CN114785399A

CN114785399A - End-to-end communication method of low earth orbit satellite communication network system

Info

Publication number: CN114785399A
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: 2022-07-22
Anticipated expiration: 2042-03-22
Also published as: CN114785399B

Abstract

The invention discloses an end-to-end communication method of a low earth orbit satellite communication network system, which is characterized in that on the basis of a ground 5G mobile communication network, the expandability of a 5G core network is utilized to increase an application service T2TAF of end-to-end control, and the control of management flows of PDU (protocol data Unit) conversation and key negotiation of a user is realized through an NEF network element of a 5GC (network access gateway), and the specific communication process comprises terminal network entry, end-to-end service conversation establishment, end-to-end conversation switching and end-to-end service conversation release. Aiming at the end-to-end service communication flow, the encryption, decryption and integrity protection of the service and data of the end-to-end communication are realized through the analysis of the shared key, so that the encryption and decryption processing processes at the base station side are reduced; the end-to-end service transmission delay is reduced, and 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-earth-orbit satellite communication, in particular to an end-to-end communication method of a low-earth-orbit satellite communication network system.

Background

1. Low earth orbit constellation satellite communication system

The low orbit constellation satellite communication system is a satellite communication system for performing signal forwarding through a low orbit constellation. Currently, the low orbit constellation satellite communication systems built or already built in the world mainly comprise starlink, O3B, OneWeb, Telesat and the like, and China mainly comprises systems such as rainbow clouds and swan gooses. Generally, a low earth constellation satellite communication system is composed of three parts, namely a space section, a ground section and an application section, as shown in fig. 1.

(1) Space segment

The space segment is comprised of a constellation of low orbit satellites. The satellite constellation is a collection of satellites which can normally work when being launched into orbit, and is generally a satellite network formed by a plurality of satellite rings which are configured in a certain mode. 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 a high-performance digital comprehensive processing load, realizes the functions of base stations such as signal receiving and transmitting, base band processing, high-level protocol processing and the like with a user terminal, and is interconnected and communicated with a nearby satellite through an inter-satellite link to construct a space-based bearing network.

(2) Ground segment

The ground segment is used as an important component of the low-earth constellation satellite communication system, completes the functions of satellite load management, service processing, network management, operation management, cross-country service settlement and the like of the low-earth constellation satellite communication system, is responsible for interconnection and intercommunication of the low-earth 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 parts of the world.

a) Operation control center

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

b) Global operation service center

The global operation service center is an important part for supporting the global operation of the satellite communication system with low earth orbit constellation. The global operation service center is connected with the comprehensive network management and operation support system of each country, 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 services such as communication, service, operation, management and the like for the low earth constellation satellite communication system, and has the functions of system resource management, user authentication and landing service encryption, service routing and exchange, service, local network operation and the like. The satellite communication system mainly comprises gateway stations deployed in various station building countries or regions and communication networks among the gateway stations, and is a main ground facility of the satellite communication system with the low-earth constellation. The low earth constellation satellite communication 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 range of low earth orbit constellation beams, the terminals are portals and application platforms for users to access a low earth orbit constellation satellite communication system, and are used for establishing data transmission links between the users and the satellites, and each terminal has switching capacity among the beams, among the satellites and among gateways and can provide continuous service for the users.

2. NTN (non-ground network)

The NTN is proposed by 3GPP, and a non-ground network is formed by using platforms such as GEO, MEO, LEO, HAPS, etc., as relay nodes or base stations in cooperation with ground network devices, so as to provide wide area coverage services for users, meet the connection requirements of the users anytime and anywhere, and ensure the availability, continuity and expandability of the services. Meanwhile, the method can be combined with a ground network, and more efficient service is provided for users. The NTN may be divided into a transparent forwarding network as a signal relay and a processing forwarding network as a base station according to the type of the satellite/high altitude platform load, as shown in fig. 3.

