CN117478207A - Satellite-to-ground link communication method, device, equipment and storage medium - Google Patents

Satellite-to-ground link communication method, device, equipment and storage medium Download PDF

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Publication number
CN117478207A
CN117478207A CN202311786178.9A CN202311786178A CN117478207A CN 117478207 A CN117478207 A CN 117478207A CN 202311786178 A CN202311786178 A CN 202311786178A CN 117478207 A CN117478207 A CN 117478207A
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satellite
determining
vector
angle
coordinate system
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CN117478207B (en
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林力
宋怡昕
陈瑞欣
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Guangdong Shiju Network Technology Co ltd
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Guangdong Shiju Network Technology Co ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/14—Relay systems
    • H04B7/15—Active relay systems
    • H04B7/185—Space-based or airborne stations; Stations for satellite systems
    • H04B7/1851—Systems using a satellite or space-based relay
    • H04B7/18513—Transmission in a satellite or space-based system
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/14—Relay systems
    • H04B7/15—Active relay systems
    • H04B7/185—Space-based or airborne stations; Stations for satellite systems
    • H04B7/1851—Systems using a satellite or space-based relay
    • H04B7/18519—Operations control, administration or maintenance
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

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  • Astronomy & Astrophysics (AREA)
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Abstract

The application discloses a satellite-to-ground link communication method, a device, equipment and a storage medium, and relates to the technical field of communication. The method comprises the following steps: acquiring satellite orbit parameters at a reference moment, and determining satellite orbit parameters at a transmission moment according to the satellite orbit parameters at the reference moment; determining an angle of the right ascent according to the transmission time, and determining a speed vector and a position vector of the satellite according to the angle of the right ascent and satellite orbit parameters at the transmission time; determining a speed vector and a position vector of the terminal according to the positioning information of the terminal, and determining a time offset and a frequency offset of a satellite-ground link according to the speed vector and the position vector of the terminal and the satellite; and compensating the transmission parameters of the communication signals according to the time offset and the frequency offset of the satellite-ground link, and transmitting the communication signals based on the compensated transmission parameters. By the technical means, the problem that the communication quality is affected by time offset and frequency offset of a satellite-ground link in the prior art is solved, and the communication quality between a satellite base station and a terminal is improved.

Description

Satellite-to-ground link communication method, device, equipment and storage medium
Technical Field
The present disclosure relates to the field of communications technologies, and in particular, to a method, an apparatus, a device, and a storage medium for satellite-to-ground link communications.
Background
The Non-terrestrial network (NTN, non-Terrestrial Network) is a wireless network mounted on a satellite or unmanned aerial vehicle (UAS, unmanned Aircraft System) platform. Starting from the R17 version, the 3GPP standards organization incorporates non-terrestrial network technology into the specifications as part of the 5G standard to achieve thousands of kilometers coverage through satellite antenna chain relay, which complements terrestrial communications to build together an air-space integrated stereo converged network. Compared to traditional 5G terrestrial communications, non-terrestrial network technologies can provide good supplementary services such as coverage blindness, broad-range broadcasting, support for high-speed mobile users (e.g., passengers in a vehicle such as a passenger aircraft), etc.
In the prior art, the implementation process of the non-ground network technology is as follows: by means of a satellite or an overhead UAS platform with load transmission or load regeneration, a communication beam is generated and an elliptical irradiation area is formed in the service area. The low-orbit (LEO) satellite-mounted satellite base station is a mainstream architecture scheme, and compared with other carriers, the low-orbit satellite has the characteristics of short satellite-to-ground distance and strong signal quality. However, when the low-orbit satellite moves fast on the orbit, the propagation delay and the Doppler frequency offset of the satellite-ground link between the satellite base station and the terminal are continuously changed, so that the communication quality between the satellite base station and the terminal is affected.
Disclosure of Invention
The application provides a satellite-ground link communication method, device, equipment and storage medium, which are used for deducing a real-time motion state according to the orbit parameters of a low orbit satellite, accurately estimating the time offset and the frequency offset of a satellite-ground link by combining the positioning information of a terminal, and carrying out compensation processing on the transmission parameters of communication signals according to the time offset and the frequency offset, so that the problem that the time offset and the frequency offset of the satellite-ground link influence the communication quality in the prior art is solved, and the communication quality between a satellite base station and the terminal is improved.
In a first aspect, the present application provides a satellite-to-ground link communication method, including:
acquiring satellite orbit parameters at a reference moment, and determining satellite orbit parameters at a transmission moment according to the satellite orbit parameters at the reference moment;
determining an angle of the right ascent according to the transmission time, and determining a speed vector and a position vector of a satellite according to the angle of the right ascent and satellite orbit parameters of the transmission time;
determining a speed vector and a position vector of a terminal according to positioning information of the terminal, and determining time offset and frequency offset of a satellite-ground link according to the speed vector and the position vector of the terminal and the satellite;
and compensating transmission parameters of the communication signals according to the time offset and the frequency offset of the satellite-ground link, and transmitting the communication signals based on the compensated transmission parameters.
In a second aspect, the present application provides a satellite-to-ground link communication device, including:
the orbit parameter determining module is configured to acquire satellite orbit parameters at a reference moment and determine satellite orbit parameters at a transmission moment according to the satellite orbit parameters at the reference moment;
the satellite vector determining module is configured to determine an angle of the right ascent according to the transmission time and determine a speed vector and a position vector of the satellite according to the angle of the right ascent and satellite orbit parameters of the transmission time;
the time frequency offset determining module is configured to determine a speed vector and a position vector of the terminal according to the positioning information of the terminal, and determine the time offset and the frequency offset of a satellite-ground link according to the speed vector and the position vector of the terminal and the satellite;
and the transmission parameter compensation module is configured to compensate the transmission parameters of the communication signals according to the time offset and the frequency offset of the satellite-ground link, and transmit the communication signals based on the compensated transmission parameters.
In a third aspect, the present application provides a satellite-to-ground link communication device, including:
one or more processors; a memory storing one or more programs that, when executed by the one or more processors, cause the one or more processors to implement the star link communication method as described in the first aspect.
In a fourth aspect, the present application provides a storage medium containing computer executable instructions which, when executed by a computer processor, are for performing the satellite-to-ground link communication method according to the first aspect.
In the application, the satellite orbit parameters of the transmission time are determined according to the satellite orbit parameters of the reference time by acquiring the satellite orbit parameters of the reference time; determining an angle of the right ascent according to the transmission time, and determining a speed vector and a position vector of the satellite according to the angle of the right ascent and satellite orbit parameters at the transmission time; determining a speed vector and a position vector of the terminal according to the positioning information of the terminal, and determining a time offset and a frequency offset of a satellite-ground link according to the speed vector and the position vector of the terminal and the satellite; and compensating the transmission parameters of the communication signals according to the time offset and the frequency offset of the satellite-ground link, and transmitting the communication signals based on the compensated transmission parameters. By the technical means, the satellite orbit parameters of the transmission time of the communication signal can be calculated based on the satellite orbit parameters of the reference time, the position and the speed of the transmission time are determined according to the satellite orbit parameters of the transmission time, the position and the speed of the terminal at the transmission time are calculated according to the positioning information of the terminal, the transmission time delay of the communication signal, namely the time offset of the satellite-to-ground link, is accurately estimated according to the position distance between the satellite and the terminal, the frequency offset of the satellite-to-ground link is accurately estimated according to the speed offset of the terminal of the satellite, and the transmission time and the transmission frequency of the communication signal are compensated according to the time offset and the frequency offset, so that the influence of the time offset and the frequency offset on the communication signal is reduced, the problem that the time offset and the frequency offset of the satellite-to-ground link influence the communication quality in the prior art is solved, and the communication quality between the satellite base station and the terminal is improved.
