Decision method for co-frequency isolation zone between satellite mobile communication and terrestrial mobile communication system

Abstract

The present invention provides a method for deciding the co-frequency isolation zone between satellite mobile communication and ground mobile communication systems. The method determines the deployment information of the ground mobile communication system with the same frequency as the satellite mobile communication system according to the regional elements in the satellite visible area; obtains the radio frequency link parameters of the ground mobile communication system; points the satellite beam center to the regional center of the ground mobile communication system; statistically calculates the base station set interference of the ground mobile communication system; determines whether the interference exceeding limit time percentage of the base station set interference is less than the time percentage limit; if it is not less than the time percentage limit, six co-frequency beams with the regional center as the starting point and N times the preset distance are obtained by performing hexagonal symmetric simulation on the satellite beam; and returns to re-count the base station set interference. In this way, the present invention can effectively reduce the interference-to-noise ratio of the ground mobile communication system base station to the satellite mobile communication system terminal.

Description

Technical Field

[0001] The present invention relates to the technical field of satellite mobile communication, and in particular to a method for deciding a co-frequency isolation zone between a satellite mobile communication and a ground mobile communication system. Background Art

[0002] Space radio frequency orbital resources are the basis for the construction and operation of communication satellite systems, and have become an important strategic resource that affects the national economy and even national security. In recent years, large-scale low-orbit constellations have set off a wave of rapid construction and deployment around the world, especially with the development and deployment of 5G / 6G. In non-terrestrial networks (NTN, Non-Terrestrial Network), communication satellites have become an important part of realizing the interconnection between the earth and the sky.

[0003] Among them, the technology of direct mobile phone connection to satellite communication is a field that has gradually emerged in recent years. It is mainly to provide communication services in areas that are not covered by traditional cellular networks (such as remote areas, oceans or disaster sites). How to achieve the co-existence of satellite mobile communications and existing terrestrial IMT (International Mobile Telecommunications) involves multiple technical difficulties, including the management of co-frequency signal interference, which is a key issue affecting satellite-ground coexistence, that is, when satellite signals and terrestrial IMT systems work in the same frequency band, how to avoid mutual interference. First, the IMT system needs to be accurately modeled, and the number and spacing of base stations required are calculated from the area and population density of urban areas according to the deployment of terrestrial mobile communication systems; then the aggregate interference between systems needs to be statistically distributed, and effective interference avoidance and mitigation technologies, such as spatial isolation technology, need to be studied.

[0004] Current spatial isolation technologies mainly include the tunneling method and the telemetry method. However, both tunneling and telemetry are only targeted at specific areas. There is no perfect method for isolating the same-frequency area when implemented in the entire satellite coverage area.

[0005] Therefore, there is an urgent need for a method that can effectively reduce the interference-to-noise ratio of a ground mobile communication system base station to a satellite mobile communication system terminal. Summary of the invention

[0006] The object of the present invention is to provide a method for determining the co-frequency isolation zone between satellite mobile communication and terrestrial mobile communication systems, so as to effectively reduce the interference-to-noise ratio of a terrestrial mobile communication system base station to a satellite mobile communication system terminal.

[0007] In order to achieve the above object, the present invention provides a method for determining the co-frequency isolation zone of a satellite mobile communication system and a terrestrial mobile communication system, comprising:

[0008] Step S1, determining the deployment information of a ground mobile communication system with the same frequency as the satellite mobile communication system according to the regional elements in the satellite visible area; wherein the ground mobile communication system includes a plurality of ground mobile communication base stations, each of which evenly serves and covers three cellular areas, and the cellular areas are connected and extended outward in a hexagonal shape; the deployment information includes the number of cells, the cell radius, the base station spacing, and the number of base stations;

[0009] Step S2, obtaining radio frequency link parameters of the ground mobile communication system;

[0010] Step S3, directing the satellite beam center to the regional center of the ground mobile communication system;

[0011] Step S4, calculating the base station set interference of the ground mobile communication system according to the radio frequency link parameter statistics;

[0012] Step S5, determining whether the interference exceeding limit time percentage of the base station set interference is less than the time percentage limit;

[0013] Step S6, if the interference exceeding limit time percentage is not less than the time percentage limit, six same-frequency beams with N times the preset distance moving outward from the center of the area at equal distances are obtained by performing hexagonal symmetry simulation on the satellite beam; and returning to step S4; wherein N is a positive integer;

[0014] Whenever the loop enters step S6, the value of parameter N is adjusted and the process returns to step S4 until the interference exceeding limit time percentage is less than the time percentage limit.

