Method for testing switching delay of air-ground data link of air telecommunication network based on LISP protocol
By building a test platform for air-to-ground data link switching in aviation telecommunications networks based on the LISP protocol in the laboratory, the problems of long time consumption and high cost in existing technologies have been solved, realizing an efficient and low-cost testing method, providing accurate test data support, and promoting the digital and intelligent development of civil aviation communication networks.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- THE SECOND RES INST OF CIVIL AVIATION ADMINISTRATION OF CHINA
- Filing Date
- 2025-02-20
- Publication Date
- 2026-05-15
AI Technical Summary
Existing technologies are time-consuming, require complex equipment, and are expensive to conduct latency tests on air-to-ground data link handover in aviation telecommunications networks, making it difficult to meet the requirements of the International Civil Aviation Organization.
A test method for handover latency of air-to-ground data links in aviation telecommunications networks based on the LISP protocol is adopted. By building a test platform in a laboratory environment, using computers, routers and channel simulators, the handover process of air-to-ground communication links is simulated. By combining LISP and OSPF protocol configurations, the signal transmission environment during flight is accurately simulated, and the handover latency is calculated by capturing packets from the router.
It enables efficient and low-cost testing, allowing for rapid completion of ground-to-air data link switching latency tests in the laboratory. This reduces the consumption of human and material resources, provides accurate test data support, and promotes the digitalization and intelligentization of civil aviation communication networks.
Smart Images
Figure CN120050214B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of civil aviation communications and is applied in a laboratory testing environment, specifically a method for testing the handover delay of air-to-ground data links in aviation telecommunications networks based on the LISP protocol. Background Technology
[0002] In the future concept of Air Traffic Management (ATM), to improve safety, airspace capacity, and flight efficiency, the exchange of data between the ground and aircraft will significantly increase, primarily including Air Traffic Services (ATS) and Airline Operations Communications (AOC). IP-based Aeronautical Telecommunications Networks (ATN / IPS) will become the new standard for future ATM infrastructure, enabling technologies such as… Figure 1 The IP "end-to-end" communication shown will gradually replace the current civil aviation communication network based on ACARS and the Airborne Telecommunications Network Open Systems Interconnection (ATN / OSI) protocol. This Future Communications Infrastructure (FCI) will enable the digital transmission of flight-critical data and voice communications between aircraft and ground-based ATMs in a resilient, secure, and timely manner, and will achieve higher communication capacity and speed by building a multi-link environment through the proposed future data links at airports, ground, air, and satellite.
[0003] Multilink operation is a data link usage concept that refers to the simultaneous use of at least two independent air-to-ground (A / G) data links to meet the requirements of flight ATS services in terms of mobility, safety, and quality of service (QoS). Multilink operation applies to all airspace except for the Ocean Extremes (ORP) area. Multilink operation also involves selecting the most suitable radio link for a given data service and seamlessly switching between available data links based on the quality of the currently used A / G data link or user preference settings.
[0004] LISP (Locator / ID Separation Protocol) provides a novel network architecture that divides IP addresses into RLOC (Routing Locator) addresses, indicating location, and EID (Endpoint Identifier) addresses, indicating identity. RLOC addresses are used for forwarding in the core network, while at the customer network edge, the outer IP address is stripped away, and the EID address is used for forwarding. Ground-based LISP civil aviation communication networks provide a solution for multi-link operations, minimizing aircraft complexity and air-to-ground data link overhead, enabling seamless switching between available data links, and maintaining communication continuity during high-speed aircraft movement.
[0005] Whether the handover latency of the air-to-ground data link in ATN / IPS can meet the relevant requirements of the International Civil Aviation Organization (ICAO) requires long-term testing and verification. Traditional testing methods involve installing ground base stations for various communication systems along the flight route and conducting flight tests using airborne terminals mounted on the aircraft. This process is time-consuming, involves complex equipment installation, and is expensive, resulting in significant resource expenditure in terms of manpower and materials. Therefore, designing a more efficient and cost-effective method for testing the handover latency of the air-to-ground data link has become a key focus for those skilled in the art. Summary of the Invention
[0006] Based on the current state of the technology, the purpose of this invention is to solve the problems of long testing times, complex equipment, and high costs associated with existing air-to-ground data link handover latency testing methods for aviation telecommunications networks based on actual flight conditions. Therefore, this invention proposes a method for testing air-to-ground data link handover latency based on the LISP protocol. This invention allows testing to be completed in a laboratory environment. By combining communication and network equipment, the testing process is highly efficient and cost-effective, thus providing sufficient test data support for the construction of next-generation civil aviation communication networks, saving human resources, avoiding time waste, and promoting the digital and intelligent air traffic control construction in the civil aviation field.