The NTN communication standard is adapted to the non-terrestrial network characteristics based on 5 GNR. Fig. 4 is a protocol stack for processing forwarding network data plane, the protocol stack of Satellite Radio Interface (SRI) realizes point-to-point high data transmission between satellite and NTN gateway, and GTP-U of NG interface user plane is carried in SRI-based high speed IP transmission channel.

In 5G NR, NG-AP implements control plane signaling between 5GC and gNB, NG-AP signaling is usually carried on top of IP-based SCTP protocol, and in NTN network, NG-AP is transmitted on SCTP link between 5GC and satellite-borne gNB through NTN gateway. The NAS protocol is transmitted over the NG-AP protocol as shown in fig. 5.

3. Peer-to-peer communication

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

Different from the ground mobile communication, in order to reduce the end-to-end communication delay, the end-to-end communication in the satellite communication system means that the terminal and the terminal forward the communication through one hop of a satellite or multiple hops of an inter-satellite link, and service data does not need to be processed and exchanged through a ground network. As can be seen with reference to the GMR-1 standard, terminal-to-terminal communication is handled directly via the direct forwarding of the satellite TTCN radio frequency link, with the control link being implemented by a terrestrial gateway station, as shown in fig. 7.

4. Disadvantages of the prior art

In the satellite communication system defined by NTN, because a ground 5G mobile communication system is adopted, in order to implement end-to-end communication of the satellite system, there are two technical solutions, one is to implement end-to-end communication through ground core network switching, as shown in fig. 8; the other is to piggy the ground UPF on the satellite and realize the end-to-end communication through the interconnection of the N9 interface of the satellite UPF, as shown in fig. 9.

The first scheme increases the transmission delay of service data, requires the service data to be exchanged with a core network, and increases the transmission delay of the service data compared with end-to-end direct communication, and is not suitable for transmission of services with high service delay requirements.

The second scheme increases the requirement for on-satellite processing resources, and on satellite processing load, the functions of a satellite-borne base station such as receiving and transmitting of user data, modulation and demodulation, coding and decoding, segmented recombination, encryption and decryption, compression and decompression and the like need to be realized, and in addition, the function of a core network User Plane (UPF) also needs to be supported. In this case, since the key allocated to the user by the network side is to realize the encryption and decryption and integrity protection functions from the user terminal to the network side, the service data of one user can reach another user after being repeatedly encrypted and decrypted by the satellite and subjected to integrity protection, thereby increasing the processing load of the service data of the user on the satellite.

Disclosure of Invention

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

The technical solution for realizing the purpose of the invention is as follows: an end-to-end communication method of a low earth orbit satellite communication network system is characterized in that on the basis of a ground 5G mobile communication network, the expandability of a 5G core network is utilized to increase the application service T2TAF of end-to-end control, and the control of management flows of PDU conversation and key negotiation of a user is realized through a NEF network element of a 5GC, and the specific communication process comprises terminal network access, end-to-end service conversation establishment, end-to-end conversation switching and end-to-end service conversation release.

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

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

(1.2) the satellite-borne gNB replies RRC connection Setup Response, and carries complete configuration information of a signaling channel between the UE and the satellite-borne gNB;

(1.3) the UE sends RRC Connection Setup completion RRC Connection Setup Complete to the satellite-borne gNB, and carries an uplink NAS message, namely a registration request;

(1.4) selecting a proper CN by the satellite-borne gNB, and forwarding a 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, bidirectional authentication is carried out between the UE and the CN, after the authentication is finished, an NAS layer safety simulation control flow is carried out between the UE and the CN, and NAS layer signaling encryption and decryption and integrity protection are started;

(1.6) the CN sends an Initial Context establishment Request Initial UE Context Setup Request to the satellite-borne gNB, and the Initial Context establishment Request carries a successful registration NAS message;

(1.7) 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;