Drawings
Fig. 1 is a flowchart of a satellite-to-ground link communication method provided in an embodiment of the present application;
FIG. 2 is a flow chart of determining satellite orbit parameters at transmission time provided by an embodiment of the present application;
FIG. 3 is a flow chart for determining the right angle provided by an embodiment of the present application;
FIG. 4 is a flow chart for determining velocity vectors and position vectors for satellites provided by embodiments of the present application;
fig. 5 is a flowchart for determining a location vector of a terminal according to an embodiment of the present application;
FIG. 6 is a schematic diagram of a spherical coordinate system provided by an embodiment of the present application;
fig. 7 is a flowchart for determining a velocity vector of a terminal according to an embodiment of the present application;
FIG. 8 is a flow chart for determining a time offset of a satellite-to-ground link provided by an embodiment of the present application;
fig. 9 is a flowchart for determining a frequency offset of a satellite-to-ground link according to an embodiment of the present application;
fig. 10 is a schematic structural diagram of a satellite-to-ground link communication device according to an embodiment of the present application;
fig. 11 is a schematic structural diagram of a satellite-to-ground link communication device according to an embodiment of the present application.
Detailed Description
In a more common existing implementation, a satellite base station is carried by a low-orbit satellite, and non-ground network communication is performed between the satellite base station and a ground terminal. Although low orbit satellites have the characteristics of close satellite-ground distance and strong signal quality compared with other carriers. However, when the low-orbit satellite moves fast on the orbit, the propagation delay and the Doppler frequency offset of the satellite-ground link between the satellite base station and the terminal are continuously changed, so that the communication quality between the satellite base station and the terminal is affected.
In order to solve the above-mentioned problems, the present embodiment provides a satellite-to-ground link communication method, so as to derive a real-time motion state according to an orbit parameter of a low orbit satellite, and then accurately estimate a time offset and a frequency offset of a satellite-to-ground link in combination with positioning information of a terminal, and perform compensation processing on transmission parameters of a communication signal according to the time offset and the frequency offset, thereby solving the problem that the time offset and the frequency offset of the satellite-to-ground link affect communication quality in the prior art, and improving communication quality between a satellite base station and the terminal.
The satellite-to-ground link communication method provided in this embodiment may be performed by a satellite-to-ground link communication device, where the satellite-to-ground link communication device may be implemented in software and/or hardware, and the satellite-to-ground link communication device may be configured by two or more physical entities or may be configured by one physical entity. For example, the satellite-to-ground link communication device may be a ground terminal.
The satellite-ground link communication equipment is provided with at least one type of operating system, wherein the operating system comprises, but is not limited to, an android system, a Linux system and a Windows system. The satellite-to-ground link communication device may install at least one application program based on the operating system, where the application program may be an application program carried by the operating system, or may be an application program downloaded from a third party device or a server. In this embodiment, the satellite-to-ground link communication apparatus has at least an application program that can execute the satellite-to-ground link communication method.
For ease of understanding, the present embodiment will be described taking a ground terminal as an example of a main body for performing the satellite-ground link communication method.
Fig. 1 is a flowchart of a satellite-to-ground link communication method according to an embodiment of the present application. As shown in fig. 1, the method for satellite-to-ground link communication includes the steps of:
s110, acquiring satellite orbit parameters at the reference time, and determining the satellite orbit parameters at the transmission time according to the satellite orbit parameters at the reference time.
The transmission time is a time when the ground terminal transmits a communication signal to the low-orbit satellite, and the reference time is a time for estimating satellite orbit parameters of the transmission time. For the current moment, the transmission moment belongs to a future time node, so that the satellite orbit parameters of the low orbit satellite at the transmission moment cannot be directly acquired, and the satellite orbit parameters of the transmission moment are required to be indirectly determined through the satellite orbit parameters of the low orbit satellite at the reference moment. When the satellite orbit parameters of the reference time are acquired, the low orbit satellite can send the satellite orbit parameters of the corresponding time to the ground terminal in real time through network broadcasting, the ground terminal takes the time corresponding to the satellite orbit parameters in the network broadcasting as the reference time, and the satellite orbit parameters in the network broadcasting as the satellite orbit parameters of the reference time. In addition, the satellite orbit parameters corresponding to the plurality of times may be preconfigured in the ground terminal, one of the times is selected as the reference time according to the transmission time, and the satellite orbit parameter corresponding to the one of the times is determined as the satellite orbit parameter of the reference time.
According to kepler celestial body motion law, the satellite orbit is an elliptical orbit taking the earth center as a focus, and the elliptical orbit is mainly described by six satellite orbit parameters of a semi-major axis, an eccentricity, an orbit inclination angle, a near-center point argument, an intersection point longitude and a near-point angle. The satellite orbit parameter takes an Earth Center Inertia (ECI) coordinate system as a reference, and the semi-long axis is half of the length of the longest line segment intersecting the ellipse through the focus; eccentricity is the ratio of the half focal length to the half major axis; the track inclination represents the inclination degree of the track plane relative to the reference plane; the amplitude angle of the near-heart point represents the positional relationship between the near-heart point and the reference plane; the longitude of the ascending intersection point represents the position relation of the orbit plane corresponding to the X axis of the geocentric inertial coordinate system; the near point angle has three expression modes, namely a true near point angle, a near point angle and a flat near point angle, wherein the true near point angle represents the relative position of the satellite in an orbit focal line; the angle of the near point is the angle between the central measurement of the ellipse and the direction of the near center point, wherein the position of the satellite on the orbit is projected on the circumscribing circle perpendicular to the semi-major axis of the ellipse; the closest point angle is the running angle of the corresponding virtual point of the satellite on the orbit on the auxiliary circle relative to the center point.
In this embodiment, fig. 2 is a flowchart of determining satellite orbit parameters at a transmission time according to an embodiment of the present application. As shown in fig. 2, the step of determining the satellite orbit parameters at the transmission time specifically includes S1101-S1103:
s1101, the semimajor axis, the eccentricity, the orbital tilt, the paraxial point argument and the ascending point longitude of the reference time are determined as the semimajor axis, the eccentricity, the orbital tilt, the paraxial point argument and the ascending point longitude of the transmission time.
For example, for the same satellite, the semimajor axis, the eccentricity, the orbital tilt, the paraxial angle of origin, and the ascending longitude of intersection in the corresponding satellite orbit parameters at different times are the same, so the semimajor axis, the eccentricity, the orbital tilt, the paraxial angle of origin, and the ascending longitude of intersection at the reference time can be directly determined as the semimajor axis, the eccentricity, the orbital tilt, the paraxial angle of origin, and the ascending longitude of intersection at the transmission time.
S1102, determining the horizontal movement angular velocity according to the semi-long axis and the gravitational constant, and determining the horizontal and proximal point angle of the transmission time according to the horizontal movement angular velocity, the difference value between the reference time and the transmission time and the horizontal and proximal point angle of the reference time.
Illustratively, the near-corner point is the only variable in satellite orbit parameters, and the near-point angle is used later in determining the position and velocity of the satellite, so this embodiment is intended to determine the near-point angle at the time of transmission. The kepler equation is satisfied between the near point angle and the plane near point angle Wherein->For the near point angle of the transmission instants +.>E is the eccentricity of the transmission moment, which is the angle of the closest point of the transmission moment. Therefore, the close point angle of the transmission time can be determined first, and then the close point angle of the transmission time can be determined.
The calculation formula of the angular velocity of the flat motion is，/>For the angular velocity of the flat movement +.>Is the constant of the gravity of the earth,，/>is a constant of universal gravitation->For the earth's mass>Is the semi-long axis of the transmission time. Substituting the gravitational constant and the semi-long axis of the transmission time into a calculation formula of the translational angular velocity to obtain the translational angular velocity. Multiplying the angular velocity of the flat motion by the time difference between the transmission time and the reference time to obtain a product, and multiplying the productThe product is added with the angle of the nearest point at the reference moment to obtain a sum, and the sum is added to the circumference radian, namely +.>And carrying out the remainder operation to obtain the closest point angle of the transmission moment. It should be noted that the calculation process can infer the calculation formula of the nearest point angle ∈ ->，/>For the straight-ahead point angle at the reference instant,Tfor the transmission time +.>For reference moment +.>Is the sign of the remainder operation. Substituting the reference time, the transmission time and the parallel-to-closest point angle speed of the reference time into a parallel-to-closest point angle calculation formula to calculate the parallel-to-closest point angle of the transmission time.
