Satellite switching determination method and device in low-orbit satellite communication network

Abstract

The invention provides a satellite switching determination method and device in a low earth orbit satellite communication network, and relates to the technical field of communication engineering.The method comprises the steps that navigation satellite ephemeris information is obtained in real time through terminal equipment, and the current position and a visible airspace topological graph of the terminal equipment are determined; acquiring a satellite ephemeris of a low-orbit satellite communication network covering the terminal equipment according to the current position of the terminal equipment; according to the satellite ephemeris, predicting the overhead service time and the corresponding moving trajectory of each low-orbit satellite, and generating a candidate switching satellite list; for the candidate switching satellite list, according to the visible airspace topological graph, amending the overhead service time and the moving trajectory of the candidate switching satellites in the list; and determining a target satellite needing to be switched and corresponding switching time based on the corrected over-the-top service time and the moving trajectory.

Description

Technical Field

[0001] The present invention relates to the technical field of communication engineering, and particularly to a method and device for determining satellite handover in a low-earth orbit satellite communication network. Background Art

[0002] This section aims to provide background or context for embodiments of the present invention. The description herein is not admitted to be prior art merely by including it in this section.

[0003] In the development process of wireless communication technology, satellite communication is considered an important direction for the future development of wireless communication technology. Satellite communication refers to the communication in which wireless communication devices on the ground use satellites as relays. A satellite communication system consists of satellites and a ground part. The characteristics of satellite communication are: large communication range; communication can be carried out as long as it is within the satellite beam coverage; not easily affected by the terrestrial environment and disasters. Satellite communication can be an effective supplement to the current terrestrial wireless cellular mobile communication.

[0004] Satellite communication systems are divided into geostationary orbit satellite communication systems and low-earth orbit satellite communication systems. For traditional geostationary orbit satellite communication systems (usually referring to geosynchronous orbit satellite communication systems), geosynchronous orbit satellites are usually used as relays. Three geosynchronous orbit satellites can achieve global coverage without the need for satellite handover. For low-earth orbit satellite communication systems, the earth's surface is usually covered by thousands to tens of thousands of satellites deployed on several orbital planes, thus forming an interconnected mesh network. Compared with geostationary orbit satellite communication systems, low-earth orbit satellite communication systems have the advantages of high network reliability, strong flexibility, low transmission delay, small path loss, large communication capacity, weak dependence on the ground network, more effective frequency reuse, and stronger global coverage ability. At the same time, the high-speed movement of low-earth orbit satellites relative to the ground causes the satellite-ground link to face frequent handover problems, and the large constellation further accelerates the handover frequency due to its low orbital altitude and high communication elevation angle. Taking a low-earth orbit satellite at an altitude of 550 km as an example, when the communication elevation angle threshold is 25°, the average handover time interval is only 2 - 3 minutes. At the same time, since the large constellation is mainly oriented to broadband services, high bandwidth, low delay jitter and other service qualities also need to be guaranteed during the frequent link handover process. In addition, the dense distribution of satellites in the large constellation and the high overlap of coverage areas also increase the frequency coordination difficulty during the satellite-ground channel handover process.

[0005] Traditional satellite communication link handover methods include handover strategies based on signal strength, handover strategies based on the longest over-the-top service time of satellites, handover strategies based on the largest number of idle channels of satellites, etc. These strategies aim to optimize the handover process and improve the handover success rate and communication quality; however, the problems of the above handover strategies are as follows:

[0006] 1. It is necessary to frequently monitor the signal levels of the current satellite and adjacent satellites, which greatly increases the power consumption of the terminal device and the consumption of air interface resources.

[0007] 2. Only based on the over - the - top time of each satellite to determine the longest service duration of the satellite and formulate the handover strategy accordingly. This does not consider the impact of building occlusion in the surrounding environment on the visible airspace, and the changes in the actual over - the - top time and the longest service duration of each satellite that may be caused by such occlusion. Therefore, this strategy is mainly applicable to outdoor open and unobstructed deployment environments. However, in urban areas with dense high - rise buildings (in extreme cases, the visible airspace is greatly reduced or even fragmented by occlusions), and in scenarios involving terminal mobile deployment, this strategy may lead to a large number of satellite handovers and frequent disconnections, thus seriously affecting the communication quality.

[0008] In summary, there is an urgent need for a technical solution that can overcome the above - mentioned defects and improve the accuracy of satellite handover and the handover efficiency in the low - earth - orbit satellite communication network. Summary of the Invention

[0009] To solve the problems existing in the prior art, the present invention proposes a method and device for determining satellite handover in a low - earth - orbit satellite communication network.

[0010] In the first aspect of the embodiments of the present invention, a method for determining satellite handover in a low - earth - orbit satellite communication network is proposed. The method includes:

[0011] Obtain the navigation satellite ephemeris information in real - time through the terminal device to determine the current position of the terminal device and the topological map of the visible airspace;

[0012] According to the current position of the terminal device, obtain the satellite ephemeris of the low - earth - orbit satellite communication network covering the terminal device;

[0013] According to the satellite ephemeris, predict the over - the - top service time and the corresponding running trajectory of each low - earth - orbit satellite, and generate a list of candidate handover satellites;

[0014] For the list of candidate handover satellites, according to the topological map of the visible airspace, correct the over - the - top service time and the running trajectory of the candidate handover satellites in the list;

[0015] Based on the corrected over - the - top service time and the running trajectory, determine the target satellite to be handed over and the corresponding handover time.

