Dynamic routing and user mobility management method and system for low-orbit satellite constellation

Abstract

The invention discloses a dynamic routing and user mobility management method and system for a low-orbit satellite constellation, and belongs to the technical field of satellite communication, and the method comprises the following steps: S1, reporting the real-time state information of a feed link; s2, storing and managing the real-time state information of the feed link; s3, selecting an exit gateway station; s4, searching the shortest delay path from the entrance satellite to the exit gateway station through an improved A * search algorithm; s5, extracting key forwarding nodes, packaging the key forwarding nodes into departure and return tickets, and issuing the departure and return tickets to an exit gateway station and an entrance satellite; s6, uplink and downlink communication is carried out through the packaged departure ticket and the packaged return ticket; according to the method, the states of the inter-satellite link and the user link with high-frequency jitter are ignored, only the dynamic change of the feed link is taken as a triggering condition of path re-calculation, and due to the characteristic, the path switching frequency is reduced, so that frequent re-routing caused by jitter of a non-key link can be avoided, and the path stability and the overall robustness of the network are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of satellite communication technology, specifically relating to a method and system for dynamic routing and user mobility management of low-Earth orbit satellite constellations. Background Technology

[0002] A large-scale low-Earth orbit satellite constellation refers to a space system deployed in low Earth orbit, consisting of hundreds or more satellites forming a collaborative network through inter-satellite links, cluster control, and other technologies to achieve wide-area global coverage and provide services such as communication, remote sensing, and navigation enhancement.

[0003] Current large-scale low-Earth orbit satellite constellation communications suffer from the following problems:

[0004] 1. Satellites orbit the Earth approximately every ninety minutes, resulting in frequent link changes that can easily trigger path recalculation, leading to frequent network rerouting and reduced path stability.

[0005] 2. Even with inter-satellite links and on-board routing capabilities, the existing static terrestrial network access point model still cannot adapt to network dynamics, which can easily cause connection fluctuations and flow interruptions.

[0006] 3. User terminals need to frequently switch their access satellites. This frequent link switching seriously affects TCP performance, and existing mobility protocols are unable to effectively cope with it.

[0007] 4. Remote areas lack gateway stations, making it difficult to maintain a continuous connection to terrestrial network access points and thus unable to achieve true global service.

[0008] In view of this, a dynamic routing and user mobility management method and system for low-Earth orbit satellite constellations are designed to solve the above problems. Summary of the Invention

[0009] This invention provides a method and system for dynamic routing and user mobility management of low-Earth orbit satellite constellations, which addresses the problems mentioned in the background section.

[0010] To achieve the above objectives, the present invention provides the following technical solution: a method for dynamic routing and user mobility management of low-Earth orbit satellite constellations, comprising the following steps:

[0011] S1: Each gateway station periodically reports the real-time status information of the power supply link through wired or wireless backhaul links;

[0012] S2: The reported real-time status information of the power supply link is stored and managed by the power supply link status database of the global ticketing arbitrator;

[0013] S3: Based on the real-time status information of the power supply links in the power supply link status database, the global ticketing arbitrator selects the exit gateway station;

[0014] S4: Based on the real-time status information of the feeder links in the feeder link status database, the global ticketing arbitrator searches for the shortest delay path from the ingress satellite to the egress gateway station by using the improved A* search algorithm to minimize end-to-end delay while avoiding congested paths or expected link breakage areas.

[0015] S5: The global ticketing arbitrator control center extracts a set of key forwarding nodes from the shortest delay path found, encapsulates them into departure and return tickets, and sends them to the exit gateway station and the inbound satellite;

[0016] S6: The inbound satellite and outbound gateway communicate uplink and downlink through encapsulated departure and return tickets.

[0017] Furthermore, the specific steps of step S1 include:

[0018] When the status of the power supply link between the gateway station and the satellite changes, the gateway station sends a power supply link status report to the global ticketing arbitrator control center through a ground wired or wireless backhaul link.

[0019] Changes in the status of the power supply link include the establishment of a new power supply link or the imminent disconnection of the power supply link;

[0020] The status report includes the gateway station's unique identifier, a list of currently connected satellite numbers, the establishment time of each feeder link, and the estimated failure time of each feeder link.

[0021] Furthermore, the specific steps of step S2 include:

[0022] After receiving the status report of the power supply link, the global ticketing arbitrator control center writes each power supply link as an independent entity into the power supply link status database.

