CN114785399B

CN114785399B - End-to-end communication method of low-orbit satellite communication network system

Info

Publication number: CN114785399B
Application number: CN202210283762.1A
Authority: CN
Inventors: 丁亚南; 鲍峰; 陆天爱; 吕智勇; 刘剑锋
Original assignee: Nanjing Panda Handa Technology Co Ltd
Current assignee: Nanjing Panda Handa Technology Co Ltd
Priority date: 2022-03-22
Filing date: 2022-03-22
Publication date: 2024-03-29
Anticipated expiration: 2042-03-22
Also published as: CN114785399A

Abstract

The invention discloses an end-to-end communication method of a low orbit satellite communication network system, which utilizes the expandability of a 5G core network to increase the application service T2TAF of end-to-end control on the basis of a ground 5G mobile communication network, and realizes the control of PDU session and key negotiation management processes of a user through NEF network elements of 5GC, wherein the specific communication process comprises terminal network access, end-to-end service session establishment, end-to-end session switching and end-to-end service session release. Aiming at the end-to-end service communication flow, the invention realizes the encryption and decryption and the integrity protection of the service and the data of the end-to-end communication through the shared key analysis, thereby reducing the encryption and decryption processing process of the base station side; the transmission delay of the end-to-end service is reduced, and meanwhile, the requirement on satellite processing resources is reduced.

Description

End-to-end communication method of low-orbit satellite communication network system

Technical Field

The invention relates to the technical field of low-orbit satellite communication, in particular to an end-to-end communication method of a low-orbit satellite communication network system.

Background

1. Low orbit constellation satellite communication system

The low orbit constellation satellite communication system is a satellite communication system for signal transfer by low orbit constellation. The low orbit constellation satellite communication systems established or already established in the world at present mainly comprise starlink, O3B, oneWeb, telesat and the like, and China mainly comprises systems such as rainbow clouds, wild geese and the like. Generally, a low orbit constellation satellite communication system is composed of three parts, namely a space segment, a ground segment and an application segment, as shown in fig. 1.

(1) Space segment

The space segment is made up of a low orbit satellite constellation. A satellite constellation is a collection of satellites that are launched into orbit to function properly, typically a satellite network consisting of a number of satellite rings configured in a certain manner. The low orbit satellite constellation is a low orbit satellite network composed of a plurality of low orbit satellites, as shown in fig. 2.

The low orbit satellite carries high-performance digital comprehensive processing load, realizes the functions of base stations such as user terminal signal receiving and transmitting, baseband processing, high-layer protocol processing and the like, and is interconnected and communicated with adjacent satellites through inter-satellite links to construct a space-based bearing network.

(2) Ground section

The ground section is used as an important component of the low-orbit constellation satellite communication system to complete the functions of satellite load management, service processing, network management, operation management, cross-country service settlement and the like of the low-orbit constellation satellite communication system, and is also responsible for interconnection and interworking of the low-orbit constellation satellite communication system and other systems, and mainly comprises an operation control center, a global operation service center and gateway stations distributed in all the places of the world.

a) Operation control center

The operation control center is a core component and a management center for operation and maintenance control of a low-orbit constellation satellite communication system, provides a centralized, unified, comprehensive and automatic platform for system management and application management, and ensures safe, stable and reliable operation of constellation and ground gateway station networks. The method mainly completes the functions of satellite load management, satellite-ground resource running condition, satellite-ground feed link state monitoring, gateway station system task planning and the like.

b) Global operation service center

The global operation service center is an important component for supporting the global operation of the low-orbit constellation satellite communication system. The global operation service center is connected with the comprehensive network management and operation support system of each country, and mainly completes the functions of global settlement, gateway station network monitoring and the like, and ensures the safe and stable operation of the global network.

c) Gateway station system

The gateway station system provides communication, business, operation, management and other services for the low orbit constellation satellite communication system, and has the functions of system resource management, user authentication and floor service encryption, service routing and exchange, business service, local network operation and the like. The system mainly comprises gateway stations deployed in various construction countries or regions and communication networks among the gateway stations, and is a main ground facility of a low-orbit constellation satellite communication system. The low orbit constellation satellite communications system can be interconnected with the ground PLMN, PSTN, internet and other private networks.

