Medium and low orbit satellite random access networking architecture and method based on space gateway station

Abstract

The invention relates to a space gateway station-based medium and low orbit satellite random access networking architecture and method, and belongs to the technical field of medium and low orbit satellite networks. Comprising a space gateway station; a ground station; an execution unit; and a user. According to the invention, the fault-tolerant capability and flexibility of the network are improved, and the construction and maintenance cost of the ground station is reduced; according to the method, the satellites can adapt to the change of a network environment, the probability of access failure and disconnection is reduced, and the reliability and the anti-interference capability of the network are greatly improved especially in an area where the satellites are alternated; the establishment speed and stability of a link are remarkably improved, communication interruption and link quality fluctuation are reduced, the transmission efficiency and the utilization rate are improved, unnecessary link switching is reduced, network delay and bandwidth waste are reduced, and the overall system performance is improved. According to the strategy, network resources can be flexibly allocated, the task completion efficiency is improved, the load balancing and task scheduling of the network are optimized, and the risk caused by link congestion or instability is reduced.

Description

Technical Field

[0001] The present invention relates to a medium- and low-orbit satellite random access networking architecture and method of a space gateway station, and belongs to the technical field of medium- and low-orbit satellite networks. Background Art

[0002] In recent years, medium and low-orbit satellite networks have attracted widespread attention in the fields of global communications, remote sensing and navigation. With their low latency, high bandwidth and wide coverage, they provide a technical basis for solving communications in remote areas, supporting large-scale Internet of Things and real-time data backhaul. Especially in the field of broadband satellite Internet, remarkable results have been achieved in constellation deployment, network optimization and multi-technology integration at home and abroad. SpaceX's Starlink project has successfully launched more than 5,000 low earthorbit (LEO) satellites to build a broadband network covering the world. The system uses dynamic beamforming technology and adaptive spectrum management strategies to achieve high throughput and low latency while ensuring wide coverage. OneWeb and Amazon's Kuiper project have also proposed routing optimization and ground station distribution optimization solutions based on inter-satellite links, respectively, to improve link efficiency and service quality.

[0003] Traditional satellite networks usually adopt a centralized scheduling architecture with ground stations as the core. Ground stations are responsible for satellite control, routing calculations, and coordination of resource allocation. However, with the continuous expansion of low-orbit satellite constellations and the increasing diversification of application tasks, this ground station-dominated scheduling model has gradually exposed efficiency bottlenecks, including increased communication delays, insufficient resource utilization, and limited adaptability to complex dynamic environments. In this context, satellite networks with automatic management capabilities have gradually attracted attention and are considered to be a potential solution to these problems. This network can improve system efficiency through intelligent scheduling and self-organization capabilities, providing a better solution for satellite communications in future large-scale and complex mission scenarios.

[0004] In addition, with the introduction of laser intersatellite links (LISLs), the communication capability and data transmission efficiency of low-orbit satellites have been greatly improved. However, the dynamic link scheduling, laser alignment efficiency and routing strategy of LISLs still need to be further optimized to adapt to complex orbital motion and multi-task requirements.

[0005] Defects and shortcomings of the existing technology:

[0006] Existing technologies have many defects and deficiencies in the networking and management of medium and low-orbit satellite networks, which need to be solved urgently. First, traditional satellite networks are highly dependent on ground stations for control and management. However, due to the limited coverage of ground stations, network performance in remote areas, oceans and polar regions is often restricted, and frequent satellite-ground station switching further increases communication delays and operating costs. It is impossible to achieve efficient scheduling and real-time control of satellites around the world, and it is difficult to realize an automated satellite network.

[0007] In order to overcome the limitations of ground stations, more and more research focuses on using inter-satellite links and geostationary orbit (GEO) satellites as relays to ground gateways to support efficient networking and resource management of medium and low orbit satellite networks. However, due to their fixed orbits and limited resources, GEO satellites are difficult to achieve full global coverage, especially in high latitudes and remote areas. In addition, due to the high altitude of the GEO orbit, signal transmission requires greater power support, which not only increases the energy consumption of the system, but also places higher requirements on the transmission and reception performance of the equipment. These technical bottlenecks have greatly limited the relay solutions that rely entirely on GEO satellites in practical applications.

[0008] Secondly, as the core of low- and medium-orbit satellite network communications, the establishment process of inter-satellite links (LISLs) is often subject to the dynamic orbital position and attitude changes of the satellite. The existing laser link capture technology still has much room for improvement in the time required for alignment and tracking.

[0009] Finally, the existing architecture lacks flexibility and adaptability in multi-task scenarios. For diverse needs such as general user communications, remote sensing data backhaul, and distributed computing tasks, the existing system lacks a unified architectural design and cannot effectively support resource allocation and priority management between different tasks. Especially in remote areas, the problem of resource waste is particularly prominent due to the large number of idle nodes and links in the satellite network. In addition, the link overhead between different orbits in the LEO constellation varies significantly. For example, it is relatively easy to establish links between satellites in the same or parallel orbits, while the maintenance cost of satellite links across orbits or running in opposite directions is relatively high. This problem has not yet been fully resolved and included in the optimization.

[0010] In summary, the current medium and low-orbit satellite networks have significant shortcomings in network scheduling, link establishment, route optimization, and multi-task collaboration capabilities. There is an urgent need for an innovative networking architecture that can achieve more efficient resource utilization, more flexible mission adaptability, and lower link establishment overhead to meet the challenges of future diversified application scenarios and complex dynamic environments.

[0011] Therefore, it is urgent to propose a low- and medium-orbit satellite random access networking architecture and method based on space gateways to solve the above technical problems. Summary of the invention

[0012] In order to solve the above problems, a medium and low orbit satellite random access networking architecture and method based on a space gateway is provided. A brief overview of the present invention is given below to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to determine the key or important parts of the present invention, nor is it intended to limit the scope of the present invention.

[0013] The technical solution of the present invention:

[0014] The network architecture of medium and low-orbit satellite random access based on space gateway station includes:

[0015] Space gateway: responsible for the core tasks of satellite status monitoring, routing calculation and resource allocation;

[0016] In the scenario where the space gateway autonomously controls the entire satellite network, the control function of the ground station is transferred to the space gateway, and the decision is made by the execution unit, and the status information of the satellite network is transmitted to the ground station by the execution unit that can establish a connection with the ground station;

[0017] Ground station: In the scenario where the ground station controls the entire satellite network, control information and status information are transmitted to the MEO satellite through the communication link between the ground station and the MEO satellite;

[0018] The ground station can communicate with LEO and process service requests;

[0019] Execution unit: including MEO and LEO satellites, mainly responsible for performing specific communications and mission operations;

[0020] User: User terminal and execution unit, realizing business request.

[0021] Preferably: the space gateway payload includes at least one wide-beam radio frequency transmitter, one multi-channel radio frequency receiver, one Beidou / GPS receiver, three sets of laser terminals and a gimbal;

[0022] The LEO layer includes three communication links: space gateway-LEO, LEO-LEO and LEO-user; the LEO satellite payload includes at least two RF transmitters, one RF receiver, one BeiDou / GPS receiver, three laser terminals and ISAC transceiver;

[0023] The role of the space gateway-LEO link is to use MEO to transmit global network information to LEO satellites through broadcasting. LEO satellites dynamically adjust their access methods and task allocation strategies based on the received information.

[0024] The LEO-LEO link is a high-speed data transmission between LEO satellites through intersatellite laser links, and a low-speed radio frequency link is used to transmit control information to assist the access and tracking of LISLs;

[0025] The LEO-user link is a communication connection established between the LEO satellite and the user terminal or ground gateway, processing service requests including voice, video, and data.

