CN109413662B - Low-earth-orbit communication satellite constellation and user station communication planning method - Google Patents
Low-earth-orbit communication satellite constellation and user station communication planning method Download PDFInfo
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Abstract
The invention discloses a low earth orbit communication satellite constellation and user station communication planning method. Obtaining the minimum communication field angle cosine of the satellite-geocentric-subscriber station according to the minimum communication elevation angle of the subscriber station; establishing a connection sequence of the user station and the satellite constellation according to the connectable time; and a method for calculating the user link beam sequence number according to the antenna configuration of the user link beam is established, and the problem of communication planning of a low earth orbit communication satellite constellation and a user station is solved.
Description
Technical Field
The invention relates to the field of communication, in particular to a low earth orbit communication satellite constellation and subscriber station communication planning method.
Background
Space-based broadband communication systems can be divided into geosynchronous orbit (GSO) and non-geosynchronous orbit (NGSO) satellite systems, depending on the orbital altitude. Because the geosynchronous orbit is nearly fixed relative to the ground, the GSO satellite communication system has low requirement on satellite tracking of GSO earth stations/user terminals, the main communication system providing global communication at present is the GSO satellite communication system, and theoretically, signal coverage in an area within 70 degrees of north and south latitude can be realized by utilizing three GSO satellites. However, the GSO satellite communication system has obvious disadvantages, including long communication distance, inability to implement signal coverage for two poles and high latitude areas, existence of south (north) mountain effect, limited rail position resources, high satellite launching and orbit entering cost and high risk, and especially the time delay problem brought by long distance, which is increasingly unable to meet the requirement of communication service on real-time performance.
Compared with a GSO satellite communication system, the NGSO satellite communication system has the main advantages of global coverage, small influence by terrain, small signal delay, strong system survivability, small transmission loss, convenient miniaturization of a user terminal, low satellite launching and orbit entering cost, high frequency resource utilization rate and the like, so that a plurality of NGSO satellite broadband communication projects are provided at home and abroad. Because the area of the signal coverage ground of one NGSO satellite is small, in order to realize global service, dozens or hundreds of satellites are required to form a constellation, the problems of internet access and information transmission in the region which cannot be covered by a ground communication system are solved, and the internet service with larger range and higher quality is provided for users. Currently, the low earth orbit satellite constellation communication system is the only means to achieve seamless coverage for global mobile communications (wang wu, zhang su update, reserve culture analysis and development of low earth orbit satellite constellation communication system suggests [ J ] satellite applications, 2015,7: 38-44.). Therefore, a plurality of low-orbit satellite constellation communication systems are proposed at home and abroad.
Because the position of the static orbit relative to the ground is close to fixed, the antenna of the ground user end of the static orbit satellite communication system points to be fixed and the satellite does not need to be switched; low earth orbit satellites move rapidly relative to the ground, so the subscriber station must frequently switch satellites to achieve long-term communication. To our knowledge, low-earth satellite communication systems are generally composed of a space segment, a ground segment and a user segment, the space segment comprising a constellation of low-earth communication satellites; the ground section comprises a comprehensive operation and control center, a gateway station and a measurement and control station; the user segment comprises a plurality of types of user stations, and no document discloses a low earth orbit communication satellite constellation and user station communication planning method at present, so the invention provides a low earth orbit communication satellite constellation and user station communication planning method.
Disclosure of Invention
The invention aims to provide a method for planning the connection between a low earth orbit communication satellite constellation and a subscriber station, which aims to solve the problems of poor communication quality, high time delay and the like of the satellite and the subscriber station in the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention discloses a method for planning the connection between a low earth orbit communication satellite constellation and a user station, which comprises the following steps:
s1, calculating the cosine of the minimum communication opening angle of the satellite-geocentric-subscriber station according to the minimum communication elevation angle of the satellite relative to the subscriber station;
s2, calculating the positions of all the user stations in the WGS84 coordinate system;
s3, acquiring the positions of all satellites in a planning period in a WGS84 coordinate system through orbit forecasting;
s4, calculating the cosine of the earth 'S heart opening angle of the satellite relative to the user station according to S2-S3, determining a satellite constellation and gateway station communication plan, and comparing the cosine of the earth' S heart opening angle with the cosine of the minimum communication opening angle in the corresponding satellite constellation and gateway station communication plan to obtain an available time period of a user link beam of the satellite in a planning period;
s5, respectively calculating the direction information pointed by the satellite to the subscriber station and the direction information of the subscriber station antenna according to the available time period obtained in the S4;
s6, in a planning cycle, calculating a connection sequence between the user station and a satellite constellation according to the available time period, the directional information from the satellite antenna to the user station and the directional information of the user station antenna;
and S7, repeating the steps S3-S6 until all planning periods are finished, and obtaining the final connected plan.