(3) Application segment

The application section consists of various fixed and mobile terminals distributed in the coverage area of the low orbit constellation beam, the terminals are portals and application platforms for users to access the low orbit constellation satellite communication system, the application sections are used for establishing data transmission links between the users and satellites, and each terminal has the switching capability among beams, satellites and gateway stations and can provide continuous business services for the users.

2. NTN (non-ground network)

The NTN is proposed by 3GPP, uses GEO, MEO, LEO, HAPS platform as relay node or base station to cooperate with ground network equipment to form non-ground network, to provide wide area coverage service for user, to meet the connection demand of user at any time and place, and to ensure service availability, continuity and expandability. And meanwhile, the system can be combined with a ground network to provide more efficient service for users. Depending on the satellite/aerial platform load type, NTNs can be divided into transparent forwarding networks as signal relays and processing forwarding networks as base stations, as shown in fig. 3.

The NTN communication standard is adaptively modified for non-terrestrial network characteristics on a 5GNR basis. Fig. 4 is a protocol stack of a forwarding network data plane, where a protocol stack of a Satellite Radio Interface (SRI) implements point-to-point high-data transmission between a satellite and an NTN gateway, and a GTP-U of a NG interface user plane is to be carried on a SRI-based high-speed IP transport channel.

In 5G NR, NG-AP enables control plane signaling between 5GC and gNB, NG-AP signaling is typically carried over an IP-based SCTP protocol, whereas in NTN networks NG-AP is transmitted over SCTP links between 5GC and a satellite-borne gNB through an NTN gateway. The NAS protocol is transported through the NG-AP protocol as shown in fig. 5.

3. End-to-end communication

In the terrestrial mobile communication 5G system, the terminal first finds the called terminal through the core network routing addressing, and establishes a service data transmission link between the calling terminal and the called terminal, the transmission of the end-to-end service data is forwarded via the core network UPF, so that the end-to-end communication can be implemented, and the control of the service transmission link is implemented by the control link from the terminal to the network side, as shown in fig. 6.

Unlike terrestrial mobile communication, in order to reduce the end-to-end communication delay, end-to-end communication in a satellite communication system refers to that a terminal and a terminal forward communication via one hop of a satellite or multiple hops via an inter-satellite link, and service data do not need to be exchanged via a terrestrial network. With reference to the GMR-1 standard, it can be seen that the terminal-to-terminal communication is directly forwarded to the process via a satellite TTCN radio frequency link, the control link being implemented by a ground gateway station, as shown in fig. 7.

4. Disadvantages of the prior art

In the satellite communication system defined by NTN, because of adopting the mobile communication system of the ground 5G, in order to realize the end-to-end communication of the satellite system, there are two technical schemes, one is to realize the end-to-end communication through the ground core network exchange, as shown in fig. 8; another is to mount the ground UPF on a satellite, and implement end-to-end communication through the N9 interface interconnect of the satellite-borne UPF, as shown in fig. 9.

The first scheme increases the transmission delay of service data, requires the service data to be exchanged to the core network, and increases the transmission delay of the service data compared with the end-to-end direct communication, thus being not suitable for the transmission of high service required by the service delay.

The second scheme increases the demand for on-board processing resources, and on satellite processing load, the functions of on-board base stations such as user data receiving and transmitting, modulation and demodulation, encoding and decoding, segmentation recombination, encryption and decryption, compression and decompression and the like are required to be realized, and in addition, the UPF function of a core network user plane is also supported. Under the condition, because the key distributed for the user by the network side realizes the encryption and decryption and integrity protection functions from the user terminal to the network side, the service data of one user can reach the other user after repeated encryption and decryption and integrity protection processing by the satellite, and the processing load of the service data of the user on the satellite is increased.