[0016] In the second aspect of the embodiments of the present invention, a device for determining satellite handover in a low - earth - orbit satellite communication network is proposed. The device includes:

[0017] An information processing module, configured to obtain ephemeris information of navigation satellites in real time through a terminal device, and determine the current position of the terminal device and a visible airspace topology map;

[0018] A satellite ephemeris acquisition module, configured to acquire the ephemeris of a low-earth orbit satellite communication network covering the terminal device according to the current position of the terminal device;

[0019] A candidate handover satellite list generation module, configured to predict the over-the-top service time and corresponding operation trajectories of each low-earth orbit satellite according to the ephemeris, and generate a candidate handover satellite list;

[0020] An information correction module, configured to correct the over-the-top service time and operation trajectories of the candidate handover satellites in the list according to the visible airspace topology map for the candidate handover satellite list;

[0021] A handover target determination module, configured to determine the target satellite to be switched and the corresponding handover time based on the corrected over-the-top service time and operation trajectories.

[0022] In a third aspect of the embodiments of the present invention, a computer device is provided, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, a method for determining satellite handover in a low-earth orbit satellite communication network is implemented.

[0023] In a fourth aspect of the embodiments of the present invention, a computer-readable storage medium is provided. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, a method for determining satellite handover in a low-earth orbit satellite communication network is implemented.

[0024] In a fifth aspect of the embodiments of the present invention, a computer program product is provided. The computer program product includes a computer program, and when the computer program is executed by a processor, a method for determining satellite handover in a low-earth orbit satellite communication network is implemented.

[0025] The satellite handover determination method and device in the low-earth orbit satellite communication network proposed by the present invention obtain the ephemeris information of navigation satellites in real time through a terminal device, determine the current position of the terminal device and the visible airspace topology map; obtain the satellite ephemeris of the low-earth orbit satellite communication network covering the terminal device according to the current position of the terminal device; predict the over-the-top service time and corresponding operating trajectories of each low-earth orbit satellite according to the satellite ephemeris, and generate a candidate handover satellite list; for the candidate handover satellite list, correct the over-the-top service time and operating trajectories of the candidate handover satellites in the list according to the visible airspace topology map; based on the corrected over-the-top service time and operating trajectories, determine the target satellite to be handed over and the corresponding handover time. The overall solution fully considers the influence of building occlusion in the surrounding environment on the visible airspace, as well as the changes in the actual over-the-top time and the longest service duration of each satellite that may be caused by this occlusion, improves the accuracy of satellite handover judgment and the satellite handover efficiency, effectively ensures the communication quality of the terminal device, and provides strong technical support for the satellite communication scenario. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0027] Figure 1 It is a schematic flowchart of a satellite handover determination method in a low-earth orbit satellite communication network according to an embodiment of the present invention.

[0028] Figure 2 It is a schematic flowchart of determining the visible airspace topology map according to an embodiment of the present invention.

[0029] Figure 3 It is a schematic flowchart of correcting the operating trajectory based on the visible airspace topology map according to an embodiment of the present invention.

[0030] Figure 4 It is a schematic diagram of the visible airspace topology map according to an embodiment of the present invention.

[0031] Figure 5 It is a schematic diagram of the visible airspace topology map and the corrected operating trajectory according to an embodiment of the present invention.

[0032] Figure 6 It is a schematic diagram of the architecture of a satellite handover determination device in a low-earth orbit satellite communication network according to an embodiment of the present invention.

[0033] Figure 7 It is a schematic diagram of the structure of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The principles and spirit of the present invention will be described below with reference to several exemplary embodiments. It should be understood that these embodiments are provided only to enable those skilled in the art to better understand and implement the present invention, and do not limit the scope of the present invention in any way. On the contrary, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0035] Those skilled in the art know that the embodiments of the present invention can be implemented as a system, device, equipment, method, or computer program product. Therefore, the present disclosure can be specifically implemented in the following forms: completely hardware, completely software (including firmware, resident software, microcode, etc.), or a combination of hardware and software.

[0036] According to an embodiment of the present invention, a method and device for determining satellite handover in a low-earth orbit satellite communication network are proposed, which relates to the field of communication engineering technology.

[0037] The principles and spirit of the present invention will be elaborated in detail below with reference to several representative embodiments of the present invention.

[0038] Figure 1 It is a schematic flowchart of a method for determining satellite handover in a low-earth orbit satellite communication network according to an embodiment of the present invention. As Figure 1 shown, the method includes:

[0039] S101, obtaining the ephemeris information of navigation satellites in real time through a terminal device, and determining the current position and visible airspace topology map of the terminal device;

[0040] S102, obtaining the satellite ephemeris of the low-earth orbit satellite communication network covering the terminal device according to the current position of the terminal device;

[0041] S103, predicting the over-the-top service time and corresponding operation trajectories of each low-earth orbit satellite according to the satellite ephemeris, and generating a list of candidate handover satellites;

[0042] S104, for the list of candidate handover satellites, correcting the over-the-top service time and operation trajectories of the candidate handover satellites in the list according to the visible airspace topology map;

[0043] S105, determining the target satellite to be switched and the corresponding handover time based on the corrected over-the-top service time and operation trajectories.

[0044] In order to more clearly explain the above method for determining satellite handover in a low-earth orbit satellite communication network, the following will be described in detail with specific embodiments.

[0045] In one embodiment, the ephemeris information of navigation satellites obtained in real time by the terminal device at least includes:

[0046] The ephemeris information of the satellites visible in real time in the GPS satellite navigation system and the ephemeris information of the satellites visible in real time in the Beidou satellite navigation system.

