Adaptive link management method and system based on satellite mobile communication

Abstract

An adaptive link management method and system based on satellite mobile communication employs a PPP-based UDP protocol for initial link negotiation. Network address and other information are exchanged through link establishment request and confirmation signaling interactions. Network segment relationships are determined based on address information: GRE encapsulation with proxy ARP assistance is used for same network segments, while standard GRE encapsulation is used for different network segments. Link endpoint identifiers are negotiated and a bidirectional transmission link is established under the selected encapsulation mode. After link establishment, both parties periodically exchange keep-alive signaling to maintain connectivity. Simultaneously, the status of connected local access devices is monitored, and information is synchronized according to a preset period and / or status changes to dynamically update the transmission path and perform IP address conflict detection and handling. The transmission link is released normally through link release signaling. This scheme improves link adaptability and bandwidth utilization, effectively prevents address conflicts, and thus enhances network reliability.

Description

Technical Field

[0001] This invention relates to the field of mobile satellite communications, and in particular to an adaptive link management method and system based on satellite mobile communications. Background Technology

[0002] PPP, as a classic point-to-point link protocol, is widely used in narrowband communication, especially in satellite mobile communication systems. Satellite communication offers advantages such as wide coverage and flexible deployment, but it also suffers from limited bandwidth, high transmission latency, and susceptibility to link jitter. In practical network deployment, satellite PPP links are typically used to connect different terrestrial local area networks, enabling cross-link data exchange.

[0003] Currently, there are many types of encapsulation and routing protocols used for cross-satellite link data transmission. Many of these solutions rely heavily on manual configuration, which is not only cumbersome but also difficult to adapt to use cases where IP network segments change dynamically (e.g., standard GRE encapsulation). In addition, some protocol messages or protocols themselves have high overhead, which can easily lead to resource loss and affect the overall transmission performance in satellite links with limited bandwidth (e.g., VXLAN protocol messages, OSPF, RIP, and other routing protocols).

[0004] Meanwhile, traditional satellite link transmission schemes still have many shortcomings: the link establishment phase lacks a complete automated signaling interaction mechanism, making it impossible to automatically complete the information exchange between the network interfaces at both ends; the encapsulation mode needs to be manually selected based on network segment relationships, resulting in insufficient adaptability and difficulty in matching the networking requirements of flexible ground terminal access locations and varied network segments; these schemes generally cannot monitor the online status of backend access devices in real time, and the transmission path remains static for a long time, easily leading to idle and wasted bandwidth resources; and they generally do not have a cross-link address conflict detection mechanism, making it difficult to troubleshoot IP address duplication issues, which poses a hidden danger to the stable operation of the network. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing satellite link transmission schemes, such as insufficient adaptive capability, inability to monitor the status of access devices in real time, lack of cross-link address conflict detection mechanism, and insufficient network operation stability. This invention proposes an adaptive link management method and system based on satellite mobile communication, which enhances the adaptive performance of transmission links, improves bandwidth utilization, effectively avoids IP address conflict risks, and improves the reliability of network operation.

[0006] The present invention adopts the following technical solution:

[0007] An adaptive link management method based on satellite mobile communication includes:

[0008] The first satellite communication terminal and the second satellite communication terminal completed the initial link negotiation based on the UDP protocol of PPP, and exchanged network address information through the interaction of link establishment request and confirmation signaling.

[0009] The network segment relationship is determined based on the exchanged network address information. If they are the same network segment, the GRE encapsulation transmission mode assisted by proxy ARP is selected; if they are different network segments, the standard GRE encapsulation transmission mode is selected. The link endpoint identifier is determined through negotiation based on the corresponding encapsulation mode, and a bidirectional transmission link is established.

[0010] After the transmission link is established, each satellite communication terminal periodically exchanges link keep-alive signaling to maintain the connectivity of the transmission link;

[0011] Monitor the status of the local access devices connected to each satellite communication terminal, synchronize status information according to a preset period and / or when the status of the local access devices changes, dynamically update the transmission path, and perform address conflict detection and processing;

[0012] When the transmission task ends, the transmission link is released normally via a link release signaling.

[0013] The first satellite communication terminal sends a link establishment request signaling to the second satellite communication terminal. After receiving the request, the second satellite communication terminal returns a link establishment confirmation signaling. Both signals carry their respective network address information. The two parties then exchange information to obtain the other party's network address information and complete the initial link negotiation.

[0014] The network address information includes the IP address of the ground network interface. In step S2, it is determined whether the two ground network interface IP addresses obtained from the interaction belong to the same network segment.

[0015] The network address information includes the PPP network port IP address; when selecting the proxy ARP-assisted GRE encapsulation transmission mode, the first satellite communication terminal and the second satellite communication terminal respectively input their own PPP network port IP address into the MD5 hash function, perform a modulo operation on a specified number of bits of the resulting hash value, and then map the operation result to the preset point-to-point subnet range to negotiate and determine the link endpoint identifier; the preset point-to-point subnet is pre-configured with a point-to-point dedicated subnet mask.

[0016] The first satellite communication terminal and the second satellite communication terminal complete communication addressing based on the point-to-point dedicated subnet mask and the acquired peer PPP network port IP address, and achieve endpoint pairing based on the negotiated link endpoint identifier, thereby establishing a bidirectional transmission link.

[0017] During the operation of the transmission link, the first satellite communication terminal and the second satellite communication terminal periodically send link keep-alive signaling to each other and receive keep-alive responses returned by the other end; if either party fails to receive a keep-alive response multiple times in a row, the transmission link is determined to be abnormal and the transmission link reconstruction is re-executed.

[0018] When any satellite communication terminal needs to disconnect, the satellite communication terminal sends a link release signal to complete the normal release of the transmission link.

[0019] Each satellite communication terminal utilizes the address resolution cache generated during the communication process to monitor the status of local access devices using a combination of passive listening and active probing. Specifically:

[0020] Each satellite communication terminal periodically detects the activity status of the local access device and extracts the terrestrial network interface IP address of the local access device to form a candidate IP set;

[0021] The status of IP addresses in the candidate IP set is verified by probing signaling, and the device activity status is determined by a multi-confirmation anti-jitter mechanism. For IP addresses determined to be offline, the corresponding address resolution cache entries are deleted.

[0022] At a preset period and / or when the status of the local access device changes, the satellite communication terminal connected to the local access device generates a status signaling message and sends it to the peer satellite communication terminal through the transmission link; after receiving the status signaling message, the peer satellite communication terminal performs the following processing:

[0023] For the local access device corresponding to the status signaling message, if the device is online, a corresponding entry is added to the forwarding table of this satellite communication terminal; if the device is offline, the corresponding entry is deleted from the forwarding table.

[0024] The ground network interface IP address in the status signaling message is compared with the set of active local access device IP addresses stored in the satellite communication terminal. If there is a duplicate IP address, it is determined that an address conflict has occurred, and at least one of the conflict alarm, blocking policy and priority policy is executed.