[0023] The feeder link status database stores the status reports of the feeder links, including:

[0024] Establishment time and expected failure time of the power supply link;

[0025] The satellite identifier currently bound to the feeder link;

[0026] The globally unique identifier of the power supply link is the gateway ID and the power supply link ID;

[0027] The scheduling frequency and historical usage records of the power supply link;

[0028] The mapping relationship between the ingress satellite and the egress gateway station of the feeder link;

[0029] The feeder link status database manages the status reports of the feeder links, including:

[0030] If it is a newly established power supply link, create an entry and initialize the scheduling count to zero;

[0031] If it is a failed power supply link, delete and release the relevant allocated tickets in a timely manner, and calculate new tickets;

[0032] The status of all power supply links is updated in real time using timestamps as an index.

[0033] Furthermore, the specific steps of step S3 include:

[0034] After receiving an entry satellite request, the global ticketing arbitrator control center locates the nearest ground network access point based on the current location of the entry satellite.

[0035] The global ticketing arbitration control center is centered on the nearest ground network access point and connects to the ten nearest gateway stations within a 1,000-kilometer radius.

[0036] The global ticketing arbitrator control center calculates the validity period of tickets for the paths between the nearest ground network access point and the ten connected gateway stations.

[0037] The global ticketing arbitrator control center will use the gateway station with the longest validity period of the ticket on the path connected to the nearest terrestrial network access point as the exit gateway station for that ticket.

[0038] The mapping relationship between the ingress satellite and the selected egress gateway station is stored in the feeder link status database.

[0039] Furthermore, the specific steps of step S4 include:

[0040] Based on the real-time status information of the feeder links in the feeder link status database, the global ticketing arbitrator control center calls the improved A* search algorithm to calculate the shortest delay path between the ingress satellite and the egress gateway station.

[0041] The path cost function is defined as:

[0042] f(n) = g(n) + h(n)

[0043] In the formula: g(n) represents the cumulative path cost from the ingress satellite to the current node; h(n) represents the estimated distance from the current node to the egress gateway station;

[0044] Add a load penalty factor to g(n), that is, when the node load is high, increase the cost to make it avoid congested paths or expected disconnection areas;

[0045] At the same time, a scheduling penalty factor is introduced into the path cost function:

[0046] g ' =d·(1+α) n

[0047] In the formula: d represents the distance of the feeder link edge visited by the current A* algorithm; n represents the number of times the feeder link is currently used by the ticket; α represents the scheduling sensitivity factor.

[0048] Furthermore, the specific steps of step S5 include:

[0049] The global ticketing arbitrator control center extracts a set of key relay nodes from the shortest delay path found, including relay gateways, relay satellites connected to relay gateways, and selected exit gateways, forming a key relay node sequence;

[0050] The sequence of key relay nodes is encapsulated into tickets, including outbound tickets and return tickets;

[0051] The issued invoices include a sequence of critical relay nodes arranged in path order and the validity period of their power supply links;

[0052] The return ticket includes a sequence of critical relay nodes arranged in reverse order of the path and the validity period of their power supply links;

[0053] The number of power supply link scheduling times used during the encapsulation process is stored in the power supply link status database, and the power supply link scheduling times and historical usage records in the power supply link status database are updated.

[0054] If a power supply link in the ticket is about to fail or the path has exceeded the ticket's validity period, the global ticketing arbitrator control center will refresh the ticket two seconds in advance to complete the replacement before the power supply link is actually disconnected and store it in the power supply link status database.

[0055] Store the encapsulated tickets to the dynamic ticket queue;

[0056] Tickets in the dynamic ticket queue are pre-allocated using on-demand or global pre-allocation strategies;

[0057] On-demand allocation means that the global ticketing arbitrator control center pre-allocates tickets to satellites that will serve high-demand areas based on satellite transit predictions and regional traffic volume.

[0058] Global pre-allocation is enabled when deployment resources allow, meaning all satellites hold at least one valid ticket to enable instant connectivity and use anywhere in the world at any time and space.

[0059] The global ticketing arbitrator control center sends the outgoing ticket to the target gateway station via TCP in unicast transmission mode based on the pre-allocation results. The target gateway station then forwards the ticket to the target ingress satellite based on the return ticket. Ticket distribution is considered complete after both send confirmation responses; otherwise, the timeout mechanism will automatically retry.

[0060] Furthermore, the specific steps of step S6 include:

[0061] Uplink communication includes:

[0062] When a user terminal accesses the network and sends data through the user link, the ingress satellite, after receiving the user data packet, looks up the issuance certificate issued in advance by the global ticketing arbitrator control center in its local cache, and encapsulates the issuance certificate as path information into the header of the data packet.