[0007] The present invention employs the following technical solutions to achieve its objective:
[0008] A method for testing the handover latency of air-to-ground data links in aviation telecommunications networks based on the LISP protocol, the method comprising the following steps:
[0009] S1. Build a test platform based on computers, routers, and channel simulators; the test platform includes corresponding equipment and subnets for at least two air-to-ground communication systems that implement link switching operations.
[0010] S2. For the various types of routers in the test platform, configure the LISP and OSPF protocols accordingly, and determine the preferred and alternative air-to-ground communication links.
[0011] S3. Configure the channel simulator to simulate the signal transmission environment during flight; connect the corresponding equipment of each air-to-ground communication system to the channel simulator;
[0012] S4. Activate the air-to-ground communication system corresponding to the preferred air-to-ground communication link and simulate the process of the ground station sending test data to the aircraft through computer simulation.
[0013] S5. Shut down the air-to-ground communication system corresponding to the preferred air-to-ground communication link, and the air-to-ground communication system corresponding to the alternative air-to-ground communication link will automatically switch and generate test data.
[0014] S6. Capture the data packets corresponding to the primary air-to-ground communication link when it is closed and the backup air-to-ground communication link is successfully switched using the router packet capture method, and calculate the air-to-ground data link switching delay.
[0015] Furthermore, the test platform built in step S1 includes an aircraft terminal, at least two air-to-ground communication systems, an ATN / IPS main network, and an AOS / ATS server. Each air-to-ground communication system includes an airborne terminal and a ground station terminal connected via a channel simulator. The aircraft terminal and the AOS / ATS server are each equipped with a corresponding computer and router, and the ATN / IPS main network is equipped with a router network. The aircraft terminal is connected to each air-to-ground communication system, each air-to-ground communication system is connected to the ATN / IPS main network, and the ATN / IPS main network is connected to the AOS / ATS server.
[0016] Specifically, in each air-to-ground communication system, radio frequency cables are used to connect the airborne end to the channel simulator, and the channel simulator to the ground station end; on the aircraft end, the ATN / IPS main network and the AOS / ATS server end, network cables are used to connect the corresponding computers and routers.
[0017] Specifically, the aircraft end is constructed through a first computer and a correspondingly configured airborne router, and the airborne router is connected to the airborne end of each air-to-ground communication system.
[0018] Specifically, each air-to-ground communication system has a ground subnet consisting of subnet routers and border routers. The ground station of each air-to-ground communication system is connected to at least one subnet router in the corresponding ground subnet. Each air-to-ground communication system is connected to the ATN / IPS main network through the border router in the corresponding ground subnet.
[0019] Specifically, the ATN / IPS mainnet is constructed using multiple mainnet routers and at least one MS / MR router; the MS / MR router is used as a LISP mapping server; the ATN / IPS mainnet is connected to the AOS / ATS server through the mainnet routers.
[0020] Specifically, the AOS / ATS server is constructed through a second computer and a correspondingly configured border router, which is connected to the main network router in the ATN / IPS main network.
[0021] Furthermore, in step S2, firstly, the LISP protocol is configured on the boundary routers of the ground subnets and the boundary routers in the AOS / ATS server of each air-to-ground communication system, and then the LISP protocol is configured on the MS / MR routers in the ATN / IPS main network. After the configuration is completed, the EID addresses of the aircraft and the AOS / ATS server are set, and the preferred air-to-ground communication link and the alternative air-to-ground communication link are determined and set. At the same time, the OSPF protocol is configured in the subnet routers and the main network routers.
[0022] Preferably, in step S3, the flight trajectory coordinate data of the aircraft used for simulation testing is generated by computer software used in conjunction with the channel simulator and imported into the channel simulator; the configuration parameters of the channel simulator are modified according to the characteristics of the air-to-ground signal transmission environment required for the simulation test, and then the channel simulator is connected to each air-to-ground communication system simultaneously.
[0023] Furthermore, in step S4, test data is generated by the second computer configured in the AOS / ATS server and transmitted through the air-to-ground communication system corresponding to the preferred air-to-ground communication link to simulate the process of the AOS / ATS server sending data to the aircraft; then in step S5, the air-to-ground communication system corresponding to the alternative air-to-ground communication link performs an automatic switching operation when the preferred air-to-ground communication link is closed.