Disclosure of Invention

The invention aims to provide an end-to-end communication method of a low-orbit satellite communication network system, so that the transmission delay of an end-to-end service is reduced, and the demand on satellite processing resources is reduced.

The technical solution for realizing the purpose of the invention is as follows: the end-to-end communication method of the low orbit satellite communication network system utilizes the expandability of the 5G core network to increase the application service T2TAF of end-to-end control on the basis of the ground 5G mobile communication network, and realizes the control of the management flows of PDU session and key negotiation of users through NEF network elements of 5GC, and the specific communication process comprises the steps of terminal network access, end-to-end service session establishment, end-to-end session switching and end-to-end service session release.

Further, the terminal accesses the network, and the specific process is as follows:

(1.1) the UE first sends an RRC connection establishment request RRC Setup Request to the on-board gNB, carrying an initial identifier of the terminal and an establishment cause; the UE is user equipment, gNB is a 5G base station, and RRC (radio resource control) represents radio resource control;

(1.2) the on-board gNB replies to the RRC connection setup response RRC Connnection Setup Response, carrying the complete configuration information of the signaling channel between the UE and the on-board gNB;

(1.3) the UE sends an RRC connection setup complete RRC Connection Setup Complete to the on-board gNB, carrying an uplink NAS message, i.e. a registration request;

(1.4) the on-board gNB will select the appropriate CN and forward the registration request message Initial UE Message; the CN represents a core network;

(1.5) the CN initiates an authentication flow to the terminal through the satellite-borne gNB, the UE and the CN perform mutual authentication, after the authentication is completed, the UE and the CN perform NAS layer security simulation control flow, and the NAS layer signaling encryption and decryption and integrity protection are started;

(1.6) the CN sending an initial context setup request Initial UE Context Setup Request to the on-board gNB, carrying a registration success NAS message;

(1.7) initiating an AS layer security mode control flow to a terminal by the satellite-borne gNB, and starting AS layer signaling encryption and decryption and integrity protection;

(1.8) the on-board gNB then sends an RRC connection reconfiguration request RRC Connection Reconfiguration to the UE and forwards a registration success NAS message;

(1.9) the UE replies to the satellite-borne gNB that the RRC connection reconfiguration is completed RRC Connection Reconfiguration, and at the moment, the establishment of the service channel between the UE and the satellite-borne gNB is completed;

(1.10) the on-board gNB replies to the CN initial UE context setup response Initial UE Context Setup Response, at which time the UE has completed network entry and established a PDU session to the T2 TAF; the T2TAF represents an end-to-end controlled application service, and the PDU represents a protocol data unit;

(1.11) the UE initiates a terminal on-line notification to the T2TAF, and at the same time, the T2TAF replies an on-line personnel list to the UE.

Further, the end-to-end service session is established as follows:

(2.1) UE a initiates an end-to-end direct transmission service request T2T Direct Transfer Request to T2TAF to establish to UE B;

(2.2) the T2TAF requests the CN to establish the end-to-end direct traffic of UEA and UEB;

(2.3) the CN checks the end-to-end service capacity of the UE A and the UE B and distributes an end-to-end service shared key;

(2.4) the CN retrieves the positions of the base stations of the UE A and the UE B, distributes a T2T service inter-satellite path, and respectively initiates PDU Session Modify requests to the satellite-borne gNB A and the satellite-borne gNB B so as to establish an Xn expansion link between the UE A and the UE B;

(2.5) the satellite-borne gNB mutually sends a service direct transmission channel establishment message according to an inter-satellite path to establish a service transmission tunnel between base stations, and at the moment, the satellite-borne gN B does not perform PDCP and SDAP processing on end-to-end service data; the PDCP represents a packet data convergence protocol, and the SDAP represents a service data adaptation protocol;