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

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

(1.10) the satellite-borne gNB replies to CN Initial UE Context establishment Response, namely Initial UE Context Setup Response, and at the moment, the UE completes network access and establishes PDU session to T2 TAF; the T2TAF represents an application service controlled end to end, and the PDU represents a protocol data unit;

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

Further, the end-to-end service session establishment specifically includes the following processes:

(2.1) UE A initiates an end-to-end Direct transmission service Request T2T Direct Transfer Request to be established to UE B to T2 TAF;

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

(2.3) the CN checks the end-to-end service capability 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, allocates a T2T service inter-satellite path, and respectively initiates a PDU Session modification request to a satellite-borne gNB A and a satellite-borne gNB B to establish an Xn extended link between the UE A and the UE B;

(2.5) the satellite-borne gNB sends service direct transmission channel establishment messages to each other according to the inter-satellite path, and establishes a service transmission channel between the base stations, and at the moment, the satellite-borne gNB does not perform PDCP and SDAP processing on end-to-end service data any more; the PDCP represents a packet data convergence protocol, and the SDAP represents a service data adaptation protocol;

(2.6) the satellite-borne gNBA and gNBB 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 distribute an end-to-end shared key to the terminal;

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

and (2.8) the satellite-borne gNB A and the satellite-borne gNB B reply the PDU session modification completion to the core network, and at the moment, the establishment of the direct transmission channel between the UE A and the UE B is completed.

Further, the end-to-end session handover specifically includes the following processes:

(3.1) the UE A carries out RRM measurement and event reporting according to the measurement configuration, and the UE reports the position information of the UE; the RRM denotes radio resource management;

(3.2) the source spaceborne gNB A makes switching judgment according to ephemeris and the information reported by the UE A, and simultaneously initiates a switching notification to the spaceborne gNB B to ensure the synchronization of the UE A and the UE B during switching;

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

(3.4) triggering air interface switching by the source spaceborne gNB A, sending RRC reconfiguration information to the terminal, executing data forwarding from the UE B to the UE A and serial number SN state transmission operation to the target gNB A by the source spaceborne gNB A in the switching process, forwarding the received data of the UE B to the target gNB A, and when the UE A accesses the target gNB A, the target gNB A knowing where to start to continue data transmission for the UE 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 to confirm that the switching process is completed to the target gNB A; the target gNB A confirms that the handover is successful by receiving the RRC reconfiguration complete message; to this end, the target gNB a starts sending 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 the 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 a network and the UE A to a target gNB A;

(3.9) target gNB A sends a UE context release message to source gNB A instructing source gNB A to release UE A's related context.

Further, the release of the end-to-end service session specifically comprises the following processes:

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

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

(4.3) the CN retrieves the positions of the base stations of the UE A and the UE B, and respectively initiates PDU Session modification requests to the satellite gNB A and the satellite gNB B to release a T2T link between the UE A and the UE B;

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

(4.5) the satellite-borne gNB A and gNB B respectively initiate RRC Connection Reconfiguration requests to the UE A and the UE B, and release the T2T session between the UE and the gNB;

(4.6) the UE A and the UE B reply RRC Connection Reconfiguration completion RRC Connection Reconfiguration to the satellite-borne gNB A and the satellite-borne gNB B respectively, and at the moment, the release of a T2T service channel between the UE and the satellite-borne gNB is completed;

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

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 the requirement on satellite processing resources is reduced; (2) aiming at an end-to-end service communication flow, encryption, decryption and integrity protection of service and data of end-to-end communication are realized through shared key analysis; (3) by utilizing the expandability of a 5G core network, an application service T2TAF of end-to-end control is added on the core network side, and the control of management processes such as PDU session, key negotiation and the like of a user is realized through an NEF network element of a 5 GC; (4) end-to-end service communication is realized by using the shared key, thereby reducing the encryption and decryption processing process at the base station side.

Drawings

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

Fig. 2 is a schematic diagram of a low-orbit constellation.

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

Figure 4 is a schematic diagram of a user plane protocol stack for a processing forwarding network.