[0047] In one embodiment, referring to Figure 2 , it is a schematic flowchart of determining the visible airspace topology diagram according to an embodiment of the present invention. As Figure 2 shown, the specific process includes:

[0048] S201, obtaining the position information of all visible navigation satellites within a preset observation time period, including the elevation angle and azimuth angle of each satellite at different observation times;

[0049] S202, according to the elevation angle and azimuth angle information of each satellite at different observation times, draw a two-dimensional graph in the Cartesian coordinate system, where the X-axis is the azimuth angle, and the azimuth angle range is 0-360°, and the Y-axis is the elevation angle, and the elevation angle range is 0-90°;

[0050] S203, connect all the data points in the two-dimensional graph in sequence according to the azimuth angle of 0-360° to form a visible airspace topology diagram; the visible airspace topology diagram represents the visible airspace condition of the terminal device at its location. In the area below the curve in the visible airspace topology diagram, it is blocked by obstacles in the surrounding environment, and the signals of the low-orbit satellites appearing in this area will not be received by the terminal device and are invisible to the terminal device.

[0051] In an actual application scenario, if there are multiple satellite position information with the same azimuth angle at different observation times, that is, there are at least two sets of position data (φ1, θ1) and (φ1, θ2), where θ1≠θ2, then one set of position data needs to be retained and other position data needs to be deleted.

[0052] The specific processing method is:

[0053] Retain the data point represented by the satellite with the lowest elevation angle, and delete the data points represented by other satellites with higher elevation angles to ensure that in the final two-dimensional graph, the azimuth angle information and the elevation angle information are in one-to-one correspondence.

[0054] Furthermore, other processing methods can also be adopted to determine the visible airspace topology diagram. The specific process is:

[0055] Obtain the position information of all visible navigation satellites within a preset observation time period;

[0056] If there are multiple satellite position information with the same azimuth angle at different observation times, the corresponding multiple sets of satellite position data are expressed as: (φ1, θ1, CN01), (φ1, θ2, CN02), ……, (φ1, θ N , CN0 N ); where φ1 represents the azimuth angle; θ1, θ2, ……, θ N represents the elevation angle, and θ i represents the i-th elevation angle; CN01, CN02, ……, CN0 N is the carrier-to-noise ratio information, and CN0 i represents the i-th carrier-to-noise ratio value; N is the total number of satellite position data;

[0057] One of the following methods is adopted for processing to make the azimuth angle information and the elevation angle information correspond one by one in the two-dimensional graph:

[0058] 1. According to the carrier-to-noise ratio information, retain the satellite position information corresponding to the highest carrier-to-noise ratio value;

[0059] 2. Calculate the average value of all elevation angles according to the following formula as the elevation angle θ 1_Final corresponding uniquely to the azimuth angle φ1:

[0060] In the formula, θ 1_Final is the elevation angle corresponding uniquely to the azimuth angle φ1; N is the total number of satellite position data; θ i is the i-th elevation angle;

[0061] 3. Calculate the elevation angle θ 1_Final corresponding uniquely to the azimuth angle φ1 according to the following formula:

[0062] In the formula, θ 1_Final is the elevation angle corresponding uniquely to the azimuth angle φ1; N is the total number of satellite position data; θ i is the i-th elevation angle; CN0 i is the i-th carrier-to-noise ratio value;

[0063] 4. Calculate the elevation angle θ 1_Final corresponding uniquely to the azimuth angle φ1 according to the following formula:

[0064] In the formula, θ 1_Final is the elevation angle corresponding uniquely to the azimuth angle φ1; N is the total number of satellite position data; θ i is the i-th elevation angle; CN0 i is the i-th carrier-to-noise ratio value.

[0065] In an embodiment, determining the visible airspace topology map further includes:

[0066] For the azimuth angle φ i , compare the elevation angle θ i at the corresponding data point of the azimuth angle φ i with the communication elevation angle threshold, and calculate the azimuth angle φ based on the following formula i for the uniquely corresponding elevation angle θ i_Final :

[0067] θ i_Final = ceil(max(θ i , θ Com_Limit )); In the formula, θ i_Final is the elevation angle uniquely corresponding to the azimuth angle φi; θ Com_Limit is the communication elevation angle threshold; φ i represents the i-th azimuth angle; θ i is the elevation angle at the data point corresponding to the azimuth angle φ i .

[0068] In one embodiment, determining the visible airspace topology map further includes:

[0069] Obtain the position information of all visible navigation satellites within a preset observation time period;

[0070] If there are multiple visible satellites within a limited azimuth angle range, the corresponding multiple sets of satellite position data are: (φ1, θ1, CN01), (φ2, θ2, CN02), ……, (φ N , θ N , CN0 N ), where φ1, φ2, ……, φ N represent azimuth angles, and φ i represents the i-th azimuth angle among them; θ1, θ2, ……, θ N represent elevation angles, and θ i represents the i-th elevation angle among them; CN01, CN02, ……, CN0 N are carrier-to-noise ratio information; N is the total number of satellite position data;

[0071] If |φ Max - φ Min | ≤ 10o, where φ i ∈ [φ Min , φ Max , and |θ Max - θ Min | ≤ 6o, where θ i ∈ [θ Min , θ Max , then calculate the elevation angle θ i corresponding to the azimuth angle φ i_Final as follows:

[0072] In the formula, θ i_Final represents the azimuth angle φ i at the unique corresponding elevation angle; φ i represents the i-th azimuth angle; θ i represents the i-th elevation angle; N is the total number of satellite position data.

[0073] In one embodiment, determining the visible airspace topology map further includes:

[0074] Obtain the position information of all visible navigation satellites within a certain observation time period. For the fixedly deployed terminal device, the certain observation time period is not less than a first preset duration (for example, 15 minutes); for the mobile deployed terminal device, the certain observation time period is not less than a second preset duration (for example, 5 seconds).