(2.6) initiating RRC Connection Reconfiguration requests to UE A and UE B by satellite-borne gNBA and gNBB respectively, establishing a T2T session between the UE and the gNB, and simultaneously distributing an end-to-end shared key to the terminal;

(2.7) the UE A and the UE B reply to the satellite-borne gNB A and gNB B respectively to finish RRC Connection Reconfiguration of RRC connection reconfiguration, and at the moment, the establishment of a service channel between the UE and the satellite-borne gNB is finished;

(2.8) the on-board gNB A and the on-board gNB B reply to the core network that PDU session modification is completed, and at this time, establishment of a direct transmission channel between the UEA and the UEB is completed.

Further, the end-to-end session switching specifically includes the following steps:

(3.1) the UE A performs RRM measurement and event reporting according to measurement configuration, and the UE reports own position information; the RRM represents radio resource management;

(3.2) the source satellite-borne gNB A makes a switching decision according to ephemeris and information reported by the UE A, and initiates a switching notification to the satellite-borne gNB B at the same time, so that the synchronization of the UE A and the UE B during switching is ensured;

(3.3) the source satellite-borne gNB A transmits a switching request message to the target gNB A, and transmits necessary relevant information for switching preparation; the target gNB A performs switching preparation, allocates resources and new inter-satellite paths for the UE, and replies a confirmation message, wherein the confirmation message contains a switching command for the UE;

(3.4) triggering the switching of an air interface by the source satellite-borne gNB A, sending an RRC reconfiguration message to the terminal, executing the data forwarding from the UE B to the UE A and the serial number SN state transmission operation to the target gNB A by the source satellite-borne gNB A in the switching process, forwarding the received data of the UE B to the target gNB A, and knowing where to start to continue transmitting the data for the UE A by the target gNB A when the UE A is accessed to the target gNB A;

(3.5) carrying out downlink synchronization on the UE A and the new cell of the target gNB A, and initiating a random access process to the target gNB A;

(3.6) after the UE A successfully accesses the target to the gNB A, the terminal sends an RRC reconfiguration complete message and confirms that the switching process is completed to the target gNB A; the target gNB A confirms that the switching is successful by receiving the RRC reconfiguration completion message; so far, the target gNB A starts to send data to the UE A;

(3.7) after receiving the switching completion message of the UE A, the target gNB A initiates a path switching process to gNB B; forwarding a data channel between the UE A and the UE B to a target gNB A;

(3.8) after receiving the switching completion message of the UE A, the target gNB A initiates a path switching process to the core network; forwarding a data channel between the network and the UE A to a target gNB A;

(3.9) the target gNB a sends a UE context release message to the source gNB a instructing the source gNB a to release the relevant context of the UE a.

Further, the end-to-end service session is released, and the specific process is as follows:

(4.1) UE a initiates an end-to-end direct transmission service release request T2T Direct Transfer Request to T2TAF to establish to UE B;

(4.2) the T2TAF requests the CN to establish an end-to-end direct traffic release request of the UEA and the UEB;

(4.3) the CN retrieves the base station positions of the UE A and the UE B, and respectively initiates PDU Session Modify requests to the satellite-borne gNB A and the satellite-borne gNB B so as to release a T2T link between the UE A and the UE B;

(4.4) the inter-satellite gNB A and the inter-satellite gNB B initiate an end-to-end service direct transmission channel release process to release a service transmission tunnel between the base stations;

(4.5) initiating RRC Connection Reconfiguration requests to the UE A and the UE B by the satellite-borne gNB A and the satellite-borne gNB B respectively, and releasing a T2T session between the UE and the gNB;

(4.6) the UE A and the UE B reply to the satellite-borne gNB A and gNB B respectively to finish RRC Connection Reconfiguration of RRC connection reconfiguration, and at the moment, the T2T service channel between the UE and the satellite-borne gNB is released completely;

and (4.7) replying the completion of PDU session modification to the core network by the satellite-borne gNB A and the satellite-borne gNB B, and releasing the inter-satellite path by the core network, wherein the release of the direct transmission channel between the UE A and the UE B is completed.