Preferably, the step S1 includes
S11, obtaining the relation between the earth center angle theta of the satellite relative to the user station and the elevation angle gamma of the satellite relative to the user station according to the sine theorem:
wherein R is the earth's equatorial radius, R is the earth's centroid distance;
s12, setting the minimum communication elevation angle gamma of the satellite relative to the user station0And calculating the minimum communication opening angle cosine of the satellite-geocentric-subscriber station:
preferably, the step S3 includes
S31, determining the initial positions of all satellites according to the observation data of the measurement and control station;
s32, acquiring the positions of all satellites in a J2000 coordinate system in a planning period by using orbit prediction;
and S33, calculating a coordinate transformation matrix from the J2000 coordinate system to the WGS-84 coordinate system in the planning period, and transforming the position vectors of all the satellites in the J2000 coordinate system to the WGS84 coordinate system.
Preferably, the step S4 includes
S41, calculating the cosine of the geocentric angle theta of the satellite relative to the subscriber station according to the position of the subscriber station in the WGS84 coordinate system and the position of the satellite in the WGS84 coordinate system as follows:
wherein, Pyh wRepresenting the position vector, P, of the subscriber station in the WGS84 coordinate systems wRepresents the position vector of the satellite in the WGS84 coordinate system, and the upper corner mark w represents the WGS84 coordinate system;
s42, determining a satellite constellation and gateway station communication plan;
and S43, comparing and judging the cosine of the opening angle theta of the geocentric satellite obtained in the S41 with the cosine of the minimum communication opening angle of the satellite-geocentric-subscriber station according to the corresponding communication plan of the satellite constellation and the gateway station, and obtaining the available time period of the satellite and the subscriber station.
Preferably, the determining the satellite constellation and gateway station connectivity plan comprises:
s421, calculating the cosine of the minimum communication field angle of the satellite-geocentric-gateway station according to the minimum communication elevation angle of the satellite relative to the gateway station;
s422, calculating the positions of all the gateway stations in a WGS84 coordinate system;
s423, acquiring the positions of all the satellites in a planning period in a WGS84 coordinate system through orbit prediction;
s424, calculating the cosine of the geocentric opening angle of all the satellites relative to the gateway station according to the steps S422-S423, and comparing the cosine with the cosine of the minimum communication opening angle in the step S1 respectively to obtain the connectable time of the satellites and the gateway station;
s425, respectively calculating the direction information of the satellite feeder link antenna and the direction information of the gateway station antenna according to the connectable time obtained in the S424;
s426, calculating a communication sequence of the gateway station and the satellite constellation in a communication planning period according to the connectable time, the direction information of the satellite feeder link antenna and the direction information of the gateway station antenna;
and S427, repeating the steps S423-S426 until all the communication planning periods are finished, and obtaining the communication planning of the satellite constellation and the gateway station.
Preferably, the direction information of the satellite-to-subscriber station pointing comprises an azimuth angle of the satellite-to-subscriber station pointing and an off-axis angle of the satellite-to-subscriber station pointing;
the direction information of the subscriber station antenna includes an azimuth angle of the subscriber station antenna and an elevation angle of the subscriber station antenna.
Preferably, the step S6 further includes:
s61, converting the directional information from the satellite to the user station into corresponding beam serial number according to the antenna beam arrangement;
and S62, calculating a connection sequence between the user station and the satellite constellation in a planning cycle according to the beam sequence number, the available time period and the direction information of the user station antenna.
Preferably, the step S61 further includes:
s611, dividing the antenna beam arrangement into four layers from inside to outside, wherein the number of each layer of beams is n in sequence1、n2、n3And n4the off-axis angle interval covered by each layer of wave beam is [0 α ] in sequence1)、[α1α2)、[α2α3) and [ alpha ]3α4)，α1、α2、α3and alpha4Off-axis angles from the satellite to the user station are all pointed;
s612, mixing the abovesatellite to subscriber station pointing azimuth βsand off-axis angle α of said satellite to subscriber station pointingsConverting to a beam number, then:
first layer αs≤α1：
second layer αs∈(α1α2]：
third layer αs∈(α2α3]：
fourth layer αs∈(α3α4]：
Preferably, the step S62 includes
S621, determining a communication sequence of the 1 st subscriber station and a satellite constellation, and setting satellites sequentially communicated with the first subscriber station at corresponding communication moments as non-communicable satellites of the rest subscriber stations;
and S622, determining a connection sequence of the S-th user station and a satellite constellation according to the satellite which is not set as the non-connectable satellite at the corresponding moment, and setting the satellite which is sequentially connected with the S-th user station at the corresponding connection moment as the non-connectable satellite of the rest user stations, wherein S is a natural number and is greater than 1.