[0075] In one embodiment, for S103, according to the satellite ephemeris, predict the over-the-horizon service time and the corresponding operating trajectory of each low-earth orbit satellite, and generate a candidate handover satellite list. The specific process includes:

[0076] Based on the over-the-horizon service time of each low-earth orbit satellite and the average value of the elevation angle of the operating trajectory during the over-the-horizon service time, select candidate handover satellites and generate a candidate handover satellite list;

[0077] Among them, the selection weight value of each low-earth orbit satellite is determined according to the following formula:

[0078]

[0079] In the formula, ω i (t,θ) is the selection weight value determined based on the trajectory elevation angle and the over-the-horizon service time; Δt M ax is the maximum value of the over-the-horizon service duration of each low-earth orbit satellite; Δt i is the over-the-horizon service duration of the i-th low-earth orbit satellite; θ Max_Mean is the maximum value of the average value of the elevation angle of the operating trajectory of each low-earth orbit satellite during their respective over-the-horizon service times; θ i_Mean is the average value of the elevation angle of the operating trajectory of the i-th low-earth orbit satellite during the over-the-horizon service time; α and β are respectively the weighting coefficients corresponding to the over-the-horizon service duration and the average value of the elevation angle; α + β = 1;

[0080] Or, the selection weight value of each low-earth orbit satellite is determined according to the following formula:

[0081]

[0082] In one embodiment, for S104, for the candidate handover satellite list, according to the visible airspace topology map, the overhead service time and the running trajectory of the candidate handover satellites in the list are corrected. The specific process includes:

[0083] In the visible airspace topology map, depict the running trajectories of each low-earth orbit satellite within the predicted overhead service time;

[0084] Among them, for the low-earth orbit satellite passing overhead, depict the azimuth-pitch two-dimensional curve of the running trajectory within the predicted overhead service time; delete the part of the azimuth-pitch two-dimensional curve that is lower than the curve of the visible airspace topology map, and retain the part that is higher than the curve of the visible airspace topology map; according to the retained part of the azimuth-pitch two-dimensional curve, obtain the corrected running trajectory, calculate the average value of the pitch angle corresponding to the corrected running trajectory, and the corrected overhead service time, and recalculate the selection weight of the low-earth orbit satellite to obtain the corrected selection weight;

[0085] Based on the corrected selection weight, re-determine the candidate handover satellites that need to be handed over, and generate a new candidate handover satellite list.

[0086] Specifically, taking the low-earth orbit satellite i passing overhead as an example, refer to Figure 3 , the specific process includes:

[0087] S301, depict the φ-θ two-dimensional curve of the running trajectory of the low-earth orbit satellite i within the predicted overhead service time;

[0088] S302, delete the part of the curve that is lower than the curve of the visible airspace topology map, and only retain the part that is higher than the curve of the visible airspace topology map;

[0089] S303, according to the retained part of the φ-θ two-dimensional curve, that is, the corrected running trajectory, calculate the average value θ of the pitch angle value corresponding to the corrected running trajectory i_Mean_Correct , and the corrected overhead service duration Δt i_Correct , and substitute them into the formula of the selection weight to recalculate the selection weight ω of the satellite i_Correct (t,θ);

[0090] S304, based on the corrected selection weight ω i_Correct (t,θ), recalculate and finally determine the candidate handover satellite list.

[0091] Further, when the corrected operating trajectory curve consists of two or more non-connected sub-curve segments, it is determined that there is an interruption in the corrected operating trajectory. Among them, if the proportion of the azimuth angle range corresponding to any one sub-curve segment in the total azimuth angle range corresponding to the uncorrected operating trajectory curve exceeds a set proportion (for example, 60%), the corrected selection weight ω i_Correct (t, θ) of the low-earth orbit satellite i corresponding to this operating trajectory curve is calculated based on this sub-curve segment. Otherwise, the corrected selection weight of the low-earth orbit satellite i corresponding to the corrected operating trajectory curve is set to 0, that is, ω i_Correct (t, θ) = 0.

[0092] Reference Figure 4 , is a schematic diagram of the visible airspace topology map of an embodiment of the present invention. Reference Figure 5 , is a schematic diagram of the visible airspace topology map and the corrected operating trajectory of an embodiment of the present invention. The abscissa in the figure is the azimuth angle, and the ordinate is the elevation angle. In Figure 5 , a communication elevation angle threshold (the blue dashed line in the figure, for example, 25 degrees) is set. The blue solid line represents the visible airspace topology map, and the black dashed line is the predicted motion trajectory of the low-earth orbit satellite. According to the visible airspace topology map, the over-the-top service time and operating trajectory of the predicted candidate handover satellite are corrected; based on the corrected over-the-top service time and operating trajectory, the target satellite to be switched and the corresponding handover time are determined.

[0093] By determining the visible airspace topology map, the present invention can intuitively present the visible airspace condition of the location where the terminal device is located. The signals of the low-earth orbit satellites in the area below the topology map curve will not be received, fully considering the influence of building occlusion in the surrounding environment on the visible airspace, and the changes in the actual over-the-top time and the longest service duration of each satellite that may be caused by this occlusion, making the satellite handover judgment more in line with the actual scenario. The visible airspace topology map can be determined in various ways to adapt to different application scenarios.

[0094] When generating the candidate handover satellite list, the present invention considers the over-the-top service duration of each satellite, and also combines the average value of the elevation angle values of the operating trajectory during the over-the-top service period to determine the selection weight of each satellite, so as to obtain the final candidate handover satellite and the corresponding handover time. The overall solution can effectively improve the accuracy and efficiency of satellite handover judgment. At the same time, when there is an interruption in the corrected operating trajectory, the present invention also gives corresponding processing methods to make the calculation results more reasonable.

[0095] It should be noted that although the operations of the method of the present invention are described in a specific order in the above embodiments and the accompanying drawings, this does not require or imply that these operations must be performed in that specific order, or that all the operations shown must be performed to achieve the desired result. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step for execution, and / or one step may be decomposed into multiple steps for execution.

[0096] After introducing the method of the exemplary embodiment of the present invention, next, with reference to Figure 6 a satellite handover determination device in a low-earth orbit satellite communication network according to an exemplary embodiment of the present invention will be introduced.