Compared with the prior art, the invention has the following advantages: (1) Aiming at the end-to-end service transmission requirement in satellite communication, an end-to-end communication flow design is provided, so that the end-to-end service transmission delay is reduced, and meanwhile, the requirement on satellite processing resources is reduced; (2) Aiming at the end-to-end service communication flow, the encryption and decryption of the service and the data of the end-to-end communication are realized through the shared key analysis, and the integrity protection is realized; (3) By utilizing the expandability of the 5G core network, an end-to-end controlled application service T2TAF is added at the core network side, and management flow control such as PDU session and key negotiation of a user is realized through a NEF network element of the 5 GC; (4) And the end-to-end service communication is realized by using the shared secret key, so that the encryption and decryption processing process of the base station side is reduced.

Drawings

Fig. 1 is a schematic diagram of a low orbit constellation satellite communication system.

Fig. 2 is a low-rail constellation diagram.

Fig. 3 is a schematic diagram of NTN networks of two different payload types.

Fig. 4 is a schematic diagram of a process forwarding network user plane protocol stack.

Fig. 5 is a schematic diagram of a process forwarding network control plane protocol stack.

Fig. 6 is a schematic diagram of end-to-end communication typical of terrestrial mobile communications.

Fig. 7 is a schematic diagram of an exemplary end-to-end communication for satellite mobile communications.

Fig. 8 is a schematic diagram of a first end-to-end communication scheme for satellite mobile communications.

Fig. 9 is a schematic diagram of a second end-to-end communication scheme for satellite mobile communications.

Fig. 10 is a terminal access flow chart.

Fig. 11 is a flow chart for end-to-end traffic session establishment.

Fig. 12 is a flow chart of a handoff in an end-to-end communication process.

Fig. 13 is an end-to-end traffic release flow diagram.

Detailed Description

The invention increases the application service T2TAF of end-to-end control by utilizing the expandability of the 5G core network on the basis of the ground 5G mobile communication network, and realizes the management flow control of PDU session, key negotiation and the like of the user through the NEF network element of the 5GC, and the process comprises three parts: terminal access, end-to-end session establishment, end-to-end session handoff, end-to-end session release, etc.

1. As shown in fig. 10, the terminal accesses the network, and the steps are as follows:

(1) The UE firstly sends an RRC connection establishment request (RRC Setup Request) to the satellite-borne gNB, wherein the RRC connection establishment request carries an initial identifier, an establishment reason and the like of the terminal; the UE is user equipment, gNB is a 5G base station, and RRC (radio resource control) represents radio resource control;

(2) The satellite-borne gNB replies an RRC connection establishment response (RRC Connnection Setup Response) carrying the complete configuration information of the signaling channel between the UE and the satellite-borne gNB;

(3) The UE sends an RRC connection setup complete (RRC Connection Setup Complete) to the on-board gNB, carrying an uplink NAS message, i.e. a registration request.

(4) The on-board gNB will select the appropriate CN and forward the registration request message (Initial UE Message); the CN represents a core network;

(5) The CN initiates an authentication flow to the terminal through the satellite-borne gNB, mutual authentication is carried out between the UE and the CN, after authentication is completed, NAS layer security simulation control flow is carried out between the UE and the CN, and NAS layer signaling encryption and decryption and integrity protection are started.

(6) The CN sends an initial context setup request (Initial UE Context Setup Request) to the on-board gNB, carrying a registration success NAS message.

(7) And the satellite-borne gNB initiates an AS layer security mode control flow to the terminal, and starts AS layer signaling encryption and decryption and integrity protection.