[0026] Preferably: it has an access-at-anytime mechanism. The access-at-anytime mechanism in the present invention means that after a low-orbit satellite enters the visible range of any space gateway station, it accesses the satellite network to perform measurement, control and communication tasks, and finally completes "measurement and control on demand, access-at-anytime"; in the giant constellation mode, the satellite's autonomous capability is enhanced, and it can independently complete network access, data transmission, orbit control requirements, etc. The satellite initiates an access request to the space gateway station as needed, and the space gateway station performs authentication, routing management, task allocation and other management.

[0027] Preferred: Use ISAC signal auxiliary link and use its sensing and positioning capabilities to support the rapid establishment and efficient maintenance of intersatellite laser links.

[0028] The method for randomly accessing medium and low orbit satellites based on a space gateway adopts the dual-layer networking architecture for randomly accessing medium and low orbit satellites based on a gateway, and includes the following steps:

[0029] Anytime access mechanism;

[0030] ISAC signaling aids link establishment;

[0031] Dynamic routing optimization.

[0032] Preferably: in step 1.1, the space gateway regularly broadcasts the identification code, access permission rules, location information, and adjacent gateway coverage areas within its management range, and the signal covers the space within its visible range;

[0033] LEO satellites that enter the beam range of the space gateway station receive the broadcast signal and parse the identification code and location information, and determine whether they are within the management range of the gateway station based on their own orbital status;

[0034] In step 1.2, after confirming that it is within the management range of the gateway, the LEO sends an access request to the gateway via a reverse microwave link pointing to the location of the space gateway, and includes the real-time status information of the LEO satellite;

[0035] After receiving the request from the satellite, the gateway station calculates the distance between the satellite and the gateway station and the estimated stay time within the management range based on the orbital data and its own position;

[0036] If the gateway has sufficient resources and the estimated stay time meets the communication requirements, access is allowed; otherwise, the request is rejected and a retry interval is set;

[0037] In step 1.3, after access is allowed:

[0038] The gateway adds the LEO satellite to its visible satellite list;

[0039] Update the gateway’s routing table based on the current network status to optimize the performance of the LEO-LEO laser link;

[0040] The gateway sends access permission and intersatellite link switching instructions to the satellite through broadcasting;

[0041] After access is denied:

[0042] The gateway sends a rejection message to the LEO satellite;

[0043] Set a fixed interval during which LEO satellites cannot apply to access the same gateway again;

[0044] Step 1.4 includes:

[0045] Step 1.4.1: Identify overlapping areas

[0046] By analyzing the broadcast signal, the LEO satellite can find that it is in the overlapping area of ​​the management range of the two gateway stations, and report the overlapping status to the gateway station through the reverse link with the gateway station being accessed;

[0047] Step 1.4.2: Assign cross-region transfer tasks

[0048] The gateway coordinates and decides on LEO-LEO routing, allocating LEO satellites as nodes for cross-regional data transmission;

[0049] The satellite takes on the communication task between the two gateways according to the instructions, providing redundant paths to enhance the stability of transmission;

[0050] Step 1.4.3: Network planning requirements

[0051] Satellite deployment must meet the following requirements: ensure that the management ranges of adjacent gateways have sufficient overlap; deploy a sufficient number of LEO satellites in the overlapped area to improve transmission stability and redundancy;

[0052] Step 1.5 includes:

[0053] Step 1.5.1: Predict the switching time

[0054] The LEO satellite estimates the time when it will leave the management range of the current gateway based on the visibility time calculated when it accesses.

[0055] Step 1.5.2: Request access in advance

[0056] The LEO satellite is in the overlapping area of ​​the management range of the two gateway stations;

[0057] The LEO satellite sends a disconnection indication to the old gateway, then adjusts the beam pointing and sends an access request to the new gateway in advance, including the current status information.

[0058] After receiving the disconnection instruction, the old signal gateway deletes the LEO satellite node from the visible satellites;

[0059] The Xinxin Gateway verifies the access according to its access rules and makes a decision to grant or deny access;

[0060] Step 1.5.3: Switch execution

[0061] If access permission is obtained, LEO establishes communication with the new gateway. The gateway dynamically calculates the visibility time and updates the network routing to ensure seamless communication links during the handover.

[0062] If access is denied, the new gateway sends a rejection command to LEO and prevents the LEO satellite from making access requests within a certain period of time;

[0063] Step 1.6 includes:

[0064] Step 1.6.1: Network status monitoring

[0065] The gateway station monitors the operating status and link performance of the LEO satellite in real time, which is completed by LEO reporting to the gateway station regularly;

[0066] Dynamically adjust access rules and task allocation strategies based on operating status and link performance;

[0067] Step 1.6.2: Parameter optimization

[0068] Optimize the retry access interval to ensure efficient use of resources;

[0069] Dynamically adjust the routing table update frequency to adapt to the rapid changes in satellite networks.

[0070] Preferably: in step 2.1, the space gateway regularly broadcasts the latest network routing information via ISAC signals; the broadcast content includes:

[0071] Intersatellite link topology information: LEO satellite network routing table;

[0072] Satellite status information within the jurisdiction: including the real-time position, speed and mission load of each LEO satellite;

[0073] Resource allocation strategy: covers the use and allocation scheme of communication resources (frequency, code and space allocation of ISAC signals), computing and storage resources;

[0074] After receiving the broadcast, the LEO satellite parses the routing information and caches it in local storage, and determines whether it is necessary to switch the intersatellite link based on its own mission and location status; if switching is required, the current link is disconnected according to the routing information, and the ISAC beam direction is adjusted to point to the predetermined target LEO satellite, preparing to establish a new link;

[0075] In step 2.2, the ISAC beam pointing adjustment during switching

[0076] The LEO satellite that receives the LEO-LEO link switching command estimates the relative position between the two LEO satellites using the predicted position broadcast by the space gateway:

[0077]

[0078] Due to the influence of factors such as signal processing delay and orbital perturbation in the system, the actual positions of the two satellites will deviate from the coordinates predicted by the gateway; a feasible error range can be expressed as follows:

[0079] Δρ LEO =t p ×v LEO +ρ LEO

[0080] Among them, t p is the system delay from the gateway prediction time to the ISAC channel propagation to the receiver, v LEO is the speed of the receiver, ρ LEO is the position error radius caused by factors such as atmospheric drag and orbital perturbations;

[0081] Assume that the actual position of LEO satellite 2 is in a certain distribution X. is the center and the radius is Δρ LEO2 sphere; set a reasonable initial capture probability P SC , there is a minimum ISAC beam radius ρ beam satisfy:

[0082]

[0083] Then the minimum beam width is:

[0084]

[0085] Therefore, the ISAC signal from LEO satellite 1 to LEO satellite 2 needs to The pointing direction and 2×2θ 0.53dB beamwidth, which can ensure P SC The probability of being captured by the receiver on LEO satellite 2;

[0086] In step 2.3, after the ISAC signal is captured, a two-dimensional search is first performed to capture the signal, the Doppler velocity value is calculated, and after the signal is analyzed, the non-coherent ranging method is used to measure the distance based on the satellite's high-precision clock;

[0087] The bidirectional ISAC link transmits more accurate real-time calibration data of LEO satellites, including but not limited to the current self-measured position and velocity, six-axis sensor data, star calibration values, star-to-star calibration values, laser terminal receiving and transmitting light axis consistency deviation, and tracking point calibration values ​​for precise pointing adjustment;

[0088] Combining ISAC ranging, velocity measurement and calibration data, the extended Kalman filter (EKF) or particle filter algorithm is used to eliminate noise and deviation to obtain a high-precision center of mass position; if the current LEO satellite has established an ISAC link with three LEO satellites at the same time, three-star positioning is further used to obtain a more accurate positioning result, so that the pointing error after calibration is in the order of hundreds of μrad;

[0089] After determining the LEO satellite's center of mass coordinates and the direction of its movement, a narrow laser beam is emitted toward the center of mass coordinates; the laser terminal is equipped with a beam position detection unit; commonly used position detectors include four-quadrant detectors and infrared focal plane detectors; the optical axis deviation is determined quickly and accurately, and the deviation value is fed back to the LEO satellite at the laser transmitting end through the ISAC signal; the LEO satellite at the laser transmitting end controls the fine tracking actuator to adjust its direction according to the deviation. The fine tracking actuator is a fast reflector driven by a voice coil motor or piezoelectric ceramics, and the optical axis alignment is completed step by step and iteratively;

[0090] In step 2.4, tracking after establishing a bidirectional laser link

[0091] Tracking is similar to the process of establishing a laser link. During tracking, the angular velocity of the laser terminal pointing to the ground is affected by the satellite's motion state. Tracking of large offsets is corrected by the satellite velocity, acceleration, angular acceleration and satellite attitude calibration values ​​transmitted by the ISAC signal. Tracking of small offsets such as vibration and thermal deformation is corrected by detecting the offset through the beam position detection unit.

