal detect a disconnection between the satellite and the ground gateway station, each network element can continue to maintain the session resources corresponding to the terminal. When the terminal's user plane data arrives at the first UPF, the first UPF can temporarily store the terminal's user plane data. If the network elements detect a restoration of the connection between the satellite and the ground gateway station, they can restore the session connection corresponding to the terminal based on the previously maintained session resources. Then, the first UPF can forward the terminal's user plane data stored when the connection was broken to the second UPF. For example, data uploaded by the terminal can be temporarily cached by the satellite UPF, and then forwarded to the ground after the connection is restored. Alternatively, data transmitted to the terminal can be temporarily cached by the ground UPF, and then uploaded to the satellite and forwarded to the terminal after the connection is restored. In other words, the interruption of mobile network services can be avoided when the connection between the satellite and the ground gateway is interrupted, the transmission of user plane data can be maintained, and the loss of important data can be avoided. Thus, it can provide a highly continuous transmission service for IoT services with massive amounts of data.

[0043] Figure 3 This is a flowchart illustrating a method for storing and forwarding user plane data according to an embodiment of this disclosure, as shown below. Figure 3 As shown, the method includes the following steps S301 to S304:

[0044] S301. During the session establishment process, the PCF receives the session policy request corresponding to the terminal sent by the SMF, and returns a session policy response including data storage and forwarding policy to the SMF according to the IoT latency tolerance service subscribed to by the terminal.

[0045] It should be noted that during the process of a terminal accessing a mobile network via satellite, the terminal first initiates a registration process. After successful registration, it initiates a session establishment process. The configuration process for the data storage and forwarding strategy in this embodiment is located within the session establishment process.

[0046] S302, SMF selects the anchor UPF and relay UPF according to the data storage and forwarding policy, and establishes the corresponding session for the terminal based on the session policy.

[0047] Among them, the anchor point UPF is the ground UPF, and the relay UPF is the satellite UPF.

[0048] It is understandable that in related technologies, the session policy response sent by the PCF to the SMF carries PDU session-related policy information.

[0049] In this embodiment of the disclosure, the PCF can feed back the data storage and forwarding policy and the PDU session-related policy to the SMF through the session policy response. After receiving the session policy response, the SMF can select the user plane function network element and establish a PDU session corresponding to the terminal with the base station in the satellite through the AMF. Then, the UE and the enterprise server transmit user plane data through the user plane function network element selected by the SMF.

[0050] Specifically, after the session is established, the UE can send uplink user plane data to the ground UPF through the base station in the satellite and the satellite UPF. The ground UPF then forwards the UE's uplink user plane data to the enterprise server. The enterprise server can transmit the UE's downlink user plane data to the satellite UPF through the ground UPF, and the satellite UPF then forwards it to the UE through the base station.

[0051] S303. If the connection between the satellite and the ground gateway is lost, the session resources corresponding to the terminal are maintained. When the target user plane data arrives at the first UPF, the first UPF stores the target user plane data.

[0052] Among them, the target user plane data is the user plane data corresponding to the terminal.

[0053] Specifically, when any network element detects a disconnection between the satellite and the ground gateway station (i.e., transmission between the satellite and the ground gateway station cannot proceed normally), the transmission connection established between the first and second UPFs via the N9 interface is broken. Each network element can continue to maintain the session resources corresponding to the terminal based on its data storage and forwarding strategy. If the connection between the satellite and the ground gateway station is broken, but the terminal continues to transmit data to the satellite, the satellite UPF can temporarily store the data in its storage module. Similarly, if the enterprise server continues to transmit data to the satellite, the ground UPF can temporarily store the data in its storage module.

[0054] S304. If the connection between the satellite and the ground gateway is restored, the session connection corresponding to the terminal is restored, and the first UPF forwards the stored target user plane data to the second UPF.

[0055] Optionally, if the first UPF is an anchor UPF, the second UPF is a relay UPF; if the first UPF is a relay UPF, the second UPF is an anchor UPF.

[0056] In other words, a ground-based UPF can temporarily store data transmitted from the ground to the satellite. After the connection is restored, the ground-based UPF can forward the stored data to the satellite. Similarly, a satellite-based UPF can also temporarily store data transmitted from the ground to the satellite. After the connection is restored, the satellite-based UPF can also forward the stored data to the ground.

[0057] For example, in the case of a large number of IoT terminals with high latency tolerance accessing mobile networks through base stations in satellites, the satellite can continue to provide services to these terminals even when the connection between the satellite and the ground gateway is lost. For instance, a large number of detection sensors can continue to upload monitoring data, and the satellite can provide temporary data storage services. When the connection between the satellite and the ground is restored, the satellite can forward the temporarily stored data to the ground.