[0097] The implementation of the satellite handover determination device in the low-earth orbit satellite communication network can refer to the implementation of the above method, and the repeated parts will not be elaborated. The terms "module" or "unit" used hereinafter may be a combination of software and / or hardware that implements a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware is also possible and contemplated.

[0098] Based on the same inventive concept, the present invention also proposes a satellite handover determination device in a low-earth orbit satellite communication network, as Figure 6 shown, the device includes:

[0099] An information processing module 610, configured to obtain navigation satellite ephemeris information in real time through a terminal device, and determine the current position and visible airspace topology map of the terminal device;

[0100] A satellite ephemeris acquisition module 620, configured to obtain the satellite ephemeris of a low-earth orbit satellite communication network covering the terminal device according to the current position of the terminal device;

[0101] A candidate handover satellite list generation module 630, configured to predict the over-the-top service time and corresponding running trajectories of each low-earth orbit satellite according to the satellite ephemeris, and generate a candidate handover satellite list;

[0102] An information correction module 640, configured to correct the over-the-top service time and running trajectories of the candidate handover satellites in the list according to the visible airspace topology map for the candidate handover satellite list;

[0103] A handover target determination module 650, configured to determine the target satellite to be switched and the corresponding handover time based on the corrected over-the-top service time and running trajectories.

[0104] In one embodiment, the navigation satellite ephemeris information obtained in real time by the information processing module 610 through the terminal device at least includes:

[0105] The ephemeris information of the satellites visible in real time by the GPS satellite navigation system and the ephemeris information of the satellites visible in real time by the Beidou satellite navigation system.

[0106] In one embodiment, the information processing module 610 determines a visible airspace topology map, including:

[0107] Obtain the position information of all visible navigation satellites within a preset observation time period, including the elevation angle and azimuth angle of each satellite at different observation times;

[0108] According to the elevation angle and azimuth angle information of each satellite at different observation times, draw a two-dimensional graph in the Cartesian coordinate system, where the X-axis is the azimuth angle, and the azimuth angle range is 0 - 360°, and the Y-axis is the elevation angle, and the elevation angle range is 0 - 90°; if there are multiple satellite position information with the same azimuth angle at different observation times, retain the data point represented by the satellite with the lowest elevation angle, and delete the data points represented by other satellites with higher elevation angles, so that in the two-dimensional graph, the azimuth angle information and the elevation angle information are in one-to-one correspondence;

[0109] Connect all the data points in the two-dimensional graph in sequence according to the azimuth angle of 0 - 360° to form a visible airspace topology map; the visible airspace topology map represents the visible airspace condition of the terminal device at its location. The area below the curve in the visible airspace topology map is blocked by obstacles in the surrounding environment, and the signals of the low-orbit satellites appearing in this area will not be received by the terminal device and are invisible to the terminal device.

[0110] In one embodiment, determining the visible airspace topology map further includes:

[0111] Obtain the carrier-to-noise ratio information of all visible navigation satellites within a preset observation time period;

[0112] If there are multiple satellite position information with the same azimuth angle at different observation times, the corresponding multiple sets of satellite position data are expressed as: (φ1,θ1,CN01), (φ1,θ2,CN02), ……, (φ1,θ N ,CN0 N ); where, φ1 represents the azimuth angle; θ1, θ2, ……, θ N represents the elevation angle, θ i represents the i-th elevation angle; CN01, CN02, ……, CN0 N is the carrier-to-noise ratio information, CN0 i represents the i-th carrier-to-noise ratio value; N is the total number of satellite position data;

[0113] Process in one of the following ways to make the azimuth angle information and the elevation angle information in the two-dimensional graph in one-to-one correspondence:

[0114] Retain the satellite position information corresponding to the highest carrier-to-noise ratio according to the carrier-to-noise ratio information;

[0115] Calculate the average value of all elevation angles according to the following formula and use it as the elevation angle θ uniquely corresponding to the azimuth angle φ1 1_Final :

[0116] In the formula, θ 1_Final is the elevation angle uniquely corresponding to the azimuth angle φ1; N is the total number of satellite position data; θ i is the i-th elevation angle;

[0117] Calculate the elevation angle θ uniquely corresponding to the azimuth angle φ1 according to the following formula 1_Final :

[0118] In the formula, θ 1_Final is the elevation angle uniquely corresponding to the azimuth angle φ1; N is the total number of satellite position data; θ i is the i-th elevation angle; CN0 i is the i-th carrier-to-noise ratio;

[0119] Calculate the elevation angle θ uniquely corresponding to the azimuth angle φ1 according to the following formula 1_Final :

[0120] In the formula, θ 1_Final is the elevation angle uniquely corresponding to the azimuth angle φ1; N is the total number of satellite position data; θ i is the i-th elevation angle; CN0 i is the i-th carrier-to-noise ratio.

[0121] In one embodiment, determining the visible airspace topology map further includes:

[0122] For the azimuth angle φ i , compare the elevation angle θ i at the data point corresponding to the azimuth angle φ i with the communication elevation angle threshold, and calculate the elevation angle θ i uniquely corresponding to the azimuth angle φ i_Final according to the following formula:

[0123] θ i_Final = ceil(max(θ i , θ Com_Limit )); In the formula, θ i_Final is the elevation angle uniquely corresponding to the azimuth angle φi; θ Com_Limit is the communication elevation angle threshold; φ i represents the i-th azimuth angle; θ i is the elevation angle at the data point corresponding to the azimuth angle φ i .