(8) The satellite-borne gNB then sends an RRC connection reconfiguration request (RRC Connection Reconfiguration) to the UE and forwards a registration success NAS message;

(9) The UE replies RRC connection reconfiguration completion to the satellite-borne gNB (RRC Connection Reconfiguration), and the establishment of a service channel between the UE and the satellite-borne gNB is completed at the moment;

(10) The on-board gNB replies with a CN initial UE context setup response (Initial UE Context Setup Response) when the UE has completed network entry and established a PDU session to the T2 TAF. The T2TAF represents an end-to-end controlled application service, and the PDU represents a protocol data unit;

(11) And the UE initiates a terminal online notification to the T2TAF, and the T2TAF replies an online personnel list to the UE.

2. The end-to-end service session establishment is as shown in fig. 11, and the steps are as follows:

(1) UE a initiates an end-to-end direct transfer service request to T2TAF to establish to UE B (T2T Direct Transfer Request);

(2) T2TAF requests CN to establish end-to-end direct transmission service of UE A and UE B

(3) The CN checks the end-to-end service capacity of the UE A and the UE B and shares a secret key for distributing the end-to-end service;

(4) The CN searches the base station position of UE A and UE B, distributes T2T service inter-satellite paths, respectively initiates PDU Session Modify requests to the satellite-borne gNB A and the satellite-borne gNB B to establish an Xn expansion link between the UE A and the UE B,

(5) And the satellite-borne gNB mutually sends a service direct transmission channel establishment message according to the inter-satellite path to establish a service transmission channel between the base stations, and at the moment, the satellite-borne gNB does not perform PDCP and SDAP processing on the end-to-end service data. The PDCP represents a packet data convergence protocol, and the SDAP represents a service data adaptation protocol;

(6) The satellite-borne gNB A and gNB B respectively initiate RRC Connection Reconfiguration requests to the UE A and the UE B, establish a T2T session between the UE and the gNB, and simultaneously distribute an end-to-end shared key to the terminal;

(7) The UE A and the UE B reply to the satellite-borne gNB A and the satellite-borne gNB B respectively to finish RRC connection reconfiguration (RRC Connection Reconfiguration), and at the moment, the establishment of a service channel between the UE and the satellite-borne gNB is finished;

(8) And replying the PDU session modification completion to the core network by the satellite-borne gNB A and the satellite-borne gNB B, wherein the establishment of a direct transmission channel between the UE A and the UE B is completed.

3. The switching in the communication process is as shown in fig. 12, and the steps are as follows:

(1) And the UE A performs RRM measurement and event reporting according to the measurement configuration, and reports own position information. The RRM represents radio resource management;

(2) The source satellite-borne gNB A makes a handover decision based on ephemeris and UE A reported information (RRM+location). And meanwhile, a switching notification is initiated to the satellite-borne gNB B, so that synchronization of the UE A and the UE B during switching is ensured.

(3) The source satellite-borne gNB A sends a switching request message to the target gNB A, and the necessary relevant information for switching preparation is transmitted. And the target gNB A performs switching preparation, allocates resources and new inter-satellite paths for the UE, and replies a confirmation message, wherein the confirmation message contains a switching command for the UE.

(4) The source satellite-borne gNB A triggers the switching of an air interface and sends an RRC reconfiguration message to the terminal, in the switching process, the source satellite-borne gNB A also executes the operations of UEB-to-UEA data forwarding and serial number SN state transmission to the target gNB A, the received data of the UEB can be forwarded to the target gNB A, and when the UE A is accessed to the target gNB A, the target gNB A knows where to start to continuously transmit the data for the UE A.

(5) The UE A performs downlink synchronization with a new cell of the target gNB A and initiates a random access process to the target gNB A;

(6) After the UE A successfully accesses the target to the NB A, the terminal sends an RRC reconfiguration completion message, and confirms that the switching process is completed to the target gNB A. And the target gNB A confirms that the switching is successful by receiving the RRC reconfiguration complete message. To this end, the target gNB a may begin transmitting data to UE a.