[0058] This disclosure provides a method for storing and forwarding user plane data. In a space-air-ground scenario, during the session establishment process, after the PCF receives the session policy request for the terminal from the SMF, the PCF can determine the data storage and forwarding policy based on the IoT latency tolerance service subscribed to by the terminal, and return this data storage and forwarding policy to the SMF in the session policy response. When the SMF selects a UPF based on the session policy response, it can select a terrestrial UPF as the anchor UPF and a satellite UPF as the relay UPF based on the data storage and forwarding policy. Then, the session corresponding to the terminal can be established based on the session policy response. Therefore, after the session is successfully established, if the network elements corresponding to the terminal detect that the connection between the satellite and the ground gateway station is disconnected, the network elements can continue to maintain the session resources corresponding to the terminal. When the user plane data of the terminal arrives at the first UPF, the first UPF can temporarily store the user plane data of the terminal. If the network elements detect that the connection between the satellite and the ground gateway station is restored, they can restore the session connection corresponding to the terminal based on the previously maintained session resources. Then, the first UPF can forward the user plane data of the terminal stored when the connection was disconnected to the second UPF. For example, data uploaded by the terminal can be temporarily cached by the satellite UPF, and then forwarded to the ground after the connection is restored. Alternatively, data transmitted to the terminal can be temporarily cached by the ground UPF, and then uploaded to the satellite and forwarded to the terminal after the connection is restored. In other words, the interruption of mobile network services can be avoided when the connection between the satellite and the ground gateway is interrupted, the transmission of user plane data can be maintained, and the loss of important data can be avoided. Thus, it can provide a highly continuous transmission service for IoT services with massive amounts of data.

[0059] Optionally, in the user plane data storage and forwarding method provided in this disclosure embodiment, the above-mentioned data storage and forwarding strategy includes at least one of the following:

[0060] Land-to-Non-Terrestrial Networks (NTN) identifiers, access aircraft parameters, uplink / downlink identifiers, duration thresholds, and data storage thresholds.

[0061] For example, if a terminal accesses a base station via satellite, the land / non-land identifier can indicate "non-land". The access spacecraft parameters can be any of the following: LEO (Low Earth orbit), MEO (Medium Earth Orbit), or GEO (Geosynchronous orbit). Uplink / downlink identifiers can indicate whether the store-and-forward strategy is applied during uplink, downlink, or both uplink and downlink user plane data transmission. Duration thresholds can indicate the effective duration of the data storage and forwarding strategy or the maximum duration of data cached in the UPF. Stored data volume thresholds can indicate the maximum amount of data cached in the UPF.

[0062] In this embodiment of the disclosure, the uplink indicates the process of the terminal transmitting data to the enterprise server via satellite, and the downlink indicates the process of the enterprise server transmitting data to the terminal via satellite.

[0063] Specifically, the session policy response can carry one or more data storage forwarding policies.

[0064] Optionally, in the user plane data storage and forwarding method provided in this embodiment, the step of SMF selecting UPF in S302 above may specifically include the following S11 and S12:

[0065] S11. Based on the uplink and downlink identifiers in the data storage and forwarding strategy, SMF selects the UPF from the ground UPFs that may or may not support the store-and-forward function as the anchor UPF.

[0066] If the uplink / downlink identifier indicates uplink and downlink, or downlink, then the anchor UPF supports store-and-forward functionality; if the uplink / downlink identifier indicates uplink, then the anchor UPF does not need to support store-and-forward functionality.

[0067] It is understandable that if multiple ground UPFs are selected based on the above selection method, the one with the best performance can be selected as the anchor UPF based on the performance of the UPF.

[0068] S12, SMF selects the UPF that supports store-and-forward function in the satellite where the terminal's access base station is located as the relay UPF based on the uplink and downlink identifiers and access aircraft parameters in the data storage and forwarding strategy.

[0069] If the uplink / downlink identifier indicates both uplink and downlink, or uplink, then the relay UPF supports store-and-forward functionality; if the uplink / downlink identifier indicates downlink, then the satellite UPF is not selected, and the terminal's access base station is the base station in the satellite.

[0070] Similarly, if a satellite includes multiple UPFs, the UPF with the best performance can be selected as the relay UPF.

[0071] Based on this scheme, when selecting user plane function network elements, SMF can select UPF based on the indication information in the data storage and forwarding strategy selected by PCF. Specifically, it can select one UPF from the ground UPFs as the anchor UPF based on the uplink and downlink identifiers. It can also determine whether a satellite UPF needs to be selected based on the uplink and downlink identifiers and the parameters of the access aircraft. If a selection is required, it can choose which satellite UPF to use as the relay UPF.

[0072] Optionally, in the user plane data storage and forwarding method provided in this embodiment, the session establishment step in S302 above may specifically include the following S21 to S24:

[0073] S21. Based on the session policy response, SMF sends N4 session establishment requests to both the relay UPF and the anchor UPF.