[0124] In one embodiment, determining the visible airspace topology map further includes:

[0125] Obtaining the position information of all visible navigation satellites within a preset observation time period;

[0126] If there are multiple visible satellites within a limited azimuth range, the corresponding multiple sets of satellite position data are: (φ1, θ1, CN01), (φ2, θ2, CN02), ……, (φ N , θ N , CN0 N ), where φ1, φ2, ……, φ N represent the azimuth angles, and φ i represents the i-th azimuth angle; θ1, θ2, ……, θ N represent the elevation angles, and θ i represents the i-th elevation angle; CN01, CN02, ……, CN0 N are the carrier-to-noise ratio information; and N is the total number of satellite position data;

[0127] If |φ Max - φ Min | ≤ 10°, where φ i ∈ [φ Min , φ Max , and |θ Max - θ Min | ≤ 6°, where θ i ∈ [θ Min , θ Max , then calculate the elevation angle θ i corresponding to the azimuth angle φ i_Final at the following formula:

[0128] In the formula, θ i_Final represents the unique elevation angle corresponding to the azimuth angle φ i ; φ i represents the i-th azimuth angle; θ i represents the i-th elevation angle; and N is the total number of satellite position data.

[0129] In one embodiment, determining the visible airspace topology map further includes:

[0130] Obtaining the position information of all visible navigation satellites within a certain observation time period, where for a fixedly deployed terminal device, the certain observation time period is not less than a first preset duration; and for a mobilely deployed terminal device, the certain observation time period is not less than a second preset duration.

[0131] In one embodiment, the candidate handover satellite list generation module 630 predicts the over-the-top service time and corresponding operating trajectories of each low-earth orbit satellite according to the satellite ephemeris, and generates a candidate handover satellite list, including:

[0132] Based on the over-the-top service time of each low-earth orbit satellite and the average value of the pitch angle of the operating trajectory during the over-the-top service time, select candidate handover satellites and generate a candidate handover satellite list;

[0133] Among them, the selection weight of each low-earth orbit satellite is determined according to the following formula:

[0134]

[0135] In the formula, ω i (t,θ) is the selection weight determined based on the trajectory pitch angle and over-the-top service time; Δt M ax is the maximum value of the over-the-top service duration of each low-earth orbit satellite; Δt i is the over-the-top service duration of the i-th low-earth orbit satellite; θ Max_Mean is the maximum value of the average pitch angle of the operating trajectories of each low-earth orbit satellite during their respective over-the-top service times; θ i_Mean is the average value of the pitch angle of the operating trajectory of the i-th low-earth orbit satellite during the over-the-top service time; α and β are the weighting coefficients corresponding to the over-the-top service duration and the average value of the pitch angle respectively; α + β = 1;

[0136] Alternatively, the selection weight of each low-earth orbit satellite is determined according to the following formula:

[0137]

[0138] In one embodiment, the information correction module 640 corrects the over-the-top service time and operating trajectory of the candidate handover satellites in the candidate handover satellite list according to the visible airspace topology map, including:

[0139] In the visible airspace topology map, depict the operating trajectories of each low-earth orbit satellite during the predicted over-the-top service time;

[0140] Among them, for the over-the-top low-earth orbit satellite, depict the azimuth-pitch angle two-dimensional curve of the operating trajectory during the predicted over-the-top service time; delete the part of the azimuth-pitch angle two-dimensional curve that is lower than the curve of the visible airspace topology map, and retain the part that is higher than the curve of the visible airspace topology map; according to the retained part of the azimuth-pitch angle two-dimensional curve, obtain the corrected operating trajectory, calculate the average value of the pitch angle corresponding to the corrected operating trajectory, and the corrected over-the-top service time, and recalculate the selection weight of the low-earth orbit satellite to obtain the corrected selection weight;

[0141] Based on the corrected option weights, re-determine the candidate switching satellites that need to be switched, and generate a new list of candidate switching satellites;

[0142] When the corrected operating trajectory curve is two or more non-connected sub-curve segments, it is determined that there is an interruption in the corrected operating trajectory; among them, if the proportion of the azimuth angle range corresponding to any one sub-curve segment in the total azimuth angle range corresponding to the uncorrected operating trajectory curve exceeds a set ratio, calculate the corrected option weight of the low-earth orbit satellite corresponding to this operating trajectory curve based on this sub-curve segment, otherwise set the corrected option weight of the low-earth orbit satellite corresponding to the corrected operating trajectory curve to 0.

[0143] It should be noted that although several modules of the satellite handover determination device in the low-earth orbit satellite communication network are mentioned in the above detailed description, this division is only exemplary and not mandatory. In fact, according to the embodiments of the present invention, the features and functions of the two or more modules described above can be embodied in one module. Conversely, the features and functions of one module described above can be further divided and embodied by multiple modules.

[0144] Based on the foregoing inventive concept, as Figure 7 shown, the present invention also proposes a computer device 700, including a memory 710, a processor 720, and a computer program 730 stored on the memory 710 and executable on the processor 720. When the processor 720 executes the computer program 730, it implements the foregoing satellite handover determination method in the low-earth orbit satellite communication network.

[0145] Based on the foregoing inventive concept, the present invention proposes a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, it implements the foregoing satellite handover determination method in the low-earth orbit satellite communication network.

[0146] Based on the foregoing inventive concept, the present invention proposes a computer program product including a computer program, and when the computer program is executed by a processor, it implements the satellite handover determination method in the low-earth orbit satellite communication network.