[0025] When the local access device corresponding to the status signaling message goes offline or its terrestrial network interface IP address is modified, the satellite communication terminal connected to the local access device sends an address release notification to the peer satellite communication terminal via the transmission link through the UDP protocol. After receiving the notification, the peer satellite communication terminal clears the corresponding conflict record, cancels the processing strategy previously executed due to the address conflict, and restores communication.

[0026] An adaptive link management system based on satellite mobile communication is characterized by comprising multiple satellite communication terminals that communicate via satellite links, wherein each satellite communication terminal is equipped with the following modules:

[0027] The negotiation module is used to complete the initial negotiation with the peer satellite communication terminal based on the PPP UDP protocol, and to exchange information such as network address through link establishment request and confirmation signaling interaction;

[0028] The transmission link establishment module determines the network segment relationship based on the exchanged network address information. If they are the same network segment, it selects the proxy ARP-assisted GRE encapsulation transmission mode. If they are different network segments, it selects the standard GRE encapsulation transmission mode. It negotiates and determines the link endpoint identifier through a hash algorithm, and establishes a bidirectional transmission link after configuring the point-to-point subnet mask.

[0029] The link keep-alive module periodically exchanges link keep-alive signaling with the peer satellite communication terminal after the transmission link is established to maintain the connectivity of the transmission link;

[0030] The status monitoring module monitors the status of the connected local access devices, synchronizes status information according to a preset period and / or when the status of the local access devices changes, dynamically updates the transmission path, and performs address conflict detection and processing.

[0031] The link release module releases the transmission link normally by using a link release signaling when the transmission task ends.

[0032] As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. In this invention, the entire link signaling process, including link establishment request / acknowledgment, network address information exchange, endpoint identifier negotiation, keep-alive detection, and address conflict detection and handling, is completed through the UDP protocol based on PPP. This achieves closed-loop control of link establishment, maintenance, and anomaly handling, and can automatically select the optimal encapsulation mode based on the real-time network status and quickly respond to link anomalies, thereby improving the overall reliability and stability of network operation.

[0034] 2. In this invention, the system automatically determines whether the two parties are in the same network segment based on the exchanged network address information, and then adaptively selects either proxy ARP-assisted GRE or standard GRE encapsulation mode. The GRE used employs lightweight encapsulation and combines it with a monitoring strategy that prioritizes address resolution caching to minimize protocol overhead and maximize bandwidth utilization.

[0035] 3. In this invention, an algorithm is used to map the MD5 hash modulo to a preset point-to-point subnet, which ensures that the same pair of satellite communication terminals can always negotiate a consistent subnet address during the establishment of the transmission link, thereby guaranteeing the determinism of the endpoint identifier; the design based on this subnet mask can achieve high address utilization and save IP identifier space.

[0036] 4. In this invention, low-overhead UDP keep-alive signaling is used, combined with a jitter prevention mechanism that confirms multiple times consecutively. This enables reliable determination of whether the link is still connected even when there is significant jitter in the transmission link. If the keep-alive response from the other end is not received for several consecutive times, the link re-establishment process is automatically initiated, thereby achieving rapid recovery after the link is abnormal and reducing the possibility of service interruption.

[0037] 5. This invention provides three address conflict detection methods: active synchronization mode, passive detection mode, and hybrid mode. Active synchronization mode synchronizes the local active IP set to the peer according to a preset period, achieving periodic conflict checking. Passive detection mode immediately queries the peer for identical IPs when the terminal device comes online, thereby quickly capturing new conflicts. The hybrid mode combines the above two modes, balancing integrity and real-time performance. This multi-mode collaboration provides flexible conflict detection methods, helping to promptly detect and handle IP duplication, thereby reducing the risk of cross-link routing anomalies and improving the operational reliability of satellite links.

[0038] 6. In this invention, the information required for transmission parameter updates, status synchronization, and address conflict detection is uniformly encapsulated in a single UDP status signaling message and sent, thereby achieving appropriate compression of signaling volume and reduction of round-trip latency, thus improving the bandwidth utilization and processing efficiency of the link while maintaining functional integrity.

[0039] 7. In this invention, when the local access device goes offline or its IP address changes, the satellite communication terminal sends an address release notification to the peer via UDP packets. After receiving the notification, the peer automatically clears the corresponding conflict records and cancels the restrictive measures previously taken to resolve the conflict, thereby eliminating residual conflicts and restoring normal communication. In addition, when any terminal needs to terminate the link, it can also send a link release signaling to achieve orderly closure of the link and avoid resource occupation or abnormalities caused by unfinished session residues. Attached Figure Description

[0040] Figure 1 This is the main flowchart of the method of the present invention;

[0041] Figure 2 A flowchart illustrating the signaling interaction process for establishing a transmission link in the method of this invention;

[0042] Figure 3Flowchart for selecting adaptive transmission encapsulation mode for satellite links;

[0043] Figure 4 This is a schematic diagram of the channel endpoint identifier negotiation of the present invention;

[0044] Figure 5 Flowchart for local access device status monitoring and link status synchronization;

[0045] Figure 6 A schematic diagram of the mechanism to prevent state jitter;

[0046] Figure 7 Flowchart for updating the transmission path selection strategy;

[0047] Figure 8 This is a diagram showing the format of a status signaling message;

[0048] Figure 9 Flowchart for handling IP address conflicts;

[0049] Figure 10 This is a state transition diagram;

[0050] Figure 11 Diagram of multi-terminal network architecture;

[0051] Figure 12 This is a block diagram of the hardware components of a satellite communication terminal.

[0052] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Detailed Implementation

[0053] The present invention will be further described below through specific embodiments.

[0054] This embodiment proposes an adaptive link management method based on satellite mobile communication. (See [link to relevant documentation]). Figure 1 and Figure 2 This includes the following steps:

[0055] The first satellite communication terminal and the second satellite communication terminal in S1 complete the initial link negotiation based on the UDP protocol of PPP, and exchange information such as network addresses through signaling interactions such as link establishment request and confirmation.

[0056] Among them, the first satellite communication terminal and the second satellite communication terminal are PPP satellite communication terminals, which operate in accordance with the PPP point-to-point link protocol and can realize end-to-end signaling interaction through the satellite link. The specific initial link negotiation includes the following:

[0057] The first satellite communication terminal sends a link establishment request signaling to the second satellite communication terminal. Upon receiving the request, the second satellite communication terminal returns a link establishment confirmation signaling. Both signals carry their respective network address information. Based on this, the two parties exchange information to obtain the other party's network address information and complete the initial link negotiation. The network address information includes at least the local PPP network interface IP address and the local terrestrial network interface IP address.

[0058] In this step, after the interaction is completed with the help of signaling carrying network address information, both parties know the PPP network port IP address and the terrestrial network interface IP address of the other party, which provides reliable data support for subsequent automatic identification of network segments and adaptive selection of appropriate data encapsulation modes.

[0059] S2 determines the network segment relationship based on the exchanged network address information. If they are the same network segment, it selects the proxy ARP-assisted GRE encapsulation transmission mode; if they are different network segments, it selects the standard GRE encapsulation transmission mode. Based on the corresponding encapsulation mode, it negotiates and determines the link endpoint identifier and establishes a bidirectional transmission link.