[0063] The encapsulated content includes the target terrestrial network access point identifier, the exit gateway identifier, the sequence of key relay nodes, the current relay step count, and the valid timestamp;

[0064] When a satellite or gateway receives a data packet containing a ticket, it parses the ticket structure in the header to obtain the "next-hop node" information. It checks whether the current node is the "current forwarding node" in the ticket. If so, it continues to search for the next relay node and forwards the packet. If the next-hop node is unreachable, it directly discards the packet without any buffering or retrying to prevent outdated path data from occupying network resources. If the current node is a relay gateway, it reads the current "step number field" from the current relay step count in the header, increments the value of this field by 1, re-encapsulates the updated header into the data packet, and continues to forward it according to the next-hop relay node. If the current node is an exit gateway, it directly delivers the data to the ground network or the target ground network access point identifier.

[0065] The next-hop node is unreachable in cases including a broken feeder link and the next critical node is also a satellite, but that satellite is located in a different shell than itself;

[0066] Downlink communication includes:

[0067] When a downlink data packet is sent from the terrestrial network to a user terminal, the terrestrial network access point must query the return ticket corresponding to the user terminal when generating a data response, and encapsulate the return ticket as a header and attach it to the data packet.

[0068] Downlink data will travel along the reverse path of key nodes within the return ticket, from the exit gateway station to the entry satellite, and finally to the user terminal;

[0069] During uplink and downlink communication, if the relay node fails or becomes unreachable due to the power supply link within the ticket, it will not perform automatic path recovery or rerouting. The global ticketing arbitrator control center will then determine in subsequent scheduling cycles whether it is necessary to redistribute new tickets for the relevant inbound satellites.

[0070] The dynamic routing and user mobility management system for low-Earth orbit satellite constellations includes:

[0071] The power supply link information upload module allows each gateway station to periodically report real-time status information of the power supply link through wired or wireless backhaul links.

[0072] The power supply link information storage module reports real-time status information of the power supply links, which is stored and managed by the power supply link status database of the global ticketing arbitrator.

[0073] The exit gateway station selection module selects the exit gateway station based on the real-time status information of the power supply link in the power supply link status database, and the global ticketing arbitrator selects the exit gateway station.

[0074] The shortest delay path search module, based on the real-time status information of the feeder links in the feeder link status database, uses the improved A* search algorithm of the global ticketing arbitrator to search for the shortest delay path from the ingress satellite to the egress gateway station with the optimization objective of minimizing end-to-end delay, while avoiding congested paths or expected link breakage areas.

[0075] The ticket encapsulation and distribution module extracts a set of key forwarding nodes from the shortest delay path found by the global ticketing arbitrator control center, encapsulates them into departure and return tickets, and distributes them to the exit gateway station and the entry satellite.

[0076] The uplink and downlink communication modules allow the inbound satellite and outbound gateway station to communicate via encapsulated departure and return tickets.

[0077] Compared with the prior art, the beneficial effects of the present invention are:

[0078] 1. This invention ignores the high-frequency jitter of inter-satellite links and user link states, and only uses the dynamic changes of the power supply link as the triggering condition for path recalculation. Due to this feature, the path switching frequency is reduced, which can avoid frequent rerouting caused by jitter of non-critical links, and significantly improve path stability and overall network robustness.

[0079] 2. The global ticketing arbitrator control center of this invention uses the A* search algorithm to quickly search for the optimal path from the ingress satellite to the egress gateway station, and combines it with the "ticket mechanism" to distribute key relay nodes to network edge nodes. This avoids the latency caused by satellite nodes calculating paths locally, and can quickly respond to link changes, improving path deployment efficiency and data forwarding speed. Forwarding is performed in a distributed manner based on tickets, thus being compatible with all current single-shell inter-satellite routes, providing room for adaptive inter-satellite routing.

[0080] 3. This invention improves the A* search algorithm by introducing a link scheduling penalty factor into the path cost function. This factor can adjust the path cost based on the number of times the link has been scheduled, effectively controlling the overuse of a single power supply link. This mechanism can dynamically guide traffic to avoid congested links, achieve dynamic balanced distribution of link load, reduce hotspot bottleneck risks, and improve link resource utilization.

[0081] 4. The ticket pre-allocation of this invention is divided into two types: one is on-demand ticket pre-allocation based on regional demand forecasting, and the other is global ticket pre-allocation based on global business coverage. This can ensure that there is an available path when the user terminal first accesses the network, thereby improving the network access timeliness and service coverage integrity.

[0082] 5. This invention uses the TCP unicast protocol for ticket issuance and confirmation, and sets a unique ticket ID and confirmation mechanism to ensure reliable delivery and avoid duplicate broadcasts. It can effectively control the bandwidth consumption of control signaling, so that it can maintain good scalability and communication efficiency even under large-scale constellations.

[0083] 6. The key relay nodes in the path ticket of this invention remain fixed during the validity period, and the data packet loss caused by path failure is avoided through the early refresh mechanism. This can ensure the consistency of the forwarding path and avoid communication interruption caused by sudden link failure. It is suitable for services with high continuity requirements such as video and voice.

[0084] 7. In this invention, the ground gateway station is responsible for global scheduling and path distribution, while the on-board nodes and relay gateway stations only need to forward data according to the ticket. They do not need to maintain the topology status or run complex routing protocols themselves, which can reduce the processing burden on the satellite end, improve the utilization rate of on-board resources, and facilitate the compatible deployment between heterogeneous constellations of multiple vendors. Attached Figure Description

[0085] Figure 1 This is a schematic diagram illustrating the basic principle of the global ticketing arbitrator of the present invention;

[0086] Figure 2 This is a schematic diagram of the data forwarding plane under the guidance of the global ticketing arbitrator of the present invention;

[0087] Figure 3 This is a schematic diagram of the module of the present invention;

[0088] In the diagram: 1. Feeder link information upload module; 2. Feeder link information storage module; 3. Outbound gateway station selection module; 4. Shortest delay path search module; 5. Ticket encapsulation and distribution module; 6. Uplink and downlink communication module. Detailed Implementation

[0089] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0090] This invention provides the following technical solution: a method for dynamic routing and user mobility management of low-Earth orbit satellite constellations, comprising the following steps:

[0091] S1: Each gateway station GS periodically reports the real-time status information of the power supply link FL through wired or wireless backhaul links;

[0092] S2: The reported real-time status information of the feeder link FL is stored and managed by the feeder link status database FLDB of the global ticketing arbitrator GTA;

[0093] S3: Based on the real-time status information of the feeder link FL in the feeder link status database FLDB, the global ticketing arbitrator GTA selects the exit gateway station GS;

[0094] S4: Based on the real-time status information of the feeder link FL in the feeder link status database FLDB, the global ticketing arbitrator GTA searches for the shortest delay path from the ingress satellite to the egress gateway station GS with the optimization objective of minimizing end-to-end delay, while avoiding congested paths or expected link breakage areas, using the improved A* search algorithm.

[0095] S5: The Global Ticketing Arbitrator (GTA) control center extracts a set of key forwarding nodes from the shortest delay path found, encapsulates them into departure and return tickets, and sends them to the exit gateway station (GS) and the inbound satellite.

[0096] S6: The inbound satellite and the outbound gateway station GS communicate uplink and downlink through encapsulated departure and return tickets.

[0097] Specifically, step S1 includes the following steps:

[0098] When the status of the feed link FL between the gateway station GS and the satellite changes, the gateway station GS sends a status report of the feed link FL to the global ticketing arbitrator GTA control center through a ground wired or wireless backhaul link.

[0099] The status of the power supply link (FL) changes, including the establishment of a new power supply link (FL) or the imminent disconnection of the power supply link (FL).

[0100] The status report includes the gateway station's unique identifier (GS), a list of currently connected satellite numbers, the establishment time of each feeder link (FL), and the estimated failure time of each feeder link (FL).

[0101] The estimated failure time of the power supply link FL is obtained by the gateway station GS based on ephemeris data and real-time elevation angle dynamic local calculation.

[0102] Specifically, step S2 includes the following steps:

[0103] After receiving the status report of the feeder link FL, the Global Ticketing Arbitrator (GTA) control center writes each feeder link FL as an independent entity into the feeder link status database FLDB.

[0104] The feeder link status database (FLDB) stores the status reports of the feeder links (FLs), including:

[0105] Establishment time and expected failure time of the power supply link (FL);

[0106] The satellite identifier currently bound to the feed link (FL);

[0107] The globally unique identifier of the feeder link FL is the ID of the gateway station GS and the ID of the feeder link FL.

[0108] Scheduling frequency and historical usage records of the power supply link (FL);

[0109] The mapping relationship between the ingress satellite and the egress gateway station GS of the feed link FL;

[0110] The feeder link status database (FLDB) manages the status reports of feeder links (FLs), including:

[0111] If it is a newly created feeder link FL, create an entry and initialize the scheduling count to zero;

[0112] If it is a failed feeder link (FL), promptly delete and release the relevant allocated tickets, and calculate new tickets.

[0113] The status of all power supply links (FLs) is updated in real time using timestamps as an index.

[0114] Specifically, step S3 includes the following steps:

[0115] After receiving an entry satellite request, the Global Ticketing Arbitrator (GTA) control center locates the nearest ground network access point (PoP) based on the current location of the entry satellite.

[0116] The Global Ticketing Arbitrator (GTA) control center is centered on the nearest terrestrial network access point (PoP) and connects to the ten nearest gateway stations (GS) within a 1,000-kilometer radius.

[0117] The Global Ticketing Arbitrator (GTA) control center calculates the validity period of tickets for the paths between the nearest terrestrial network access point (PoP) and the ten connected gateway stations (GS), using the following expression:

[0118]

[0119] In the formula: Represents the set of all feeder links (FLs) traversed in the path; ExpectedLossTime iIndicates the expected expiration time of ticket i; CurrentTime indicates the current time;

[0120] ExpectedLossTime i Provided by the feeder link state database FLDB;

[0121] CurrentTime is provided by the time synchronization system;

[0122] The Global Ticket Arbitrator (GTA) control center designates the gateway station GS with the longest ticket validity period on the path connected to the nearest terrestrial network access point (PoP) as the exit gateway station GS for that ticket. The expression is as follows:

[0123]

[0124] In the formula: This represents all gateway stations (GS) connected to the nearest terrestrial network access point (PoP).

[0125] The mapping relationship between the ingress satellite and the selected egress gateway station GS is stored in the feeder link status database FLDB;

[0126] The storage of the feeder link status database FLDB in S2 includes the mapping relationship between the ingress satellite and the egress gateway station GS of the feeder link FL.

[0127] Specifically, step S4 includes the following steps:

[0128] Based on the real-time status information of the feeder link FL in the feeder link status database FLDB, the Global Ticket Arbitrator (GTA) control center calls the improved A* search algorithm to calculate the shortest delay path between the ingress satellite and the egress gateway station GS.

[0129] The path cost function is defined as:

[0130] f(n) = g(n) + h(n)

[0131] In the formula: g(n) represents the cumulative path cost from the ingress satellite to the current node; h(n) represents the estimated distance from the current node to the egress gateway station GS;

[0132] Add a load penalty factor to g(n), that is, when the node load is high, increase the cost to make it avoid congested paths or expected disconnection areas;

[0133] The calculation of h(n) is based on whether there is an Earth occlusion. If there is a line-of-sight occlusion between the exit gateway station GS and the currently visited node, the great circle distance is used, and the radius of the circle is the Earth radius. If there is no line-of-sight occlusion between the exit gateway station GS and the currently visited node, the Euclidean distance, i.e. the straight-line distance, is used.

[0134] To prevent overload of a single feeder link (FL), the Global Ticket Arbitrator (GTA) control center introduces a scheduling penalty factor into the path cost function:

[0135] g ' =d·(1+α) n

[0136] In the formula: d represents the distance of the feeder link FL edge visited by the current A* algorithm; n represents the number of times the feeder link FL is currently used by the ticket; α represents the scheduling sensitivity factor;

[0137] The distance d is the Euclidean distance;

[0138] n corresponds to the scheduling frequency of the feeder link FL, which is provided by the feeder link status database FLDB;

[0139] α can be flexibly configured based on regional priority, service level, or business type;

[0140] For example, higher α values ​​can be used in hotspot areas to distribute the pressure; specific gateway stations (GS) can reserve high-priority feeder link (FL) resources to achieve service differentiation.

[0141] Specifically, step S5 includes the following steps:

[0142] The Global Ticketing Arbitrator (GTA) control center extracts a set of key relay nodes from the shortest latency path found, including the relay gateway station GS, the relay satellite connected to the relay gateway station GS, and the selected exit gateway station GS, forming a sequence of key relay nodes;

[0143] The sequence of key relay nodes is encapsulated into tickets, including outbound tickets and return tickets;

[0144] The issued invoices include a sequence of critical relay nodes arranged in path order and the validity period of their feeder links (FLs).

[0145] The return ticket includes a sequence of critical relay nodes arranged in reverse order of the path and the validity period of their feeder links (FLs).

[0146] Corresponding to the "tickets" in S2 and S3;

[0147] The number of FL scheduling times used in the encapsulation process is stored in the FLDB (Feed Link Status Database), and the FLDB is updated with the number of FL scheduling times and historical usage records of the feed link.

[0148] This corresponds to "Scheduling frequency and historical usage records of the power supply link FL" in S2;

[0149] If a feeder link FL in the ticket is about to fail or the path has exceeded the ticket's validity period, the Global Ticket Arbitrator (GTA) control center will refresh the ticket two seconds in advance to complete the replacement before the feeder link FL is actually disconnected and store it in the feeder link status database FLDB.

[0150] This corresponds to "If it is a failed feeder link FL, delete and release the relevant allocated tickets in a timely manner, and calculate new tickets" in S2;

[0151] Store the encapsulated tickets to the dynamic ticket queue;

[0152] Tickets in the dynamic ticket queue are pre-allocated using on-demand or global pre-allocation strategies;

[0153] On-demand allocation means that the Global Ticketing Arbitrator (GTA) control center pre-allocates tickets to satellites serving high-demand areas based on satellite transit predictions and regional traffic volume.

[0154] Global pre-allocation is enabled when deployment resources allow, meaning all satellites hold at least one valid ticket to enable instant connectivity and use anywhere in the world at any time and space.

[0155] The Global Ticketing Arbitrator (GTA) control center sends the outgoing ticket to the target gateway station (GS) via TCP in unicast transmission mode based on the pre-allocation results. The target gateway station (GS) then forwards the ticket to the target ingress satellite based on the return ticket. Once both send confirmation responses, the ticket distribution is considered complete; otherwise, the timeout mechanism will automatically retry.

[0156] Specifically, step S6 includes the following steps:

[0157] Uplink communication includes:

[0158] When the user terminal UT accesses the network and sends data through the user link UL, the ingress satellite, after receiving the user data packet, looks up the issuance certificate issued in advance by the Global Ticket Arbitrator (GTA) control center in its local cache, and encapsulates the issuance certificate as path information into the header of the data packet.

[0159] The encapsulated content includes the target terrestrial network access point (PoP) identifier, the egress gateway station (GS) identifier, the sequence of key relay nodes, the current relay step count, and a valid timestamp;

[0160] When a satellite or gateway station (GS) receives a data packet containing a ticket, it parses the ticket structure in the header to obtain the "next-hop node" information. It checks whether the current node is the "current forwarding node" in the ticket. If so, it continues to search for the next relay node and forwards the packet. If the next-hop node is unreachable, it directly discards the packet without any buffering or retrying to prevent outdated path data from occupying network resources. If the current node is a relay gateway station (GS), it reads the current "step number field" from the current relay step count in the header, increments the value of this field by 1, re-encapsulates the updated header into the data packet, and continues to forward it according to the next-hop relay node. If the current node is an exit gateway station (GS), it directly delivers the data to the terrestrial network or the target terrestrial network access point (PoP) identifier.

[0161] The next-hop node is unreachable in cases including a disconnected feeder link (FL) and the next critical node is also a satellite, but that satellite is located in a different shell than itself.

[0162] Downlink communication includes:

[0163] When generating a data response, the access point point (PoP) of the terrestrial network must query the return ticket corresponding to the user terminal (UT) and encapsulate the return ticket as a header in the data packet for the downlink data packet sent from the terrestrial network to the user terminal (UT).

[0164] Downlink data will travel along the reverse path of key nodes within the return ticket, from the exit gate station GS to the ingress satellite, and finally to the user terminal UT.

[0165] During uplink and downlink communication, if the relay node fails or becomes unreachable due to the failure of the feeder link (FL) within the ticket, it will not perform automatic path recovery or rerouting. The Global Ticket Arbitrator (GTA) control center will determine in subsequent scheduling cycles whether it is necessary to redistribute new tickets for the relevant inbound satellites.

[0166] The dynamic routing and user mobility management system for low-Earth orbit satellite constellations includes:

[0167] Feeder link information upload module 1: Each gateway station GS periodically reports the real-time status information of the feeder link FL through wired or wireless backhaul links.

[0168] The power supply link information storage module 2 reports real-time status information of the power supply link FL, which is stored and managed by the power supply link status database FLDB of the global ticketing arbitrator GTA.

[0169] The export gateway station selection module 3 selects the export gateway station GS based on the real-time status information of the feeder link FL in the feeder link status database FLDB and the global ticketing arbitrator GTA.

[0170] The shortest delay path search module 4 searches for the shortest delay path from the ingress satellite to the egress gateway station GS based on the real-time status information of the feeder link FL in the feeder link status database FLDB and the global ticketing arbitrator GTA. This is achieved by using the improved A* search algorithm to minimize end-to-end delay while avoiding congested paths or expected link breakage areas.

[0171] Ticket encapsulation and distribution module 5: The Global Ticket Arbitrator (GTA) control center extracts a set of key forwarding nodes from the shortest delay path found, encapsulates them into departure and return tickets, and distributes them to the exit gateway station (GS) and the inbound satellite.

[0172] Uplink and downlink communication module 6, the inlet satellite and the exit gateway station GS conduct uplink and downlink communication through encapsulated departure and return tickets.

[0173] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for dynamic routing and user mobility management of low-Earth orbit satellite constellations, characterized in that, Includes the following steps: S1: Each gateway station periodically reports the real-time status information of the power supply link through wired or wireless backhaul links; S2: The reported real-time status information of the power supply link is stored and managed by the power supply link status database of the global ticketing arbitrator; S3: Based on the real-time status information of the power supply links in the power supply link status database, the global ticketing arbitrator selects the exit gateway station; S4: Based on the real-time status information of the feeder links in the feeder link status database, the global ticketing arbitrator searches for the shortest delay path from the ingress satellite to the egress gateway station by using the improved A* search algorithm to minimize end-to-end delay while avoiding congested paths or expected link breakage areas. S5: The global ticketing arbitrator control center extracts a set of key forwarding nodes from the shortest delay path found, encapsulates them into departure and return tickets, and sends them to the exit gateway station and the inbound satellite; S6: The inbound satellite and outbound gateway communicate uplink and downlink through encapsulated departure and return tickets.

2. The dynamic routing and user mobility management method for low-Earth orbit satellite constellations according to claim 1, characterized in that: The specific steps of step S1 include: When the status of the power supply link between the gateway station and the satellite changes, the gateway station sends a power supply link status report to the global ticketing arbitrator control center through a ground wired or wireless backhaul link. Changes in the status of the power supply link include the establishment of a new power supply link or the imminent disconnection of the power supply link; The status report includes the gateway station's unique identifier, a list of currently connected satellite numbers, the establishment time of each feeder link, and the estimated failure time of each feeder link.

3. The dynamic routing and user mobility management method for low-Earth orbit satellite constellations according to claim 2, characterized in that: The specific steps of step S2 include: After receiving the status report of the power supply link, the global ticketing arbitrator control center writes each power supply link as an independent entity into the power supply link status database. The feeder link status database stores the status reports of the feeder links, including: Establishment time and expected failure time of the power supply link; The satellite identifier currently bound to the feeder link; The globally unique identifier of the power supply link is the gateway ID and the power supply link ID; The scheduling frequency and historical usage records of the power supply link; The mapping relationship between the ingress satellite and the egress gateway station of the feeder link; The feeder link status database manages the status reports of the feeder links, including: If it is a newly established power supply link, create an entry and initialize the scheduling count to zero; If it is a failed power supply link, delete and release the relevant allocated tickets in a timely manner, and calculate new tickets; The status of all power supply links is updated in real time using timestamps as an index.

4. The dynamic routing and user mobility management method for low-Earth orbit satellite constellations according to claim 3, characterized in that: The specific steps of step S3 include: After receiving an entry satellite request, the global ticketing arbitrator control center locates the nearest ground network access point based on the current location of the entry satellite. The global ticketing arbitration control center is centered on the nearest ground network access point and connects to the ten nearest gateway stations within a 1,000-kilometer radius. The global ticketing arbitrator control center calculates the validity period of tickets for the paths between the nearest ground network access point and the ten connected gateway stations. The global ticketing arbitrator control center will use the gateway station with the longest validity period of the ticket on the path connected to the nearest terrestrial network access point as the exit gateway station for that ticket. The mapping relationship between the ingress satellite and the selected egress gateway station is stored in the feeder link status database.

5. The method and system for dynamic routing and user mobility management of low-Earth orbit satellite constellations according to claim 4, characterized in that: The specific steps of step S4 include: Based on the real-time status information of the feeder links in the feeder link status database, the global ticketing arbitrator control center calls the improved A* search algorithm to calculate the shortest delay path between the ingress satellite and the egress gateway station. The path cost function is defined as: f(n) = g(n) + h(n) In the formula: g(n) represents the cumulative path cost from the ingress satellite to the current node; h(n) represents the estimated distance from the current node to the egress gateway station; Add a load penalty factor to g(n), that is, when the node load is high, increase the cost to make it avoid congested paths or expected disconnection areas; At the same time, a scheduling penalty factor is introduced into the path cost function: g ' =d·(1+α) n In the formula: d represents the distance of the feeder link edge visited by the current A* algorithm; n represents the number of times the feeder link is currently used by the ticket; α represents the scheduling sensitivity factor.

6. The dynamic routing and user mobility management method for low-Earth orbit satellite constellations according to claim 5, characterized in that: The specific steps of step S5 include: The global ticketing arbitrator control center extracts a set of key relay nodes from the shortest delay path found, including relay gateways, relay satellites connected to relay gateways, and selected exit gateways, forming a key relay node sequence; The sequence of key relay nodes is encapsulated into tickets, including outbound tickets and return tickets; The issued invoices include a sequence of critical relay nodes arranged in path order and the validity period of their power supply links; The return ticket includes a sequence of critical relay nodes arranged in reverse order of the path and the validity period of their power supply links; The number of power supply link scheduling times used during the encapsulation process is stored in the power supply link status database, and the power supply link scheduling times and historical usage records in the power supply link status database are updated. If a power supply link in the ticket is about to fail or the path has exceeded the ticket's validity period, the global ticketing arbitrator control center will refresh the ticket two seconds in advance to complete the replacement before the power supply link is actually disconnected and store it in the power supply link status database. Store the encapsulated tickets to the dynamic ticket queue; Tickets in the dynamic ticket queue are pre-allocated using on-demand or global pre-allocation strategies; On-demand allocation means that the global ticketing arbitrator control center pre-allocates tickets to satellites that will serve high-demand areas based on satellite transit predictions and regional traffic volume. Global pre-allocation is enabled when deployment resources allow, meaning all satellites hold at least one valid ticket to enable instant connectivity and use anywhere in the world at any time and space. The global ticketing arbitrator control center sends the outgoing ticket to the target gateway station via TCP in unicast transmission mode based on the pre-allocation results. The target gateway station then forwards the ticket to the target ingress satellite based on the return ticket. Ticket distribution is considered complete after both send confirmation responses; otherwise, the timeout mechanism will automatically retry.

7. The dynamic routing and user mobility management method for low-Earth orbit satellite constellations according to claim 6, characterized in that: The specific steps of step S6 include: Uplink communication includes: When a user terminal accesses the network and sends data through the user link, the ingress satellite, after receiving the user data packet, looks up the issuance certificate issued in advance by the global ticketing arbitrator control center in its local cache, and encapsulates the issuance certificate as path information into the header of the data packet. The encapsulated content includes the target terrestrial network access point identifier, the exit gateway identifier, the sequence of key relay nodes, the current relay step count, and the valid timestamp; When a satellite or gateway receives a data packet containing a ticket, it parses the ticket structure in the header to obtain the "next-hop node" information. It checks whether the current node is the "current forwarding node" in the ticket. If so, it continues to search for the next relay node and forwards the packet. If the next-hop node is unreachable, the packet is discarded directly without any buffering or retrying to prevent outdated path data from occupying network resources. If the current node is a relay gateway, it reads the current "step number field" from the current relay step count in the header, increments the value of this field by 1, re-encapsulates the updated header into the data packet, and continues to forward it according to the next-hop relay node. If the current node is an exit gateway, it directly delivers the data to the ground network or the target ground network access point identifier. The next-hop node is unreachable in cases including a broken feeder link and the next critical node is also a satellite, but that satellite is located in a different shell than itself; Downlink communication includes: When a downlink data packet is sent from the terrestrial network to a user terminal, the terrestrial network access point must query the return ticket corresponding to the user terminal when generating a data response, and encapsulate the return ticket as a header and attach it to the data packet. Downlink data will travel along the reverse path of key nodes within the return ticket, from the exit gateway station to the entry satellite, and finally to the user terminal; During uplink and downlink communication, if the relay node fails or becomes unreachable due to the power supply link within the ticket, it will not perform automatic path recovery or rerouting. The global ticketing arbitrator control center will then determine in subsequent scheduling cycles whether it is necessary to redistribute new tickets for the relevant inbound satellites.

8. The low-Earth orbit satellite constellation dynamic routing and user mobility management system according to claim 7, characterized in that, include: The power supply link information upload module (1) allows each gateway station to periodically report the real-time status information of the power supply link through wired or wireless backhaul links. The power supply link information storage module (2) reports real-time status information of the power supply link, which is stored and managed by the power supply link status database of the global ticketing arbitrator. The export gateway selection module (3) selects the export gateway based on the real-time status information of the power supply link in the power supply link status database. The global ticketing arbitrator selects the export gateway. The shortest delay path search module (4) searches for the shortest delay path from the ingress satellite to the egress gateway station based on the real-time status information of the feeder link in the feeder link status database and the global ticketing arbitrator searches for the shortest delay path from the ingress satellite to the egress gateway station by using the improved A* search algorithm to minimize end-to-end delay while avoiding congested paths or expected broken link areas. Ticket encapsulation and distribution module (5): The global ticketing arbitrator control center extracts a set of key forwarding nodes from the shortest delay path found, encapsulates them into departure and return tickets, and distributes them to the exit gateway station and the entry satellite. Uplink and downlink communication module (6): The inbound satellite and the outbound gateway station communicate uplink and downlink through encapsulated departure and return tickets.

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