Preferably, when the connected sequence of the subscriber station and the satellite constellation is planned, the method further comprises: and selecting the satellite with the longest connection time, wherein the connection time is longer than the set shortest connection time.
The invention has the following beneficial effects:
1. according to the low-earth-orbit communication satellite constellation and subscriber station communication planning method, due to the fact that the low-earth-orbit satellite moves fast relative to the ground, the communication planning method can solve the problem of fast and frequent switching of communication between the satellite and the subscriber station.
2. According to the low-earth-orbit communication satellite constellation and subscriber station communication planning method, because the low-earth-orbit communication satellite constellation is close to the ground subscriber station, the communication planning method can greatly reduce the communication time delay between the satellite and the subscriber station.
Drawings
The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.
Fig. 1 shows a flow chart of a method for connectivity planning of a constellation of low earth orbit communication satellites and subscriber stations in an embodiment;
FIG. 2 is a schematic diagram illustrating the spatial geometry of a satellite and a subscriber station in an embodiment;
FIG. 3 is a diagram showing the arrangement of gateway station sites and subscriber station sites in an embodiment;
FIG. 4 illustrates a satellite with subscriber stations connected at different times in an embodiment;
figure 5 shows the gateway station numbers of the subscriber station connected through the satellite at different times in an embodiment;
figure 6 shows user link beam numbering in an embodiment.
Detailed Description
In order to more clearly illustrate the invention, the invention is further described below with reference to preferred embodiments and the accompanying drawings. Similar parts in the figures are denoted by the same reference numerals. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.
The planning method for the communication between the low earth orbit communication satellite constellation and the user station can solve the problem of the communication between the low earth orbit communication satellite constellation and the ground user station. Before establishing a communication sequence between a satellite and a subscriber station, the communication sequence between the satellite and a gateway station needs to be established first to determine that a satellite subscriber link beam can provide communication service; the satellite is communicated with the subscriber station through a subscriber link, and when algorithm description is performed by taking a multi-beam switching antenna array antenna as an example, after the pointing information from the satellite to the subscriber station is obtained, the pointing information from the satellite to the subscriber station is converted into a beam sequence number of the subscriber link according to the arrangement mode of beams of the subscriber link.
As shown in fig. 1, in an embodiment of the present invention, a method for planning connectivity between a low earth orbit communication satellite constellation and a subscriber station is disclosed, which includes: s1, calculating the cosine of the minimum communication opening angle of the satellite-geocentric-subscriber station according to the minimum communication elevation angle of the satellite relative to the subscriber station; s2, calculating the positions of all the user stations in the WGS84 coordinate system; s3, acquiring the positions of all satellites in a planning period in a WGS84 coordinate system through orbit forecasting; s4, calculating the cosine of the earth 'S heart opening angle of the satellite relative to the user station according to S2-S3, determining a satellite constellation and gateway station communication plan, and comparing the cosine of the earth' S heart opening angle with the cosine of the minimum communication opening angle in the corresponding satellite constellation and gateway station communication plan to obtain an available time period of a user link beam of the satellite in a planning period; s5, respectively calculating the direction information pointed by the satellite to the subscriber station and the direction information of the subscriber station antenna according to the available time period obtained in the S4; s6, in a planning cycle, calculating a connection sequence between the user station and a satellite constellation according to the available time period, the directional information from the satellite antenna to the user station and the directional information of the user station antenna; and S7, repeating the steps S3-S6 until all planning periods are finished, and obtaining the final connected plan.
As shown in fig. 2, in the present embodiment, step S1 calculates the cosine of the minimum communication opening angle of the satellite-geocenter-subscriber station according to the minimum communication elevation angle of the satellite relative to the subscriber station: according to the sine theorem, the relationship between the geocentric angle θ of the satellite relative to the subscriber station and the elevation angle γ of the satellite relative to the subscriber station can be obtained:
wherein R is the equator radius of the earth, R is the geocentric distance of the satellite, and for the satellite running in the near circular orbit, the geocentric distance is approximately equal to the semimajor axis a, and R is approximately equal to a.
Using equation (1), the minimum communication elevation angle γ of the satellite relative to the subscriber station can be based0(given values) the cosine of the minimum communication opening angle of the satellite-geocentric-subscriber station is calculated:
since the dot product of the two unit vectors is the cosine of the included angle between the two vectors, when determining whether the satellite is in the connectable area of the subscriber station, in order to avoid performing the inverse cosine calculation with a large amount of calculation, the determination can be made by directly using the cosine discriminant of the included angle in equation (3),
cos(θ)＞cos(θ0) (3)
in this embodiment, step S2 is to calculate the positions of all the subscriber stations in the WGS84 coordinate system. The process specifically comprises the following steps: the position of all subscriber stations in the WGS-84 cartesian coordinate system (referred to in this patent as the "WGS-84 coordinate system") is calculated. Defining the geographic longitude, latitude and altitude of the subscriber station as L, B and H, respectively, the subscriber station's position in the WGS-84 coordinate system has a component of
Wherein N is the curvature radius of the unitary-mortise ring,
eeis the ellipsoidal eccentricity of the earth.
In this embodiment, the step S3 is to obtain the positions of all satellites in the WGS84 coordinate system in one planning period through orbit prediction. The method specifically comprises the following steps: at the initial moment of task planning, determining the initial positions of all satellites according to the observation data of the measurement and control station; then, the positions of all the satellites in the J2000 geocentric inertial coordinate system (referred to as the 'J2000 coordinate system' for short) in a planning period are obtained by using orbit prediction, and a coordinate transformation matrix from the J2000 coordinate system to the WGS-84 geocentric rectangular coordinate system (referred to as the 'WGS 84 coordinate system' for short) is calculated during the period, and meanwhile, the position vectors of all the satellites in the J2000 coordinate system are transformed to the WGS84 coordinate system. In addition, when acquiring the velocity of all the satellites in the WGS84 coordinate system in the planning period, the velocity can be acquired according to the above method.
In this embodiment, when determining the available time periods of the user link beams of all satellites in a planning period, first, according to S2-S3, calculating the cosine of the opening angle of the satellite with respect to the user station, determining the communication plan between the satellite constellation and the gateway station, according to the communication plan between the satellite constellation and the gateway station, comparing the cosine of the opening angle of the earth with the cosine of the minimum communication opening angle of the satellite-the earth-the user station, to obtain the available time periods meeting the requirements,
wherein the position vector of the subscriber station in the WGS-84 coordinate system is represented by Pyh wIndicating the position vector of the satellite in the WGS-84 coordinate system by Ps wMeaning that the cosine of the satellite's opening angle θ with respect to the subscriber station is
Wherein the upper superscript w represents the WGS-84 coordinate system.
According to equation (5), the cosine of the geocentric angle of all satellites relative to all subscriber stations at any moment can be calculated, and then whether the satellite and the subscriber stations meet the communication condition in space is judged by using an included angle cosine discriminant (3).
As shown in fig. 3, since the subscriber station performs information exchange with the gateway station through the satellite, the precondition that the satellite user link beam is available is that the satellite is in communication with the gateway station, that is, it is required to first determine a communication plan between the satellite constellation and the gateway station, which specifically includes: s421, calculating the cosine of the minimum communication field angle of the satellite-geocentric-gateway station according to the minimum communication elevation angle of the satellite relative to the gateway station; s422, calculating the positions of all the gateway stations in a WGS84 coordinate system; s423, acquiring the positions of all the satellites in a planning period in a WGS84 coordinate system through orbit prediction; s424, calculating the cosine of the geocentric opening angle of all the satellites relative to the gateway station according to the steps S422-S423, and comparing the cosine with the cosine of the minimum communication opening angle in the step S1 respectively to obtain the connectable time of the satellites and the gateway station; s425, respectively calculating the direction information of the satellite feeder link antenna and the direction information of the gateway station antenna according to the connectable time obtained in the S424; s426, calculating a communication sequence of the gateway station and the satellite constellation in a communication planning period according to the connectable time, the direction information of the satellite feeder link antenna and the direction information of the gateway station antenna; and S427, repeating the steps S423-S426 until all the communication planning periods are finished, and obtaining the communication planning of the satellite constellation and the gateway station. It should be noted that, the manner of obtaining the communication plan between the satellite constellation and the gateway station is similar to the manner of the communication plan between the satellite constellation and the subscriber station, but if the satellite feeder antenna and the gateway station use the servo reflector antenna, the process of converting the azimuth angle and the off-axis angle into the corresponding beam sequence number when the multi-beam switching antenna array is used can be omitted, and if the multi-beam switching antenna array is used, the conversion is required.
As can be seen from the above, the manner taken to obtain the available time period may be understood as: and (4) solving an intersection with the corresponding connectable time according to the available time of the satellite connected with the subscriber station, which is obtained by meeting the criterion (3), so as to obtain the available time period of the satellite and the subscriber station.
In the present embodiment, according to step S5: using the available time period obtained at S4, direction information of the satellite-to-subscriber station pointing direction and direction information of the subscriber station antenna are calculated, respectively. The specific steps in calculating the direction information of the satellite to the user station are: calculating the azimuth angle and the off-axis angle pointed by the satellite to the user station in the available time period; the unit vectors of an arbitrary coordinate system along the + X axis and the + Z axis can be expressed in the coordinate system
In the process that the user link antenna of the satellite is communicated with the user station antenna, the user link antenna of the satellite points to the user station, and the connecting line vector of the satellite to the user station is expressed as follows in a WGS-84 coordinate system:
Ps→yh w＝Pyh w-Ps w(7)
position vector Ps→yh wFrom the WGS-84 coordinate system to the J2000 Earth's center inertial coordinate system (referred to in this patent as the "J2000 coordinate system") Ps→yh iThen converted from the J2000 coordinate system to the orbital coordinate system Ps→yh oThe upper corner marks i and o represent the J2000 coordinate system and the track coordinate system, respectively, then
the included angle between the direction from the satellite to the user station and the satellite orbit coordinate system and the Z axis is defined as an off-axis angle and is alphasRepresents:
β is used for included angle between projection of connecting line vector from satellite to user station on XY plane of orbit coordinate system and satellite orbit coordinate system plus X axissRepresents:
wherein, Ps→yh-xy o＝[Ps→yh o(1)Ps→yh o(2)0]，Ps→yh-xy oIs Ps→yh oProjection on the XY plane of the orbital coordinate system.
the satellite-to-subscriber station orientation obtained above is defined by an off-axis angle αsand azimuth angle βsDescribing that for the multi-beam switching antenna array, the azimuth angle and the off-axis angle need to be converted into corresponding beam serial numbers, assuming that the antenna beam arrangement is divided into four layers, namely an inner layer and an outer layer, from inside to outside, the number of beams in each layer is n1、n2、n3And n4the off-axis angle interval covered by each layer of wave beam is [0 α ] respectively1]、(α1α2]、(α2α3]and (α)3α4]. The formula for converting the azimuth and off-axis angles to beam numbers is as follows:
first layer (. alpha.) ofs≤α1)：
second layer (. alpha.) ofs∈(α1α2])：
third layer (. alpha.) ofs∈(α2α3])：
fourth layer (. alpha.) ofs∈(α3α4])：
When calculating the direction information of the subscriber station antenna, specifically: the azimuth and elevation of the subscriber station antenna direction during the connectable time are calculated. During the process that the user link antenna of the satellite is communicated with the user station antenna, the antenna of the user station points to the satellite, and the connecting line vector of the user station to the satellite is expressed as follows in a WGS-84 coordinate system:
Pyh→s w＝Ps w-Pyh w(10)
will Pyh→s wConverting from WGS84 rectangular coordinates to geographical coordinates of northeast, and recording as Pyh→s d(the upper corner mark d represents the geographical coordinate system of the northeast), the included angle between the connecting line vector of the subscriber station to the satellite and the XOY plane of the geographical coordinate system of the northeast is defined as the elevation angle of the antenna direction of the subscriber station, and gamma is useddAnd (4) showing.
User arrival guardthe projection of the star connecting line vector on the XY plane of the geographic coordinate system of the northeast, the geographic coordinate system of the northeast and the included angle of the X axis are taken as the azimuth angle target value of the antenna direction of the subscriber station, and beta is useddAnd (4) showing.
Wherein, Pyh→s-xy d＝[Pyh→s d(1)Pyh→s d(2)0]，Pyh→s-xy dIs Pyh→s dProjection on the XY plane of the geographic coordinate system.
In this embodiment, the step S6 further includes: s61, converting the directional information from the satellite to the user station into corresponding beam serial number according to the antenna beam arrangement; s62, calculating a connection sequence between the user station and the satellite constellation in a planning cycle according to the beam sequence number, the available time period and the direction information of the user station antenna,
determining a communication sequence of a 1 st user station and a satellite constellation, and setting satellites sequentially communicated with the first user station at corresponding communication moments as non-connectable satellites of the rest user stations; determining a connected sequence of the S user station and a satellite constellation according to the satellite which is not set as the unconnected satellite at the corresponding time, and setting the satellite which is sequentially connected with the S user station at the corresponding connected time as the unconnected satellite of the rest user stations, wherein S is a natural number and is greater than 1. When determining the connection sequence of the user station and the satellite constellation, establishing the connection sequence of the user station and the satellite according to the criterion that the connection time of the user station and the satellite is longest.
In this embodiment, after the connected sequence in one planning period is obtained, the above steps are repeatedly executed to complete all the connected sequences in all the planning periods, so that the connected planning of the satellite constellation and the subscriber station is realized.
In summary, the present invention is based on establishing a connection planning sequence between a satellite constellation and a gateway station, and obtaining an available time period during which a satellite can provide a communication service, that is: determining a satellite communicated by a user station in a planning period, obtaining direction information from the user station to the satellite and from the satellite to the user station in the communication period, and sequentially establishing a communication sequence of the 1 st, 2 nd, … … th and n number of user stations and a satellite constellation in the planning period; and after the task planning of one planning period is finished, repeating the steps to carry out long-term task planning of the communication between the satellite constellation and the user station.
To further illustrate, a more specific embodiment of the present invention provides a method for planning connectivity between a low earth orbit communication satellite constellation and a subscriber station, where the satellite constellation has already been placed in orbit to complete deployment, and the method for planning connectivity establishes a connectivity relationship between the satellite constellation and the subscriber station, and obtains a beam sequence number of a subscriber station antenna and a satellite subscriber link during the connectivity.
In this embodiment, taking the task planning period equal to 1 day as an example, the initial time of the connectivity planning is 2016 year, 1 month, 1 day, 0 hour and 0 minute, and the simulation step length is 5 seconds. The satellite constellation is distributed on 13 orbital planes, each orbital plane comprises 12 satellites, and 156 satellites in total, wherein the table 1 is the initial orbital parameters of the satellite constellation, and n in the tableoutAnd ninNumber of satellite in orbital plane and orbital plane, nout∈[1,2,3,…,12,13]，nin∈[1,2,3,…,11,12]The number of the satellite is defined as nsate＝(nout-1)×12+nin. The longitude, latitude and altitude of the gateway station sites are shown in table 2, each site is provided with 4 gateway stations, and the total number of the gateway stations is 40. The longitude, latitude and altitude of the subscriber station address are shown in table 3, and the total number of subscriber stations is S ═ 10. The shortest connection time between the satellite and the subscriber station is set to delta tminThe initial time and the end time of the first connectivity planning period are defined as t 60sec, respectively00 and tf＝86400sec。
TABLE 1 initial orbital parameters of communication constellation satellites
| Parameter(s) | Numerical value |
| Semi-major axis, km | 7410.5 |
| Eccentricity ratio | 0.001 |
| Inclination of the track, deg | 80 |
| Ascending crossing Red meridian, deg | Ω0+(nout-1)×200/13 |
| Argument of perigee, |
10 |
| Flat proximal angle, deg | M0+(nout-1)×6/13×30+(nin-1)×30 |
TABLE 2 longitude, latitude and altitude of gateway station site
TABLE 3 longitude, latitude, and altitude of the subscriber station site
| Station address serial number | (latitude, longitude) | Height, m |
| 1 | (39.904°，116.407°) | ﹣203 |
| 2 | (51.5°，-0.117°) | 0 |
| 3 | (-15°，49°) | 0 |
| 4 | (39.4012°，76.134°) | 0 |
| 5 | (18.253°，109.512°) | 0 |
| 6 | (46.800°，130.319°) | 0 |
| 7 | (31.230°，121.474°) | 0 |
| 8 | (23.12°，113.25°) | 0 |
| 9 | (43.45°，87.36°) | 0 |
| 10 | (60°，180°) | 0 |
The method for planning the connection between the low earth orbit communication satellite constellation and the user station comprises the following specific steps:
calculating cosine of the minimum communication opening angle according to the minimum communication elevation angle, wherein the minimum communication elevation angle of the satellite relative to the user station is set as gamma 020 deg., the cosine of the minimum communication opening angle of the satellite with respect to the subscriber station can be calculated according to equation (2),
cos(θ0)＝0.961
the position of all subscriber stations in the WGS-84 coordinate system is calculated. From the geographic longitude, geographic latitude and altitude of the 10 subscriber station sites of Table 3, the position component of each subscriber station in the WGS-84 coordinate system can be calculated as
TABLE 4 three-dimensional position component of subscriber station
firstly establishing a communication relation between a satellite and a gateway station to obtain a communication plan between the satellite and the gateway station, determining available time periods of user link wave beams of all satellites in a planning period according to the communication plan between the satellite and the gateway station and a minimum communication field angle, calculating an azimuth angle and an off-axis angle pointed by the satellite to a user station in the available time periods, and calculating an azimuth angle β pointed by the satellite to a first user station in the communicable time period by using equations (8) and (9)sand off-axis angle αsconverting the direction from satellite to user station into beam sequence number, calculating azimuth angle and elevation angle of antenna direction of user station in available time period, calculating azimuth angle beta of antenna direction of user station in connectable time period by using equations (11) and (12)dAnd elevation angle gammad(ii) a According to the available time period, the beam sequence number and the azimuth angle of the antenna direction of the subscriber stationAnd elevation angle, determining a communication sequence of the first subscriber station and the satellite constellation, and marking the satellite communicated with the first subscriber station at the corresponding moment as a satellite which is not connected with the rest subscriber stations; determining the connection sequence of the 2 nd subscriber station and the satellite constellation by using the method and marking the satellite connected with the 2 nd subscriber station at the corresponding moment as the satellite which is not connected with the rest subscriber stations, and so on, calculating the connection sequence of the 3 rd subscriber station, the 4 th subscriber station, the … … and the S subscriber station and the satellite constellation. When the required whole communication planning period is completed, the communication planning of the satellite constellation and the user station can be realized. The specific connections are shown in fig. 4-6.