(7) And after receiving the switching completion message of the UE A, the target gNB A initiates a path switching process to the gNB B. Forwarding a data channel between the UE A and the UE B to a target gNB A;

(8) And after receiving the switching completion message of the UE A, the target gNB A initiates a path switching process to the core network. Forwarding a data channel between the network and the UE A to a target gNB A;

(9) The target gNB a sends a UE context release message to the source gNB a indicating that the source gNB a can release the relevant context of the UE a.

4. The service session release is as shown in fig. 13, and the steps are as follows:

after the end-to-end service transmission is completed, the UE A initiates a service release process to the T2TAF, which is specifically as follows:

(1) UE a initiates an end-to-end direct transport service release request (T2T Direct Transfer Request) to T2TAF to establish to UE B;

(2) T2TAF requests CN to establish end-to-end direct transmission service release request of UE A and UE B

(3) The CN retrieves the base station locations where UE a and UE B are located, and initiates PDU Session Modify requests to the on-board gNB a and on-board gNB, respectively, to release the T2T link between UE a and UE B,

(4) The satellite-borne gNB A and the satellite-borne gNB B mutually initiate an end-to-end service direct transmission channel release process, and a service transmission tunnel between base stations is released;

(5) The satellite-borne gNB A and gNB B respectively initiate RRC Connection Reconfiguration requests to the UE A and the UE B, and the T2T session between the UE and the gNB is released;

(6) The UE A and the UE B reply to the satellite-borne gNB A and the satellite-borne gNB B respectively to finish RRC connection reconfiguration (RRC Connection Reconfiguration), and at the moment, the release of a T2T service channel between the UE and the satellite-borne gNB is finished;

(7) And the satellite-borne gNB A and the satellite-borne gNB B reply PDU session modification completion to the core network, the core network releases the inter-satellite path, and at the moment, the release of the direct transmission channel between the UE A and the UE B is completed.

At this time, the end-to-end traffic direct transmission channel release between UE a and UE B is completed, but UE a and UE B still remain for PDU session to CN, and the procedure release may be completed through the normal terminal release procedure.

In summary, the present invention proposes an encryption and decryption and integrity protection for the service and data of the end-to-end communication through the shared key analysis aiming at the end-to-end service communication flow; providing an application service T2TAF controlled end to end at the core network side by utilizing the expandability of the 5G core network, and realizing management flow control such as PDU session and key negotiation of a user through a NEF network element of 5 GC; the end-to-end service communication is realized by using the shared secret key, so that the encryption and decryption processing process of the base station side is reduced. Compared with the NTN network architecture defined by directly adopting 3GPP, the end-to-end service transmission delay is reduced, and compared with the satellite-borne UPF scheme, the demand for satellite processing resources is reduced.

Claims

1. An end-to-end communication method of a low orbit satellite communication network system is characterized in that on the basis of a ground 5G mobile communication network, the scalability of a 5G core network is utilized, an end-to-end controlled application service T2TAF is increased, the control of management flows of PDU session and key negotiation of a user is realized through NEF network elements of 5GC, and the specific communication process comprises terminal network access, end-to-end service session establishment, end-to-end session switching and end-to-end service session release;

adding an end-to-end controlled application service T2TAF at the core network side, and executing an end-to-end service communication flow; the communication flow comprises network access of the terminal, and the specific process is as follows:

(1.11) the UE initiates a terminal online notification to the T2TAF, and meanwhile, the T2TAF replies an online personnel list to the UE;

the communication flow also comprises end-to-end service session establishment, and the specific process is as follows:

(2.8) replying the completion of PDU session modification to the core network by the satellite-borne gNB A and the satellite-borne gNB B, wherein the establishment of a direct transmission channel between the UEA and the UEB is completed;

the communication flow also comprises end-to-end session switching, and the specific process is as follows:

(3.9) the target gNB a sending a UE context release message to the source gNB a instructing the source gNB a to release the relevant context of the UE a;

the communication flow also comprises end-to-end service session release, and the specific process is as follows: