A method for evaluating the impact of antenna pointing errors on high-throughput satellite communication systems

Abstract

The present invention discloses a method for evaluating the influence of antenna pointing error on high-throughput satellite communication system, and relates to the technical field of high-throughput satellite communication. In the present invention, by reasonably modeling the high-throughput satellite communication system and antenna pointing error, the influence of antenna pointing error on important performance indicators such as system capacity, carrier-to-interference ratio, and capacity matching rate is effectively evaluated, thereby guiding the reasonable selection and optimization determination of antenna pointing accuracy, so as to provide support for the construction of the next generation of very high throughput satellite communication system; the problem of evaluating the influence of antenna pointing error on the performance of the next generation of very high throughput satellite communication system is solved, and by system-level modeling and evaluation of indicators such as system capacity and capacity matching rate, it is helpful to reasonably select and optimize the pointing accuracy of satellite antennas.

Description

Technical Field

[0001] The present invention relates to the technical field of high-throughput satellite communication, and in particular to a method for evaluating the influence of antenna pointing error on a high-throughput satellite communication system. Background Art

[0002] With the continuous development of high-speed Internet services, the geosynchronous orbit (GEO) broadband satellite communication system has developed from C- and Ku-band wide beams to high-throughput satellites based on Ku- and Ka-band spot beams. The system capacity has been greatly improved, and high-speed Internet access has been truly realized. At present, high-throughput satellites have become one of the hot spots in the field of satellite communications. Many countries and regions, including China, have successfully launched multiple high-throughput satellites. During the operation of GEO satellites in orbit, they are affected by factors such as the unevenness of the earth's gravitational field and changes in solar radiation pressure, which will cause deviations in roll attitude, pitch attitude, and yaw attitude, and then cause the drift of the satellite antenna pointing. For high-throughput satellites, the spot beams formed by multi-beam antennas are usually narrow beams and high gain. If there is a large deviation in the pointing of the on-orbit antenna, the actual beam gain of the antenna will decrease, which will eventually lead to problems such as poor communication quality and reduced system capacity.

[0003] Compared with previous high-throughput satellites, the next generation of very high-throughput (VHTS) communication satellites have extremely narrow beam widths, and narrower beams will make the system more sensitive to antenna pointing errors. In order to meet system performance, antenna pointing accuracy needs to be further improved. From the perspective of system design, antenna pointing accuracy, as a key system indicator, is closely related to other system indicators such as coverage area, pattern design, and system capacity. Therefore, it is necessary to study the impact of antenna pointing errors on system performance, and guide the reasonable selection and optimization of satellite antenna pointing accuracy through system-level modeling and evaluation. Summary of the invention

[0004] The purpose of the present invention is to solve the above problem and to propose a method for evaluating the impact of antenna pointing error on a high-throughput satellite communication system.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for evaluating the impact of antenna pointing errors on a high-throughput satellite communication system comprises the following steps:

[0007] S1: Initialize the satellite coverage area, operating frequency band and bandwidth, frequency reuse factor, terminal location, satellite antenna gain and other parameter configurations;

[0008] S2: Establish the relationship model between antenna pointing error and antenna gain;

[0009] S3: Calculate the satellite equivalent isotropic radiated power and downlink carrier-to-noise ratio;

[0010] S4: Calculate system capacity and capacity matching rate;

[0011] S5: Based on the above parameters and models, compare the impact of antenna pointing error on system capacity and capacity matching rate in different scenarios.

[0012] Preferably, the specific method for parameter configuration in step S1 is:

[0013] The satellite coverage height is H sat , consider that there are N beams in the entire coverage area, each beam corresponds to a regular hexagonal coverage area, and the beam width is θ 3dB , then the coverage radius of each beam is:

[0014] r=H sat *tan(θ 3dB )

[0015] Let B tot represents the system operating bandwidth. Without considering dual polarization and frequency guard interval, assuming that the frequency reuse factor of the system is M, the bandwidth used by each beam is:

[0016]

[0017] In addition, there are K geographically evenly distributed terminals within the coverage area of ​​each satellite beam.

[0018] Preferably, the method for establishing the relationship model between the antenna pointing error and the antenna gain in step S2 is:

[0019] Let (x s ,y s ,H sat ) represents the satellite coordinates, Represents the original coordinates of the center of beam n. When there is a pointing error in the satellite's transmitting antenna, the center of beam n will be offset. Taking the offset in the y-axis direction as an example, the offset in the y-axis direction of the center of beam n can be expressed as:

[0020]

[0021] where α n is the angle between the line connecting the original position of the center of beam n and the satellite and the line connecting the satellite and the sub-satellite point. When a pointing error occurs in the y-axis direction, the coordinates of the center of beam n become At this time, the distance between it and the satellite can be expressed as:

[0022]

[0023] Let the coordinates of terminal k be (xnk ,y nk ,0), the straight-line distance between the satellite and terminal k can be expressed as:

[0024]

[0025] The straight-line distance between terminal k and the center of beam n can be expressed as:

[0026]

[0027] Therefore, when there is a pointing error in the satellite, the angle between the line connecting the terminal and the satellite and the line connecting the beam center and the satellite can be calculated as:

[0028]

[0029] Assume that the satellite antenna transmission gain corresponding to the terminal located at the center of the beam is G peak , then the satellite antenna transmission gain corresponding to the terminal k distance is:

[0030]

[0031] Preferably, the calculation method of the satellite equivalent isotropic radiated power and the downlink carrier-to-noise ratio in step S3 is:

[0032] The satellite equivalent isotropic radiated power can be expressed as:

[0033] EIRP nk (dBW) = PL t +G nk

[0034] Where P is the rated output power of the satellite transmitter; L t is the feeder loss of the satellite transmission system; let the receiving quality factor (G / T) of terminal k be GT nk (dB / K), the carrier-to-noise ratio of the downlink can be calculated as:

[0035] [C / N] nk (dB) = EIRP nk -PL nk -ΔPL nk +GT nk -10lg(κB beam )

[0036] Among them, PL nk is the free space propagation loss, ΔPL nk is the additional downlink loss, and κ is the Boltzmann constant.

[0037] Preferably, the calculation method of the system capacity and the capacity matching ratio in step S4 is:

[0038] Since each user is located at a different location, link budget is performed for each user. If the system supports adaptive coding and modulation, the highest spectrum efficiency of the terminal can be obtained according to the satellite-to-ground communication link budget and DVB-S2 adaptive coding and modulation mode. nk represents the spectral efficiency of terminal k, then the capacity of beam n can be expressed as the average spectral efficiency of all users in the beam multiplied by the beam bandwidth:

[0039]

[0040] The total system capacity is the sum of the capacities of all beams and can be expressed as:

[0041]

[0042] The default data traffic demand for beam n is α times its total beam capacity n times, the capacity requirement of beam n can be expressed as R n =α n C n , the capacity matching ratio can be defined as the total service data rate that is satisfied divided by the total service demand rate, that is:

[0043]

[0044] Preferably, the method for comparing the impact of antenna pointing error on system capacity and capacity matching rate in different scenarios in step S5 is:

[0045] First, set the ratio of the antenna pointing error to the beam width; then, set the number of frequency reuse colors; in addition, set the ratio of the data service demand of the beam to its total beam capacity; finally, set the distribution range of the random change of user demand. Then, by adjusting the above settings, the impact of antenna pointing error on system capacity and capacity matching rate under different frequency reuse conditions, different service demand amounts and different user demand distributions can be analyzed.

[0046] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0047] 1. This application solves the problem of evaluating the impact of antenna pointing errors on the performance of the next generation very high throughput satellite communication system. Through system-level modeling and evaluation of indicators such as system capacity and capacity matching rate, it helps to reasonably select and optimize the pointing accuracy of satellite antennas. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A schematic diagram of the execution process flow of a method for evaluating the impact of antenna pointing errors on a high-throughput satellite communication system provided in accordance with an embodiment of the present invention is shown;

[0049] Figure 2 A schematic diagram of a system model provided according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0050] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] See also Figure 1-2 , the present invention provides a technical solution:

[0052] A method for evaluating the impact of antenna pointing errors on a high-throughput satellite communication system comprises the following steps:

[0053] S1: Initialize the satellite coverage area, operating frequency band and bandwidth, frequency reuse factor, terminal location, satellite antenna gain and other parameter configurations;

[0054] S2: Establish the relationship model between antenna pointing error and antenna gain;

[0055] S3: Calculate the satellite equivalent isotropic radiated power and downlink carrier-to-noise ratio;

[0056] S4: Calculate system capacity and capacity matching rate;

[0057] S5: Based on the above parameters and models, compare the impact of antenna pointing error on system capacity and capacity matching rate in different scenarios.

[0058] Specifically, Figure 1 and Figure 2 As shown, the specific method of parameter configuration in step S1 is:

[0059] Assume that the satellite coverage height is H sat , consider that there are N beams in the entire coverage area, each beam corresponds to a regular hexagonal coverage area, and the beam width is θ 3dB , then the coverage radius of each beam is:

[0060] r=H sat *tan(θ 3dB )

[0061] Let B tot represents the system operating bandwidth. Assuming that dual polarization and frequency guard interval are not considered and the frequency reuse factor of the system is M, the bandwidth used for each beam is:

[0062]

[0063] In addition, it is assumed that there are K geographically evenly distributed terminals within the coverage area of ​​each satellite beam;

[0064] The method for establishing the relationship model between the antenna pointing error and the antenna gain in step S2 is:

[0065] Let (x s ,y s ,H sat ) represents the satellite coordinates, Represents the original coordinates of the center of beam n. When there is a pointing error in the satellite's transmitting antenna, the center of beam n will be offset. Taking the offset in the y-axis direction as an example, the offset in the y-axis direction of the center of beam n can be expressed as:

[0066]

[0067] where α n is the angle between the line connecting the original position of the center of beam n and the satellite and the line connecting the satellite and the sub-satellite point. When a pointing error occurs in the y-axis direction, the coordinates of the center of beam n become At this time, the distance between it and the satellite can be expressed as:

[0068]

[0069] Let the coordinates of terminal k be (x nk ,y nk ,0), the straight-line distance between the satellite and terminal k can be expressed as:

[0070]

[0071] The straight-line distance between terminal k and the center of beam n can be expressed as:

[0072]

[0073] Therefore, when there is a pointing error in the satellite, the angle between the line connecting the terminal and the satellite and the line connecting the beam center and the satellite can be calculated as:

[0074]

[0075] Assume that the satellite antenna transmission gain corresponding to the terminal located at the center of the beam is G peak , then the satellite antenna transmission gain corresponding to the terminal k distance is:

[0076]

[0077] The calculation method of satellite equivalent isotropic radiated power and downlink carrier-to-noise ratio in step S3 is:

[0078] The satellite equivalent isotropic radiated power can be expressed as:

[0079] EIRP nk (dBW) = PL t +G nk

[0080] Where P is the rated output power of the satellite transmitter; L t is the feeder loss of the satellite transmission system; let the receiving quality factor (G / T) of terminal k be GT nk (dB / K), the carrier-to-noise ratio of the downlink can be calculated as:

[0081] [C / N] nk (dB) = EIRP nk -PL nk -ΔPL nk +GT nk -10lg(κB beam )

[0082] Among them, PL nk is the free space propagation loss, ΔPL nk is the additional loss of the downlink, including atmospheric absorption, pointing error and polarization loss, etc., κ is the Boltzmann constant;

[0083] The calculation method of the system capacity and capacity matching ratio in step S4 is:

[0084] Since each user is located at a different location, link budget is performed for each user. If the system supports adaptive coding and modulation, the highest spectrum efficiency of the terminal can be obtained according to the satellite-to-ground communication link budget and DVB-S2 adaptive coding and modulation mode. nk represents the spectral efficiency of terminal k, then the capacity of beam n can be expressed as the average spectral efficiency of all users in the beam multiplied by the beam bandwidth:

[0085]

[0086] The total system capacity is the sum of the capacities of all beams and can be expressed as:

[0087]

[0088] Assume that the default data traffic demand of beam n is α of its total beam capacity n times, the capacity requirement of beam n can be expressed as R n =α n C n , the capacity matching ratio can be defined as the total service data rate that is satisfied divided by the total service demand rate, that is:

[0089]

[0090] The comparison method of the impact of antenna pointing error on system capacity and capacity matching rate in different scenarios in step S5 is as follows:

[0091] First, set the ratio of the antenna pointing error to the beam width, which is generally not more than 50%; then, set the number of frequency multiplexing colors, which is generally seven-color multiplexing, four-color multiplexing, etc.; in addition, set the ratio of the data service demand of the beam to its total beam capacity; finally, set the distribution range of the random changes in user demand. Then, by adjusting the above settings, the impact of antenna pointing error on system capacity and capacity matching rate under different frequency multiplexing conditions, different service demands and different user demand distributions can be analyzed.

[0092] This application solves the problem of evaluating the impact of antenna pointing errors on the performance of the next generation very high throughput satellite communication system. Through system-level modeling and evaluation of indicators such as system capacity and capacity matching rate, it helps to reasonably select and optimize the pointing accuracy of satellite antennas.

[0093] The above description of the embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for evaluating the impact of antenna pointing errors on a high-throughput satellite communication system, characterized in that: The following steps are involved: S1: Initialize the satellite coverage area, operating frequency band and bandwidth, frequency reuse factor, terminal location, and satellite antenna gain parameter configuration; S2: Establish the relationship model between antenna pointing error and antenna gain; The method for establishing the relationship model between the antenna pointing error and the antenna gain in step S2 is: Let (x s ,y s ,H sat ) represents the satellite coordinates, Represents the original coordinates of the center of beam n. When there is a pointing error in the satellite's transmitting antenna, the center of beam n will be offset. Taking the offset in the y-axis direction as an example, the offset in the y-axis direction of the center of beam n can be expressed as: where α n is the angle between the line connecting the original position of the center of beam n and the satellite and the line connecting the satellite and the sub-satellite point. When a pointing error occurs in the y-axis direction, the coordinates of the center of beam n become At this time, the distance between it and the satellite can be expressed as: Let the coordinates of terminal k be (x nk ,y nk ,0), the straight-line distance between the satellite and terminal k can be expressed as: The straight-line distance between terminal k and the center of beam n can be expressed as: Therefore, when there is a pointing error in the satellite, the angle between the line connecting the terminal and the satellite and the line connecting the beam center and the satellite can be calculated as: Assume that the satellite antenna transmission gain corresponding to the terminal located at the center of the beam is G peak , then the satellite antenna transmission gain corresponding to the terminal k distance is: S3: Calculate the satellite equivalent isotropic radiated power and downlink carrier-to-noise ratio; S4: Calculate system capacity and capacity matching rate; S5: Based on the above parameters and models, compare the impact of antenna pointing error on system capacity and capacity matching ratio in different scenarios; The comparison method of the influence of antenna pointing error on system capacity and capacity matching rate in different scenarios in step S5 is as follows: First, set the ratio of the antenna pointing error to the beam width; then, set the number of frequency reuse colors; in addition, set the ratio of the data service demand of the beam to its total beam capacity; finally, set the distribution range of the random change of user demand. Then, by adjusting the above settings, the impact of antenna pointing error on system capacity and capacity matching rate under different frequency reuse conditions, different service demand amounts and different user demand distributions can be analyzed.

2. The method for evaluating the impact of antenna pointing error on a high-throughput satellite communication system according to claim 1, characterized in that: The specific method of parameter configuration in step S1 is: The satellite coverage height is H sat , consider that there are N beams in the entire coverage area, each beam corresponds to a regular hexagonal coverage area, and the beam width is θ 3dB , then the coverage radius of each beam is: r=H sat *time(θ 3dB ) Let B tot represents the system operating bandwidth. Without considering dual polarization and frequency guard interval, assuming that the frequency reuse factor of the system is M, the bandwidth used by each beam is: In addition, there are K geographically evenly distributed terminals within the coverage area of ​​each satellite beam.

3. The method for evaluating the impact of antenna pointing error on a high-throughput satellite communication system according to claim 1, characterized in that: The calculation method of the satellite equivalent isotropic radiated power and the downlink carrier-to-noise ratio in step S3 is: The satellite equivalent isotropic radiated power can be expressed as: EIRP nk (dBW)=PL t +G nk Where P is the rated output power of the satellite transmitter; L t is the feeder loss of the satellite transmission system; let the receiving quality factor (G / T) of terminal k be GT nk (dB / K), the carrier-to-noise ratio of the downlink can be calculated as: [C / N] nk (dB)=EIRP nk -PL nk -ΔPL nk +GT nk -10lg(κB beam ) Among them, PL nk is the free space propagation loss, ΔPL nk is the additional downlink loss, and κ is the Boltzmann constant.

4. The method for evaluating the impact of antenna pointing error on a high-throughput satellite communication system according to claim 1, characterized in that: The calculation method of the system capacity and the capacity matching rate in step S4 is: Since each user is located at a different location, link budget is performed for each user. If the system supports adaptive coding and modulation, the highest spectrum efficiency of the terminal can be obtained according to the satellite-to-ground communication link budget and DVB-S2 adaptive coding and modulation mode. nk represents the spectral efficiency of terminal k, then the capacity of beam n can be expressed as the average spectral efficiency of all users in the beam multiplied by the beam bandwidth: The total system capacity is the sum of the capacities of all beams and can be expressed as: The default data traffic demand for beam n is α times its total beam capacity n times, the capacity requirement of beam n can be expressed as R n =α n C n , the capacity matching ratio can be defined as the total service data rate that is satisfied divided by the total service demand rate, that is:

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