[0060] In this step, see Figure 3 and Figure 4 Based on the IP addresses of the two terrestrial network interfaces obtained in step S1, the network segment affiliation is determined. Based on the determination result, the GRE encapsulation method for the satellite link is adaptively selected, and endpoint identifier negotiation is performed.

[0061] If the IP addresses of the two terrestrial network interfaces are determined to be in the same network segment, a GRE encapsulation transmission mode assisted by proxy ARP is adopted, and the proxy ARP function is enabled. This encapsulation mode uses a proxy APP to achieve Layer 2 addressing and communication between terminals in the same network segment of the GRE tunnel. Under this configuration, the first satellite communication terminal and the second satellite communication terminal respectively input their own PPP network port IP addresses into the MD5 hash function, perform a modulo operation on a specified number of bits in the resulting hash value, and then map the operation result to the preset point-to-point subnet range to negotiate and determine the link endpoint identifier; the preset point-to-point subnet is pre-configured with a point-to-point dedicated subnet mask.

[0062] For example, after taking the last 16 bits of the hash value and performing a modulo operation, the result is mapped to the 169.254.0.0 / 31 subnet range, and the endpoint identifiers at both ends are negotiated and determined. The endpoint identifiers at both ends can be mutually announced via endpoint identifier announcement signaling. A calculation example is shown in Table 1 below:

[0063]

[0064] The two satellite communication terminals obtain their endpoint addresses through MD5 hash calculation based on their respective PPP network port IP addresses. This ensures that regardless of which end of the same pair of satellite communication terminals starts first, the negotiated and generated addresses are always consistent and unique, and the order is independent of the size of the PPP network port IP address, thus preventing address conflicts.

[0065] If the determination result is different network segments, the standard GRE encapsulation transmission mode is adopted. When adopting this mode, the endpoint identifiers of both ends are negotiated and determined by the conventional method of signaling interaction between terminals (such as 10.0.0.1 for end A and 10.0.0.2 for end B). After the negotiation is completed, they are mutually notified through endpoint identifier announcement signaling.

[0066] After both ends complete the adaptive selection of encapsulation mode and the interactive confirmation of link endpoint identifiers, the first and second satellite communication terminals complete communication addressing based on the preset point-to-point dedicated subnet mask and the acquired peer PPP network port IP address, and achieve endpoint pairing based on the negotiated and agreed link endpoint identifiers, thereby establishing a bidirectional transmission link. For example, using 255.255.255.254 corresponding to the / 31 subnet as the point-to-point dedicated subnet mask, this subnet does not require configuration of network address and broadcast address. Compared with the traditional / 30 subnet, it can save identifier space and improve the utilization rate of the limited address range of the satellite link. The advantages of the / 31 subnet are explained in Table 2 below.

[0067]

[0068] After the S3 transmission link is established, each satellite communication terminal periodically exchanges link keep-alive signaling to maintain the connectivity of the transmission link.

[0069] In this embodiment, both parties confirm that the transmission link has entered the working state through the link establishment completion signaling. During the operation of the transmission link, the first satellite communication terminal and the second satellite communication terminal periodically (e.g., every 30 seconds by default) send link keep-alive signaling to each other and receive keep-alive responses returned by the other end to detect the connectivity of the transmission link; if either party fails to receive a keep-alive response multiple times (e.g., 3 times) consecutively, it is determined that the transmission link is abnormal, triggering the transmission link reconstruction process, that is, re-executing steps S1 and S2 to reconstruct the transmission link.

[0070] Examples of link keep-alive configuration parameters corresponding to this embodiment are shown in Table 3 below:

[0071]

[0072] S4 monitors the status of the local access devices connected to each satellite communication terminal, synchronizes status information according to a preset period and / or when the status of the local access devices changes, dynamically updates the transmission path, and performs address conflict detection and processing.

[0073] In this step, each satellite communication terminal uses the address resolution cache generated during the communication process to monitor the status of local access devices using a combination of passive listening and active probing. Specifically:

[0074] Each satellite communication terminal periodically checks the activity status of its local access devices. It can extract the terrestrial network interface IP addresses of the local access devices to form a candidate IP set by periodically reading ARP cache data (e.g., the / proc / net / arp file).

[0075] The status of IP addresses in the candidate IP set is verified by probe signaling, and a multi-confirmation anti-jitter mechanism is used to determine the device's activity status. Multiple consecutive confirmations (default 3) are required before a status change is triggered. For IP addresses determined to be offline, the corresponding address resolution cache entry is deleted. See [link to documentation]. Figure 6 .

[0076] In this embodiment, according to a preset period and / or when the status of the local access device changes, the satellite communication terminal connected to the local access device generates a status signaling message and sends it to the peer satellite communication terminal via the transmission link. The status signaling message includes the following fields: version number, message type, flag bit, sequence number, timestamp, sending device identifier, receiving device identifier, IP address list, and processing strategy. Bit 0 in the flag bit indicates online or offline status, specifically including the key fields in Table 4 below (see Table 4 for details). Figure 8 .

[0077]

[0078] After receiving the status signaling message, the peer satellite communication terminal performs the following processing:

[0079] Transmission path selection parameter update: See Figure 7 For the local access device corresponding to the status signaling message, if the device is online, a corresponding entry will be added to the forwarding table of this satellite communication terminal; if the device is offline, the corresponding entry will be deleted from the forwarding table.

[0080] Address conflict detection and handling: See [link] Figure 9 The system compares the IP address of the ground network interface in the status signaling message with the set of IP addresses of active local access devices stored in the satellite communication terminal. If there is a duplicate IP address, it is determined that an address conflict has occurred, and at least one of the conflict alarm, blocking policy and priority policy is executed.

[0081] Based on the aforementioned status signaling message interaction mechanism, this embodiment configures three address conflict detection working modes:

[0082] The first type is the active synchronization mode, in which each satellite communication terminal generates status signaling messages based on the status of the local access device according to a preset period and sends them to the peer satellite communication terminal through the established transmission link, dynamically updates the transmission path, and performs address conflict detection and processing.

[0083] The second type is passive detection mode. When the status of the local access device changes, the corresponding satellite communication terminal generates a status signaling message based on the status of the local access device and sends it to the peer satellite communication terminal via the established transmission link, dynamically updating the transmission path and performing address conflict detection and handling. See also Figure 5 This is a flowchart of local access terminal status monitoring and link status synchronization in passive detection mode.

[0084] The third type is a hybrid mode, which includes both the active synchronization mode and the passive detection mode mentioned above. It can promptly capture new address conflicts caused by changes in the status of local access devices, and can also rely on periodic synchronization to check for missed conflicts, reducing the risk of routing anomalies and packet forwarding failures caused by duplicate IP addresses across links.

[0085] In this embodiment, in addition to the aforementioned IP reporting and conflict detection logic based on state signaling, three auxiliary signaling interaction mechanisms are also set up: address active query, conflict resolution and recovery, and link active release. The specific implementation is as follows:

[0086] Active address lookup: When it is necessary to actively confirm the existence of a certain IP address, the satellite communication terminal can send an address lookup request signaling to the other end. Upon receiving the lookup request, the other end satellite communication terminal retrieves its own stored set of active IPs of local access devices and replies with the lookup result through an address lookup response signaling.

[0087] Conflict resolution and link status recovery: When the local access device corresponding to the status signaling message goes offline or its terrestrial network interface IP address is modified, the satellite communication terminal connected to the local access device sends an address release notification to the peer satellite communication terminal via UDP signaling through the transmission link; after receiving the address release notification, the peer satellite communication terminal clears the corresponding conflict record, cancels the processing policy previously executed due to the address conflict, and restores communication.

[0088] Link release: When any satellite communication terminal needs to disconnect, the satellite communication terminal sends a link release signal. Both ends complete the cancellation of transmission link parameters and the reclamation of link resources according to the release signal, thus completing the normal release of the transmission link.

[0089] When the S5 transmission task ends, the transmission link is released normally through the link release signaling.

[0090] Based on the aforementioned implementation scheme of establishing a point-to-point transmission link between two satellite communication terminals and completing IP synchronization and conflict detection by relying on status signaling, when the network contains three or more satellite communication terminals, any two groups of satellite communication terminals still independently build transmission links according to the aforementioned transmission link establishment logic; each satellite communication terminal maintains an independent local forwarding table for each communication peer.

[0091] In a multi-terminal networking scenario, N satellite communication terminals independently establish transmission links with each other, forming a mesh topology. The total number of networking links satisfies the formula N×(N-1) / 2. (See also...) Figure 11 Taking a network of three satellite communication terminals as an example, three point-to-point transmission links are formed. Satellite communication terminal A establishes transmission link AB with satellite communication terminal B, satellite communication terminal A establishes transmission link AC with satellite communication terminal C, and satellite communication terminal B establishes transmission link BC with satellite communication terminal C.

[0092] In this multi-terminal networking scenario, address conflict detection still uses the three working modes mentioned above: each satellite communication terminal can generate status signaling messages according to a preset period, or generate status signaling messages immediately when the status of the local access device changes, and broadcast them to all other peer satellite communication terminals in the network using the message format specified above. Relying on periodic reporting, event triggering, or a combination of both, the three address conflict detection mechanisms of active synchronization mode, passive detection mode, and hybrid description are respectively implemented.

[0093] In this embodiment, the message type definitions for the aforementioned various interactive signaling types are shown in Table 5 below:

[0094]

[0095] In Table 5, A refers to the first satellite communication terminal that initiates the request to establish a transmission link, and B is the second satellite communication terminal that it interfaces with.

[0096] In this embodiment, a unified format specification is adopted for the interactive signaling in the above table. All types of signaling messages include a general header (8 bytes) of a length less than the specified length, and its data structure is defined as follows:

[0097] struct signal_header {

[0098] uint8_t version; / / Protocol version number, currently 0x01

[0099] uint8_t type; / / Message type (0x01-0x06)

[0100] uint8_t flags; / / Flags

[0101] uint8_t reserved; / / Reserved field

[0102] uint16_t sequence; / / Sequence number, used for deduplication and sorting.

[0103] uint16_t length; / / Total message length (including header)

[0104] };

[0105] When a satellite communication terminal initiates a transmission link establishment process, it sends a link establishment request signaling to the peer. This link establishment request signaling has a message type identifier of 0x01. This signaling extends the link negotiation parameters on top of the general header, and the specific data structure definition is as follows:

[0106] struct link_setup_req {

[0107] struct signal_header header; / / type=0x01

[0108] uint32_t ppp_ip; / / Local PPP network port IP address (network byte order)

[0109] uint32_t eth0_ip; / / Local terrestrial network interface IP address

[0110] uint32_t timestamp; / / Send timestamp (Unix timestamp, seconds)

[0111] uint16_t keep_alive_interval; / / Recommended keep-alive interval (seconds), default 30

[0112] uint8_t encap_mode_support; / / Bitmap of supported encapsulation modes

[0113] uint8_t reserved2[3]; / / Reserved

[0114] };

[0115] The definitions of each bit in the encapsulation mode support bitmap encap_mode_support are shown in Table 6 below:

[0116]

[0117] After receiving the link establishment request signaling and completing parameter verification, the remote satellite communication terminal replies with a link establishment confirmation signaling. The message type is identified as 0x02, which is used to feedback the link establishment processing result. Its data structure is defined as follows:

[0118] struct link_setup_cfm {

[0119] struct signal_header header; / / type=0x02

[0120] uint32_t ppp_ip; / / Local PPP network port IP address

[0121] uint32_t eth0_ip; / / Local terrestrial network interface IP address

[0122] uint32_t timestamp; / / Send timestamp

[0123] uint16_t keep_alive_interval; / / Recommended keep-alive interval on this end

[0124] uint8_t selected_encap_mode; / / Selected encapsulation mode

[0125] uint8_t result; / / Processing result: 0 = success, 1 = rejection

[0126] uint8_t reject_reason; / / Reason for rejection (only valid when result=1)

[0127] };

[0128] To ensure reliable transmission of various control signals between satellite communication terminals and avoid signaling interaction failures due to link jitter and packet loss, this embodiment adopts a timeout retransmission mechanism that combines real-time RTT estimation and dynamic RTO calculation. At the same time, it configures an exponential backoff retransmission strategy and a maximum retransmission limit to achieve reliable signaling transmission and automatic identification of link faults.

[0129] This embodiment measures and updates the signaling round-trip time (RTT) in real time using a smooth weighted algorithm, and dynamically adjusts the retransmission timeout (RTO) accordingly. It mainly includes the following parameters and steps:

[0130] Initial configuration parameters:

[0131] Initial retransmission timeout RTO: 3000ms (3 seconds);

[0132] Minimum RTO: 1000ms (1 second);

[0133] Maximum RTO: 60000ms (60 seconds);

[0134] Maximum number of retransmissions: 5;

[0135] SRTT smoothing factor α: 0.125;

[0136] RTTVAR variance smoothing factor β: 0.25;

[0137] RTT update algorithm:

[0138] Calculate the difference between the current RTT and the smoothed RTT (SRTT); update the SRTT using a weighted average; update the RTT volatility value RTTVAR using a weighted average; calculate the new RTO according to the formula:

[0139] RTO = SRTT + 4 × RTTVAR

[0140] Limit the RTO to a preset minimum / maximum range.

[0141] Exponential backoff mechanism: Each time a retransmission occurs, the retransmission timeout is multiplied by a power of 2 times the number of retransmissions, to avoid frequent retransmissions exacerbating link load.

[0142] Each satellite communication terminal is equipped with a signaling retransmission manager to uniformly maintain all sent but unacknowledged signaling. The implementation process is as follows:

[0143] When sending signaling, record the sequence number, sending time, and number of retransmissions;

[0144] Start a timeout timer based on the current RTO;

[0145] If no response is received within the timeout period, a retransmission will be performed, and exponential backoff will be enabled.

[0146] If no response is received after the maximum number of retransmissions (5 times), the link is determined to be faulty, and the link anomaly handling process is triggered.

[0147] After receiving the response from the other end, calculate the RTT based on the sending time and receiving time, and update the RTO;

[0148] Clear pending confirmation signals to complete a reliable signaling interaction.

[0149] Based on this, this embodiment proposes an adaptive link management system based on satellite mobile communication to implement the above-mentioned adaptive link management method based on satellite mobile communication. It includes multiple satellite communication terminals that communicate through satellite links. Each satellite communication terminal is equipped with a negotiation module, a transmission link establishment module, a link keep-alive module, a status monitoring module, and a link release module.

[0150] The negotiation module is used to complete the initial link negotiation with the peer satellite communication terminal based on the PPP UDP protocol, and to exchange information such as network addresses through signaling interactions such as link establishment requests and confirmations. This negotiation module is used to execute the above-mentioned step S1.

[0151] The transmission link establishment module determines the network segment relationship based on the exchanged network address information. If they are on the same network segment, it selects the proxy ARP-assisted GRE encapsulation transmission mode; if they are on different network segments, it selects the standard GRE encapsulation transmission mode. It then negotiates and determines the link endpoint identifier using a hash algorithm, configures the point-to-point subnet mask, and establishes a bidirectional transmission link. This transmission link establishment module is used to execute step S2 described above.

[0152] The link keep-alive module is used to periodically exchange keep-alive signaling with the satellite communication terminal at the other end to maintain the connectivity of the transmission link after it is established. This module is used to perform step S3 of the above method.

[0153] The status monitoring module is used to monitor the status of the connected local access devices, synchronize status information according to a preset period and / or when the status of the local access devices changes, dynamically update the transmission path, and perform address conflict detection and handling. This module is used to perform step S4 of the above method.

[0154] The link release module is used to complete the normal release of the transmission link by means of a link release signaling at the end of the transmission task. This module is used to execute step S5 of the above method.

[0155] In the system of this embodiment, each satellite communication terminal maintains the following states (Table 7) during the transmission link establishment process:

[0156]

[0157] See Figure 10 The specific state transition events are described in Table 8 below:

[0158]

[0159] The simplified state transition table is shown in Table 9 below:

[0160]

[0161] When the satellite communication terminal is in the INIT initial state, it sends a link establishment request signaling to the outside world, and the state jumps to WAIT_ACK.

[0162] After receiving a connection establishment confirmation signal from the peer in the WAIT_ACK state, the system switches to the NEGOTIATING state to negotiate the endpoint identifier; once the endpoint identifier negotiation is completed, the state changes to ESTABLISHED.

[0163] After receiving the link establishment completion signal, the ESTABLISHED state activates the link and transitions to the ACTIVE normal operating state.

[0164] During ACTIVE operation, a link release request is received from the peer, and the RELEASING link release state is entered.

[0165] RELEASING completes the release of link resources, shuts down the link, and the state falls back to INIT;

[0166] When a satellite communication terminal experiences a fault such as message timeout or link anomaly in any working state, it will switch to the FAULT fault state. After the fault is repaired or the link is retried, the FAULT state will return to the INIT initial state, and the link establishment process can be restarted.

[0167] In this embodiment, the satellite communication terminal that initiates the link establishment process actively initiates the link establishment process through the negotiation module. Parameter negotiation, state transitions, and retrying in case of errors are completed through signaling interaction. A specific execution flow is illustrated below:

[0168] Initiator initialization configuration

[0169] The initiator is pre-configured with default operating parameters: the default keep-alive interval is 30 seconds, the maximum number of retry attempts for link establishment is 3, and the interval between each retry is 5 seconds; the initiator maintains a local link state machine, which is initially set to the INIT initial state, and integrates the aforementioned signaling timeout retransmission manager to ensure reliable transmission of link establishment signaling.

[0170] Initiating the transmission link establishment process

[0171] The initiating end is only allowed to start the link establishment process in the initial INIT state. After starting, it immediately switches the local state to WAIT_ACK waiting for response. Then, it constructs and encapsulates the link establishment request signaling, which carries the local PPP network interface IP address, the local terrestrial network interface IP address, the default keep-alive interval, the bitmap of the supported encapsulation mode (supporting both standard GRE encapsulation and proxy ARP assisted GRE encapsulation), and the sending timestamp.

[0172] Signaling transmission and retransmission management

[0173] The initiating end sends a link establishment request signaling through the signaling sender and retransmission manager. The retransmission manager automatically performs timeout detection, exponential backoff retransmission, and maximum retransmission count control. After sending the signaling, it waits for the other end to return a link establishment confirmation signaling.

[0174] Process link establishment confirmation signaling

[0175] If the initiating end receives a confirmation signal from the peer and the connection establishment result is successful, it parses and saves the peer's PPP network interface IP address, the peer's terrestrial network interface IP address, the peer's suggested keep-alive interval, and the final encapsulation mode selected through negotiation. At the same time, it switches the local link state to the NEGOTIATING negotiation state and enters the subsequent endpoint identifier negotiation stage.

[0176] If the confirmation signal carries a chain establishment rejection result, the initiating end records the reason for rejection, restores the local state to the initial INIT state, and starts the chain establishment retry mechanism.

[0177] Chain establishment failure and retry mechanism

[0178] If the link establishment confirmation signaling fails to be transmitted due to timeout, link abnormality, or other reasons, the initiating end will switch its local state to FAULT. Provided that the maximum number of retries has not been exceeded, the link establishment process will be restarted after waiting for the preset retry interval. If the link establishment is still unsuccessful after the maximum number of retries has been reached, the current link establishment process will be terminated.

[0179] As the receiver of the link establishment, the satellite communication terminal processes the link establishment request sent by the other end through the transmission link establishment module, and completes parameter verification, encapsulation mode negotiation and response feedback. The specific implementation process is as follows:

[0180] Request reception and status verification

[0181] The responding end is initially in the INIT initial state. When it receives a link establishment request signaling sent by the peer end, it first checks the local link status. If the current status is not the initial state, it directly returns a link establishment confirmation signaling carrying the reason for rejection to the peer end and rejects this link establishment request.

[0182] Parallel parameter parsing and storage

[0183] After the status verification is passed, the responding end parses the core parameters in the request signaling, including the peer's PPP network interface IP address, the peer's terrestrial network interface IP address, the peer's suggested keep-alive interval and the bitmap of the supported encapsulation mode, and completes local caching.

[0184] Packaging mode negotiation and selection

[0185] The responding end determines whether the local terrestrial network interface IP address and the remote terrestrial network interface IP address belong to the same network segment, and selects the final encapsulation mode according to a preset strategy based on the encapsulation mode bitmap supported by the remote end:

[0186] If both ends are on the same network segment, and the other end supports the GRE encapsulation transmission mode assisted by proxy ARP, then this mode should be selected first.

[0187] If the two ends are on different network segments and the other end supports the standard GRE encapsulation transmission mode, then the standard GRE encapsulation transmission mode shall be selected.

[0188] If the local machine and the peer do not have a common supported encapsulation mode, a connection establishment rejection signal is returned to the peer and the process is terminated.

[0189] Link establishment confirmation response sent

[0190] After the encapsulation mode is successfully selected, the responding end constructs and sends a link establishment confirmation signal to the peer end. The signal carries a link establishment success identifier and the negotiated encapsulation mode. At the same time, the local link state is switched to NEGOTIATING endpoint identifier negotiation state, and the endpoint identifier waiting process is started to enter the subsequent negotiation stage.

[0191] To maintain the connectivity of the transmission link and detect link anomalies in a timely manner, each satellite communication terminal uses a link keep-alive module to automate the entire process of link keep-alive, including timed transmission, response detection, anomaly determination, and link recovery. A specific implementation logic example is provided below:

[0192] Basic keep-alive parameters for the link keep-alive module: The default keep-alive transmission interval is 30 seconds, the maximum allowed number of consecutive lost keep-alive responses is 3, and the fast retry interval for keep-alive failure is 1 second. The module has a built-in timed scheduling mechanism to maintain the online status flag of the peer and the consecutive lost response count, and also integrates the aforementioned signaling timeout retransmission mechanism to ensure reliable keep-alive signaling interaction.

[0193] After the transmission link enters normal working state, the link keep-alive module starts a timed scheduling task, periodically generates and sends keep-alive signaling according to the configured keep-alive interval. The signaling carries a sequence number and a sending timestamp, and the sending and timeout management are completed through the signaling retransmission manager.

[0194] If the link keep-alive module successfully receives the keep-alive response from the peer, it clears the consecutive lost response count. If the peer was previously marked as offline, it updates the peer's online status to normal and restores the local link status to the ACTIVE working state.

[0195] If the keep-alive signaling fails to be sent or no response is received, the consecutive lost response count is incremented. When the number of lost responses has not reached the maximum value, the link keep-alive module starts the fast retry mechanism and resends the keep-alive signaling. When the number of consecutive lost responses reaches the preset maximum value, it is determined that the peer link is disconnected, the peer online status is updated to offline, the local link status is switched to FAULT fault status, and the link reconstruction process is automatically triggered.

[0196] When the link failure is recovered and a keep-alive response is received again, the link keep-alive module resets the fault count, restores the peer's online status and the local link's normal working status, and completes the automated fault recovery of the transmission link.

[0197] In this embodiment, a sequence number management unit can also be configured to be uniformly responsible for the generation, duplication verification, and maintenance of signaling sequence numbers. A sliding receive window mechanism is used to achieve signaling deduplication and prevention of message replay attacks. The specific control logic is explained below:

[0198] Pre-set the relevant configuration parameters for the sequence number: the upper limit of the sequence number value is 65535, and the length of the receiving sliding window is 1024; the sequence number management unit maintains the current sequence number of the signaling to be sent on the local end, the latest received sequence number of the peer end, and a storage set for caching the received valid sequence numbers.

[0199] When the terminal generates a signaling message to be sent, the sequence number management unit increments the local sequence number and then performs a modulo operation on the maximum sequence number value to obtain the unique sequence number corresponding to this signaling message, which is then encapsulated and sent along with the signaling message.

[0200] Upon receiving the signaling from the peer, a duplicate check is first performed: when the difference between the sequence number to be sequenced and the latest received sequence number falls within the receiving window range, the local cache set is searched. If the sequence number already exists, it is determined to be a duplicate message and discarded; sequence numbers outside the window range are directly treated as illegal messages.

[0201] For valid signaling that passes verification, its sequence number is stored in the received sequence number set, and the latest received sequence number is refreshed locally; at the same time, expired sequence numbers in the set that are earlier than "latest received sequence number - window length" are automatically cleaned up to reduce cache usage and avoid continuous expansion of storage space.

[0202] This embodiment combines existing mechanisms such as timeout retransmission, keep-alive detection, and sequence number verification mentioned above to classify, identify, and handle various abnormal faults during communication, ensuring the reliability of link operation. Specific typical anomaly handling rules are shown in Table 10 below:

[0203]

[0204] To achieve automated repair of faulty links, the transmission link establishment module in this embodiment also executes a standardized link anomaly recovery process through the link recovery manager. This process, combined with resource cleanup, state reset, and exponential backoff retry strategies, ensures that the link can be automatically rebuilt after an abnormal interruption. The specific implementation logic is as follows:

[0205] When a link failure is detected and the recovery process is triggered, the link recovery manager performs the following operations in sequence:

[0206] Resource cleanup: Clear all pending and incomplete signaling in the signaling retransmission manager and release abnormal communication resources;

[0207] State Reset: Forces the local link state machine to return to the initial INIT state, preparing for re-establishing the link;

[0208] Sequence Number Reset: Resets the signaling sequence number manager, clears the historical received sequence number cache, and avoids confusion between new and old session messages.

[0209] After completing the environmental cleanup, the system initiates link reconstruction using an exponential backoff retry strategy:

[0210] Initialize the retry count and the base retry interval;

[0211] The link reconstruction attempt is performed repeatedly, and the waiting interval is doubled after each failed retry.

[0212] If the retry interval reaches the preset maximum value, the upper limit will remain unchanged and will not increase further.

[0213] If the link is successfully established within the maximum allowed number of recovery retries, the recovery is considered successful and the process ends normally.

[0214] If the link fails to recover after exceeding the maximum number of retries, the link recovery is deemed to have failed, an alarm is output, and administrators are notified to intervene.

[0215] The single recovery attempt process is as follows: actively re-initiate a link establishment request to the peer and start a timed waiting mechanism; if the link negotiation is completed and the system enters normal working state within the specified time, the recovery is returned as successful; if the timeout occurs and the process is not completed, the recovery is deemed to have failed.

[0216] This embodiment achieves unified processing of local access device status monitoring, transmission path policy updates, and IP address conflict detection through a status monitoring module. It merges transmission path parameter information and IP status information into a single status notification message, enabling the simultaneous transmission of both types of information with a single send, effectively reducing satellite link bandwidth consumption.

[0217] To further reduce the number of message exchanges, the status monitoring module supports a batch status reporting mechanism. When multiple local access devices experience status changes simultaneously, the module aggregates all online and offline IPs into a single status notification message, completing batch synchronization through a single UDP transmission, thus reducing communication overhead in the transmission link.

[0218] The status monitoring module can include four functional sub-units, each responsible for managing the status of local access devices throughout their entire lifecycle: the PC status monitoring unit verifies the online status of terminals by traversing the local ARP cache and using arping detection, and filters out instantaneous network disturbances through a continuous counting mechanism to achieve status debouncing; the link status synchronization unit dynamically adds or removes local policy routing entries based on received remote status notification messages, and maintains the local forwarding table in real time; the IP conflict detection unit summarizes the entire network IP ledger and cross-compares it to promptly identify duplicate IPs and archive conflict information; and the conflict handling unit selectively performs abnormal alarms, traffic blocking, or priority-based access operations for conflicting IPs according to preset control rules.

[0219] The status monitoring module incorporates two core data storage structures and standardizes interaction and handling rules: The first is a PC status log table, storing terminal IPs, consecutive online / offline counts, and the last online and offline times, providing data support for status debouncing logic; the second is an IP conflict log table, fully recording conflicting IPs, associated local and remote device numbers, conflict start and end times, conflict frequency, and handling progress. In addition, the module uniformly defines four types of interaction signaling formats, corresponding to status notifications, status responses, IP query requests, and IP query response messages, and configures three differentiated conflict handling strategies: alarm-only, traffic blocking, and priority scheduling.

[0220] Specifically, when the status monitoring module detects a conflict through cross-terminal IP address comparison, it initiates a conflict handling process, records the conflict event, issues an alarm, and executes a preset handling strategy. The specific process is as follows:

[0221] The status monitoring module first creates or updates IP conflict records, storing information such as conflicting IP addresses, local device identifiers, peer device identifiers, first and latest detection times, and cumulative number of conflicts in the conflict record table to complete the archiving of conflict events. Then, it generates local system alarms and sends conflict alarm notifications to peer terminals and upper-level management units through the transmission link to achieve abnormal event synchronization.

[0222] After recording and reporting are completed, the module performs differentiated handling based on the currently configured conflict resolution strategy:

[0223] Alarm-only policy: Only log conflict information and output alarm messages; do not interfere with terminal communication processes.

[0224] Traffic blocking strategy: Block traffic forwarding for conflicting IPs by configuring firewall commands, add the IP to the local blocking list, and prohibit it from transmitting data via satellite link;

[0225] Priority decision-making strategy: Compare the priorities of the local and remote devices. If the local device has a lower priority, automatically block local conflicting IP traffic to ensure that high-priority terminals have priority in occupying IP resources and avoid network address conflicts that could lead to communication abnormalities.

[0226] When a local access device that causes an IP conflict goes offline or actively changes its IP address, the status monitoring module automatically triggers the conflict recovery process, synchronously updates the conflict record, and removes traffic restrictions. The specific processing logic is as follows:

[0227] Once the status monitoring module detects that a conflicting IP address has been released, it immediately marks the corresponding conflict record as resolved and records the conflict resolution time. At the same time, it sends a conflict resolution notification message to all peer satellite communication terminals in the network, informing them that the IP address has been restored to availability.

[0228] If the IP address has previously been blocked by a firewall due to a conflict, the module automatically calls system commands to delete the corresponding iptables blocking rule, removes the IP address from the local blocking list, and restores normal communication permissions.

[0229] Through the aforementioned automation mechanism, abnormal control can be lifted immediately after the IP address is released, enabling unmanned processing of the entire process of conflict resolution and link restoration.

[0230] The satellite communication terminal in this embodiment adopts an integrated hardware design that integrates radio frequency transceiver, baseband processing, BeiDou positioning and timing, Ethernet interface, data storage, main control computing, and overall power supply. The terminal integrates multiple functional hardware units, see [link to relevant documentation]. Figure 12 The detailed breakdown of the overall hardware modules is as follows:

[0231] The antenna unit integrates two independent antenna components: an S-band 4-element duplex microstrip patch satellite communication antenna, which can be used for both transmission and reception, with an antenna gain ≥10dBi; and an L-band BeiDou dual-frequency receiving, positioning, and timing antenna, with an antenna gain ≥4.5dBi, which are responsible for satellite radio frequency signal transmission and reception, BeiDou satellite positioning, and clock synchronization reception, respectively. The BeiDou positioning and timing antenna is an L-band BeiDou dual-frequency receiving antenna with a gain of not less than 4.5dBi.

[0232] The RF front-end unit is located between the antenna unit and the baseband processing unit, and includes a low-noise amplifier, an RF duplexer, and a transmit power amplifier. The low-noise amplifier is installed close to the antenna end to amplify the weak downlink satellite RF signals, with a noise figure ≤1.8dB and a gain ≥28dB. The duplexer achieves isolation between transmit and receive signals on the same antenna, with a transmit / receive isolation ≥80dB, ensuring that the antennas do not interfere with each other during time-division multiplexing. The power amplifier amplifies the uplink service RF signals, with a rated output power ≥10W, and integrates over-temperature and over-current hardware protection circuits.

[0233] The main control chip of the baseband processing unit is the Xilinx Zynq-7030 chip, which is responsible for implementing the full protocol stack processing of the satellite air interface physical layer. The hardware is compatible with mainstream satellite mobile communication standards such as DVB-S2, RRC, and GMR-1. Internally, it is divided into a modulation and demodulation unit, a channel encoding and decoding unit, and a PPP protocol processing unit. The modulation and demodulation unit supports QPSK, 8PSK, and 16APSK multi-standard modulation and demodulation. The encoding and decoding unit is equipped with LDPC and Turbo channel encoding and decoding algorithms. The PPP protocol processing unit completes the entire process management of PPP link negotiation, link keep-alive maintenance, and link teardown across satellite links.

[0234] The Beidou positioning and timing module is equipped with the Hexin Xingtong UM982 positioning chip, which is compatible with multi-system satellite joint calculation. It outputs the local geographical location information and high-precision reference clock in real time. The positioning accuracy of the whole machine is better than 10m and the timing accuracy is better than 100ns, providing a unified standard time reference for the timing synchronization of terminal communication frames throughout the entire link.

[0235] The Ethernet interface module (eth0) integrates a MAC controller and a PHY transceiver, providing a 10 / 100 / 1000Mbps adaptive wired network port for connecting to a local switch, enabling data communication and interaction between this terminal and various terminal devices within the local area network.

[0236] The storage module adopts an integrated eMCP storage architecture of 2GB DDR3 + 16GB eMMC: 16GB eMMC non-volatile memory is used to store solidified data such as whole machine firmware, factory configuration, operating parameters, PC online ledger, IP conflict logs, etc.; 2GB DDR3 memory serves as program running memory and high-speed cache for business data; and a reserved SD card expansion slot is provided for external storage card expansion as needed.

[0237] The system control unit uses the LC1860C as the main application processor, loads and runs the whole machine application software, and realizes all upper-layer business functions such as adaptive GRE encapsulation strategy selection, online status inspection of downstream terminals, cross-device routing information synchronization, IP conflict detection and hierarchical handling, and local human-machine interaction control.

[0238] The power supply and interface unit is responsible for the overall power distribution and power protection: it supports DC 10V~36V wide voltage external power supply, has a built-in 100Wh backup lithium battery, and can achieve seamless hot switching between external power supply and battery power supply; it is equipped with multiple DC-DC conversion circuits to regulate the output of multiple sets of hardware required operating voltages such as 4.2V, 12V, and 36V; the standby power consumption of the whole machine is ≤2W, and it also integrates full-dimensional hardware protection for reverse connection, input overvoltage, and output overcurrent.

[0239] From the perspective of signal transmission links, the downlink receiving link is as follows: the satellite transmits radio frequency signals, which are picked up by the S-band satellite communication antenna and then sent to a low-noise amplifier to perform small signal noise reduction and amplification. The amplified radio frequency signals are then connected to the baseband processing unit to complete radio frequency demodulation and baseband parsing. The parsed data is uniformly scheduled by the system control unit and finally converted into a protocol format through the Ethernet interface module before being sent to various terminals on the ground local area network.