[0092] ISAC beam pointing is adjusted synchronously;

[0093] In step 2.5, the ISAC signal and the laser signal

[0094] ISAC signals mainly transmit the above-mentioned measurement and control information;

[0095] Laser signals mainly transmit business data. At the same time, according to system requirements, lasers can be used to measure the distance between two terminals and the time difference between terminal reference clock sources.

[0096] Preferred: The number of hops is cumulative in each link and can be represented by a constant H; the delay D ij Including transmission delay D t and on-board processing delay D p :

[0097] D ij =D t +D p

[0098] Link tracking difficulty T ij The relative speed of the satellite v needs to be considered ij , pointing angle change rate φ ij , orbital angle θ ij wait:

[0099] T ij =f(v ij ,φ ij ,θ ij )

[0100] Link idle probability estimation F ij The historical idle probability over a period of time can be used and the current link resource utilization U ij :

[0101]

[0102] The present invention has the following beneficial effects:

[0103] (1) Using space gateways as management relays for medium and low orbit satellite networks

[0104] Analysis of improvements: The present invention proposes to use space gateways as management relays for medium and low orbit satellite networks, eliminating the reliance on ground stations and overcoming the limitations of GEO satellites. By setting up gateways in space, LEO satellites can flexibly access and obtain global network information (such as link status, routing tables, locations, and synchronous clocks). This solution effectively expands the coverage of satellite networks, reduces reliance on a single management center, and improves the flexibility and stability of the network.

[0105] Advantages: This solution not only improves the fault tolerance and flexibility of the network, but also reduces the cost of ground station construction and maintenance.

[0106] (2) Anytime access mechanism

[0107] Improvement analysis: The solution of the present invention proposes an access-on-demand mechanism based on a space gateway. LEO satellites can dynamically learn their management range based on broadcast signals, automatically initiate access requests, and connect with the space gateway. This flexible access method enables satellites to dynamically select access points based on their own locations and mission requirements, thereby ensuring the stability and continuity of the network.

[0108] Advantages: This solution enables satellites to adapt to changes in the network environment, reducing the probability of access failure and disconnection, especially in areas where there is a shift between satellites, greatly improving the reliability and anti-interference capabilities of the network.

[0109] (3) ISAC technology supports the establishment of intersatellite links

[0110] Analysis of improvements: The present invention adopts ISAC (Integrated Communication and Perception) technology, and uses ISAC signals to provide accurate relative positioning information to help satellites quickly complete link alignment and laser link establishment. Through ISAC technology, satellites can perceive the relative position and attitude of other satellites in real time, thereby completing laser link alignment in a shorter time and optimizing the link establishment process. This technical improvement not only reduces the link establishment time, but also improves the link stability and communication efficiency.

[0111] Advantages: ISAC technology significantly improves the speed and stability of link establishment, reduces communication interruptions and link quality fluctuations, and improves the transmission efficiency of intersatellite links.

[0112] (4) Dynamic LISL link scheduling optimization

[0113] Improvement analysis: The present invention proposes a scheduling strategy for dynamically adjusting the intersatellite link (LISL) according to mission requirements, satellite visibility and link performance; by real-time monitoring of the satellite relative position, mission load and link status, the scheduling process of LISL is optimized to improve the link utilization efficiency and system response speed; especially when the relative position of the satellite changes greatly, the frequency of link switching can be minimized by optimizing scheduling to ensure the continuity and stability of the mission;

[0114] Advantages: This solution can effectively improve link utilization, reduce unnecessary link switching, reduce network latency and bandwidth waste, and thus improve overall system performance.

[0115] (5) Dynamic routing optimization in multi-task scenarios

[0116] Improvement analysis: The present invention proposes to dynamically adjust the routing strategy according to the task priority and resource requirements in a multi-task scenario; the remote sensing data backhaul task can give priority to satellites with a high probability of being idle and relatively stable links to avoid frequent link switching, thereby ensuring the stability of the task and the efficiency of data transmission; and for ordinary user communication tasks with higher latency requirements, low latency and high throughput paths are given priority; this improvement enables the routing strategy to be dynamically optimized according to the specific requirements of the task, thereby improving resource utilization and the overall performance of the system;

[0117] Advantages: This strategy can flexibly allocate network resources and improve the efficiency of task completion. It also optimizes network load balancing and task scheduling, and reduces the risks caused by link congestion or instability. BRIEF DESCRIPTION OF THE DRAWINGS

[0118] Figure 1 This is a two-layer networking architecture diagram based on the gateway station for random access to medium and low-orbit satellites;

[0119] Figure 2 This is the working mode diagram of the ISAC signal and laser link;

[0120] Figure 3 It is a routing graph for user communication, remote sensing data transmission and computing task offloading;

[0121] Figure 4 It is a random access map.

[0122] Figure 5 It is an access (network access) flow chart.

[0123] Figure 6 It is a cross-region node connection graph.

[0124] Figure 7 It is a switching flow chart.

[0125] Figure 8 ISAC signals are initially aligned to establish a stable control data link diagram.

[0126] Fig. 9 It is the establishment of laser link assisted by ISAC technology.

[0127] Fig.10 It is the block diagram of link tracking control system. DETAILED DESCRIPTION

[0128] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is described below by the specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0129] Specific implementation method 1: Combination Figure 1-3 This embodiment is described. The low- and medium-orbit satellite random access networking architecture based on the space gateway station in this embodiment includes:

[0130] Space Gateway (Gateway): responsible for satellite status monitoring, routing calculation and resource allocation.

[0131] In the scenario where the space gateway autonomously controls the entire satellite network, the control function of the ground station is transferred to the MEO layer of the space gateway, and the MEO satellite of the execution unit makes decisions. At the same time, the LEO satellite of the execution unit that can establish a connection with the ground gateway is used to transmit the status information of the satellite network to the ground station, so as to reduce the dependence of the low-orbit constellation on the ground station;

[0132] The space gateway station includes a MEO layer and / or a high LEO layer. The space gateway station (network architecture and management framework) uses MEO or LEO satellites as the anchor point of the network and undertakes the core tasks of satellite status monitoring, routing calculation and resource allocation. The space gateway station payload includes at least one wide-beam RF transmitter, a multi-channel RF receiver, a Beidou / GPS receiver, three sets of laser terminals and pan / tilt and communication interfaces, computing resources, and storage resources.