[0015] Furthermore, after step S5, the method further includes:

[0016] Step S7: If the interference exceeding limit time percentage is less than the time percentage limit, the current shifting distance is obtained as the same-frequency isolation distance between the satellite mobile communication and the terrestrial mobile communication at the current longitude and latitude.

[0017] Further, the base station set interference in step S4 is calculated based on the following formula:

[0018]

[0019] Where I is the base station set interference, P k is the transmission power of the kth ground mobile communication base station, G t (θ k ) is the transmitting antenna gain of the kth ground mobile communication base station pointing to the satellite terminal, θ k is the link relative to the main lobe angle of the transmitting antenna, Loss kis the path loss from the kth ground mobile communication base station to the satellite terminal, G r (a k ) is the receiving antenna gain of the satellite terminal, a k is the main lobe angle of the link relative to the receiving antenna.

[0020] Furthermore, the radio frequency link parameters include a base station antenna model, a base station antenna downtilt angle, and a base station transmit power.

[0021] Further, the regional elements include urban area and population density; the urban area is the sum of the areas of all the cellular areas, and the base station spacing in the deployment information is calculated based on the following formula:

[0022]

[0023] Wherein, D is the base station spacing, β is the coefficient, and ρ is the population density.

[0024] Furthermore, the regional center of the ground mobile communication system is the cellular cluster center of the ground same-frequency mobile communication system.

[0025] The method for deciding the same-frequency isolation zone between satellite mobile communication and ground mobile communication system of the present invention determines the deployment information of the ground mobile communication system with the same frequency as the satellite mobile communication system according to the regional elements in the satellite visible area; obtains the radio frequency link parameters of the ground mobile communication system; points the satellite beam center to the regional center of the ground mobile communication system; statistically calculates the interference of the base station set of the ground mobile communication system; determines whether the interference exceeding limit time percentage of the base station set interference is less than the time percentage limit; if it is not less than the time percentage limit, then the satellite beam is subjected to hexagonal symmetric simulation, and the six same-frequency beams are obtained to leave the coverage area of ​​the mobile communication system at equal distances through the hexagonal symmetric simulation. After reaching the interference protection limit, a link can be established with the satellite mobile communication satellite. In this way, the present invention realizes the decision of the same-frequency isolation zone between satellite mobile communication and ground mobile communication system, and reduces the interference-to-noise ratio of the ground mobile communication system base station to the satellite mobile communication system terminal; through the hexagonal symmetric simulation, the interference of the ground mobile communication system terminal to the satellite mobile communication system meets the interference protection limit, and realizes the same-frequency sharing of the satellite mobile communication system and the ground mobile communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A flowchart of the steps of the co-frequency isolation zone decision method for the satellite mobile communication and terrestrial mobile communication system provided in one embodiment of the present invention;

[0027] Figure 2 A schematic diagram of a satellite mobile communication system and a ground mobile communication system of the present invention;

[0028] Figure 3 A terrestrial mobile communication system deployment diagram used in the method for determining the co-frequency isolation zone between satellite mobile communication and terrestrial mobile communication systems provided in an embodiment of the present invention;

[0029] Figure 4 A schematic diagram of a base station transmission downtilt angle of the ground mobile communication base station;

[0030] Figure 5a to Figure 5b is a schematic diagram of an interference link of the ground mobile communication base station;

[0031] Figure 6 A schematic diagram of a method for determining a co-frequency isolation zone between a satellite mobile communication system and a terrestrial mobile communication system provided in an embodiment of the present invention, wherein the center of a satellite beam points to the center of a region of a terrestrial mobile communication system;

[0032] Figure 7 A schematic diagram of a hexagonal symmetric simulation of a co-frequency isolation zone decision method for a satellite mobile communication and a terrestrial mobile communication system provided in an embodiment of the present invention;

[0033] Figure 8 It is a cumulative probability distribution curve of co-channel interference of terminals without co-channel isolation zone decision in the prior art;

[0034] Fig. 9 The cumulative probability distribution curve of terminal co-channel interference using the co-channel isolation zone decision method for satellite mobile communication and terrestrial mobile communication systems provided by an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0036] It should be noted that references to "one embodiment", "embodiment", "example embodiment", etc. in this specification refer to the embodiment described, which may include specific features, structures or characteristics, but not every embodiment must include these specific features, structures or characteristics. In addition, such expressions do not refer to the same embodiment. Furthermore, when describing specific features, structures or characteristics in conjunction with an embodiment, whether or not there is an explicit description, it has been shown that it is within the knowledge of those skilled in the art to combine such features, structures or characteristics into other embodiments.

[0037] In addition, certain words are used in the specification and subsequent claims to refer to specific components or parts. Those with ordinary knowledge in the relevant field should understand that manufacturers can use different nouns or terms to refer to the same component or part. This specification and subsequent claims do not use differences in names as a way to distinguish components or parts, but use differences in the functions of components or parts as the criteria for distinction. "Including" and "including" mentioned throughout the specification and subsequent claims are open-ended terms and should be interpreted as "including but not limited to". In addition, the word "connected" here includes any direct and indirect electrical connection means. Indirect electrical connection means include connection through other devices.

[0038] Figure 2 The satellite mobile communication system and the ground mobile communication system are shown, including satellites and terminals in the satellite mobile communication system, and satellite beam coverage; the ground mobile communication system includes orbital base stations and terminals, and ground cellular structures; the satellite mobile communication system terminal communicates with the satellite in a certain beam of the satellite, and the ground mobile communication system base station communicates with the terminal in the cellular. In actual applications, the satellite beam overlaps with the ground mobile communication coverage and there is a situation where the satellite signal and the ground mobile communication system work in the same frequency band. At this time, the terminals in the overlapping area will be subject to the same frequency interference between the satellite mobile communication system and the ground mobile communication system.

[0039] Aiming at the problem of potential interference risk caused by overlapping frequency deployment between satellite mobile communication system and terrestrial mobile communication system, the present invention provides a method for deciding the same-frequency isolation zone between satellite mobile communication and terrestrial mobile communication system. By designing the isolation zone decision method, when the interference exceeding limit time percentage is greater than or equal to the time percentage limit, the satellite beam is subjected to hexagonal symmetric simulation to obtain six same-frequency beams equidistant from the coverage area of ​​the mobile communication system. After reaching the interference protection limit, a link can be established with the satellite mobile communication satellite; thereby reducing the interference-to-noise ratio of the terrestrial mobile communication system base station to the satellite mobile communication system terminal.

[0040] Figure 1 A method for determining a co-frequency isolation zone between a satellite mobile communication system and a terrestrial mobile communication system provided by an embodiment of the present invention is shown, comprising the following steps:

[0041] S1: Determine the deployment information of a ground mobile communication system with the same frequency as the satellite mobile communication system based on the regional elements within the satellite visible area; wherein the ground mobile communication system includes a number of ground mobile communication base stations, each of which evenly serves and covers three cellular areas, and the cellular areas are connected and extended outward in a hexagonal shape; the deployment information includes the number of cells, the cell radius, the base station spacing and the number of base stations; the satellite visible area refers to the ground area that can be radiated by satellite signals.

[0042] The terrestrial mobile communication system of this embodiment is specifically as follows Figure 3 As shown, the service of each ground mobile communication base station covers three cellular areas, namely, three hexagons. The ground mobile communication base station is located at the center of the three cellular areas, and the cellular areas continue to expand outward in a hexagonal connection, namely, the cellular areas covered by different ground mobile communication base stations do not overlap, and the cellular areas covered by different ground mobile communication base stations are connected; the cellular radius R and base station spacing D obtained in step S1 are shown in the figure.

[0043] The regional elements in step S1 are specifically the city area and population density, that is, in step S1, for the visible area of ​​the satellite, the deployment of the ground mobile communication system with the same frequency as the satellite mobile communication system is determined by the city area and population density, including the number of cells M, the cell radius R, the base station spacing D and the number of base stations N; assuming that the city area is a square; the city area is the sum of the areas of all cell areas, that is, the city area is the sum of the areas of M cells, then the base station spacing D is calculated based on the following formula: Where D is the base station spacing, β is the coefficient, and ρ is the population density. Then, a ground mobile communication system deployment diagram can be established based on the determined deployment information, that is, Figure 3 The deployment diagram shown.

[0044] S2: Obtain radio frequency link parameters of the ground mobile communication system.

[0045] Specifically, the radio frequency link parameters of this embodiment include at least a base station antenna model, a base station antenna downtilt angle, and a base station transmit power; wherein the base station antenna downtilt angle is as follows: Figure 4 As shown, each ground mobile communication base station in this embodiment deploys three antennas, each antenna covers a cellular area, and the angle between the antenna plane and the plane perpendicular to the ground is the downtilt angle γ k , 0°≤γ k ≤90°.

[0046] See also Figure 5a to Figure 5b , the figure shows the base station antenna 10 and the satellite mobile communication system terminal 20 of this embodiment, when the downtilt angle γ k =0°, the main lobe of the base station antenna of the ground mobile communication system points horizontally; when 0°<γ k When ≤90°, the angle between the main lobe pointing 11 of the base station antenna of the ground mobile communication system and the horizontal line is equal to the downtilt angle γ k ; where the link angle relative to the main lobe of the transmitting antenna is θ k And the link angle relative to the receiving antenna main lobe is α k As shown in the picture.

[0047] S3: Direct the satellite beam center to the regional center of the ground mobile communication system. This step S3 is specifically the initial operation of satellite beam pointing. When it is subsequently determined that the isolation zone decision does not need to be executed, there is no need to perform hexagonal symmetry simulation on the satellite beam.

[0048] See also Figure 6 The circular mark in the figure is a satellite beam 21. First, the center of the satellite beam 21 is directed to the regional center of the ground mobile communication system, that is, the center of the satellite beam 21 overlaps with the regional center of the ground mobile communication system; the hexagon in the figure is a cellular cluster 23 of the ground co-frequency mobile communication system, and the six pointing arrows in the figure represent the subsequent satellite beam shifting path 24 simulated by hexagonal symmetry to avoid co-frequency interference.

[0049] The regional center of this embodiment is specifically the cellular cluster center of the ground co-frequency mobile communication system, that is, the center of the set of all cellular areas.

[0050] S4: Calculate the base station set interference of the ground mobile communication system according to the radio frequency link parameter statistics.

[0051] In specific implementation, the base station set interference in step S4 is calculated based on the following formula:

[0052]

[0053] Where I is the base station set interference, P k is the transmission power of the kth ground mobile communication base station, G t (θ k ) is the transmitting antenna gain of the kth ground mobile communication base station pointing to the satellite terminal, θ k is the link relative to the main lobe angle of the transmitting antenna, Loss k is the path loss from the kth ground mobile communication base station to the satellite terminal, G r (a k ) is the receiving antenna gain of the satellite terminal, a k is the main lobe angle of the link relative to the receiving antenna.

[0054] S5: Determine whether the interference exceeding limit time percentage of the base station set interference is less than the time percentage limit; that is, based on the statistical calculation results of the above step S4, determine whether the following conditions are met: Pprob (I ≥ I-th) < Prob-th; wherein the time percentage limit is determined by the terminal characteristics of the satellite mobile communication system of the disturbed system, for example, the time percentage limit of this embodiment is ten percent; then in this step S5, specifically by calculating the time percentage that the base station set interference is greater than or equal to -10dB, if it is greater than or equal to 10%, it is necessary to make an isolation zone decision to enter the subsequent step S6.