[0024] In step S6, the time t1 when the preferred air-to-ground communication link is shut down is recorded. Simultaneously, packet capture is performed on the MS / MR routers in the ATN / IPS main network, and the time t2 of the data packet corresponding to the shutdown of the preferred air-to-ground communication link is recorded, yielding the shutdown delay T1 = t2 - t1. Then, when the alternative air-to-ground communication link is successfully switched over, packet capture is performed on the MS / MR routers in the ATN / IPS main network, and the time t3 of the data packet corresponding to the successful switch is recorded, yielding the first switching delay T2 = t3 - t2. Subsequently, when the AOS / ATS server receives data after the successful switch, packet capture is performed on the border routers in the AOS / ATS server, and the time t4 of the data packet corresponding to the data reception is recorded, yielding the second switching delay T4 = t4 - t3. Thus, the switching delay T = T1 + T2 + T3 for switching from the preferred air-to-ground communication link to the alternative air-to-ground communication link is calculated.
[0025] In summary, due to the adoption of this technical solution, the beneficial effects of this invention are as follows:
[0026] The testing method of this invention is highly flexible, allowing for dynamic adjustment of the number of network nodes according to testing requirements. Furthermore, by utilizing a channel simulator, the real-world environment of air-to-ground data propagation can be accurately simulated; different propagation environments can be simulated simply by changing relevant parameters. This method enables testers to select different systems under test according to actual needs, quickly build a test network that meets the requirements, and thus efficiently and accurately test the handover latency of air-to-ground data links in various environments.
[0027] Compared to traditional testing methods, this invention significantly reduces testing costs and time. Traditional methods typically require deploying ground base stations for various communication systems on the ground and conducting tests via actual flights with onboard terminals, each test costing hundreds of thousands of yuan and taking a considerable amount of time. Using the method of this invention, all necessary testing can be completed in a laboratory environment, avoiding not only the high costs of flight testing but also saving significant time and resources.
[0028] The computers, communication, and network equipment used in this invention are all standard products that can be directly purchased from the market, and their reliability has been widely verified. Furthermore, all parameters required for flight trajectory modeling and transmission channel simulation are supported by a solid theoretical foundation, ensuring the effectiveness and feasibility of the entire testing process. The network protocol configuration also follows common standards, making the testing process easy to implement. Attached Figure Description
[0029] Figure 1 A schematic diagram of the future ATN / IPS aviation telecommunications network;
[0030] Figure 2 This is a simplified flowchart of the overall testing method of the present invention;
[0031] Figure 3 This is a schematic diagram of the test platform built for this invention;
[0032] Figure 4 This is a schematic diagram illustrating the data link switching process in the method of the present invention.
[0033] Figure 5 This is a schematic diagram of Map-Register drop IP packets in an embodiment of the present invention;
[0034] Figure 6 This is a schematic diagram of the Map-Register IP packet in an embodiment of the present invention;
[0035] Figure 7 This is a schematic diagram of a Map-Reply IP packet in an embodiment of the present invention. Detailed Implementation
[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0037] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.
[0038] Example
[0039] A method for testing the handover latency of air-to-ground data links in aviation telecommunications networks based on the LISP protocol. Figure 2 The overall process of this method is briefly described, and its steps can be summarized as follows:
[0040] S1. Build a test platform based on computers, routers, and channel simulators; the test platform includes corresponding equipment and subnets for at least two air-to-ground communication systems that implement link switching operations.
[0041] S2. For the various types of routers in the test platform, configure the LISP and OSPF protocols accordingly, and determine the preferred and alternative air-to-ground communication links.
[0042] S3. Configure the channel simulator to simulate the signal transmission environment during flight; connect the corresponding equipment of each air-to-ground communication system to the channel simulator;
[0043] S4. Activate the air-to-ground communication system corresponding to the preferred air-to-ground communication link and simulate the process of the ground station sending test data to the aircraft through computer simulation.
[0044] S5. Shut down the air-to-ground communication system corresponding to the preferred air-to-ground communication link, and the air-to-ground communication system corresponding to the alternative air-to-ground communication link will automatically switch and generate test data.
[0045] S6. Capture the data packets corresponding to the primary air-to-ground communication link when it is closed and the backup air-to-ground communication link is successfully switched using the router packet capture method, and calculate the air-to-ground data link switching delay.