[0147] The satellite handover determination method and device in the low-earth orbit satellite communication network proposed by the present invention obtain the ephemeris information of navigation satellites in real time through a terminal device, and determine the current position of the terminal device and the visible airspace topology map; according to the current position of the terminal device, obtain the satellite ephemeris of the low-earth orbit satellite communication network covering the terminal device; according to the satellite ephemeris, predict the over-the-top service time and corresponding operation trajectories of each low-earth orbit satellite, and generate a candidate handover satellite list; for the candidate handover satellite list, according to the visible airspace topology map, correct the over-the-top service time and operation trajectories of the candidate handover satellites in the list; based on the corrected over-the-top service time and operation trajectories, determine the target satellite to be handed over and the corresponding handover time. The overall solution fully considers the influence of building occlusion in the surrounding environment on the visible airspace, as well as the changes in the actual over-the-top time and the longest service duration of each satellite that may be caused by this occlusion, improves the accuracy of satellite handover judgment and the satellite handover efficiency, effectively ensures the communication quality of the terminal device, and provides strong technical support for the satellite communication scenario.

[0148] In the technical solution of this application, the acquisition, storage, use, processing, etc. of data all comply with the relevant regulations of laws and regulations.

[0149] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a device, or a computer program product. Therefore, the present invention can adopt the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0150] The present invention is described with reference to the flowcharts and / or block diagrams of methods and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, and the combination of processes and / or blocks in the flowchart and / or block diagram, can be realized by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate for realizing in the process Figure 1 one process or multiple processes and / or blocks Figure 1 a device for the functions specified in one block or multiple blocks.

[0151] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and the instruction device realizes in the processFigure 1 one process or multiple processes and / or blocks Figure 1 the functions specified in one block or multiple blocks.

[0152] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide for implementing the process Figure 1 one process or multiple processes and / or blocks Figure 1 the steps of the functions specified in one block or multiple blocks.

[0153] Finally, it should be noted that the above-described embodiments are only specific embodiments of the present invention, used to illustrate the technical solutions of the present invention, rather than limiting it. The protection scope of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: Any person skilled in the art within the technical scope disclosed by the present invention can still modify the technical solutions recorded in the foregoing embodiments, or can easily think of changes, or make equivalent replacements for some of the technical features; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for determining satellite switching in a low-orbit satellite communication network, characterized in that: The method includes: Obtaining navigation satellite ephemeris information in real time through the terminal device to determine the current position of the terminal device and the visible airspace topology map; According to the current position of the terminal device, obtaining the satellite ephemeris of the low-orbit satellite communication network covering the terminal device; According to the satellite ephemeris, predict the over-the-top service time and the corresponding running trajectory of each low-orbit satellite, and generate a candidate switching satellite list; For the candidate switching satellite list, according to the visible airspace topology map, correct the overhead service time and running trajectory of the candidate switching satellites in the list; Based on the corrected over-the-top service time and operation trajectory, determine the target satellite that needs to be switched and the corresponding switching time.

2. The method for determining satellite switching in a low-orbit satellite communication network according to claim 1, characterized in that: The navigation satellite ephemeris information obtained in real time by the terminal device includes at least: The GPS satellite navigation system can see the ephemeris information of satellites in real time, and the Beidou satellite navigation system can see the ephemeris information of satellites in real time.

3. The method for determining satellite switching in a low-orbit satellite communication network according to claim 1, characterized in that: Determine the visible airspace topology, including: Obtain the position information of all visible navigation satellites within the preset observation time period, including the elevation angle and azimuth angle of each satellite at different observation times; According to the pitch angle and azimuth information of each satellite at different observation times, a two-dimensional graph is drawn in a Cartesian coordinate system, wherein the X-axis is the azimuth, the azimuth range is 0-360°, and the Y-axis is the pitch angle, the pitch angle range is 0-90°; if there are multiple satellite position information with the same azimuth at different observation times, the data points represented by the satellite with the lowest pitch angle are retained, and the data points represented by other satellites with higher pitch angles are deleted, so that in the two-dimensional graph, the azimuth information corresponds to the pitch angle information one by one; All data points in the two-dimensional graph are connected in sequence according to the azimuth angle of 0-360° to form a visible airspace topology map; the visible airspace topology map represents the visible airspace status at the location of the terminal device. The area below the curve in the visible airspace topology map is blocked by obstructions in the surrounding environment. The signals of low-orbit satellites appearing in this area will not be received by the terminal device and will be invisible to the terminal device.

4. The method for determining satellite switching in a low-orbit satellite communication network according to claim 3, characterized in that: Determine the visible airspace topology map, including: Obtain the carrier-to-noise ratio information of all visible navigation satellites within a preset observation time period; If there are multiple satellite position information with the same azimuth at different observation times, the corresponding multiple sets of satellite position data are expressed as: (φ1, θ1, CN01), (φ1, θ2, CN02), ..., (φ1, θ N ,CN0 N ), where φ1 represents the azimuth; θ1, θ2, ..., θ N represents the pitch angle, θ i represents the i-th pitch angle; CN01, CN02, ..., CN0 N is the carrier-to-noise ratio information, CN0 i represents the i-th carrier-to-noise ratio value; N is the total number of satellite position data; Use one of the following methods to process so that the azimuth information and the elevation angle information in the two-dimensional graph correspond one to one: According to the carrier-to-noise ratio information, the satellite position information corresponding to the highest carrier-to-noise ratio value is retained; Calculate the average of all pitch angles according to the following formula as the pitch angle θ corresponding to the azimuth φ1 1_Final : In the formula, θ 1_Final is the unique pitch angle corresponding to the azimuth φ1; N is the total number of satellite position data; θ i is the i-th pitch angle; The unique pitch angle θ corresponding to the azimuth angle φ1 is calculated according to the following formula 1_Final : In the formula, θ 1_Final is the unique pitch angle corresponding to the azimuth φ1; N is the total number of satellite position data; θ i is the i-th pitch angle; CN0 i is the i-th carrier-to-noise ratio value; The unique pitch angle θ corresponding to the azimuth angle φ1 is calculated according to the following formula 1_Final : In the formula, θ 1_Final is the unique pitch angle corresponding to the azimuth φ1; N is the total number of satellite position data; θ i is the i-th pitch angle; CN0 i is the ith carrier-to-noise ratio value.