[0074] The N4 session establishment request includes at least one of the following: PDU session identifier, N9 core network tunnel information, store-and-forward indication information, uplink / downlink identifier, duration threshold, and storage data volume threshold.

[0075] It should be noted that when the SMF sends an N4 session establishment request to the relay UPF, it can also include information about the anchor UPF, indicating the anchor UPF to the relay UPF; when the SMF sends an N4 session establishment request to the anchor UPF, it can also include information about the relay UPF, indicating the relay UPF to the anchor UPF.

[0076] S22, SMF receives N4 session establishment responses sent by relay UPF and anchor UPF.

[0077] S23, SMF returns session information to AMF.

[0078] The session information includes at least one of the following: PDU session identifier, N3 core network tunnel information, store-and-forward indication information, and data storage duration threshold.

[0079] S24. AMF sends a PDU session request to the access base station so that the base station can determine whether to establish a PDU session corresponding to the terminal.

[0080] The PDU session request includes session information.

[0081] Specifically, after determining that a PDU session can be established, the base station will return N3 access network tunnel information to the AMF, the AMF will forward the N3 access network tunnel information to the SMF, and the SMF will forward the N3 access tunnel information to the relay UPF.

[0082] Based on this scheme, during the session establishment process, after receiving the session policy response, the SMF can instruct each UPF on the data storage and forwarding policy during the N4 session establishment process with each UPF, so that each UPF can obtain the data storage and forwarding policy selected by the PCF. Then, during the PDU session establishment process between the SMF and the base station, the SMF instructs the base station on the data storage and forwarding policy, so that each network element involved in the session corresponding to the terminal can obtain the data storage and forwarding policy selected by the PCF, so that each network element can perform corresponding processing when it detects the disconnection of the satellite and ground gateway station.

[0083] Optionally, in the user plane data storage and forwarding method provided in this embodiment, the above-mentioned S303 can be specifically executed through the following S31:

[0084] S31. If the connection between the satellite and the ground gateway station is lost, the target network element starts a timer according to the duration threshold, and maintains the session, resources and context corresponding to the target network element and the terminal as long as the connection loss duration does not exceed the duration threshold.

[0085] The target network element includes at least one of the following: access base station, AMF, SMF, PCF, anchor point UPF, and relay UPF.

[0086] For example, the access base station can maintain user information and SMF connection-related information, the AMF can maintain user information and base station connection-related information, the SMF can maintain user information and session information, the PCF can maintain user information and SMF connection-related information, and the UPF can maintain the N4 session state.

[0087] It is understandable that in the scenario of discontinuous feeder between air and space, satellite UPF or ground UPF needs to store messages until a usable feeder link is available before forwarding data. While maintaining the session, resources and terminal context corresponding to the target network element and the terminal, the validity of the data can be identified and the terminal context can be maintained after the connection is restored, so that the data forwarded before and after the connection is broken remains continuous.

[0088] Based on this scheme, when the network elements involved in the terminal's session detect that the connection between the satellite and the ground gateway station has been lost, they can each start a timer corresponding to the data storage and forwarding strategy. If the timer expires, each network element will maintain the session, resources and context corresponding to the terminal, which will facilitate the restoration of the previously used session and resources when the connection between the satellite and the ground gateway station is subsequently detected to be restored, and will also ensure the continuity of the context.

[0089] Optionally, combined Figure 3 ,like Figure 4 As shown, in the user plane data storage and forwarding method provided in this embodiment, after S303 described above, the following S305 may also be included:

[0090] S305. If the connection disconnection duration does not exceed the duration threshold, and the user plane data corresponding to the terminal stored in the first UPF exceeds the storage data volume threshold, then the first UPF discards the user plane data packets corresponding to the terminal received subsequently.

[0091] For example, after the connection between the satellite and the ground gateway station is detected to be lost, the terminal or enterprise server can perform corresponding emergency operations within a certain period of time, such as backing up data. Therefore, the first UPF can store only a certain amount of data, which can avoid the loss of data before the terminal or enterprise server performs emergency operations after the connection is lost.

[0092] Based on this scheme, if the duration after the connection between the satellite and the ground gateway station is lost does not exceed the duration threshold, and the amount of data stored in the first UPF exceeds the threshold, the first UPF will no longer store subsequent received user plane data packets, thus avoiding the waste of storage resources.

[0093] Optionally, in the user plane data storage and forwarding method provided in this disclosure embodiment, after the satellite is disconnected from the ground gateway station, while the various network elements related to the terminal in the network maintain sessions, resources, and context, the above-mentioned S304 can be executed by the following S41:

[0094] S41. If the connection disconnection duration does not exceed the duration threshold and the connection between the satellite and the ground gateway station is restored, the target network element restores the connection of the session corresponding to the terminal based on the maintained resources, and the first UPF uses the maintained N9 core network tunnel information to forward the stored target user plane data to the second UPF.