[0133] LEO layer: LEO satellites are mainly responsible for performing specific communications and mission operations, including three communication links: space gateway-LEO, LEO-LEO and LEO-user; LEO satellite payloads include at least two RF transmitters (one for communicating with the space gateway and the other for communicating with users), one RF receiver, one BeiDou / GPS receiver, three sets of laser terminals and ISAC transceivers and communication interfaces, computing resources, and storage resources;

[0134] Ground station: In the scenario where the entire satellite network is controlled by the ground station, control information and status information are transmitted to the MEO satellite through the communication link between the ground gateway and the MEO satellite;

[0135] The ground station can communicate with LEO and process multiple types of service requests including voice, video, and data;

[0136] Execution unit: including MEO (medium earth orbit) satellites and / or relatively high LEO (low earth orbit) satellites, mainly responsible for performing specific communications and mission operations;

[0137] User: The user terminal communicates with the LEO of the execution unit to realize multiple types of service requests including voice, video, and data;

[0138] The role of the space gateway-LEO link is to use MEO to transmit global network information (such as link status, routing table, location information and synchronization clock, etc.) to LEO satellites through broadcasting. LEO satellites dynamically adjust their own access mode and task allocation strategy based on the received information, and realize fast and flexible link selection and route switching in a dynamic network environment.

[0139] LEO-LEO links are high-speed data transmission between LEO satellites through intersatellite laser links (LISLs), and control information is transmitted using low-speed radio frequency links to assist in the access and tracking of LISLs, ensuring network connectivity within the constellation;

[0140] The LEO-user link is a communication connection established between the LEO satellite and the user terminal or ground gateway, processing multiple types of service requests including voice, video, and data;

[0141] It has an access-on-demand mechanism. The access-on-demand mechanism in the present invention means that after a low-orbit satellite enters the visual range of any space gateway station, it can automatically, quickly and effectively access the satellite network to perform measurement, control and communication tasks, and finally complete "on-demand measurement, control and access-on-demand"; in the giant constellation mode, the satellite's autonomous capability is enhanced, and it can independently complete network access, data transmission, orbit control requirements, etc. The satellite initiates an access request to the space gateway station as needed, and the space gateway station performs authentication, routing management, task allocation and other management;

[0142] Step 1: Access-Transmission-Switching Mechanism

[0143] Under the random access framework, LEO satellites can identify their own management scope by receiving broadcast signals from space gateways, and send access requests to the gateways, while reporting their own status information (such as orbital position, mission load, etc.). Based on the received status information, the space gateway calculates the distance of the LEO satellite and its stay time in the visible range to decide whether to allow access; if allowed, the gateway will update its visible satellite list and generate a new routing table, and issue LEO-LEO link switching instructions to optimize the performance of the intersatellite link; if access is not allowed, the gateway will reject the request and set an interval time so that the LEO satellite cannot apply to access the same gateway again during this time period;

[0144] When a LEO satellite is located in the overlapping area of ​​two space gateway management areas, the satellite can be assigned as a node for cross-regional data transmission and undertake tasks between different gateway management areas. To ensure reliable data transmission between adjacent gateway areas, satellite network deployment needs to ensure that there is a sufficiently large overlapping area between the two gateway management areas and be equipped with a certain number of available satellites to form redundant paths, thereby improving the stability and efficiency of transmission.

[0145] In addition, when a LEO satellite is about to leave the management range of the current gateway (which can be predicted by the visible time calculated during access), the satellite will send an access request to the new gateway in advance; once access permission is obtained, the LEO satellite will establish a connection with the new gateway and terminate the connection with the previous gateway to ensure seamless switching of communication links and continuous network coverage; such a dynamic access mechanism effectively improves the adaptability and resource utilization efficiency of the LEO satellite network;

[0146] (1) Access process:

[0147] After receiving the information broadcast by the space gateway, the LEO satellite evaluates its distance from the space gateway and the visible time, and sends an access request to the gateway. The space gateway determines whether to allow access based on the satellite's request, combined with the coverage and mission requirements. If the access is successful, the LEO satellite will update the visible satellite list of the gateway, and obtain the mission instructions and routing table; if the access fails, the LEO satellite will reapply after a set time interval.

[0148] (2) Dynamic switching:

[0149] When a LEO satellite is about to leave the coverage of the current gateway, it will initiate an access request to the next gateway in advance according to its movement trajectory to complete seamless switching.

[0150] Advantages: Avoid task interruption due to switching delay and ensure business continuity;

[0151] Step 2: Using ISAC signal auxiliary link, in order to improve the capture and tracking efficiency of inter-satellite links (LISLs), the present invention introduces the communication and perception integration (ISAC) technology, and uses its perception and positioning capabilities to support the rapid establishment and efficient maintenance of inter-satellite laser links;

[0152] To improve the acquisition and tracking efficiency of intersatellite links (LISLs), this solution introduces the integrated communication and sensing (ISAC) technology, which uses its sensing and positioning capabilities to support the rapid establishment and efficient maintenance of intersatellite laser links; ISAC signals provide accurate satellite relative positioning information, helping LEO satellites to achieve fast and efficient alignment operations during laser link alignment. During laser link alignment, ISAC signals can provide real-time feedback on the relative position and velocity of the satellite, providing guidance for the precise alignment of the laser link;

[0153] During the laser link establishment process, the ISAC signal is not only used to improve the alignment accuracy, but also to form a continuous and stable data transmission channel in the early stage of link establishment to transmit the control information of the laser link. Through this control information, the LEO satellite and the laser equipment can dynamically calibrate the attitude to ensure that the laser beam is always aligned with the target satellite, reducing errors and instability in the alignment process. This continuous data transmission capability greatly improves the reliability of the link and avoids frequent interruptions during the link establishment process.

[0154] In addition, ISAC technology can significantly reduce the time required for laser link alignment; traditional laser link alignment requires step-by-step scanning and calibration from wide beam to narrow beam, which usually takes a long time to perform precise alignment and will interfere with other running high-speed laser links; through ISAC technology, satellites and laser equipment can quickly obtain relative positioning information and adjust the direction and attitude of the laser beam in real time, significantly shortening the alignment time and improving the performance of dynamic links; ultimately, ISAC technology not only optimizes the stability and efficiency of laser links, but also enhances the adaptability of the system, especially in dynamic and complex satellite environments, ensuring the reliability and efficient transmission capabilities of intersatellite links;

[0155] (1) ISAC signal generation and transmission: ISAC signals carry both perception information and control instructions to help satellites quickly locate each other. One possible ISAC signal is to use orthogonal frequency division multiplexing (OFDM), with each subcarrier using direct-sequence spread spectrum (DSSS); this waveform can modulate positioning information on a spread spectrum sequence (such as a pseudo-random sequence PRN) to enhance anti-interference capabilities, provide accurate time delay and Doppler shift information, and transmit it together with communication data to improve time resolution for accurate relative distance measurement; the transmitted data needs to include satellite relative velocity estimation, attitude information correction, link quality measurement, laser beam alignment correction and other information;

[0156] (2) Laser link alignment: The ISAC signal is initially captured through a wide microwave beam. The satellite adjusts the satellite attitude and the laser terminal pointing direction based on the motion and attitude information to achieve initial alignment. The laser alignment error is calculated based on the link quality at the laser receiver end. The error and laser beam calibration instructions are transmitted back through the ISAC signal to dynamically adjust the direction and width of the laser beam to optimize the data transmission rate and stability.