S1103, determining the near point angle of the transmission time according to the near point angle and the eccentricity of the transmission time.
Exemplary, the plains equation based on the angle of the closest point and the eccentricity at the time of transmissionAnd (5) resolving to obtain a near point angle of the transmission moment. Wherein, when the eccentricity is->In the time of satellite orbit, the satellite orbit is round and is close to the point angle +.>Equal to the angle of the plain point +.>The method comprises the steps of carrying out a first treatment on the surface of the When eccentricity +>When the satellite orbit is elliptical, the Kepler equation can be solved by an iteration methodDue to->The iteration->Is convergent, is->. Can make the initialReasonable control standard is set>Ending the iteration when the difference meeting the control standard, i.e. convergence, is smaller than a specific threshold value, and finally obtaining +.>As a solution to the kepler equation, i.e. as a near point angle to the moment of transmission.
S120, determining an angle of the right ascent according to the transmission time, and determining a speed vector and a position vector of the satellite according to the angle of the right ascent and satellite orbit parameters of the transmission time.
Illustratively, satellite orbit parameters are referenced to a geocentric inertial (ECI) coordinate system, satellite velocity and position for determining time and frequency offsets for a satellite-to-earth link are referenced to a geocentric earth fixed (ECEF) coordinate system, both coordinate systems are referenced to a geocentric origin and to a north pole as the Z-axis, but the geocentric inertial coordinate system is referenced to a spring point (i.e., the intersection of the equatorial plane and the equator) as the X-axis, and the geocentric earth fixed coordinate system is referenced to a 0 longitude and equator intersection as the X-axis. Therefore, the deflection angle of the X axis of the geocentric inertial coordinate system and the X axis of the geocentric geodetic coordinate system is equal to the right-angle, and the satellite orbit parameters can be converted into the geodetic coordinate system through the right-angle, and then the satellite speed and the satellite position under the geodetic coordinate system are determined.
The right-hand angle is the angle from the spring festival along the equator to the intersection of the celestial body hour circle and the equator, and the right-hand angle corresponding to the transmission moment can be determined based on the time length from the transmission moment to the current 12 am in the spring festival. Fig. 3 is a flowchart for determining an angle of the right ascent provided in an embodiment of the present application. As shown in fig. 3, the step of determining the right angle specifically includes S1201-S1202:
s1201, determining the time interval between the noon of the spring festival and the transmission time of the year corresponding to the transmission time.
S1202, determining a time ratio of the time interval to the earth rotation period, and determining the product of the decimal part of the time ratio and the circumference radian as the right angle.
The midday spring festival is exemplified by 12 midday spring festival, the transmission time is subtracted by 12 midday spring festival in the same year, and the calculated difference is taken as the time interval. The time interval is divided by the earth rotation period to obtain a time ratio, and the time interval and the earth rotation period are divided by the same time unit, so the time ratio obtained by dividing the time interval and the earth rotation period is in days. And the rotation angle corresponding to one day isThe fractional part of the time ratio is a period of no more than one day, which is multiplied by the circumference arc, i.e. >And obtaining the right ascension angle corresponding to the transmission time.
It should be noted that the calculation process can infer that the calculation formula of the right angle is:
wherein,angle of right angle, ->For the period of earth rotation>For the time interval between the transmission time and the spring festival 12 am in the same year. Substituting the time interval and the earth rotation period into the calculation formula to calculate the right angle.
After determining the right ascent angle, determining a speed vector and a position vector of the low orbit satellite in a geocentric fixed coordinate system at the transmission time based on the right ascent angle and satellite orbit parameters at the transmission time. In this embodiment, fig. 4 is a flowchart for determining a velocity vector and a position vector of a satellite provided in an embodiment of the present application. As shown in fig. 4, the step of determining the velocity vector and the position vector of the satellite specifically includes S1203-S1204:
s1203, determining unit vectors of the near-center point and the semi-diameter direction under a geocentric fixed coordinate system according to the near-center point argument angle, the ascending intersection longitude, the orbit inclination angle and the right ascent angle at the transmission time.
For example, if the X-axis is directed in the direction of the near-center point in a rectangular coordinate system having the track plane as the XY plane, the initial unit vector of the near-center point And the unit vector of the near-heart point in the geocentric fixed coordinate system +.>Will be +.>The rotation matrix is multiplied by left to obtain. Unit vector of near-heart point in geocentric earth fixed coordinate system>Is +_associated with the initial unit vector>The expression between them is as follows:
wherein,for the near-centroid angle of the transmission moment, +.>For the track inclination at the moment of transmission +.>，/>Longitude of the intersection point of rise for the moment of transmission, +.>For the right angle of the transmission moment, +.>For the first rotation matrix +.>For the second rotation matrix +.>Is a third rotation matrix. The increasing direction of the right angle is from east to west, and the longitude of the rising intersection point of the geocentric inertial coordinate system is opposite to the longitude, so that the rising intersection point longitude of the geocentric fixed coordinate system can be obtained through correction of the right angle, and the accuracy of calculation is ensured.
If the X-axis is directed in the half-diameter direction in a rectangular coordinate system with the track plane as the XY plane, the initial unit vector in the half-diameter direction isThen the unit vector of the semi-diameter direction in the geocentric fixed coordinate system +.>Will be +.>The rotation matrix is multiplied by left to obtain. Unit vector of semi-diameter direction under geocentric ground fixed coordinate system>And start unit vector->The expression between them is as follows:
Wherein,is a third rotation matrix.
From the above expression, it can be seen that the first rotation matrix is determined according to the opposite number of the paraxial point amplitude angles, the second rotation matrix is determined according to the opposite number of the track inclination angles, the third rotation matrix is determined according to the opposite number of the differences between the longitude of the ascending intersection point and the right ascent angle, and the fourth rotation matrix is determined according to the differences between the opposite number of the paraxial point amplitude angles and the ninety degree angles; performing rotation transformation on the initial unit vector of the near-center point according to the first rotation matrix, the second rotation matrix and the third rotation matrix to obtain the unit vector of the near-center point under a geocentric fixed coordinate system; and carrying out rotation transformation on the initial unit vector in the semi-diameter direction according to the fourth rotation matrix, the second rotation matrix and the third rotation matrix to obtain the unit vector in the semi-diameter direction under a geocentric ground fixed coordinate system. The expressions of the first rotation matrix, the second rotation matrix, the third rotation matrix and the fourth rotation matrix are as follows:
the first rotation matrix can be obtained by substituting the opposite numbers of the amplitude angles of the near center points into a matrix calculation formula rotating around the Z axis, the second rotation matrix can be obtained by substituting the opposite numbers of the track inclination angles into a matrix calculation formula rotating around the X axis, the third rotation matrix can be obtained by substituting the opposite numbers of the differences of the longitude of the rising intersection points and the right angle into a matrix calculation formula rotating around the Z axis, and the fourth rotation matrix can be obtained by substituting the differences of the opposite numbers of the amplitude angles of the near center points and the ninety angle into a matrix calculation formula rotating around the Z axis. And multiplying the initial unit vector of the near-center point by the third rotation matrix, the second rotation matrix and the first rotation matrix in turn to obtain the unit vector of the near-center point under the geocentric fixed coordinate system. And multiplying the initial unit vector in the semi-diameter direction by a fourth rotation matrix, a second rotation matrix and the first rotation matrix in turn to obtain the unit vector in the semi-diameter direction under the geocentric ground fixed coordinate system.