[0095] In other words, within the effective time of the data storage and forwarding strategy, if each network element senses that the connection between the satellite and the ground gateway station has been restored, each relevant network element can restore its corresponding connection based on the configuration information in the previous registration process and session establishment process. That is, each network element can continue to transmit the user plane data corresponding to the terminal using the previously configured port, resources, and other information. At this time, the first UPF can forward the user plane data of the terminal stored in the storage module of the first UPF to the second UPF through the N9 port based on the previously maintained tunnel information. This can avoid the loss of important data due to the temporary disconnection of the connection between the satellite and the ground gateway station for some reason in the space-air-ground scenario.

[0096] Specifically, within the time threshold, the satellite and the ground gateway station reconnect, and the control plane signaling between the base station and network elements uses the previous identifiers for connection (such as control plane IP address, port, etc.). The satellite UPF sends the data packets of the PDU session to the data forwarding module, and the data forwarding module sends the original tunnel information to the ground UPF. Similarly, the ground UPF forwards the stored uplink data to the satellite UPF.

[0097] It should be noted that in practical applications, the first UPF can transmit the stored data packets sequentially according to the storage order. At the same time, it can continue to cache the received data packets in the storage module of the first UPF until the transmission speed is dynamically balanced. The forwarding module of the first UPF no longer caches the newly received data packets in the storage module and can directly forward the received data packets.

[0098] Based on this scheme, if the connection disconnection duration does not exceed the effective duration of the data storage and forwarding strategy, after the connection between the satellite and the ground gateway station is restored, each network element restores the connection corresponding to the session based on the maintained resources. After the connection is restored, the first UPF can continue to forward the stored user plane data to the second UPF, thereby ensuring that the user plane data corresponding to the terminal remains continuous and is not lost.

[0099] Optionally, combined Figure 3 ,like Figure 5 As shown, in the user plane data storage and forwarding method provided in this embodiment, after the above-described S303, the following S306 may also be included:

[0100] S306. If the connection disconnection duration exceeds the duration threshold, the first UPF deletes the user plane data corresponding to the terminal stored therein, and the target network element releases the session, resources and context corresponding to the terminal.

[0101] It is understandable that, due to the base station, the target network element received the store-and-forward instruction for the session during the session establishment process. Although the control plane signaling is unreachable, the target network element will start a timer based on the maximum data storage duration. Within the duration, the resources and context of the session and terminal will be maintained; after the duration is exceeded, the resources and context of the terminal and session will be automatically released.

[0102] It is understandable that if the disconnection between the satellite and the ground gateway station lasts for more than a certain duration, the network failure may be temporarily unrecoverable. Therefore, the user plane data of the terminal stored in the UPF may not need to be relayed. For example, if the data following this part is not transmitted in time, the data in this part will not be meaningful to retain and will not need to be transmitted to the terminal or enterprise server. Therefore, the first UPF can stop retaining the user plane data corresponding to the terminal when it detects that the disconnection between the satellite and the ground gateway station has lasted for a long time, thereby reducing the waste of storage resources.

[0103] Based on this scheme, when the duration of the disconnection between the satellite and the ground gateway exceeds the corresponding duration threshold in the data storage and forwarding strategy, the first UPF can delete the user plane data corresponding to the terminal stored in the storage module of the first UPF. The relevant network elements in the communication system can release the session, configured resources, and context of the terminal in each network element, thereby reducing resource waste.

[0104] Optionally, when the first UPF is a relay UPF and the second UPF is an anchor UPF, S303 above may include S32 below, and S304 above may include S42 below:

[0105] S32. If the connection between the satellite and the ground gateway is lost, the session resources corresponding to the terminal are maintained. The uplink data packet in the N3 tunnel arrives at the relay UPF. The relay UPF stores the uplink data packet in the N3 tunnel. The uplink data packet in the N3 tunnel is the target user plane data.

[0106] S42. If the connection between the satellite and the ground gateway station is restored, the session connection corresponding to the terminal is restored, and the relay UPF forwards the N3 tunnel uplink data packets stored to the anchor UPF.

[0107] Specifically, the relay UPF can forward the uplink data packets of the N3 tunnel received by the N3 interface through the N9 interface.

[0108] Based on this scheme, after the satellite disconnects from the ground gateway station, the satellite UPF can store the N3 tunnel uplink data packets sent by the base station through the N3 tunnel in the satellite UPF. After the satellite and the ground gateway station reconnect, that is, after the N9 tunnel connection is restored, the satellite UPF can forward the N3 tunnel uplink data packets stored in the satellite UPF to the ground UPF through the N9 tunnel.

[0109] Optionally, when the first UPF is an anchor UPF and the second UPF is a relay UPF, S303 above may include S33 below, and S304 above may include S43 below:

[0110] S33. If the connection between the satellite and the ground gateway is lost, the session resources corresponding to the terminal are maintained. When the downlink data packet of N6 tunnel arrives at the anchor point UPF, the anchor point UPF stores the downlink data packet of N6 tunnel. The downlink data packet of N6 tunnel is the target user plane data.