[0157] (3) Tracking calibration: Use sensing data to calibrate satellite attitude in real time to ensure link stability;

[0158] Advantages: shorten the laser link establishment time and improve the communication capacity and stability of the system;

[0159] Specific implementation method 2: Combination Figure 4-10 The present embodiment is described. The medium and low orbit satellite random access method based on the space gateway of the present embodiment adopts a two-layer networking architecture of medium and low orbit satellite random access based on the gateway, and the space gateway (MEO layer / high LEO layer): the space gateway adopts MEO or relatively high LEO satellite as the anchor point of the network, and undertakes the core tasks of satellite status monitoring, routing calculation and resource allocation; in the scenario where the ground station controls the entire satellite network, control information and status information can be transmitted to the MEO satellite through the communication link between the ground gateway and the MEO satellite; in the scenario where the space gateway autonomously controls the entire satellite network, the control function of the ground station is transferred to the MEO layer, and the MEO satellite makes the decision, and at the same time, the LEO satellite that can establish a connection with the ground gateway is used to transmit the status information of the satellite network to the ground, so as to reduce the dependence of the low orbit constellation on the ground station;

[0160] LEO layer: LEO satellites are mainly responsible for performing specific communications and mission operations, including three communication links: space gateway-LEO, LEO-LEO and LEO-user; the role of the space gateway-LEO link is to use MEO to transmit global network information (such as link status, routing table, location information and synchronization clock, etc.) to LEO satellites through broadcasting. LEO satellites dynamically adjust their own access methods and task allocation strategies based on the received information, and realize fast and flexible link selection and route switching in a dynamic network environment; LEO-LEO link is a LEO satellite that transmits high-speed data through intersatellite laser links (LISLs), and uses low-speed radio frequency links to transmit control information to assist LISLs in access and tracking, ensuring network connectivity within the constellation; LEO-user link is a communication connection established between LEO satellites and user terminals or ground gateways, processing multiple types of service requests including voice, video and data;

[0161] System architecture design:

[0162] (1) Space Gateway Function

[0163] The space gateway (MEO layer) obtains real-time information of LEO satellites in its jurisdiction through wide-area coverage, including location, mission load and communication link status. In specific implementation, the space gateway regularly broadcasts routing tables, synchronization clock information and link status;

[0164] Function: Coordinate LEO satellites in the region to achieve dynamic resource allocation;

[0165] Advantages: Centralized management and global vision;

[0166] (2)LEO satellite functions

[0167] LEO satellites perform tasks according to the instructions of the space gateway, including communication access, link establishment, data transmission, etc. Each LEO satellite will regularly upload its orbit status, mission status, remaining resources and other information for the space gateway to optimize its decision-making;

[0168] Function: Perform dynamic access, carry user communication tasks and cross-regional data transmission tasks;

[0169] Advantages: High flexibility, convenient for distributed execution of tasks;

[0170] The method comprises:

[0171] Anytime access mechanism, including:

[0172] Step 1.1: The gateway broadcasts the signal. First, the space gateway regularly broadcasts the identification code, access permission rules, location information, and adjacent gateway coverage areas within its management range. The signal covers the space within its visible range (such as the blue beam range of space gateway A and the yellow beam range of space gateway B).

[0173] Then, LEO satellites that enter the beam range of the space gateway station receive the broadcast signal and parse the identification code and location information, and determine whether they are within the management range of the gateway station based on their own orbital status;

[0174] Step 1.2: LEO satellite access request. After confirming that it is within the management range of the gateway, the LEO (such as low-orbit satellite A) sends an access request to the gateway through a reverse microwave link pointing to the location of the space gateway (such as the deep blue beam of low-orbit satellite A), and contains the real-time status information of the LEO satellite (such as orbital position, mission load, routing, etc.);

[0175] After receiving the request from the satellite, the gateway station calculates the distance between the satellite and the gateway station and the estimated stay time within the management range based on the orbital data and its own position;

[0176] If the gateway has sufficient resources and the estimated stay time meets the communication requirements, access is allowed; otherwise, the request is rejected and a retry interval is set;

[0177] Step 1.3: Access permission and routing update. After access is allowed:

[0178] The gateway adds the LEO satellite to its visible satellite list;

[0179] Update the gateway’s routing table based on the current network status to optimize the performance of the LEO-LEO laser link;

[0180] The gateway sends access permission and inter-satellite link switching instructions to the satellite through broadcasting (for example, allowing low-orbit satellite A to establish a laser link with low-orbit satellite B);

[0181] Or after denying access:

[0182] The gateway sends a rejection message to the LEO satellite;

[0183] Set a fixed interval time during which the LEO satellite cannot apply to access the same gateway again; Steps 1.1 to 1.3 are as follows Figure 5 As shown;

[0184] Step 1.4: Cross-region node allocation, including:

[0185] Step 1.4.1: Identify overlapping areas

[0186] By analyzing the broadcast signal, the LEO satellite can find that it is in the overlapping area of ​​the management range of the two gateway stations, and report the overlapping status to the gateway station through the reverse link with the gateway station being accessed; (such as LEO satellite B reporting to gateway station A);

[0187] Step 1.4.2: Assign cross-region transfer tasks

[0188] The gateway coordinates the decision-making of LEO-LEO routing and allocates LEO satellites as nodes for cross-regional data transmission (e.g., LEO satellite A-LEO satellite B-LEO satellite C)

[0189] The satellite takes on the communication task between the two gateways according to the instructions, providing redundant paths to enhance the stability of transmission;

[0190] Step 1.4.3: Network planning requirements

[0191] Satellite deployment must meet the following requirements: ensure that the management ranges of adjacent gateways have sufficient overlap; deploy a sufficient number of LEO satellites in the overlapped area to improve transmission stability and redundancy;

[0192] Step 1.5: Dynamic access switching, including:

[0193] Step 1.5.1: Predict the switching time

[0194] The LEO satellite estimates the time when it will leave the management range of the current gateway station based on the visibility time calculated when it accesses the network (e.g., LEO satellite B is about to leave the management range of gateway station A);

[0195] Step 1.5.2: Request access in advance

[0196] At this time, the LEO satellite is in the overlapping area of ​​the management range of the two gateway stations (for example, LEO satellite B is located in the overlapping area of ​​gateway station A and gateway station B);

[0197] The LEO satellite sends a disconnection indication to the old gateway, then adjusts the beam direction (for example, LEO satellite B adjusts the solid beam to the dashed beam direction), and sends an access request to the new gateway in advance, including the current status information;

[0198] After receiving the disconnection instruction, the old signal gateway deletes the LEO satellite node from the visible satellites;

[0199] The Xinxin Gateway verifies the access according to its access rules and makes a decision to grant or deny access;

[0200] Step 1.5.3: Switch execution

[0201] If access permission is obtained, LEO establishes communication with the new gateway. The gateway dynamically calculates the visibility time and updates the network routing to ensure seamless communication links during the handover.

[0202] If access is denied, the new gateway sends a rejection command to LEO and prevents the LEO satellite from making access requests within a certain period of time;

[0203] Step 1.6: Performance monitoring and optimization, including:

[0204] Step 1.6.1: Network status monitoring

[0205] The gateway station monitors the operating status and link performance of the LEO satellite in real time, which is completed by LEO reporting to the gateway station regularly;

[0206] Dynamically adjust access rules and task allocation strategies based on operating status and link performance;

[0207] Step 1.6.2: Parameter optimization

[0208] Optimize the retry access interval to ensure efficient use of resources;

[0209] Dynamically adjust the routing table update frequency to adapt to the rapid changes in satellite networks;

[0210] ISAC signals assist in link establishment, including:

[0211] Step 2.1: The space gateway broadcasts the route switch;

[0212] The Space Gateway regularly broadcasts the latest network routing information via ISAC signals; the broadcast content includes:

[0213] Intersatellite link topology information: LEO satellite network routing table;

[0214] Satellite status information within the jurisdiction: including the real-time position, speed and mission load of each LEO satellite;

[0215] Resource allocation strategy: covers the use and allocation scheme of communication resources (frequency, code and space allocation of ISAC signals), computing and storage resources;

[0216] After receiving the broadcast, the LEO satellite parses the routing information and caches it in local storage, and determines whether it is necessary to switch the intersatellite link based on its own mission and location status; if switching is required, the current link is disconnected according to the routing information, and the ISAC beam direction is adjusted to point to the predetermined target LEO satellite, preparing to establish a new link;

[0217] Step 2.2: Alignment; Adjustment of ISAC beam pointing during switching

[0218] The LEO satellite that receives the LEO-LEO link switching command estimates the relative position between the two LEO satellites using the predicted position broadcast by the space gateway:

[0219]

[0220] Due to the influence of factors such as signal processing delay and orbital perturbation in the system, the actual positions of the two satellites will deviate from the coordinates predicted by the gateway; a feasible error range can be expressed as follows:

[0221] Δρ LEO =t p ×v LEO +ρ LEO

[0222] Among them, t p is the system delay from the gateway prediction time to the ISAC channel propagation to the receiver, v LEO is the speed of the receiver, ρ LEO is the position error radius caused by factors such as atmospheric drag and orbital perturbations;

[0223] It can be assumed that the actual position of LEO satellite 2 is in a certain distribution X (such as three-dimensional Gaussian distribution) is the center and the radius is Δρ LEO2 sphere; set a reasonable initial capture probability P SC , there is a minimum ISAC beam radius ρ beam satisfy:

[0224]

[0225] Then the minimum beam width is:

[0226]

[0227] Therefore, the ISAC signal from LEO satellite 1 to LEO satellite 2 needs to The pointing direction and 2×2θ 0.5 (If the position of LEO satellite 1 has been corrected, use 2θ 0.5 The 3dB beam width can ensure that the P SC The probability of being captured by the receiver on LEO satellite 2; A feasible ISAC signal is OFDM-direct spread spectrum signal;

[0228] In the system, a larger fixed beam width can be uniformly set to meet the capture performance at various distances and reduce the computational overhead of beamforming. Generally speaking, the position error of LEO satellites is in the mrad order, within the beam range of microwave signals, but exceeds the divergence angle of laser terminals (tens to hundreds of μrad order; therefore, microwave signals can be used to directly establish effective communication links without the need to use certain capture strategies to scan and cover uncertain areas.

[0229] Step 2.3: Establishment of laser link with the assistance of ISAC technology; After the ISAC signal is captured, firstly, a two-dimensional search of time and frequency is performed to capture the signal, calculate the Doppler velocity value, and after analyzing the signal, use the non-coherent ranging method to measure the distance by relying on the high-precision satellite clock;

[0230] The bidirectional ISAC link transmits more accurate real-time calibration data of LEO satellites, including but not limited to the current self-measured position and velocity, six-axis sensor data (acceleration, angular acceleration, etc.), star calibration values ​​(satellite attitude and direction), star mark calibration values ​​(referenced to the benchmark data provided by the ground station), laser terminal receiving and transmitting light axis consistency deviation and tracking point calibration values ​​for precise pointing adjustment;

[0231] Combining ISAC ranging, velocity measurement and calibration data, the extended Kalman filter (EKF) or particle filter algorithm is used to eliminate noise and deviation to obtain a high-precision center of mass position; if the current LEO satellite has established an ISAC link with three LEO satellites at the same time, three-star positioning is further used to obtain a more accurate positioning result, so that the pointing error after calibration is in the order of hundreds of μrad;

[0232] After determining the LEO satellite's center of mass coordinates and the direction of its movement, a narrow laser beam is emitted toward the center of mass coordinates. The laser terminal is equipped with a beam position detection unit. Common position detectors include quadrant avalanche photodetector (QAPD) and infrared focal plane detector. The optical axis deviation is determined quickly and accurately, and the deviation value is fed back to the LEO satellite at the laser transmitting end through the ISAC signal. The LEO satellite at the laser transmitting end controls the fine tracking actuator to adjust its direction according to the deviation. The fine tracking actuator is a fast steering mirror (FSM) driven by a voice coil motor or piezoelectric ceramics, and the optical axis alignment is completed step by step through iterations.

[0233] Step 2.4: Tracking; Tracking after establishing a two-way laser link

[0234] Tracking is similar to the process of establishing a laser link. During tracking, the angular velocity of the laser terminal pointing to the direction of rotation is affected by the satellite's motion state (attitude, speed, acceleration). Tracking of large offsets is corrected by the satellite speed, acceleration, angular acceleration and satellite attitude calibration values ​​transmitted by the ISAC signal. Tracking of small offsets such as vibration and thermal deformation is corrected by detecting the offset through the beam position detection unit.

[0235] ISAC beam pointing is adjusted synchronously;

[0236] Step 2.5: Data transmission, ISAC signal and laser signal

[0237] ISAC signals mainly transmit the above-mentioned measurement and control information;

[0238] Laser signals mainly transmit business data. At the same time, according to system requirements, lasers can be used to measure the distance between two terminals and the time difference between terminal reference clock sources.

[0239] For example, a two-way one-way inter-satellite ranging solution using the BeiDou-3 satellite laser communication terminal uses two laser terminals A and B on two different satellites; both parties agree that the rising edge of the second pulse is aligned with the falling edge of the last bit of the frame synchronization header, and the timing starts after the last bit of the frame synchronization header is sent, which is recorded as t SA and t SB , when the frame synchronization header with the same frame count in seconds is received, the timing stops, recorded as t RA and t RB ;

[0240] The time difference T between the time when A sends data and the time when it receives data from B A And the time difference T from when satellite B sends data to when it receives data from satellite A B They are

[0241] TA =t RA -t SA

[0242] T B =t RB -t SB

[0243] The time difference between the two satellites is:

[0244]

[0245] Where S1 and S2 are the propagation delays from A to B and from B to A respectively; T SA (t) and T RA (t) are the transmission and reception delays of device A respectively; T SB (t) and T RB (t) are the transmission and reception delays of device B respectively;

[0246] The relative clock difference between the two stars is:

[0247]

[0248] Dynamic routing optimization:

[0249] In multi-orbit satellite communication systems, dynamic routing optimization between LEO satellites is crucial; since ISAC technology improves LISL performance, the overhead of LEO-LEO links is also reduced accordingly, and the link cost function in routing calculation needs to be redefined; routing strategies not only consider traditional hop counts and delays, but also need to integrate link tracking difficulty, task priority, and resource occupancy to achieve optimal resource allocation in multi-task scenarios;

[0250] First, in traditional routing strategies, link overhead is usually evaluated based on the number of hops and communication delay of the inter-satellite link. However, the communication links between LEO satellites are dynamically changing and are affected by factors such as satellite orbit type, relative motion speed, and laser alignment accuracy. Therefore, simple hop count and delay calculations cannot fully reflect the actual link performance. In order to more accurately evaluate the actual link overhead, this scheme introduces a new indicator called "link tracking difficulty"; this indicator quantifies the tracking difficulty of each inter-satellite link under dynamic conditions based on factors such as the satellite's relative orbit, attitude change rate, and the stability of the laser link; by incorporating this factor into the routing calculation, it is possible to avoid excessive data transmission on high-difficulty tracking links, thereby improving the reliability and efficiency of communications;

[0251] Secondly, in a multi-task scenario, different types of services have different requirements for network resources. For example, the global coverage of low-orbit satellite Internet makes it possible for real-time return of remote sensing data, so that remote sensing satellites on the other side of the earth can also relay to the ground station through low-orbit satellite Internet. In this scenario, the characteristics of remote sensing data return missions are large data volume and may need to travel a long distance to reach the ground station. Therefore, this type of mission has high requirements for link stability, bandwidth and latency. In this case, simply relying on priority to select links is not accurate enough. To this end, the scheme proposes a dynamic routing selection strategy based on future idle probability. Specifically, when selecting links, the system will give priority to those LEO satellites with a high idle probability in the future. These satellites are usually located in the sky above the open sea and where aircraft routes are not dense. They are not easy to receive user requests from the ground, sea, and sky. They can maintain a relatively stable communication state for a longer time and reduce the frequency and complexity of link switching. By reducing link switching, the remote sensing data return mission can maintain stable high-bandwidth transmission for a longer time, ensuring efficient data return.