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

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

Fig. 7 is a typical end-to-end communication diagram of satellite mobile communication.

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

Fig. 9 is a diagram illustrating a second peer-to-peer communication scheme for satellite mobile communications.

Fig. 10 is a terminal network entry flowchart.

Fig. 11 is an end-to-end traffic session establishment flow diagram.

Fig. 12 is a handover flow diagram during end-to-end communication.

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

Detailed Description

On the basis of a ground 5G mobile communication network, the invention utilizes the expandability of a 5G core network to increase the application service T2TAF of end-to-end control, and realizes the management flow control of PDU conversation, key negotiation and the like of a user through an NEF network element of a 5GC, and the process comprises three parts: terminal network access, end-to-end session establishment, end-to-end session switching, end-to-end session release and the like.

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

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

(2) the satellite-borne gNB replies an RRC connection Setup Response (RRC connection Setup Response) carrying complete configuration information of a 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 satellite-borne gNB, carrying an uplink NAS message, i.e. a registration request.

(4) The satellite-borne 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, the UE and the CN perform bidirectional authentication, after the authentication is completed, the UE and the CN perform NAS layer safety simulation control flow, and the NAS layer signaling encryption and decryption and integrity protection are started.

(6) The CN sends an Initial Context establishment Request (Initial UE Context Setup Request) to the satellite-borne gNB, and carries a successful registration 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 (RRC Connection Reconfiguration) to the satellite-borne gNB, and at the moment, the establishment of a service channel between the UE and the satellite-borne gNB is completed;

(10) the spaceborne gNB replies to the CN with an Initial UE Context Setup Response (Initial UE Context Setup Response), at which point the UE has completed network entry and established a PDU session to the T2 TAF. The T2TAF represents an application service controlled end to end, and the PDU represents a protocol data unit;

(11) and the UE initiates a terminal on-line notification to the T2TAF, and meanwhile, the T2TAF replies an on-line personnel list to the UE.

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

(1) UE A initiates an end-to-end Direct transmission service Request (T2T Direct Transfer Request) to be established to UE B to T2 TAF;

(2) t2TAF requests CN to establish end-to-end direct transmission service of UE A and UE B

(3) CN checks end-to-end service ability of UE A and UE B, and shares secret key for distributing end-to-end service;

(4) CN retrieves the base station position of UE A and UE B, allocates T2T service inter-satellite path, and initiates PDU Session Modify request to satellite gNB A and satellite gNB B respectively to establish Xn extended link between UE A and UE B,

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

(6) satellite-borne gNB A and gNB B respectively initiate RRC Connection Reconfiguration requests to UE A and 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) UE A and UE B reply RRC Connection Reconfiguration completion (RRC Connection Reconfiguration) to the satellite-borne gNB A and the satellite-borne gNB B respectively, and at the moment, the establishment of a service channel between the UE and the satellite-borne gNB is completed;

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

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

(1) and the UE A carries out RRM measurement and event reporting according to the measurement configuration, and reports the position information of the UE. The RRM denotes radio resource management;

(2) the source satellite-borne gNB a makes handover decisions based on ephemeris and UE a reported information (RRM + location). And meanwhile, a switching notice is initiated to the satellite-borne gNB B, so that the UE A and the UE B are ensured to be synchronous during switching.

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

(4) The source spaceborne gNB A triggers the switching of an air interface and sends RRC reconfiguration information to the terminal, the source spaceborne gNB A also executes the operations of UE B-to-UE A data forwarding and serial number SN state transmission to the target gNB A in the switching process, the data of the UE B received by the source spaceborne gNB A can be forwarded to the target gNB A, and when the UE A accesses the target gNB A, the target gNB A knows where to start to continue transmitting data for the UE A.