[0111] S43. If the connection between the satellite and the ground gateway station is restored, the session connection corresponding to the terminal is restored, and the anchor UPF forwards the N6 tunnel downlink data packets stored in the relay UPF.

[0112] Specifically, the anchor point UPF can forward downlink data packets from the N6 tunnel received by the N6 interface through the N9 interface.

[0113] Based on this scheme, after the satellite and the ground gateway station disconnect, the ground UPF can store the downlink data packets of the N6 tunnel sent by the enterprise server through the N6 tunnel in the ground UPF. After the satellite and the ground gateway station reconnect, that is, after the N9 tunnel connection is restored, the ground UPF can forward the downlink data packets of the N6 tunnel stored in the ground UPF to the satellite UPF through the N9 tunnel.

[0114] It is understandable that when the satellite loses connection with the ground gateway station, the N9 tunnel will disconnect. At this time, the satellite UPF can detect that the ground UPF is unreachable, and the ground UPF can detect that the satellite UPF is unreachable. According to the data storage and forwarding strategy, it triggers its UPF's store-and-forward function. All uplink data packets from the N3 tunnel will be forwarded to the data storage module after arriving at the satellite UPF data forwarding module. All downlink data packets from the N6 tunnel will be stored sequentially using the PDU session identifier index after arriving at the ground UPF data forwarding module. When the maximum data storage time is exceeded, the UPF will delete the stored session data and release the resources of the PDU session; when the maximum data storage volume is exceeded, the received data packets will be discarded directly.

[0115] Figure 6 This disclosure provides a message flow diagram for establishing a user plane data storage and forwarding session in an air-space-ground scenario, as provided in an embodiment of the present disclosure. A sensor, acting as the UE, establishes a connection with the satellite, successfully registers, and completes the PCF selection and session establishment process according to standard procedures. During this time, the satellite maintains a connection with the ground gateway station. Figure 6 As shown, it may include the following S601 to S614:

[0116] S601, SMF selects PCF.

[0117] S602, SMF, and PCF establish terminal session policies.

[0118] SMF sends an SM Policy Association Establishment (i.e., session policy request) to PCF, and PCF returns an Npcf_SMPolicyControl_Create Response message (i.e., session policy response) to SMF.

[0119] The Npcf_SMPolicyControl_Create Response message carries the following: Store and ForwardPolicy = {NTN = True, Aircraft Parameters = {Orbit = LEO, Altitude = 1500}, UpLinkParameters = {Active = True, Max Storage Time = 120, Max Storage Size = 65536}, DownLink Parameters = {Active = True, Max Storage Time = 120, Max Storage Size = 6553600}}. That is, the data storage and forwarding policy is: {Land / Non-Land Identifier = True, Aircraft Parameters = {Orbit = LEO, Altitude = 1500}, Uplink Parameters = {Active = True, Max Storage Time = 120, Max Storage Size = 65536}, Downlink Parameters = {Active = True, Max Storage Time = 120, Max Storage Size = 6553600}}.

[0120] Altitude is measured in km, Max Holding Time in seconds, and Max Storage Size in bits.

[0121] S603 and SMF select a ground UPF as PSA (UPF of PDU session anchor) and select a UPF on the same aircraft as the base station as I-UPF (Initial UPF, relay UPF).

[0122] S604 and SMF send an N4 Session Establishment Request message to the satellite UPF.

[0123] The N4 Session Establishment Request message includes: {PDU Session ID=1, Store and Forward Parameters={UpLink Parameters={Active=True, Max StorageTime=120, Max Storage Size=65536}, DownLink Parameters={Active=False}}. That is, {PDU Session ID=1, Storage and Forward Parameters={Uplink Parameters={Active=True, Max Storage Time=120, Max Storage Size=65536}, Downlink Parameters={Active=False}}.

[0124] S605, the satellite UPF returned a success message in the N4 Session Establishment Response message, confirming the request information.

[0125] S606, SMF sends an N4 Session Establishment Request message to the ground UPF.

[0126] The N4 Session Establishment Request message includes: {PDU Session ID=1, Store and Forward Parameters={UpLink Parameters={Active=False}, DownLink Parameters={Active=True, Max Storage Time=120, Max Storage Size=6553600}}. That is, {PDU Session ID=1, Storage and Forward Parameters={Uplink Parameters={Active=False}, Downlink Parameters={Active=True, Max Storage Time=120, Max Storage Size=6553600}}.

[0127] S607, the ground-based UPF returned a success message in the N4 Session Establishment Response message, confirming the request information.

[0128] S608, SMF sends a Namf_Communication_N1N2MessageTransfer request message (i.e., N1N2 message transfer request) to AMF.

[0129] The Namf_Communication_N1N2MessageTransfer request message carries: N2SMcontainer; Store and Forward Parameters = {Active = True, Period = 120}; Store and Forward Indicator = True (i.e., N2 SM container; store and forward parameters = {Active = True, Period = 120}; store and forward indicator = True).

[0130] S609, AMF returns a Namf_Communication_N1N2MessageTransfer response message (i.e., N1N2 message transmission response) to SMF.

[0131] The Namf_Communication_N1N2MessageTransfer response message indicates successful reception.

[0132] S610 and AMF send an N2 PDU Session Request message to the base station.

[0133] The N2 PDU session request carries store and forward parameters: Store and Forward Parameters = {Active = True, Period = 120}.

[0134] S611. The base station returns an N2 PDU Session Response to the AMF, indicating that the session was successfully established and carrying confirmation information. At this time, user plane uplink traffic can be successfully sent.

[0135] S612, AMF sends Nsmf__PDUSession_UpdateSMContext Request information to SMF.

[0136] The Nsmf__PDUSession_UpdateSMContext Request message carries AN Tunnel Info, and the SMF then sends an N4 Session Modification Request message to the satellite UPF.

[0137] The Nsmf__PDUSession_UpdateSMContext Request message carries AN Tunnel Info information so that downlink traffic from the satellite UPF as an I-UPF can be sent to the RAN through the N3 tunnel.

[0138] S613, SMF sends an N4 session modification request to the satellite UPF.

[0139] S614. The satellite UPF sends an N4 session modification response to the SMF, carrying confirmation information. At this point, user plane uplink traffic can be successfully transmitted.

[0140] At time t0, the satellite disconnects from the ground gateway. The RAN, AMF, and SMF maintain control plane connection information and the UE context, and simultaneously start the Store and Forward Timer. The satellite UPF and ground UPF sense the disconnection of the N9 tunnel link. The satellite UPF begins forwarding subsequent uplink data from the UE to its internal data storage module; the ground UPF begins forwarding subsequent downlink data from the UE to its internal data storage module. Both simultaneously start the Store and Forward Timer. Assuming 60 seconds later, the satellite and ground gateway reconnect. The RAN, AMF, and SMF sense the restoration of the control plane link and release the Store and Forward Timer. The satellite UPF and ground UPF sense the restoration of the N9 tunnel link. The satellite UPF begins forwarding the stored uplink data in order through the data forwarding module and sending it to the ground UPF via the N9 tunnel; the ground UPF begins forwarding the stored downlink data in order through the data forwarding module and sending it to the satellite UPF via the N9 tunnel. Both simultaneously release the Store and Forward Timer.

[0141] This disclosure provides a method for storing and forwarding user plane data in an air-space-ground scenario. By introducing a UPF with data storage and forwarding capabilities into the satellite, and enhancing the signaling process between the SMF, UPF, PCF, AMF, and base station, a delay-tolerant data service can be implemented in an air-space-ground discontinuous feeder scenario. This allows for the development of massive IoT services based on this feature.

[0142] Figure 7 This is a schematic diagram of the structure of a UPF provided in an embodiment of the present disclosure, as shown below. Figure 7 As shown, the UPF700 includes: a data storage module 701 and a data forwarding module 702; the data storage module 701 is used to: if the connection between the satellite and the ground gateway station is lost, and the target user plane data arrives at the UPF, store the target user plane data, which is the user plane data corresponding to the terminal; the data forwarding module 702 is used to: if the connection between the satellite and the ground gateway station is restored, forward the target user plane data in the data storage module 701.

[0143] In this embodiment, a UPF (User Plane Frame) with user plane data storage and forwarding capabilities is introduced into the space-air-ground scenario, thereby enabling latency-tolerant data services for massive IoT devices in discontinuous space-air-ground feeder scenarios. Simultaneously, this solution avoids excessive modifications to base stations and achieves bidirectional data storage and forwarding through space-ground user plane collaboration.

[0144] The UPF 700 provided in this embodiment can achieve Figures 1 to 6 To avoid repetition, the various processes implemented by the anchor UPF or relay UPF in the method implementation examples will not be described again here.

[0145] Optionally, such as Figure 8 As shown, this disclosure also provides a UPF 800, including a processor 801, a memory 802, and a program or instructions stored in the memory 802 and executable on the processor 801. When the program or instructions are executed by the processor 801, they implement the various processes of the UPF in the above-described user plane data storage and forwarding method embodiments and achieve the same technical effects. To avoid repetition, they will not be described again here.

[0146] It should be noted that, Figure 9 The network entity or network element 900 shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments disclosed herein.

[0147] like Figure 9 As shown, network element 900 includes a Central Processing Unit (CPU) 901, which can perform various appropriate actions and processes based on programs stored in ROM (Read Only Memory) 902 or programs loaded from storage section 908 into RAM (Random Access Memory) 903. RAM 903 also stores various programs and data required for system operation. CPU 901, ROM 902, and RAM 903 are interconnected via bus 904. I / O (Input / Output) interface 905 is also connected to bus 904.

[0148] The following components are connected to I / O interface 905: an input section 906 including a keyboard, mouse, etc.; an output section 907 including CRT (Cathode Ray Tube), LCD (Liquid Crystal Display), and speakers, etc.; a storage section 908 including a hard disk, etc.; and a communication section 909 including a network interface card such as a LAN (Local Area Network) card and a modem, etc. The communication section 909 performs communication processing via a network such as the Internet. A drive 910 is also connected to I / O interface 905 as needed. A removable medium 911, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on drive 910 as needed so that computer programs read from it can be installed into storage section 908 as needed.

[0149] In particular, according to embodiments of this disclosure, the processes described below with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of this disclosure include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via communication section 909, and / or installed from removable medium 911. When the computer program is executed by the central processing unit (CPU 901), it performs various functions defined in the system of this application.

[0150] This disclosure also provides a readable storage medium storing a program or instructions. When the program or instructions are executed by a processor, they implement the various processes of the above-described user plane data storage and forwarding method embodiments and achieve the same technical effects. To avoid repetition, these will not be described again here.

[0151] The processor is the processor in the electronic device described in the above embodiments. The readable storage medium includes computer-readable storage media, such as ROM, RAM, magnetic disk, or optical disk.

[0152] This disclosure also provides a chip, which includes a processor and a communication interface. The communication interface is coupled to the processor. The processor is used to run programs or instructions to implement the various processes of the above-described user plane data storage and forwarding method embodiments, and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0153] It should be understood that the chip mentioned in the embodiments of this disclosure may also be referred to as a system-on-a-chip, system chip, chip system, or system-on-a-chip, etc.

[0154] This disclosure provides a computer program product containing instructions that, when run on a computer, causes the computer to perform the steps of the user plane data storage and forwarding method described above, and achieves the same technical effect. To avoid repetition, it will not be described again here.

[0155] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this disclosure is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0156] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this disclosure, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of this disclosure.

[0157] The embodiments of this disclosure have been described above with reference to the accompanying drawings. However, this disclosure is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this disclosure without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this disclosure.

Claims

1. A method for storing and forwarding user plane data, applied in an air-space-ground scenario, characterized in that, The method includes: During the session establishment process, the Policy and Accounting Function (PCF) receives the session policy request corresponding to the terminal sent by the Session Management Function (SMF), and returns a session policy response including data storage and forwarding policies to the SMF based on the IoT latency tolerance service subscribed to by the terminal. The SMF selects the anchor user plane function network element (UPF) and the relay UPF according to the data storage and forwarding strategy, and establishes a session corresponding to the terminal based on the session strategy response; the anchor UPF is a terrestrial UPF, and the relay UPF is a satellite UPF; wherein, the SMF selects the UPF that needs to support store-and-forward function as the anchor UPF according to the uplink and downlink identifiers in the data storage and forwarding strategy; the SMF selects the UPF that supports store-and-forward function in the satellite where the terminal's access base station is located as the relay UPF according to the uplink and downlink identifiers and access aircraft parameters in the data storage and forwarding strategy; If the connection between the satellite and the ground gateway is lost, the session resources corresponding to the terminal are maintained. When the target user plane data arrives at the first UPF, the first UPF stores the target user plane data, which is the user plane data corresponding to the terminal. If the connection between the satellite and the ground gateway is restored, the session connection corresponding to the terminal is restored, and the first UPF forwards the stored target user plane data to the second UPF. Wherein, the first UPF is an anchor UPF and the second UPF is a relay UPF; or, the first UPF is a relay UPF and the second UPF is an anchor UPF.

2. The method of claim 1, wherein, The data storage forwarding strategy includes at least one of the following: Land-to-non-land identifier, access aircraft parameters, uplink / downlink identifier, duration threshold, and stored data volume threshold.

3. The method according to claim 1, characterized in that, If the SMF selects a UPF from the ground UPFs that needs to support store-and-forward functionality as the anchor UPF based on the uplink / downlink identifier in the data storage and forwarding strategy; If the uplink / downlink identifier indicates uplink and downlink, or downlink, then the anchor point UPF supports store-and-forward functionality; if the uplink / downlink identifier indicates uplink, then the anchor point UPF does not need to support store-and-forward functionality.

4. The method according to claim 1, characterized in that, If the SMF selects the UPF that supports store-and-forward function as the relay UPF in the satellite where the terminal's access base station is located, based on the uplink and downlink identifiers and access aircraft parameters in the data storage and forwarding strategy; If the uplink / downlink identifier indicates both uplink and downlink, or uplink, then the relay UPF supports store-and-forward functionality; if the uplink / downlink identifier indicates downlink, then the relay UPF is not selected, and the access base station is a base station in the satellite.