[0252] Unlike remote sensing data backhaul tasks, user communication tasks usually require lower latency and higher throughput, and requests are frequent; therefore, for such tasks, routing strategies need to focus more on response time and the immediacy of communication rather than the long-term stability of the link; in this scenario, the main basis for link selection is latency minimization, that is, priority is given to satellite links with lower latency and faster response capabilities; specifically, user communication tasks will dynamically adjust their priorities based on their requirements for latency and throughput; when there is a peak in requests in the satellite network, the system can use a traffic balancing mechanism to evenly distribute traffic to different LEO satellite links to avoid latency fluctuations caused by overloading a certain link; at the same time, the system will also give priority to links with faster access and lower maintenance costs, and select the most appropriate link through real-time monitoring and prediction of the load conditions of links between satellites. This not only guarantees the user's communication latency requirements, but also improves network throughput and ensures user experience. In addition, between frequent communication requests and link switching, the system will also introduce link switching overhead evaluation to avoid frequent link switching from causing too much impact on latency and throughput; before each link switching, the system will evaluate the quality of the current link and the quality of the future link, and switch based on the optimal latency and throughput prediction to ensure smooth user communication; in addition to link tracking difficulty and task priority, the "resource occupancy" of the link is also fully considered in this solution; with the diversification of satellite missions and the expansion of network scale, resources in satellite networks (such as bandwidth, power, etc.) may become congested, especially in mission-intensive areas; in this case, based on the real-time network status, the routing strategy will dynamically evaluate the resource occupancy of the link and give priority to those links with low resource utilization and large idle bandwidth; this resource-aware routing strategy can effectively avoid link overload and improve the overall throughput and reliability of the network;

[0253] Dynamic routing optimization: Definition of the cost function in dynamic routing optimization: Unlike the terrestrial core network, the low-orbit satellite network is a dynamic environment. To achieve efficient routing calculation in a dynamic environment, it is necessary to comprehensively consider the number of hops, delay, link tracking difficulty, and link idle probability; among them, the number of hops is accumulated in each link and can be expressed by a constant H; the delay D ij Including transmission delay D t and on-board processing delay D p :

[0254] D ij =D t +D p

[0255] Link tracking difficulty T ij The relative speed of the satellite v needs to be considered ij , pointing angle change rate φ ij , orbital angle θij wait:

[0256] T ij =f(v ij ,φ ij ,θ ij )

[0257] Link idle probability estimation F ij The historical idle probability over a period of time can be used and the current link resource utilization U ij :

[0258]

[0259] Dynamic routing optimization in multi-task scenarios ( Figure 2 (Figure 1) Routing diagram for multi-task scenarios

[0260] Ordinary users need low-latency, high-throughput communication services and can choose paths with low latency and fewer hops. ij Using product type αD ij or exponential The amplification of α can be 2 or 3, and a larger H is used as the hop cost;

[0261] Remote sensing data backhaul requires high bandwidth and low link switching probability communication services, and it is necessary to give priority to paths with small delays and fewer hops. When optimizing the path, it can select communication links that are not currently occupied by users and have a high idle probability, and can target the idle probability parameter F. ij Make adjustments, such as Where β is a constant greater than 1, and can be selected as 5; the greater the historical idle probability, the lower the overhead; the smaller the current link utilization, the lower the overhead;

[0262] Computational task allocation requires low task execution latency and sufficient resources. Satellites with short distances and sufficient resources can be selected. The strategy needs to comprehensively consider the overhead of users and remote sensing data, and the idle probability parameter F ij Increase its cost, for example using product-type amplification At the same time, since the satellite resources in the overlapping areas of the two space gateways are occupied more, the probability of link idleness is very low, which can further avoid the use of cross-regional satellites;

[0263] The above scheme improves the definition of overhead, and uses Dijkstra and other algorithms to calculate the shortest route in the low-orbit satellites accessed within the management area of ​​the space gateway, so that dynamic routing can adapt to the needs of various business types, achieve efficient use of resources and optimize network performance.

[0264] Taking into account the characteristics of different task types, the dynamic routing strategy of this solution not only considers the priority of the task when selecting the link, but also combines the demand characteristics of the task, such as link stability, bandwidth requirements, latency requirements, link switching overhead and other multi-dimensional factors, to form a more detailed resource allocation mechanism.

[0265] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be arranged and combined, and those skilled in the art can exhaust all possibilities based on the mathematical knowledge of arrangement and combination. Therefore, the present invention will no longer describe the technical solutions after arrangement and combination one by one, but it should be understood that the technical solutions after arrangement and combination have been disclosed by the present invention.

[0266] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. The low- and medium-orbit satellite random access networking architecture based on space gateways is characterized by: include: Space gateway: responsible for the core tasks of satellite status monitoring, routing calculation and resource allocation; In the scenario where the space gateway autonomously controls the entire satellite network, the control function of the ground station is transferred to the space gateway, and the decision is made by the execution unit, and the status information of the satellite network is transmitted to the ground station by the execution unit that can establish a connection with the ground station; Ground station: In the scenario where the ground station controls the entire satellite network, control information and status information are transmitted to the MEO satellite through the communication link between the ground station and the MEO satellite; The ground station can communicate with LEO and process service requests; Execution unit: including MEO and LEO satellites, mainly responsible for performing specific communications and mission operations; User: User terminal and execution unit, realizing business request.

2. According to claim 1, the low- and medium-orbit satellite random access networking architecture based on space gateway is characterized in that: The space gateway payload includes at least one wide-beam RF transmitter, a multi-channel RF receiver, a BeiDou / GPS receiver, three laser terminals and a gimbal; The LEO layer includes three communication links: space gateway-LEO, LEO-LEO and LEO-user; the LEO satellite payload includes at least two RF transmitters, one RF receiver, one BeiDou / GPS receiver, three laser terminals and ISAC transceiver; The role of the space gateway-LEO link is to use MEO to transmit global network information to LEO satellites through broadcasting. LEO satellites dynamically adjust their access methods and task allocation strategies based on the received information. The LEO-LEO link is a high-speed data transmission between LEO satellites through intersatellite laser links, and a low-speed radio frequency link is used to transmit control information to assist the access and tracking of LISLs; The LEO-user link is a communication connection established between the LEO satellite and the user terminal or ground gateway, processing service requests including voice, video, and data.

3. The low- and medium-orbit satellite random access networking architecture based on space gateway according to claim 2 is characterized in that: The random access mechanism in the present invention means that after a low-orbit satellite enters the visible range of any space gateway station, it accesses the satellite network to perform measurement, control and communication tasks, and finally completes "on-demand measurement and control, random access"; in the giant constellation mode, the satellite's autonomous capability is enhanced, and it can independently complete network access, data transmission, orbit control needs, etc. The satellite initiates an access request to the space gateway station as needed, and the space gateway station performs authentication, routing management, task allocation and other management.

4. The medium and low orbit satellite random access networking architecture based on space gateway according to claim 3 is characterized by: The ISAC signal auxiliary link is adopted, and its perception and positioning capabilities are utilized to support the rapid establishment and efficient maintenance of the inter-satellite laser link.

5. A method for random access to medium and low orbit satellites based on a space gateway, characterized in that: The medium and low-orbit satellite random access networking architecture based on a space gateway as described in any one of claims 1 to 4 is adopted, comprising the following steps: Anytime access mechanism; ISAC signaling aids link establishment; Dynamic routing optimization.