[0046] This embodiment will provide detailed examples of the various aspects of the above method, which is applicable to various civil aviation communication systems. In this embodiment, a Very High Frequency (VHF) radio and an L-band Digital Aviation Communication System (L-DACS) are used as examples. The VHF radio corresponds to... Figure 3 The test platform shown includes air-to-ground communication system 1 and L-DACS system corresponding to air-to-ground communication system 2. In the test, a VHF radio is selected as the primary air-to-ground communication link, and data is transmitted to the aircraft via a computer-simulated AOS / ATS server. The link corresponding to the VHF radio, as the primary air-to-ground communication link, is manually disconnected, and then automatically switches to the L-DACS system's air-to-ground communication link. The time from the link disconnection error to the corresponding router updating the EID-to-RLOC path and caching it in the LISP mapping server is calculated to test the air-to-ground data link switching latency. (See [link to relevant documentation]). Figure 4 The illustration.
[0047] like Figure 3 As shown, this embodiment uses the following device and configuration information as an example.
[0048] The aircraft is simulated by computer LIVM1 with IP address set to 10.1.1.5; R1 is the airborne router with IP address set to 10.1.1.1.
[0049] The air-to-ground data link consists of airborne and ground station equipment from two air-to-ground communication systems, as well as a channel simulator, to simulate the real propagation of civil aviation air-to-ground data.
[0050] In the ground subnet of the air-to-ground communication system 1, the specific configuration of multiple routers is as follows: R2 is an access router with an IP address of 192.168.22.1; R3 and R4 are border routers (xTR) with IP addresses of 192.168.23.1 and 192.168.24.1, respectively.
[0051] In the ground subnet of the air-to-ground communication system 2, the specific configuration of multiple routers is as follows: R5 is an access router with an IP address of 192.168.11.1; R6 is a border router (xTR) with an IP address of 192.168.12.1.
[0052] Multiple main network routers in the ATN / IPS main network include Figure 3R7 to R13 are configured with IP addresses of 10.0.100.1, 10.0.101.1, 10.0.102.1, 10.0.103.1, 10.0.104.1, 10.0.105.1, and 10.0.106.1, respectively; an additional MS / MR router is configured as a LISP mapping server with IP address 10.0.20.1.
[0053] The AOS / ATS server is simulated by a computer LIVM2 with an IP address of 10.2.1.4; R14 is a border router (xTR) with an IP address of 10.2.1.1.
[0054] In this embodiment, the computer can be a personal computer, which is a general off-the-shelf product; the specific model of each router can be H3C MSR2630; and the channel simulator is the Spirent Vertex series of channel simulator products manufactured by Spirent Communications.
[0055] according to Figure 3 Connect each device in the above manner and set the corresponding IP address to build a test platform; in each air-to-ground communication system, use radio frequency cables to connect the airborne end to the channel simulator, and the channel simulator to the ground station end; on the aircraft end, ATN / IPS main network and AOS / ATS server end, use network cables to connect the corresponding computer and router network.
[0056] To configure the LISP protocol for routers R3, R4, R6, and R14, which act as border routers (xTRs), the main configuration commands are as follows:
[0057] Router(config)#system-view
[0058] Router(config)#lisp
[0059] Router(config-lisp)#itr
[0060] Router(config-lisp)#itr map-resolver 10.0.20.1
[0061] Router(config-lisp)#etr
[0062] Router(config-lisp)#database-mapping XXXX XXXX priority Xweight X
[0063] (R3 fills in 192.168.23.1 10.0.100.5priority 30weight 30;
[0064] Enter 192.168.24.1 10.0.101.5 priority 20 weight 20 in R4;
[0065] Enter 192.168.12.1 10.0.102.5 priority 10 weight 10 in R6;
[0066] R14 should be entered as 10.2.1.1 10.0.105.5 (priority 10, weight 10).
[0067] Router(config-lisp)#etr map-server 10.0.20.1authentication-mode sha-1authentication-key plaintext 123456
[0068] Router(config-lisp)#quit
[0069] Next, configure the MS / MR router, which acts as the LISP mapping server, with the aircraft's EID set to AIR and the AOS / ATS server's EID set to ATS. The preferred air-to-ground communication link (EID-to-RLOC) is set to the data link corresponding to the VHF radio (i.e., via subnet router R3). The main configuration commands are as follows:
[0070] Router(config)#system-view
[0071] Router(config)#lisp
[0072] Router(config-lisp)#map-resolver
[0073] Router(config-lisp)#map-server
[0074] Router(config-lisp)#site A
[0075] Router(config-lisp-site-A)#authentication-mode sha-1authentication-key plaintext 123456
[0076] Router(config-lisp-site-A)#eid-prefix 10.1.1.5AIR
[0077] Router(config-lisp-site-A)#eid-prefix 10.2.1.4ATS
[0078] Router(config-lisp-site-A)#database-mapping AIR 192.168.23.1priority30
[0079] Router(config-lisp-site-A)#quit
[0080] Router(config)#quit
[0081] Next, configure the OSPF (Open Shortest Path First) protocol on the routers in the ground subnet and ATN / IPS mainnet of the air-to-ground communication system. The main configuration commands are as follows:
[0082] Router(config)#router ospf[process-id]
[0083] The above process completes steps S1 and S2 of the method. Next, we proceed to step S3.