Where figure 5 shows the numbers of the gateway stations connected by the satellite at different times by the first subscriber station, the circles in the figure representing the initial times of communication of the subscriber station with the satellite and the squares representing the end times of communication. From the global diagram, it can be seen that the 1 st subscriber station is only communicated with the 1 st and 9 th gateway stations through the satellite, and from observing the gateway station site and the first subscriber station site layout of fig. 2, it can be seen that the 1 st subscriber station (yh _1) is closer to the gateway station 1(xg _1) and the gateway station 9(xg _9), and the subscriber station is communicated with the closer gateway station through the satellite, thereby laterally proving the correctness of the satellite constellation and subscriber station communication planning method.
It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention, and it will be obvious to those skilled in the art that other variations or modifications may be made on the basis of the above description, and all embodiments may not be exhaustive, and all obvious variations or modifications may be included within the scope of the present invention.
Claims (10)
1. A method for planning connectivity between a constellation of low earth orbit communication satellites and a subscriber station, the method comprising the steps of
S1, calculating the cosine of the minimum communication opening angle of the satellite-geocentric-subscriber station according to the minimum communication elevation angle of the satellite relative to the subscriber station;
s2, calculating the positions of all the user stations in the WGS84 coordinate system;
s3, acquiring the positions of all satellites in a planning period in a WGS84 coordinate system through orbit forecasting;
s4, calculating the cosine of the earth 'S heart opening angle of the satellite relative to the user station according to S2-S3, determining a satellite constellation and gateway station communication plan, and comparing the cosine of the earth' S heart opening angle with the cosine of the minimum communication opening angle in the corresponding satellite constellation and gateway station communication plan to obtain an available time period of a user link beam of the satellite in a planning period;
s5, respectively calculating the direction information pointed by the satellite to the subscriber station and the direction information of the subscriber station antenna according to the available time period obtained in the S4;
s6, in a planning cycle, calculating a connection sequence between the user station and a satellite constellation according to the available time period, the directional information from the satellite antenna to the user station and the directional information of the user station antenna;
and S7, repeating the steps S3-S6 until all planning periods are finished, and obtaining the final connected plan.
2. The method for planning connectivity of a low earth orbit communication satellite constellation with a subscriber station as claimed in claim 1, wherein the step S1 comprises
S11, obtaining the relation between the earth center angle theta of the satellite relative to the user station and the elevation angle gamma of the satellite relative to the user station according to the sine theorem:
wherein R is the earth's equatorial radius, R is the earth's centroid distance;
s12, setting the minimum communication elevation angle gamma of the satellite relative to the user station0And calculating the minimum communication opening angle cosine of the satellite-geocentric-subscriber station:
3. the method for planning connectivity of a low earth orbit communication satellite constellation with a subscriber station as claimed in claim 1, wherein the step S3 comprises
S31, determining the initial positions of all satellites according to the observation data of the measurement and control station;
s32, acquiring the positions of all satellites in a J2000 coordinate system in a planning period by using orbit prediction;
and S33, calculating a coordinate transformation matrix from the J2000 coordinate system to the WGS-84 coordinate system in the planning period, and transforming the position vectors of all the satellites in the J2000 coordinate system to the WGS84 coordinate system.
4. The method for planning connectivity of a low earth orbit communication satellite constellation with a subscriber station as claimed in claim 1, wherein the step S4 comprises
S41, calculating the cosine of the geocentric angle theta of the satellite relative to the subscriber station according to the position of the subscriber station in the WGS84 coordinate system and the position of the satellite in the WGS84 coordinate system as follows:
wherein, Pyh wRepresenting the position vector, P, of the subscriber station in the WGS84 coordinate systems wRepresents the position vector of the satellite in the WGS84 coordinate system, and the upper corner mark w represents the WGS84 coordinate system;
s42, determining a satellite constellation and gateway station communication plan;
and S43, comparing and judging the cosine of the opening angle theta of the geocentric satellite obtained in the S41 with the cosine of the minimum communication opening angle of the satellite-geocentric-subscriber station according to the corresponding communication plan of the satellite constellation and the gateway station, and obtaining the available time period of the satellite and the subscriber station.
5. The method of claim 4 wherein determining a plan for connectivity between a constellation of low earth orbit communication satellites and a subscriber station comprises determining a plan for connectivity between a constellation of satellites and a gateway station
S421, calculating the cosine of the minimum communication field angle of the satellite-geocentric-gateway station according to the minimum communication elevation angle of the satellite relative to the gateway station;
s422, calculating the positions of all the gateway stations in a WGS84 coordinate system;
s423, acquiring the positions of all the satellites in a planning period in a WGS84 coordinate system through orbit prediction;
s424, calculating the cosine of the geocentric opening angle of all the satellites relative to the gateway station according to the steps S422-S423, and comparing the cosine with the cosine of the minimum communication opening angle in the step S1 respectively to obtain the connectable time of the satellites and the gateway station;
s425, respectively calculating the direction information of the satellite feeder link antenna and the direction information of the gateway station antenna according to the connectable time obtained in the S424;
s426, calculating a communication sequence of the gateway station and the satellite constellation in a communication planning period according to the connectable time, the direction information of the satellite feeder link antenna and the direction information of the gateway station antenna;
and S427, repeating the steps S423-S426 until all the communication planning periods are finished, and obtaining the communication planning of the satellite constellation and the gateway station.
6. The method of claim 1, wherein the direction information of the satellite-to-subscriber station pointing direction comprises an azimuth angle of the satellite-to-subscriber station pointing direction and an off-axis angle of the satellite-to-subscriber station pointing direction;
the direction information of the subscriber station antenna includes an azimuth angle of the subscriber station antenna and an elevation angle of the subscriber station antenna.
7. The method for planning connectivity of a low earth orbit communication satellite constellation with a subscriber station as claimed in claim 6, wherein the step S6 further comprises:
s61, converting the directional information from the satellite to the user station into corresponding beam serial number according to the antenna beam arrangement;
and S62, calculating a connection sequence between the user station and the satellite constellation in a planning cycle according to the beam sequence number, the available time period and the direction information of the user station antenna.
8. The method for planning connectivity of a low earth orbit communication satellite constellation with a subscriber station as claimed in claim 7, wherein the step S61 further comprises:
s611, dividing the antenna beam arrangement into four layers from inside to outside, wherein the number of each layer of beams is n in sequence1、n2、n3And n4the off-axis angle interval covered by each layer of wave beam is [0 α ] in sequence1)、[α1α2)、[α2α3) and [ alpha ]3α4)，α1、α2、α3and alpha4Off-axis angles from the satellite to the user station are all pointed;
s612, pointing the satellite to the user station to an azimuth angle betasand off-axis angle α of said satellite to subscriber station pointingsConverting to a beam number, then:
first layer αs≤α1：
second layer αs∈(α1α2]：
third layer αs∈(α2α3]：
fourth layer αs∈(α3α4]：
9. The method for planning connectivity of a low earth orbit communication satellite constellation with a subscriber station as claimed in claim 7, wherein the step S62 comprises
S621, determining a communication sequence of a first user station and a satellite constellation, and setting satellites sequentially communicated with the first user station at corresponding communication time as non-communicable satellites of the rest user stations;
and S622, determining a connection sequence of the S-th user station and a satellite constellation according to the satellite which is not set as the non-connectable satellite at the corresponding moment, and setting the satellite which is sequentially connected with the S-th user station at the corresponding connection moment as the non-connectable satellite of the rest user stations, wherein S is a natural number and is greater than 1.
10. The method for planning connectivity between a subscriber station and a low earth orbit communication satellite constellation according to any one of claims 1-9, wherein when planning a connectivity sequence between the subscriber station and the satellite constellation, the method further comprises: and selecting the satellite with the longest connection time, wherein the connection time is longer than the set shortest connection time.
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