(5) The UE A and a new cell of a target gNB A carry out downlink synchronization and initiate a random access process to the target gNB A;

(6) and 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. The target gNB a confirms that the handover is successful by receiving the RRC reconfiguration complete message. To this end, the target gNB a may start 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 the target gNB A initiates a path switching process to the core network after receiving the switching completion message of the UE A. Forwarding a data channel between a network and the UE A to a target gNB A;

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

4. The service session release is 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 transmission service release Request (T2T Direct Transfer Request) to the T2TAF, wherein the end-to-end Direct transmission service release Request is established to the 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 positions of the base stations of the UE A and the UE B, respectively initiates PDU Session Modify requests to the satellite gNB A and the satellite gNB B to release the T2T link between the UE A and the 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 to release a service transmission tunnel between the base stations;

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

(6) UE A and UE B reply RRC Connection Reconfiguration completion (RRC Connection Reconfiguration) to the satellite-borne gNB A and the satellite-borne gNB B respectively, and at the moment, the T2T service channel between the UE and the satellite-borne gNB is released and completed;

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

At this time, the end-to-end service direct transmission channel between the UE a and the UE B is released, but the UE a and the UE B still keep the PDU session to the CN, and the process release can be completed through a normal terminal release process.

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

Claims

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

2. The end-to-end communication method of the low earth orbit satellite communication network system of claim 1, wherein the terminal accesses the network by the following specific procedures:

(1.2) the satellite-borne gNB replies RRC connection Setup Response, carrying complete configuration information of a signaling channel between the UE and the satellite-borne gNB;

(1.8) the spaceborne 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 RRC Connection Reconfiguration to the spaceborne gNB to complete RRC Connection Reconfiguration, and at the moment, the establishment of a service channel between the UE and the spaceborne gNB is completed;

(1.10) the satellite-borne gNB replies to CN Initial UE Context establishment Response, namely Initial UE Context Setup Response, and at the moment, the UE completes network access and establishes PDU session to T2 TAF; the T2TAF represents an application service of end-to-end control, and the PDU represents a protocol data unit;

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

3. The end-to-end communication method of the low earth orbit satellite communication network system of claim 1, wherein the end-to-end service session is established by the following specific procedures:

(2.1) the UE A initiates an end-to-end Direct transmission service Request T2T Direct Transfer Request to the UE B to the T2 TAF;

(2.5) the satellite-borne gNB sends service direct transmission channel establishment information to each other according to the inter-satellite path, and establishes a service transmission channel between the base stations, and at the moment, the satellite-borne gNB does not perform PDCP and SDAP processing on end-to-end service data any more; the PDCP represents a packet data convergence protocol, and the SDAP represents a service data adaptation protocol;

and (2.8) the satellite-borne gNB A and the satellite-borne gNB B reply to the core network that the PDU session modification is completed, and at the moment, the establishment of the direct transmission channel between the UE A and the UE B is completed.

4. The end-to-end communication method of the low earth orbit satellite communication network system of claim 2, wherein the end-to-end session handover comprises the following specific procedures:

(3.2) the source satellite-borne gNB A makes switching judgment according to ephemeris and information reported by the UE A, and simultaneously initiates a switching notification to the satellite-borne gNB B to ensure that the UE A and the UE B are synchronous during switching;

(3.3) the source satellite-borne gNB A sends 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 a new inter-satellite path for the UE, and replies a confirmation message, wherein the confirmation message contains a switching command for the UE;

(3.5) carrying out downlink synchronization on the UE A and a 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 completion message and confirms that the switching process is completed to the target gNB A; the target gNB A confirms that the handover is successful by receiving the RRC reconfiguration complete message; to this end, the target gNB a starts sending data to the UE a;

(3.7) after receiving the handover 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;

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

5. The end-to-end communication method of the low earth orbit satellite communication network system of claim 1, wherein the end-to-end service session release specifically comprises the following steps:

(4.1) the UE A initiates a release Request T2T Direct Transfer Request for establishing an end-to-end Direct transmission service to the UE B to the T2 TAF;

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