6. The method for random access to medium and low orbit satellites based on a space gateway according to claim 5, characterized in that: Anytime access mechanism, including: Step 1.1: The gateway broadcasts the signal. The space gateway regularly broadcasts the identification code, access permission rules, location information, and adjacent gateway coverage areas within its management range. The signal covers the space within its visible range. LEO satellites that enter the beam range of the space gateway station receive the broadcast signal and parse the identification code and location information, and determine whether they are within the management range of the gateway station based on their own orbital status; Step 1.2: LEO satellite access request. After confirming that it is within the management range of the gateway, the LEO sends an access request to the gateway via a reverse microwave link pointing to the location of the space gateway, and includes the real-time status information of the LEO satellite. After receiving the request from the satellite, the gateway station calculates the distance between the satellite and the gateway station and the estimated stay time within the management range based on the orbital data and its own position; If the gateway has sufficient resources and the estimated stay time meets the communication requirements, access is allowed; otherwise, the request is rejected and a retry interval is set; Step 1.3: Access permission and routing update. After access is allowed: The gateway adds the LEO satellite to its visible satellite list; Update the gateway’s routing table based on the current network status to optimize the performance of the LEO-LEO laser link; The gateway sends access permission and intersatellite link switching instructions to the satellite through broadcasting; After access is denied: The gateway sends a rejection message to the LEO satellite; Set a fixed interval during which LEO satellites cannot apply to access the same gateway again; Step 1.4: Cross-region node allocation, including: Step 1.4.1: Identify overlapping areas By analyzing the broadcast signal, the LEO satellite can find that it is in the overlapping area of ​​the management range of the two gateway stations, and report the overlapping status to the gateway station through the reverse link with the gateway station being accessed; Step 1.4.2: Assign cross-region transfer tasks The gateway coordinates and decides on LEO-LEO routing, allocating LEO satellites as nodes for cross-regional data transmission; The satellite takes on the communication task between the two gateways according to the instructions, providing redundant paths to enhance the stability of transmission; Step 1.4.3: Network planning requirements Satellite deployment must meet the following requirements: ensure that the management ranges of adjacent gateways have sufficient overlap; deploy a sufficient number of LEO satellites in the overlapped area to improve transmission stability and redundancy; Step 1.5: Dynamic access switching, including: Step 1.5.1: Predict the switching time The LEO satellite estimates the time when it will leave the management range of the current gateway based on the visibility time calculated when it accesses. Step 1.5.2: Request access in advance The LEO satellite is in the overlapping area of ​​the management range of the two gateway stations; The LEO satellite sends a disconnection indication to the old gateway, then adjusts the beam pointing and sends an access request to the new gateway in advance, including the current status information. After receiving the disconnection instruction, the old signal gateway deletes the LEO satellite node from the visible satellites; The Xinxin Gateway verifies the access according to its access rules and makes a decision to grant or deny access; Step 1.5.3: Switch execution If access permission is obtained, LEO establishes communication with the new gateway. The gateway dynamically calculates the visibility time and updates the network routing to ensure seamless communication links during the handover. If access is denied, the new gateway sends a rejection command to LEO and prevents the LEO satellite from making access requests within a certain period of time; Step 1.6: Performance monitoring and optimization, including: Step 1.6.1: Network status monitoring The gateway station monitors the operating status and link performance of the LEO satellite in real time, which is completed by LEO reporting to the gateway station regularly; Dynamically adjust access rules and task allocation strategies based on operating status and link performance; Step 1.6.2: Parameter optimization Optimize the retry access interval to ensure efficient use of resources; Dynamically adjust the routing table update frequency to adapt to the rapid changes in satellite networks.

7. The method for random access to medium and low-orbit satellites based on a space gateway according to claim 6, characterized in that: ISAC signals assist in link establishment, including: Step 2.1: The space gateway broadcasts the route switch; The Space Gateway regularly broadcasts the latest network routing information via ISAC signals; the broadcast content includes: Intersatellite link topology information: LEO satellite network routing table; Satellite status information within the jurisdiction: including the real-time position, speed and mission load of each LEO satellite; Resource allocation strategy: covers the use and allocation scheme of communication resources (frequency, code and space allocation of ISAC signals), computing and storage resources; After receiving the broadcast, the LEO satellite parses the routing information and caches it in local storage, and determines whether it is necessary to switch the intersatellite link based on its own mission and location status; if switching is required, the current link is disconnected according to the routing information, and the ISAC beam direction is adjusted to point to the predetermined target LEO satellite, preparing to establish a new link; Step 2.2: Alignment; Adjustment of ISAC beam pointing during switching The LEO satellite that receives the LEO-LEO link switching command estimates the relative position between the two LEO satellites using the predicted position broadcast by the space gateway: Due to the influence of factors such as signal processing delay and orbital perturbation in the system, the actual positions of the two satellites will deviate from the coordinates predicted by the gateway; a feasible error range can be expressed as follows: Dr. LEO =t p ×v LEO +r LEO Among them, t p is the system delay from the gateway prediction time to the ISAC channel propagation to the receiver, v LEO is the speed of the receiver, ρ LEO is the position error radius caused by factors such as atmospheric drag and orbital perturbations; Assume that the actual position of LEO satellite 2 is in a certain distribution X. The center is Δρ, and the radius is LEO2 sphere; set a reasonable initial capture probability P SC , there is a minimum ISAC beam radius ρ beam satisfy: Then the minimum beam width is: Therefore, the ISAC signal from LEO satellite 1 to LEO satellite 2 needs to The pointing direction and 2×2θ 0.5 3dB beamwidth, which can ensure P SC The probability of being captured by the receiver on LEO satellite 2; Step 2.3: Establishment of laser link with the assistance of ISAC technology; After the ISAC signal is captured, firstly, a two-dimensional search of time and frequency is performed to capture the signal, calculate the Doppler velocity value, and after analyzing the signal, use the non-coherent ranging method to measure the distance by relying on the high-precision satellite clock; The bidirectional ISAC link transmits more accurate real-time calibration data of LEO satellites, including but not limited to the current self-measured position and velocity, six-axis sensor data, star calibration values, star-to-star calibration values, laser terminal receiving and transmitting light axis consistency deviation, and tracking point calibration values ​​for precise pointing adjustment; Combining ISAC ranging, velocity measurement and calibration data, the extended Kalman filter (EKF) or particle filter algorithm is used to eliminate noise and deviation to obtain a high-precision center of mass position; if the current LEO satellite has established an ISAC link with three LEO satellites at the same time, three-star positioning is further used to obtain a more accurate positioning result, so that the pointing error after calibration is in the order of hundreds of μrad; After determining the LEO satellite's center of mass coordinates and the direction of its movement, a narrow laser beam is emitted toward the center of mass coordinates; the laser terminal is equipped with a beam position detection unit; commonly used position detectors include four-quadrant detectors and infrared focal plane detectors; the optical axis deviation is determined quickly and accurately, and the deviation value is fed back to the LEO satellite at the laser transmitting end through the ISAC signal; the LEO satellite at the laser transmitting end controls the fine tracking actuator to adjust its direction according to the deviation. The fine tracking actuator is a fast reflector driven by a voice coil motor or piezoelectric ceramics, and the optical axis alignment is completed step by step and iteratively; Step 2.4: Tracking; Tracking after establishing a two-way laser link Tracking is similar to the process of establishing a laser link. During tracking, the angular velocity of the laser terminal pointing to the ground is affected by the satellite's motion state. Tracking of large offsets is corrected by the satellite velocity, acceleration, angular acceleration and satellite attitude calibration values ​​transmitted by the ISAC signal. Tracking of small offsets such as vibration and thermal deformation is corrected by detecting the offset through the beam position detection unit. ISAC beam pointing is adjusted synchronously; Step 2.5: Data transmission, ISAC signal and laser signal ISAC signals mainly transmit the above-mentioned measurement and control information; Laser signals mainly transmit business data. At the same time, according to system requirements, lasers can be used to measure the distance between two terminals and the time difference between terminal reference clock sources.

8. The method for random access to medium and low orbit satellites based on a space gateway according to claim 7, characterized in that: The number of hops is cumulative in each link and can be represented by a constant H; the delay D ij Including transmission delay D t and on-board processing delay D p : D ij =D t +D p Link tracking difficulty T ij The relative speed of the satellite v needs to be considered ij , pointing angle change rate φ ij , orbital angle θ ij wait: T ij =f(v ij ,f ij ,i ij ) Link idle probability estimation F ij The historical idle probability over a period of time can be used and the current link resource utilization U ij :

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