5. The method for determining satellite switching in a low-orbit satellite communication network according to claim 3, characterized in that: Determine the visible airspace topology map, including: For the azimuth φ i , compare the azimuth φ i The corresponding data point pitch angle θ i The azimuth angle φ is calculated based on the following formula: i The only corresponding pitch angle θ i_Final : θ i_Final = ceil(max(θ i ,θ Com_Limit )); where θ i_Final is the unique pitch angle corresponding to the azimuth angle φi; θ Com_Limit is the faith angle threshold; i represents the i-th azimuth; θ i is the azimuth angle φ i The pitch angle at the corresponding data point.

6. The method for determining satellite switching in a low-orbit satellite communication network according to claim 3, characterized in that: Determine the visible airspace topology map, including: Obtain the position information of all visible navigation satellites within a preset observation time period; If there are multiple visible satellites within a limited azimuth range, the corresponding multiple sets of satellite position data are: (φ1, θ1, CN01), (φ2, θ2, CN02), ..., (φ N ,θ N ,CN0 N ), among which, φ1, φ2,...,φ N represents the azimuth, φ i represents the i-th azimuth angle; θ1, θ2, ..., θ N represents the pitch angle, θ i represents the i-th pitch angle; CN01, CN02, ..., CN0 N is the carrier-to-noise ratio information; N is the total number of satellite position data; If |φ Max -φ Min |≤10°, where φ i ∈[φ Min ,φ Max ], and |θ Max -θ Min |≤6°, where θ i ∈[θ Min ,θ Max ], the azimuth angle φ is calculated according to the following formula i The corresponding pitch angle θ i_Final : In the formula, θ i_Final Indicates the azimuth angle φ i The only corresponding pitch angle at i represents the i-th azimuth; θ i represents the i-th elevation angle; N is the total number of satellite position data.

7. The method for determining satellite switching in a low-orbit satellite communication network according to claim 1, characterized in that: Determine the visible airspace topology map, including: Obtain the position information of all visible navigation satellites within a certain observation time period; wherein, for the certain observation time period, for a fixedly deployed terminal device, it shall not be less than a first preset time length; for a mobile deployed terminal device, it shall not be less than a second preset time length.

8. The method for determining satellite switching in a low-orbit satellite communication network according to claim 1, characterized in that: According to the satellite ephemeris, the over-the-top service time and the corresponding running trajectory of each low-orbit satellite are predicted, and a candidate switching satellite list is generated, including: Based on the over-the-top service time of each low-orbit satellite and the average value of the pitch angle of the running track during the over-the-top service time, select candidate switching satellites and generate a candidate switching satellite list; The selection weight of each low-orbit satellite is determined according to the following formula: In the formula, ω i (t,θ) is the selection weight determined based on the trajectory pitch angle and the overhead service time; Δt Max is the maximum value of the overhead service time of each low-orbit satellite; Δt i is the service time of the i-th low-orbit satellite; θ Max_Mean is the maximum value of the average value of the pitch angle of each low-orbit satellite during its service time; θ i_Mean is the average value of the pitch angle of the trajectory of the i-th low-orbit satellite during the over-the-top service time; α and β are weighting coefficients corresponding to the over-the-top service time and the average value of the pitch angle, respectively; α+β=1; Alternatively, the selection weight of each low-orbit satellite is determined according to the following formula:

9. The method for determining satellite switching in a low-orbit satellite communication network according to claim 8, characterized in that: For the candidate switching satellite list, the over-the-top service time and the running track of the candidate switching satellite in the list are corrected according to the visible airspace topology map, including: In the visible airspace topology map, the running track of each low-orbit satellite within the predicted over-the-top service time is depicted; Among them, for the low-orbit satellite that passes overhead, a two-dimensional azimuth-pitch angle curve of the running trajectory within the predicted over-the-top service time is drawn; the part of the azimuth-pitch angle two-dimensional curve that is lower than the visible airspace topology map curve is deleted, and the part that is higher than the visible airspace topology map curve is retained; according to the retained part of the azimuth-pitch angle two-dimensional curve, a corrected running trajectory is obtained, the average value of the pitch angle corresponding to the corrected running trajectory and the corrected over-the-top service time are calculated, and the selection weight of the low-orbit satellite is recalculated to obtain a corrected selection weight; Based on the modified selection weights, re-determine the candidate switching satellites to be switched, and generate a new candidate switching satellite list; When the corrected operation trajectory curve is two or more unconnected sub-curve segments, it is determined that there is an interruption in the corrected operation trajectory; wherein, if the proportion of the azimuth angle range corresponding to any sub-curve segment to the total azimuth angle range corresponding to the uncorrected operation trajectory curve exceeds a set proportion, the corrected selection weight of the low-orbit satellite corresponding to the operation trajectory curve is calculated based on the sub-curve segment, otherwise the corrected selection weight of the low-orbit satellite corresponding to the corrected operation trajectory curve is set to 0.

10. A satellite switching determination device in a low-orbit satellite communication network, characterized in that: The device includes: An information processing module is used to obtain navigation satellite ephemeris information in real time through a terminal device, and determine the current position of the terminal device and a visible airspace topology map; A satellite ephemeris acquisition module, used to acquire the satellite ephemeris of the low-orbit satellite communication network covering the terminal device according to the current position of the terminal device; A candidate switching satellite list generation module is used to predict the over-the-top service time and the corresponding running trajectory of each low-orbit satellite according to the satellite ephemeris, and generate a candidate switching satellite list; An information correction module, for correcting the over-the-top service time and the running track of the candidate switching satellites in the candidate switching satellite list according to the visible airspace topology map; The switching target determination module is used to determine the target satellite to be switched and the corresponding switching time based on the corrected over-the-top service time and operation trajectory.

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