[0240] Uplink transmission link: Local area network service data is accessed by the terminal via the Ethernet interface module. After being collected and processed by the main control processing module, it is forwarded to the satellite communication baseband module. The baseband processing unit sequentially completes data framing and carrier modulation to generate radio frequency signals. The radio frequency signals are sent to the transmit power amplifier for power enhancement, and then converted into space electromagnetic waves for transmission via the S-band satellite communication antenna, thus completing the uplink transmission of data to the on-orbit satellite.

[0241] In this invention, the terms "first," "second," and "third," etc., are used only to distinguish similar objects and are not necessarily used to describe a specific order or sequence, nor should they be interpreted as indicating or implying relative importance. In the description, "multiple" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0242] It should be noted that although several modules or units for the device used to perform actions have been mentioned in the detailed description above, this division is not mandatory. In fact, according to embodiments of this disclosure, the features and functions of two or more modules or units described above can be embodied in one module or unit. Conversely, the features and functions of one module or unit described above can be further divided and embodied by multiple modules or units.

[0243] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein.

[0244] The above are merely specific embodiments of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention using this concept shall be considered as infringing upon the protection scope of the present invention.

Claims

1. An adaptive link management method based on satellite mobile communication, characterized in that, include: The first satellite communication terminal and the second satellite communication terminal completed the initial link negotiation based on the UDP protocol of PPP, and exchanged network address information through the interaction of link establishment request and confirmation signaling. The network segment relationship is determined based on the exchanged network address information. If they are on the same network segment, the GRE encapsulation transmission mode assisted by proxy ARP is selected; if they are on different network segments, the standard GRE encapsulation transmission mode is selected. The link endpoint identifier is determined through negotiation based on the corresponding encapsulation mode, and a bidirectional transmission link is established. After the transmission link is established, each satellite communication terminal periodically exchanges link keep-alive signaling to maintain the connectivity of the transmission link; Monitor the status of the local access devices connected to each satellite communication terminal, synchronize status information according to a preset period and / or when the status of the local access devices changes, dynamically update the transmission path, and perform address conflict detection and processing; When the transmission task ends, the transmission link is released normally via a link release signaling.

2. The adaptive link management method based on satellite mobile communication as described in claim 1, characterized in that, The first satellite communication terminal sends a link establishment request signaling to the second satellite communication terminal. After receiving the request, the second satellite communication terminal returns a link establishment confirmation signaling. Both signals carry their respective network address information. The two parties then exchange information to obtain the other party's network address information and complete the initial link negotiation.

3. The adaptive link management method based on satellite mobile communication as described in claim 1, characterized in that, The network address information includes the IP address of the ground network interface. In step S2, based on the IP addresses of the ground network interfaces obtained from the interaction, it is determined whether the two belong to the same network segment.

4. The adaptive link management method based on satellite mobile communication as described in claim 1, characterized in that, The network address information includes the PPP network port IP address; when selecting the proxy ARP-assisted GRE encapsulation transmission mode, the first satellite communication terminal and the second satellite communication terminal respectively input their own PPP network port IP address into the MD5 hash function, perform a modulo operation on the specified number of bits of the obtained hash value, and then map the operation result to the preset point-to-point subnet range to negotiate and determine the link endpoint identifier. The preset point-to-point subnet is pre-configured with a dedicated point-to-point subnet mask.

5. The adaptive link management method based on satellite mobile communication as described in claim 4, characterized in that, The first satellite communication terminal and the second satellite communication terminal complete communication addressing based on the point-to-point dedicated subnet mask and the acquired peer PPP network port IP address, and achieve endpoint pairing based on the negotiated link endpoint identifier, thereby establishing a bidirectional transmission link.

6. The adaptive link management method based on satellite mobile communication as described in claim 1, characterized in that, During the operation of the transmission link, the first satellite communication terminal and the second satellite communication terminal periodically send link keep-alive signaling to each other and receive keep-alive responses returned by the other end; if either party fails to receive a keep-alive response multiple times in a row, the transmission link is determined to be abnormal and the transmission link reconstruction is re-executed. When any satellite communication terminal needs to disconnect, the satellite communication terminal sends a link release signal to complete the normal release of the transmission link.

7. The adaptive link management method based on satellite mobile communication as described in claim 1, characterized in that, Each satellite communication terminal utilizes the address resolution cache generated during the communication process to monitor the status of local access devices using a combination of passive listening and active probing. Specifically: Each satellite communication terminal periodically detects the activity status of the local access device and extracts the terrestrial network interface IP address of the local access device to form a candidate IP set; The status of IP addresses in the candidate IP set is verified by probing signaling, and the device activity status is determined by a multi-confirmation anti-jitter mechanism. For IP addresses determined to be offline, the corresponding address resolution cache entries are deleted.

8. The adaptive link management method based on satellite mobile communication as described in claim 1, characterized in that, At a preset period and / or when the status of the local access device changes, the satellite communication terminal connected to the local access device generates a status signaling message and sends it to the peer satellite communication terminal through the transmission link; after receiving the status signaling message, the peer satellite communication terminal performs the following processing: For the local access device corresponding to the status signaling message, if the device is online, a corresponding entry is added to the forwarding table of this satellite communication terminal; if the device is offline, the corresponding entry is deleted from the forwarding table. The ground network interface IP address in the status signaling message is compared with the set of active local access device IP addresses stored in the satellite communication terminal. If there is a duplicate IP address, it is determined that an address conflict has occurred, and at least one of the conflict alarm, blocking policy and priority policy is executed.

9. The adaptive link management method based on satellite mobile communication as described in claim 8, characterized in that, When the local access device corresponding to the status signaling message goes offline or its terrestrial network interface IP address is modified, the satellite communication terminal connected to the local access device sends an address release notification to the peer satellite communication terminal via the transmission link through the UDP protocol. After receiving the notification, the peer satellite communication terminal clears the corresponding conflict record, cancels the processing strategy previously executed due to the address conflict, and restores communication.

10. An adaptive link management system based on satellite mobile communication, characterized in that, This includes multiple satellite communication terminals that communicate via satellite links, and each satellite communication terminal is equipped with the following modules: The negotiation module is used to complete the initial negotiation with the peer satellite communication terminal based on the PPP UDP protocol, and to exchange information such as network address through link establishment request and confirmation signaling interaction; The transmission link establishment module determines the network segment relationship based on the exchanged network address information. If they are the same network segment, it selects the proxy ARP-assisted GRE encapsulation transmission mode. If they are different network segments, it selects the standard GRE encapsulation transmission mode. It negotiates and determines the link endpoint identifier through a hash algorithm, and establishes a bidirectional transmission link after configuring the point-to-point subnet mask. The link keep-alive module periodically exchanges link keep-alive signaling with the peer satellite communication terminal after the transmission link is established to maintain the connectivity of the transmission link; The status monitoring module monitors the status of the connected local access devices, synchronizes status information according to a preset period and / or when the status of the local access devices changes, dynamically updates the transmission path, and performs address conflict detection and processing. The link release module releases the transmission link normally by using a link release signaling when the transmission task ends.

Images