5. The method of claim 2, wherein, The step of establishing a session corresponding to the terminal based on the session policy response includes: Based on the session policy response, the SMF sends an N4 session establishment request to the relay UPF and the anchor UPF respectively; the N4 session establishment request includes at least one of the following: PDU session identifier, N9 core network tunnel information, store-and-forward indication information, uplink / downlink identifier, duration threshold, and storage data volume threshold. The SMF receives the N4 session establishment response sent by the relay UPF and the anchor UPF; The SMF returns session information to the Access and Mobility Management Function (AMF) network element. The session information includes: PDU session identifier, N3 core network tunnel information, store-and-forward indication information, and store data duration threshold. The AMF sends a PDU session request to the access base station so that the base station can determine whether to establish a PDU session corresponding to the terminal. The PDU session request includes the session information, and the access base station is a base station in the satellite.

6. The method of claim 2, wherein, If the connection between the satellite and the ground gateway station is lost, the session resources corresponding to the terminal will be maintained, including: If the connection between the satellite and the ground gateway station is lost, the target network element starts a timer according to the duration threshold, and maintains the session, resources and context corresponding to the target network element and the terminal as long as the connection loss duration does not exceed the duration threshold. The target network element includes at least one of the following: access base station, AMF, SMF, PCF, anchor point UPF, and relay UPF.

7. The method of claim 6, wherein, After the first UPF stores the target user plane data, the method further includes: If the connection disconnection duration does not exceed the duration threshold, and the user plane data corresponding to the terminal stored in the first UPF exceeds the storage data volume threshold, then the first UPF discards the subsequently received user plane data packets corresponding to the terminal.

8. The method according to claim 6 or 7, characterized in that, If the connection between the satellite and the ground gateway station is restored, the session connection corresponding to the terminal is restored, and the first UPF forwards the stored target user plane data to the second UPF, including: If the disconnection duration does not exceed the duration threshold and the connection between the satellite and the ground gateway is restored, the target network element restores the connection of the session corresponding to the terminal based on the maintained resources, and the first UPF uses the maintained N9 core network tunnel information to forward the stored target user plane data to the second UPF.

9. The method according to claim 6 or 7, characterized in that, After the first UPF stores the target user plane data, the method further includes: If the connection disconnection duration exceeds the duration threshold, the first UPF deletes the stored user plane data corresponding to the terminal, and the target network element releases the session, resources, and context corresponding to the terminal.

10. The method according to any one of claims 1 to 7, characterized in that, When the target user plane data arrives at the first UPF, the first UPF stores the target user plane data, including: When the uplink data packet of the N3 tunnel arrives at the anchor point UPF, the anchor point UPF stores the uplink data packet of the N3 tunnel, and the uplink data packet of the N3 tunnel is the target user plane data; or, When the downlink data packet of the N6 tunnel arrives at the relay UPF, the relay UPF stores the downlink data packet of the N6 tunnel, which is the target user plane data.

11. The method of claim 10, wherein, The first UPF forwards the target user plane data to the second UPF, including: The anchor point UPF forwards the stored N3 tunnel uplink data packets to the relay UPF; or, The relay UPF forwards the stored N6 tunnel downlink data packets to the anchor UPF.

12. A store-and-forward system for user plane data, characterized by The storage and forwarding system includes: Policy and Charging Function (PCF), Session Management Function (SMF), Satellite User Plane Function (UPF), and Ground UPF; The PCF is used to receive the session policy request corresponding to the terminal sent by the SMF during the session establishment process, and return a session policy response including data storage and forwarding policy to the SMF according to the IoT latency tolerance service subscribed by the terminal. The SMF is used to select the anchor UPF and relay UPF according to the data storage and forwarding policy, and to establish a session corresponding to the terminal based on the session policy response; the anchor UPF is the ground UPF, and the relay UPF is the satellite UPF; wherein, the SMF selects the UPF that needs to support store-and-forward function as the anchor UPF according to the uplink and downlink identifiers in the data storage and forwarding policy; the SMF selects the UPF that supports store-and-forward function in the satellite where the terminal's access base station is located as the relay UPF according to the uplink and downlink identifiers and access aircraft parameters in the data storage and forwarding policy; Each network element in the storage and forwarding system is used to maintain the session resources corresponding to the terminal if the connection between the satellite and the ground gateway station is lost. A first UPF is configured to store target user plane data when the target user plane data arrives at the first UPF, wherein the target user plane data is the user plane data corresponding to the terminal; wherein the first UPF is an anchor UPF and the second UPF is a relay UPF; or, the first UPF is a relay UPF and the second UPF is an anchor UPF. Each network element in the storage and forwarding system is also used to restore the session connection corresponding to the terminal if the connection between the satellite and the ground gateway station is restored. The first UPF is also used to forward the target user plane data to the second UPF after the session connection corresponding to the terminal is restored.

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