[0084] The dedicated software tools included with the Spirent Vertex channel simulator are used to generate the aircraft's flight trajectory coordinate data, which is then imported via a USB-RS232 / RJ45 cable.
[0085] Based on the characteristics of the air-to-ground signal transmission environment required for simulation testing, parameters such as path loss, multipath effect, and Doppler shift are set to ensure accurate simulation of signal transmission during flight.
[0086] The VHF radio transceiver and the airborne and ground station ends of the L-DACS system are respectively connected to the two bidirectional channels of the channel simulator.
[0087] The following is a detailed description of steps S4 to S6 in the method.
[0088] Data transmission: Test data is sent to the aircraft via computer LIVM2, simulating the AOS / ATS server.
[0089] Link switching: Close the data link corresponding to the VHF radio station and record the closing time t1.
[0090] Calculate the "Map-Register drop" time for the data link corresponding to the VHF radio station: Capture packets of the received data at the MS / MR router to confirm that the MS / MR router has received the register drop IP packet sent by router R3 or R4 (e.g., Figure 5 As shown in the figure, record the time t2 at this moment. Then the time taken for the VHF radio's data link "Map-Register drop" is T1 = t2 - t1.
[0091] Calculate the data link "Map-Register" time for the L-DACS system: Capture packets of received data at the MS / MR router to confirm that the MS / MR router has received the register IP packet sent by router R6 (e.g., Figure 6 As shown in the figure, record the time t3 at this moment. Then the data link "Map-Register" time of the L-DACS system is T2 = t3 - t2.
[0092] Calculate the data link "Map-Reply" timeout for the L-DACS system: Capture packets at router R14 to confirm that router R14 has received the Map-Reply IP packet sent by router R6 (e.g., ...). Figure 7 As shown in the figure, record the time t4 at this moment. Then, the time taken for the data link corresponding to the L-DACS system to update the EID-to-RLOC path is T3 = t4 - t3.
[0093] Through the above calculation process, the complete handover delay from the data link corresponding to the VHF radio station to the data link corresponding to the L-DACS system is T = T1 + T2 + T3, thereby realizing the handover delay test of the air-to-ground data link in the aviation telecommunications network based on the LISP protocol.
Claims
1. A method for testing the handover latency of air-to-ground data links in aviation telecommunications networks based on the LISP protocol, characterized in that, The method includes the following steps: S1. Build a test platform based on computers, routers, and channel simulators; the test platform includes corresponding equipment and subnets for at least two air-to-ground communication systems that implement link switching operations. S2. For the various types of routers in the test platform, configure the LISP and OSPF protocols accordingly, and determine the preferred and alternative air-to-ground communication links. S3. Configure the channel simulator to simulate the signal transmission environment during flight; connect the corresponding equipment of each air-to-ground communication system to the channel simulator; S4. Activate the air-to-ground communication system corresponding to the preferred air-to-ground communication link and simulate the process of the ground station sending test data to the aircraft through computer simulation. S5. Shut down the air-to-ground communication system corresponding to the preferred air-to-ground communication link, and the air-to-ground communication system corresponding to the alternative air-to-ground communication link will automatically switch and generate test data. S6. Capture the data packets corresponding to the primary air-to-ground communication link when it is closed and the backup air-to-ground communication link is successfully switched using the router packet capture method, and calculate the air-to-ground data link switching delay.
2. The method for testing the handover delay of air-to-ground data links in aviation telecommunications networks based on the LISP protocol according to claim 1, characterized in that: The test platform built in step S1 includes an aircraft terminal, at least two air-to-ground communication systems, an ATN / IPS main network, and an AOS / ATS server. Each air-to-ground communication system includes an airborne terminal and a ground station terminal connected through a channel simulator. The aircraft terminal and the AOS / ATS server are each equipped with a corresponding computer and router, and the ATN / IPS main network is equipped with a router network. The aircraft terminal is connected to each air-to-ground communication system, each air-to-ground communication system is connected to the ATN / IPS main network, and the ATN / IPS main network is connected to the AOS / ATS server.