It should be noted that the expressions of the initial unit vectors of the first rotation matrix, the second rotation matrix, the third rotation matrix, and the near-center point are substituted intoIt can be deduced that the unit vector of the near-heart point is +.>The calculation formula of (2) is as follows:
a first rotation matrix, a second rotation matrix, a fourth rotation matrix and a half-diameter directionExpression substitution of initial unit vectorIt is possible to derive the unit vector +.>The calculation formula of (2) is as follows:
therefore, the angle of the paraxial point of the transmission time, the orbit inclination, the longitude of the ascending intersection point and the right ascent angle can be substitutedIs calculated by the formula of>In the calculation formula of (2), calculate +.>And->。
And S1204, determining a speed vector and a position vector of the satellite under the geocentric fixed coordinate system according to the unit vectors of the near-center point and the semi-path direction under the geocentric fixed coordinate system and the semi-long axis, the eccentricity and the near-point angle of the transmission moment.
The position vector of the satellite in the geocentric fixed coordinate system is determined by a unit vector of the near-center point and the semi-path direction in the geocentric fixed coordinate system and a semi-long axis, an eccentricity and a near-center point angle of the transmission moment based on a preset satellite position calculation formula. The satellite position calculation formula is:
Wherein,is the position vector of the satellite. Semi-long axis of transmission time->Eccentricity->Near point angle->Unit vector of near-heart point under geocentric fixed coordinate system +.>And a unit vector of the semi-diameter direction in the geocentric fixed coordinate system +.>Substituting the position vector into a satellite position calculation formula to obtain the satellite position vector +.>。
Further, based on a preset satellite speed calculation formula, the speed vector of the satellite in the geocentric and geodetic coordinate system is determined through the unit vectors of the near-center point and the semi-path direction in the geodetic and geodetic coordinate system, the semi-long axis, the eccentricity and the near-center point angles of the transmission moment and the position vector of the satellite. The satellite speed calculation formula is:
wherein,is the velocity vector of the satellite, +.>Is the modulo length of the satellite's position vector. Semi-long axis of transmission time->CentrifugingRate->Near point angle->Unit vector of near-heart point under geocentric fixed coordinate system +.>Unit vector of semi-diameter direction under geocentric ground fixed coordinate system>Gravitational constant->And the module length of the satellite's position vector +.>Substituting the velocity vector into a satellite velocity calculation formula to obtain the velocity vector +.>。
S130, determining a speed vector and a position vector of the terminal according to the positioning information of the terminal, and determining the time offset and the frequency offset of the satellite-ground link according to the speed vector and the position vector of the terminal and the satellite.
Illustratively, the ground terminal obtains real-time positioning information from its own GNSS (global navigation satellite system). Because the movement condition of the ground terminal is not obvious compared with the flying speed of the low-orbit position, the real-time positioning information of the ground terminal can be acquired when the transmission time is short, and the real-time positioning information is used as the positioning information of the ground terminal at the transmission time.
The positioning information of the ground terminal includes longitude, latitude symbols, and even some positioning information includes altitude, and the position vector of the ground terminal in the geocentric geodetic fixed coordinate system can be determined based on the longitude, latitude symbols, and altitude in the positioning information. Fig. 5 is a flowchart for determining a location vector of a terminal according to an embodiment of the present application. As shown in fig. 5, the step of determining the location vector of the terminal specifically includes S1301-S1302:
s1301, determining the longitude as the azimuth angle, and determining the elevation angle according to the latitude and the latitude symbol.
Fig. 6 is a schematic diagram of a spherical coordinate system according to an embodiment of the present application. As shown in fig. 6, azimuth angleEqual to the longitude, elevation of the ground terminal>The relation with latitude is: when the latitude symbol is north, elevation angle +>Equal to the difference of ninety degrees minus the latitude value, elevation angle ++when the latitude symbol is south >Equal to the sum of the ninety degree angle plus the latitude value.
S1302, determining a position vector of the terminal under a geocentric and geodetic fixed coordinate system according to the sum value of the altitude and the earth radius, the azimuth angle and the elevation angle.
The calculation formula of the position vector of the terminal under the geocentric fixed coordinate system is as follows:
wherein,for the position vector of the terminal in the geocentric geodetic coordinate system,/for the terminal>For the X-axis coordinate of the terminal in the geocentric fixed coordinate system, < >>Y-axis coordinates of the terminal in the geocentric earth fixed coordinate system,>for the Z-axis coordinate of the terminal in the geocentric fixed coordinate system, +>For the earth radius>For locating the height in the information. Substituting the height, the earth radius, the azimuth angle and the elevation angle in the positioning information into a calculation formula of a position vector corresponding to the terminal, and obtaining the position vector of the terminal under a geocentric fixed coordinate system.
Further, the speed of the ground terminal can be divided into two components of the ground plane direction and the direction perpendicular to the ground plane, but the case that the terminal moves at a high speed in the direction perpendicular to the ground plane is rare, so that the speed component in the direction can be ignored when calculating the speed of the ground terminal, and the speed vector of the terminal in the ground-centered geodetic coordinate system is determined by the speed in the direction of the ground plane. The positioning information acquired by the GNSS comprises a horizontal angle and a horizontal speed value, wherein the horizontal angle is an angle for clockwise rotating the terminal in the north direction of the ground plane, and the horizontal speed value is a speed value of the terminal in the ground plane direction. The velocity vector of the terminal in the geocentric fixed coordinate system can be determined by the horizon and the horizon velocity values in the positioning information. Fig. 7 is a flowchart illustrating determining a velocity vector of a terminal according to an embodiment of the present application. As shown in fig. 7, the step of determining a velocity vector of the terminal specifically includes S1303-S1306:
S1303, determining a unit speed vector of the terminal under a first auxiliary coordinate system according to the horizon angle, wherein the first auxiliary coordinate system is a north-east coordinate system.
The first auxiliary coordinate system is exemplified by taking an origin as a terminal, taking an XY plane as a ground plane, namely a plane tangential to a spherical surface through the terminal, taking an X axis as a north-right direction, taking a positive rotation of the X axis by 90 degrees according to a horizontal angle as a Y axis direction, and taking a positive direction of a Z axis as a direction to point to the earth center according to a right-hand principle. That is, the first auxiliary coordinate system is the north-east coordinate with the terminal as the origin. In the first auxiliary coordinate system, the unit speed vector of the terminal is:
wherein,for the unit speed vector of the terminal in the first auxiliary coordinate system +.>Is the horizon angle. Substituting the horizon angle into the calculation formula to obtain the unit speed vector of the terminal under the first auxiliary coordinate system.
S1304, determining a Z-axis rotation matrix of the first auxiliary coordinate system and the second auxiliary coordinate system according to the opposite number of azimuth angles, and determining a Y-axis rotation matrix of the first auxiliary coordinate system and the second auxiliary coordinate system according to the difference between the one hundred eighty degrees angle and the elevation angle, wherein the origin of the second auxiliary coordinate system is a terminal, and the XYZ axis is parallel to the XYZ axis of the geocentric earth fixed coordinate system.
The second auxiliary coordinate system is rotatable about the Y-axis by the first auxiliary coordinate systemAnd rotation about the Z axis>The unit speed vector of the terminal under the second auxiliary coordinate system can be obtained by multiplying the unit speed vector of the terminal under the first auxiliary coordinate system by the corresponding Y-axis rotation matrix and Z-axis rotation matrix. The expression of the unit speed vector of the terminal in the second auxiliary coordinate system is as follows:
wherein,for unit velocity vectors of the terminal in a second auxiliary coordinate system，/>For the Z-axis rotation matrix,is a Y-axis rotation matrix. The expressions for the Z-axis rotation matrix and the Y-axis rotation matrix are as follows:
the expressions of the Z-axis rotation matrix and the Y-axis rotation matrix show that the Y-axis rotation matrix can be obtained by substituting the difference between the angle of one hundred and eighty degrees and the elevation angle into a matrix calculation formula rotating around the Y-axis, and the Z-axis rotation matrix can be obtained by substituting the opposite number of azimuth angles into a matrix calculation formula rotating around the Z-axis.
And S1305, determining the unit speed vector of the terminal under the second auxiliary coordinate system according to the unit speed vector, the Y-axis rotation matrix and the Z-axis rotation matrix of the terminal under the first auxiliary coordinate system.
Exemplary, the terminal is given a unit speed vector in the first auxiliary coordinate system Substituting the Y-axis rotation matrix and the Z-axis rotation matrix into the expression +.>Obtaining the unit speed vector of the terminal under the second auxiliary coordinate system>。
S1306, determining the speed vector of the terminal under the geocentric fixed coordinate system according to the unit speed vector of the terminal under the second auxiliary coordinate system and the horizontal speed value.
Illustratively, after the unit speed vector of the terminal under the second auxiliary coordinate system is obtained, the unit speed vector of the terminal under the second auxiliary coordinate system is multiplied by the horizontal speed value of the terminal to obtain the speed vector of the terminal under the second auxiliary coordinate system. Since the second auxiliary coordinate system and the geocentric fixed coordinate system are in translation relation with different origins and consistent axial directions, the velocity vector of the terminal under the second auxiliary coordinate system and the velocity vector under the geocentric fixed coordinate system are equivalent, i.e. the velocity vector of the terminal under the second auxiliary coordinate system can be determined as the velocity vector of the terminal under the geocentric fixed coordinate system.
It is noted that based onAnd->The calculation formula of the velocity vector of the terminal under the geocentric fixed coordinate system can be deduced as follows:
wherein,for the velocity vector of the terminal in the geocentric geodetic coordinate system,/for the velocity vector of the terminal in the geodetic coordinate system >Is the horizon speed value. The horizon speed value can be +.>Elevation angle->Azimuth angle->And horizon +.>Substituting terminal under earth center earth fixed coordinate systemThe calculation formula of the velocity vector of (2) can be obtained>。
In this embodiment, the time offset of the satellite-to-ground link is understood to be the time required for the communication signal to travel between the ground terminal and the low-orbit satellite, i.e., the transmission delay of the communication signal. After determining the position vectors of the terminal and the satellite in the geocentric fixed coordinate system, the distance between the terminal and the satellite can be determined by the two position vectors, and the time offset of the satellite-ground link can be determined according to the distance and the signal propagation speed. Fig. 8 is a flowchart illustrating determining a time offset of a satellite-to-ground link according to an embodiment of the present application. As shown in fig. 8, the step of determining the time offset of the satellite-to-ground link specifically includes S1307-S1308:
s1307, subtracting the position vector of the terminal from the position vector of the satellite to obtain the position vector of the satellite-ground link.
Illustratively, the position vector for the satellite-to-ground link is:
wherein,for the position vector of the satellite-ground link, +.>、/>And->Is the position coordinates of the terminal on the X axis, Y axis and Z axis under the geocentric fixed coordinate system.
S1308, the ratio of the module length of the position vector of the satellite-to-ground link to the light velocity is determined as the time offset of the satellite-to-ground link.
Exemplary, the modulo length of the position vector of the satellite-to-ground link is the distance between the terminal and the satellite, and the speed of light is the signalThe velocity of the number propagation is divided by the modulo length of the position vector of the satellite-to-ground link by the speed of light to obtain the time offset of the satellite-to-ground link. Wherein the modular length of the position vector of the satellite-ground linkThe method comprises the following steps:
time offset of satellite-ground linkThe method comprises the following steps:
wherein,is the speed of light.
In this embodiment, the frequency offset of the satellite-to-ground link may be understood as a doppler frequency offset caused by the relative movement between the terminal and the satellite. After determining velocity vectors of the terminal and the satellite in the geocentric, geodetic, fixed coordinate system, a relative velocity between the terminal and the satellite may be determined based on the velocity vectors to determine the satellite-to-earth link based on the relative velocity, carrier frequency of the communication signal, and propagation velocity. Fig. 9 is a flowchart illustrating determining a frequency offset of a satellite-to-ground link according to an embodiment of the present application. As shown in fig. 9, the step of determining the frequency offset of the satellite-to-ground link specifically includes S1309-S1311:
s1309, subtracting the velocity vector of the terminal from the velocity vector of the satellite to obtain the velocity vector of the satellite-ground link.
Illustratively, the velocity vector for the satellite-to-ground link is:
wherein,for the velocity vector of the satellite-ground link, +. >、/>And->The velocity components of the velocity vector of the satellite in the geocentric fixed coordinate system in the X-axis, Y-axis and Z-axis, respectively +.>、/>And->The velocity components of the velocity vector of the terminal in the geocentric fixed coordinate system in the X, Y and Z axes, respectively.
S1310, determining a cosine value of a vector included angle between a speed vector and a position vector of the satellite-ground link, and determining a product of the cosine value of the vector included angle and a modular length of the speed vector of the satellite-ground link as a relative speed between the satellite and the terminal.
Illustratively, the relative velocity between the satellite and the terminal is the difference between the velocity component of the velocity vector of the satellite on the signal propagation path and the velocity component of the velocity vector of the terminal on the signal propagation path, so that the cosine of the vector angle between the velocity vector and the position vector of the satellite-to-ground link, which characterizes the projected relationship of the velocity vector on the signal propagation path, can be determined before calculating the relative velocity between the satellite and the terminal. And multiplying the module length of the velocity vector of the satellite-ground link by the cosine value of the vector included angle to obtain the relative velocity between the satellite and the terminal. Relative velocityThe expression of (2) is:
wherein,is the modular length of the velocity vector of the satellite-ground link, < > >The cosine value of the vector included angle is expressed as follows:
from the expression of the relative velocity and the expression of the cosine value of the vector included angle, the expression of the relative velocity can be simplified as follows:
substituting the speed vector and the position vector of the satellite-ground link into the calculation formula to calculate the relative speed.
S1311, multiplying the ratio of the relative speed to the optical speed by the carrier frequency to obtain the frequency offset of the satellite-ground link.
Exemplary frequency offset for the satellite-to-ground linkThe method comprises the following steps:
wherein,is the carrier frequency of the communication signal. And substituting the carrier frequency, the light speed and the relative speed of the communication signal into the calculation formula to obtain the frequency offset of the satellite-ground link.
And S140, compensating the transmission parameters of the communication signals according to the time offset and the frequency offset of the satellite-ground link, and transmitting the communication signals based on the compensated transmission parameters.
The transmission time of the communication signal is adjusted according to the time offset of the satellite-ground link, so that the communication signal sent by the ground terminal can arrive at the satellite base station carried by the low-orbit satellite on time, the signal transmission efficiency is improved, and the influence of the time offset on the communication link between the satellite base station and the terminal is eliminated. The transmission frequency of the communication signal is adjusted according to the frequency offset of the satellite-ground link, so that the problems of signal distortion, error code and the like are avoided, the influence of the frequency offset on the communication link between the satellite base station and the terminal is eliminated, and the stability and reliability of the communication between the satellite base station and the terminal are improved.
In summary, in the satellite-to-ground link communication method provided by the embodiment of the application, satellite orbit parameters at a reference time are obtained, and the satellite orbit parameters at a transmission time are determined according to the satellite orbit parameters at the reference time; determining an angle of the right ascent according to the transmission time, and determining a speed vector and a position vector of the satellite according to the angle of the right ascent and satellite orbit parameters at the transmission time; determining a speed vector and a position vector of the terminal according to the positioning information of the terminal, and determining a time offset and a frequency offset of a satellite-ground link according to the speed vector and the position vector of the terminal and the satellite; and compensating the transmission parameters of the communication signals according to the time offset and the frequency offset of the satellite-ground link, and transmitting the communication signals based on the compensated transmission parameters. By the technical means, the satellite orbit parameters of the transmission time of the communication signal can be calculated based on the satellite orbit parameters of the reference time, the position and the speed of the transmission time are determined according to the satellite orbit parameters of the transmission time, the position and the speed of the terminal at the transmission time are calculated according to the positioning information of the terminal, the transmission time delay of the communication signal, namely the time offset of the satellite-to-ground link, is accurately estimated according to the position distance between the satellite and the terminal, the frequency offset of the satellite-to-ground link is accurately estimated according to the speed offset of the terminal of the satellite, and the transmission time and the transmission frequency of the communication signal are compensated according to the time offset and the frequency offset, so that the influence of the time offset and the frequency offset on the communication signal is reduced, the problem that the time offset and the frequency offset of the satellite-to-ground link influence the communication quality in the prior art is solved, and the communication quality between the satellite base station and the terminal is improved.
On the basis of the above embodiments, fig. 10 is a schematic structural diagram of a satellite-to-ground link communication device according to an embodiment of the present application. Referring to fig. 10, the satellite-to-ground link communication device provided in this embodiment specifically includes: an orbit parameter determination module 21, a satellite vector determination module 22, a time-frequency offset determination module 23 and a time-frequency offset determination module 24.
Wherein, the orbit parameter determining module 21 is configured to obtain the satellite orbit parameter at the reference time, and determine the satellite orbit parameter at the transmission time according to the satellite orbit parameter at the reference time;
a satellite vector determination module 22 configured to determine an angle of the right ascent from the transmission time, and to determine a velocity vector and a position vector of the satellite from the angle of the right ascent and a satellite orbit parameter at the transmission time;
a time-frequency offset determining module 23 configured to determine a velocity vector and a position vector of the terminal according to the positioning information of the terminal, and determine a time offset and a frequency offset of the satellite-to-ground link according to the velocity vector and the position vector of the terminal and the satellite;
the transmission parameter compensation module 24 is configured to compensate the transmission parameters of the communication signal according to the time offset and the frequency offset of the satellite-to-ground link, and transmit the communication signal based on the compensated transmission parameters.
On the basis of the above embodiment, the satellite orbit parameters include a semi-major axis, an eccentricity, an orbit inclination angle, a near-center point argument angle, a rising intersection point longitude, and a near-point angle, and the near-point angle includes a near-point angle and a flat near-point angle; accordingly, the track parameter determination module 21 includes: a first orbit parameter determination unit configured to determine a semimajor axis, an eccentricity, an orbit inclination angle, a near-center point argument and an ascending intersection longitude of a reference time as the semimajor axis, the eccentricity, the orbit inclination angle, the near-center point argument and the ascending intersection longitude of a transmission time; a second orbit parameter determining unit configured to determine a translational angular velocity according to the semi-major axis and the gravitational constant, and determine a translational angle of the transmission time according to the translational angular velocity, a difference between the reference time and the transmission time, and a translational angle of the reference time; and a third track parameter determination unit configured to determine a closest point angle at the transmission time based on the closest point angle and the eccentricity at the transmission time.
On the basis of the above embodiment, the satellite vector determination module 22 includes: a time interval determining unit configured to determine a time interval between a spring festival noon of a year corresponding to the transmission time and the transmission time; and the right angle determining unit is configured to determine the time ratio of the time interval to the earth rotation period and determine the ratio of the decimal part of the time ratio to the circumferential radian as the right angle.
On the basis of the above embodiment, the satellite vector determination module 22 includes: a unit vector determination unit configured to determine a unit vector of the near-center point and the semi-diameter direction in a geocentric fixed coordinate system according to the near-center point argument angle, the ascending intersection longitude, the orbit inclination angle, and the right ascent angle at the transmission time; and a satellite vector determining unit configured to determine a velocity vector and a position vector of the satellite in the geocentric fixed coordinate system based on the unit vectors in the geocentric and semi-diameter directions and the semi-long axis, the eccentricity, and the near point angle of the transmission time.
On the basis of the above-described embodiment, the unit vector determination unit includes: a first matrix determining subunit configured to determine a first rotation matrix according to an inverse number of the paraxial point argument, a second rotation matrix according to an inverse number of the track inclination angle, a third rotation matrix according to an inverse number of a difference value between the longitude of the ascending intersection point and the right ascent angle, and a fourth rotation matrix according to a difference value between the inverse number of the paraxial point argument and the ninety degree angle; the first unit vector determining subunit is configured to perform rotation transformation on the initial unit vector of the near-center point according to the first rotation matrix, the second rotation matrix and the third rotation matrix to obtain the unit vector of the near-center point under a geocentric fixed coordinate system; the second unit vector determining subunit is configured to perform rotation transformation on the initial unit vector in the half-path direction according to the fourth rotation matrix, the second rotation matrix and the third rotation matrix to obtain the unit vector in the half-path direction under the geocentric ground fixed coordinate system.
On the basis of the above-described embodiment, the satellite vector determination unit includes: the satellite position vector determining subunit is configured to determine a position vector of the satellite under the geocentric earth fixed coordinate system through a unit vector under the geocentric point and the semi-path direction and a semi-long axis, an eccentricity and a near point angle of transmission time based on a preset satellite position calculation formula; the satellite speed vector determining subunit is configured to determine a speed vector of the satellite in the geocentric and geodetic coordinate system by a unit vector of the near-center point and the semi-path direction in the geocentric and geodetic coordinate system, a semi-long axis, an eccentricity and a near-point angle of the transmission moment and a position vector of the satellite based on a preset satellite speed calculation formula;
the satellite position calculation formula is:
the satellite speed calculation formula is:
wherein,is the position vector of the satellite under the geocentric earth fixed coordinate system,/for the satellite>Is the velocity vector of the satellite in the geocentric geodetic coordinate system,/for the satellite>For the semi-long axis of the transmission time, +.>For the near point angle of the transmission instants +.>For the eccentricity of the transmission moment, +.>Is a unit vector of a near-heart point under a geocentric fixed coordinate system,/>is a unit vector of the semi-path direction under a geocentric fixed coordinate system, Is the gravitational constant->Is the modulo length of the satellite's position vector.
On the basis of the above embodiment, the positioning information includes longitude, latitude symbol and altitude; accordingly, the time-frequency offset determining module 23 includes: an angle determining unit configured to determine the longitude as an azimuth angle, and determine an elevation angle from the latitude and the latitude symbol; and the terminal position vector determining unit is configured to determine a position vector of the terminal under a geocentric fixed coordinate system according to the sum value of the altitude and the earth radius, the azimuth angle and the elevation angle.
On the basis of the embodiment, the positioning information further comprises a horizon angle and a horizon speed value; accordingly, the time-frequency offset determining module 23 includes: a third unit vector determining unit configured to determine a unit speed vector of the terminal in a first auxiliary coordinate system according to the azimuth angle, the first auxiliary coordinate system being a northeast coordinate system; a second matrix determining unit configured to determine a Z-axis rotation matrix of the first auxiliary coordinate system and the second auxiliary coordinate system according to the opposite number of azimuth angles, determine a Y-axis rotation matrix of the first auxiliary coordinate system and the second auxiliary coordinate system according to a difference between one hundred eighty degrees and elevation angles, an origin of the second auxiliary coordinate system being a terminal and XYZ axes being parallel to XYZ axes of the geocentric fixed coordinate system; a fourth unit vector determination unit configured to determine a unit velocity vector of the terminal in the second auxiliary coordinate system based on the unit velocity vector of the terminal in the first auxiliary coordinate system, the Y-axis rotation matrix, and the Z-axis rotation matrix; and the terminal speed vector determining unit is configured to determine the speed vector of the terminal under the geocentric and geodetic fixed coordinate system according to the unit speed vector of the terminal under the second auxiliary coordinate system and the horizon speed value.
On the basis of the above embodiment, the time-frequency offset determining module 23 includes: the link position vector determining unit is configured to subtract the position vector of the terminal from the position vector of the satellite to obtain the position vector of the satellite-ground link; and the time offset determining unit is configured to determine the ratio of the modular length of the position vector of the satellite-ground link to the light speed as the time offset of the satellite-ground link.
On the basis of the above embodiment, the time-frequency offset determining module 23 includes: the link speed vector determining unit is configured to subtract the speed vector of the terminal from the speed vector of the satellite to obtain the speed vector of the satellite-ground link; a relative speed determining unit configured to determine a cosine value of a vector angle between a speed vector and a position vector of the satellite-ground link, and determine a product of the cosine value of the vector angle and a modular length of the speed vector of the satellite-ground link as a relative speed between the satellite and the terminal; and the frequency offset determining unit is configured to multiply the ratio of the relative speed to the light speed by the carrier frequency to obtain the frequency offset of the satellite-ground link.
In the above, in the satellite-to-earth link communication device provided by the embodiment of the present application, the satellite orbit parameter at the transmission time is determined according to the satellite orbit parameter at the reference time by acquiring the satellite orbit parameter at the reference time; determining an angle of the right ascent according to the transmission time, and determining a speed vector and a position vector of the satellite according to the angle of the right ascent and satellite orbit parameters at the transmission time; determining a speed vector and a position vector of the terminal according to the positioning information of the terminal, and determining a time offset and a frequency offset of a satellite-ground link according to the speed vector and the position vector of the terminal and the satellite; and compensating the transmission parameters of the communication signals according to the time offset and the frequency offset of the satellite-ground link, and transmitting the communication signals based on the compensated transmission parameters. By the technical means, the satellite orbit parameters of the transmission time of the communication signal can be calculated based on the satellite orbit parameters of the reference time, the position and the speed of the transmission time are determined according to the satellite orbit parameters of the transmission time, the position and the speed of the terminal at the transmission time are calculated according to the positioning information of the terminal, the transmission time delay of the communication signal, namely the time offset of the satellite-to-ground link, is accurately estimated according to the position distance between the satellite and the terminal, the frequency offset of the satellite-to-ground link is accurately estimated according to the speed offset of the terminal of the satellite, and the transmission time and the transmission frequency of the communication signal are compensated according to the time offset and the frequency offset, so that the influence of the time offset and the frequency offset on the communication signal is reduced, the problem that the time offset and the frequency offset of the satellite-to-ground link influence the communication quality in the prior art is solved, and the communication quality between the satellite base station and the terminal is improved.
The satellite-to-ground link communication device provided by the embodiment of the application can be used for executing the satellite-to-ground link communication method provided by the embodiment, and has corresponding functions and beneficial effects.
Fig. 11 is a schematic structural diagram of a satellite-to-ground link communication device according to an embodiment of the present application, and referring to fig. 11, the satellite-to-ground link communication device includes: a processor 31, a memory 32, a communication device 33, an input device 34 and an output device 35. The number of processors 31 in the star link communication device may be one or more and the number of memories 32 in the star link communication device may be one or more. The processor 31, memory 32, communication means 33, input means 34 and output means 35 of the satellite to ground link communication device may be connected by a bus or other means.
The memory 32 is used as a computer readable storage medium for storing software programs, computer executable programs, and modules, such as program instructions/modules corresponding to the satellite-to-ground link communication method according to any embodiment of the present application (e.g., the orbit parameter determination module 21, the satellite vector determination module 22, the time-to-frequency offset determination module 23, and the time-to-frequency offset determination module 24 in the satellite-to-ground link communication apparatus). The memory 32 may mainly include a storage program area that may store an operating system, at least one application program required for functions, and a storage data area; the storage data area may store data created according to the use of the device, etc. In addition, memory 32 may include high-speed random access memory, and may also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other non-volatile solid-state storage device. In some examples, the memory may further include memory remotely located with respect to the processor, the remote memory being connectable to the device through a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
The communication means 33 are for data transmission.
The processor 31 executes various functional applications of the device and data processing, i.e., implements the above-described satellite-to-ground link communication method, by running software programs, instructions, and modules stored in the memory 32.
The input means 34 may be used to receive entered numeric or character information and to generate key signal inputs related to user settings and function control of the device. The output means 35 may comprise a display device such as a display screen.
The satellite-to-ground link communication device provided by the embodiment can be used for executing the satellite-to-ground link communication method provided by the embodiment, and has corresponding functions and beneficial effects.
The embodiments also provide a storage medium containing computer executable instructions, which when executed by a computer processor, are for performing a method of star-to-ground link communication, the method comprising: acquiring satellite orbit parameters at a reference moment, and determining satellite orbit parameters at a transmission moment according to the satellite orbit parameters at the reference moment; determining an angle of the right ascent according to the transmission time, and determining a speed vector and a position vector of the satellite according to the angle of the right ascent and satellite orbit parameters at the transmission time; determining a speed vector and a position vector of the terminal according to the positioning information of the terminal, and determining a time offset and a frequency offset of a satellite-ground link according to the speed vector and the position vector of the terminal and the satellite; and compensating the transmission parameters of the communication signals according to the time offset and the frequency offset of the satellite-ground link, and transmitting the communication signals based on the compensated transmission parameters.
Storage media-any of various types of memory devices or storage devices. The term "storage medium" is intended to include: mounting media such as CD-ROM, floppy disk or tape devices; computer system memory or random access memory such as DRAM, DDR RAM, SRAM, EDO RAM, lanbas (Rambus) RAM, etc.; nonvolatile memory such as flash memory, magnetic media (e.g., hard disk or optical storage); registers or other similar types of memory elements, etc. The storage medium may also include other types of memory or combinations thereof. In addition, the storage medium may be located in a first computer system in which the program is executed, or may be located in a second, different computer system connected to the first computer system through a network such as the internet. The second computer system may provide program instructions to the first computer for execution. The term "storage medium" may include two or more storage media residing in different locations (e.g., in different computer systems connected by a network). The storage medium may store program instructions (e.g., embodied as a computer program) executable by one or more processors.
Of course, the storage medium containing the computer executable instructions provided in the embodiments of the present application is not limited to the above-mentioned satellite-to-ground link communication method, and may also perform the related operations in the satellite-to-ground link communication method provided in any embodiment of the present application.
The satellite-to-ground link communication device, the storage medium and the satellite-to-ground link communication equipment provided in the foregoing embodiments may perform the satellite-to-ground link communication method provided in any embodiment of the present application, and technical details not described in detail in the foregoing embodiments may be referred to the satellite-to-ground link communication method provided in any embodiment of the present application.
The foregoing description is only of the preferred embodiments of the present application and the technical principles employed. The present application is not limited to the specific embodiments described herein, but is capable of numerous obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the present application. Therefore, while the present application has been described in connection with the above embodiments, the present application is not limited to the above embodiments, but may include many other equivalent embodiments without departing from the spirit of the present application, and the scope of the present application is determined by the scope of the claims.

Claims (13)

1. A satellite-to-ground link communication method, comprising:
acquiring satellite orbit parameters at a reference moment, and determining satellite orbit parameters at a transmission moment according to the satellite orbit parameters at the reference moment;
determining an angle of the right ascent according to the transmission time, and determining a speed vector and a position vector of a satellite according to the angle of the right ascent and satellite orbit parameters of the transmission time;
determining a speed vector and a position vector of a terminal according to positioning information of the terminal, and determining time offset and frequency offset of a satellite-ground link according to the speed vector and the position vector of the terminal and the satellite;
and compensating transmission parameters of the communication signals according to the time offset and the frequency offset of the satellite-ground link, and transmitting the communication signals based on the compensated transmission parameters.
2. The satellite-to-ground link communication method of claim 1, wherein the satellite orbit parameters include a semi-major axis, an eccentricity, an orbit inclination angle, a near-center point argument, a rising intersection longitude, and a near-point argument, the near-point argument including a near-point argument and a near-point argument;
correspondingly, the determining the satellite orbit parameter at the transmission time according to the satellite orbit parameter at the reference time includes:
Determining the semimajor axis, the eccentricity, the track inclination angle, the near-center point amplitude angle and the rising intersection point longitude of the reference moment as the semimajor axis, the eccentricity, the track inclination angle, the near-center point amplitude angle and the rising intersection point longitude of the transmission moment;
determining a horizontal movement angular velocity according to a semi-long axis and a gravitational constant, and determining a horizontal and proximal point angle of the transmission moment according to the horizontal movement angular velocity, a difference value between the reference moment and the transmission moment and the horizontal and proximal point angle of the reference moment;
and determining the close point angle of the transmission moment according to the close point angle and the eccentricity of the transmission moment.
3. The satellite-to-ground link communication method according to claim 1, wherein said determining an angle of an optical link from the transmission time comprises:
determining the time interval between the noon of the spring festival of the year corresponding to the transmission time and the transmission time;
and determining the time ratio of the time interval to the earth rotation period, and determining the ratio of the decimal part of the time ratio to the circumferential radian as an angle of the right ascension.
4. The satellite-to-ground link communication method according to claim 1, wherein the determining a velocity vector and a position vector of the satellite based on the right angle and the satellite orbit parameter at the transmission time comprises:
Determining unit vectors of the near-center point and the semi-diameter direction under a geocentric ground fixed coordinate system according to the near-center point amplitude angle, the ascending intersection point longitude, the orbit inclination angle and the right ascent angle at the transmission moment;
and determining a speed vector and a position vector of the satellite under the geocentric fixed coordinate system according to the unit vectors of the near-center point and the semi-path direction under the geocentric fixed coordinate system and the semi-long axis, the eccentricity and the near-point angle of the transmission moment.
5. The satellite-to-ground link communication method according to claim 4, wherein the determining unit vectors of the near-center point and the semi-path direction in a geocentric-to-earth fixed coordinate system based on the near-center point argument, the ascending intersection longitude, the orbit inclination angle, and the right ascent angle at the transmission time comprises:
determining a first rotation matrix according to the opposite number of the near-center point amplitude angles, determining a second rotation matrix according to the opposite number of the track dip angles, determining a third rotation matrix according to the opposite number of the differences between the longitude of the ascending intersection point and the right ascent angle, and determining a fourth rotation matrix according to the differences between the opposite number of the near-center point amplitude angles and the ninety degree angles;
performing rotation transformation on the initial unit vector of the near-center point according to the first rotation matrix, the second rotation matrix and the third rotation matrix to obtain the unit vector of the near-center point under a geocentric fixed coordinate system;
And carrying out rotation transformation on the initial unit vector in the half-diameter direction according to the fourth rotation matrix, the second rotation matrix and the third rotation matrix to obtain the unit vector in the half-diameter direction under a geocentric fixed coordinate system.
6. The satellite-to-ground link communication method according to claim 4, wherein the determining the velocity vector and the position vector of the satellite in the geocentric-to-ground-fixed coordinate system based on the unit vectors of the near-center point and the semi-path direction in the geocentric-to-ground-fixed coordinate system and the semi-long axis, the eccentricity, and the near-center point angle of the transmission time, comprises:
determining a position vector of the satellite under the geocentric ground fixed coordinate system through the unit vectors of the near-center point and the semi-diameter direction under the geocentric ground fixed coordinate system and the semi-long axis, the eccentricity and the near-center point angle of the transmission moment based on a preset satellite position calculation formula;
determining a speed vector of the satellite under a geocentric and geodetic coordinate system by using the unit vectors of the near-center point and the semi-path direction under the geocentric and geodetic coordinate system based on a preset satellite speed calculation formula, and the semi-long axis, the eccentricity and the near-center point angle of the transmission moment and the position vector of the satellite;
The satellite position calculation formula is as follows:
the satellite speed calculation formula is as follows:
wherein,for the position vector of the satellite under the geocentric fixed coordinate system,/for the satellite>Is on the ground for the satelliteVelocity vector in the geocentric fixed coordinate system, < >>For the semi-long axis of the transmission moment, +.>For the angle of the closest point of the transmission moment, < >>For the eccentricity of the transmission moment, +.>For the unit vector of the near-heart point under the geocentric fixed coordinate system, +.>For the unit vector of the semi-diameter direction under the geocentric ground fixed coordinate system, +.>Is the gravitational constant->Is the modulo length of the position vector of the satellite.
7. The satellite-to-ground link communication method of claim 1, wherein the positioning information comprises longitude, latitude symbols, and altitude;
correspondingly, the determining the speed vector and the position vector of the terminal according to the positioning information of the terminal comprises the following steps:
determining the longitude as an azimuth angle, and determining an elevation angle according to the latitude and the latitude symbol;
and determining a position vector of the terminal under a geocentric fixed coordinate system according to the sum of the altitude and the earth radius, the azimuth angle and the elevation angle.
8. The satellite-to-ground link communication method of claim 7, wherein the positioning information further comprises a horizon angle and a horizon speed value;
Correspondingly, the determining the speed vector and the position vector of the terminal according to the positioning information of the terminal comprises the following steps:
determining a unit speed vector of the terminal under a first auxiliary coordinate system according to the horizon angle, wherein the first auxiliary coordinate system is a north-east coordinate system;
determining a Z-axis rotation matrix of the first auxiliary coordinate system and the second auxiliary coordinate system according to the opposite number of the azimuth angles, and determining a Y-axis rotation matrix of the first auxiliary coordinate system and the second auxiliary coordinate system according to a difference value between a hundred-eighty degree angle and the elevation angle, wherein an origin of the second auxiliary coordinate system is a terminal, and an XYZ axis is parallel to an XYZ axis of a geocentric earth fixed coordinate system;
determining a unit speed vector of the terminal under the second auxiliary coordinate system according to the unit speed vector of the terminal under the first auxiliary coordinate system, the Y-axis rotation matrix and the Z-axis rotation matrix;
and determining the speed vector of the terminal under the geocentric fixed coordinate system according to the unit speed vector of the terminal under the second auxiliary coordinate system and the horizontal speed value.
9. The method of satellite-to-ground link communication according to claim 1, wherein said determining the time and frequency offsets of the satellite-to-ground links based on the velocity vectors and the position vectors of the terminal and the satellites comprises:
Subtracting the position vector of the terminal from the position vector of the satellite to obtain the position vector of the satellite-ground link;
and determining the ratio of the modular length of the position vector of the satellite-ground link to the light speed as the time offset of the satellite-ground link.
10. The method of satellite-to-ground link communication according to claim 9, wherein said determining the time and frequency offsets of the satellite-to-ground links based on the velocity vectors and the position vectors of the terminal and the satellites comprises:
subtracting the speed vector of the terminal from the speed vector of the satellite to obtain the speed vector of the satellite-ground link;
determining a cosine value of a vector included angle between a speed vector and a position vector of the satellite-ground link, and determining a product of the cosine value of the vector included angle and a modular length of the speed vector of the satellite-ground link as a relative speed between the satellite and the terminal;
and multiplying the ratio of the relative speed to the light speed by a carrier frequency to obtain the frequency offset of the satellite-ground link.
11. A satellite-to-ground link communication device, comprising:
the orbit parameter determining module is configured to acquire satellite orbit parameters at a reference moment and determine satellite orbit parameters at a transmission moment according to the satellite orbit parameters at the reference moment;
The satellite vector determining module is configured to determine an angle of the right ascent according to the transmission time and determine a speed vector and a position vector of the satellite according to the angle of the right ascent and satellite orbit parameters of the transmission time;
the time frequency offset determining module is configured to determine a speed vector and a position vector of the terminal according to the positioning information of the terminal, and determine the time offset and the frequency offset of a satellite-ground link according to the speed vector and the position vector of the terminal and the satellite;
and the transmission parameter compensation module is configured to compensate the transmission parameters of the communication signals according to the time offset and the frequency offset of the satellite-ground link, and transmit the communication signals based on the compensated transmission parameters.
12. A satellite-to-ground link communication device, comprising:
one or more processors;
memory storing one or more programs that, when executed by the one or more processors, cause the one or more processors to implement the star link communication method of any of claims 1-10.
13. A storage medium containing computer executable instructions which, when executed by a computer processor, are for performing the satellite-to-ground link communication method of any one of claims 1-10.
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