3. The method for testing the handover delay of air-to-ground data links in aviation telecommunications networks based on the LISP protocol according to claim 2, characterized in that: In each air-to-ground communication system, radio frequency cables are used to connect the airborne end to the channel simulator, and the channel simulator to the ground station end; on the aircraft end, the ATN / IPS main network and the AOS / ATS server end, network cables are used to connect the corresponding computer and router network.
4. The method for testing the handover delay of air-to-ground data links in aviation telecommunications networks based on the LISP protocol according to claim 2, characterized in that: The aircraft-side is constructed through a first computer and a correspondingly configured airborne router, which is connected to the airborne end of each air-to-ground communication system.
5. The method for testing the handover delay of air-to-ground data links in aviation telecommunications networks based on the LISP protocol according to claim 2, characterized in that: Each air-to-ground communication system has a ground subnet consisting of subnet routers and border routers. The ground station of each air-to-ground communication system is connected to at least one subnet router in the corresponding ground subnet. Each air-to-ground communication system is connected to the ATN / IPS main network through the border router in the corresponding ground subnet.
6. The method for testing the handover delay of air-to-ground data links in aviation telecommunications networks based on the LISP protocol according to claim 5, characterized in that: The ATN / IPS mainnet is constructed using multiple mainnet routers and at least one MS / MR router; the MS / MR router is used as a LISP mapping server; the ATN / IPS mainnet is connected to the AOS / ATS server through the mainnet routers.
7. The method for testing the handover delay of air-to-ground data links in aviation telecommunications networks based on the LISP protocol according to claim 2, characterized in that: The AOS / ATS server is constructed through a second computer and a correspondingly configured border router, which is connected to the main network router in the ATN / IPS main network.
8. The method for testing the handover delay of air-to-ground data links in aviation telecommunications networks based on the LISP protocol according to claim 6, characterized in that: In step S2, firstly, the LISP protocol is configured on the boundary routers of the ground subnets and the boundary routers in the AOS / ATS server of each air-to-ground communication system. Then, the LISP protocol is configured on the MS / MR routers in the ATN / IPS main network. After the configuration is completed, the EID addresses of the aircraft and the AOS / ATS server are set, and the preferred air-to-ground communication link and the alternative air-to-ground communication link are determined and set. At the same time, the OSPF protocol is configured in the subnet routers and the main network routers.
9. The method for testing the handover delay of air-to-ground data links in aviation telecommunications networks based on the LISP protocol according to claim 1, characterized in that: In step S3, the flight trajectory coordinate data of the aircraft used for simulation testing is generated by computer software used in conjunction with the channel simulator and imported into the channel simulator; the configuration parameters of the channel simulator are modified according to the characteristics of the air-to-ground signal transmission environment required for the simulation test, and then the channel simulator is connected to each air-to-ground communication system simultaneously.
10. The method for testing the handover delay of air-to-ground data links in aviation telecommunications networks based on the LISP protocol according to claim 2, characterized in that: In step S4, test data is generated by the second computer configured in the AOS / ATS server and transmitted through the air-to-ground communication system corresponding to the preferred air-to-ground communication link, simulating the process of the AOS / ATS server sending data to the aircraft. Then proceed to step S5, where the air-to-ground communication system corresponding to the alternative air-to-ground communication link performs an automatic switching operation when the preferred air-to-ground communication link is closed. In step S6, the time t1 corresponding to the air-to-ground communication system corresponding to the primary air-to-ground communication link is recorded. At the same time, packets are captured on the MS / MR router in the ATN / IPS main network, and the time t2 corresponding to the primary air-to-ground communication link being closed is recorded. The closing delay T1 = t2 - t1 is obtained. Immediately after the successful handover of the alternative air-to-ground communication link, packet capture is performed on the MS / MR router in the ATN / IPS main network, and the time t3 of the data packet corresponding to the successful handover is recorded to obtain the first handover delay T2 = t3 - t2; subsequently, when the AOS / ATS server receives data after the successful handover, packet capture is performed on the border router in the AOS / ATS server, and the time t4 of the data packet corresponding to the data reception is recorded to obtain the second handover delay T4 = t4 - t3; Therefore, the handover delay T = T1 + T2 + T3 is calculated to be the handover time from the preferred air-to-ground communication link to the alternative air-to-ground communication link.