[0055] S6: If the interference exceeding limit time percentage is not less than the time percentage limit, then six co-frequency beams with N times the preset distance moving outward from the center of the region are obtained by performing hexagonal symmetric simulation on the satellite beam; and return to step S4 to recalculate the base station aggregate interference statistics; wherein N is a positive integer. Figure 7 As shown, six co-frequency beams 201 are obtained through hexagonal symmetric simulation, which are equidistant from the coverage area of ​​the mobile communication system by ΔL. The hexagonal symmetric simulation strategy of this embodiment is that each satellite beam shift path is ΔL away from the ground co-frequency mobile communication system cell group; ΔL is the preset distance. In step S6, the Monte Carlo simulation method can be used to perform hexagonal symmetric simulation to simulate the interference of the ground mobile communication system base station to the satellite mobile communication system terminal under multiple snapshots.

[0056] Whenever the loop enters step S6, the value of parameter N is adjusted and returns to step S4 until the interference exceeds the limit time percentage is less than the time percentage limit. In specific implementation, the value of parameter N is incremented in sequence, and the value of N starts from 1, that is, when entering step S6 for the first time, the six co-frequency beams 201 are respectively shifted along the satellite beam shifting path 24 at a distance of ΔL; thereafter, when the loop enters step S6 by returning to step S4, the value of N is incremented to 2, and the six co-frequency beams are shifted at 2ΔL, and so on, until the interference exceeds the limit time percentage is less than the time percentage limit and the loop does not return to step S4.

[0057] Furthermore, after step S5, the method further includes:

[0058] Step S7: If the interference exceeding time percentage is less than the time percentage limit, the current shifting distance is obtained as the same-frequency isolation distance between the satellite mobile communication and the ground mobile communication at the current longitude and latitude. If the interference exceeding time percentage is less than the time percentage limit, the satellite communication system can be accessed for satellite communication, and the current shifting distance is obtained as the same-frequency isolation distance between the satellite mobile communication and the ground communication at the current longitude and latitude.

[0059] The method for deciding the co-frequency isolation zone between satellite mobile communication and terrestrial mobile communication systems provided by the embodiment of the present invention not only realizes the decision of the co-frequency isolation zone between satellite mobile communication and terrestrial mobile communication systems, and reduces the interference-to-noise ratio of the terrestrial mobile communication system base station to the satellite mobile communication system terminal; but also through hexagonal symmetry simulation, the interference of the terrestrial mobile communication system terminal to the satellite mobile communication system meets the interference protection limit, thereby realizing the co-frequency sharing of the satellite mobile communication system and the terrestrial mobile communication system.

[0060] In a specific application example, the distance decision of the co-frequency isolation zone between the satellite mobile communication system A (the disturbed constellation system) and the town B (the disturbing ground system) is considered, and the constellation orbit parameters are shown in Table 1;

[0061] Table 1:

[0062]

[0063]

[0064] Assume that the number of ground mobile communication system base stations in town B with the same frequency as satellite mobile communication system A is 60, the number of cells is 180, the cell radius is 500m, the base station spacing is 750m, each base station has 3 antennas, the antenna downtilt angle is 0 degrees, each antenna communicates with the ground mobile communication system terminal in the cell, and the main beam direction is adjusted according to the link communication direction. The Monte Carlo simulation method is used, that is, the interference of the ground mobile communication system base station to the satellite mobile communication system terminal under multiple snapshots is simulated.

[0065] Figure 8 The cumulative probability distribution curve of the I / N of the satellite mobile communication terminal is shown when the base station of the satellite mobile communication system does not make a co-frequency isolation zone decision and still communicates with the satellite mobile communication system in towns. It can be seen that the terminal I / N exceeds the limit value at this time (the limit is that the percentage of time when I / N is greater than -12.2dB does not exceed 10%).

[0066] Fig. 9 The satellite mobile communication system base station adopts the method described in the embodiment of the present invention to make a hexagonal co-frequency isolation zone decision, and the satellite mobile communication terminal I / N cumulative probability distribution curve is shown after the extrapolated spacing is ΔL, 2*ΔL, and 3*ΔL respectively. It can be seen that by adopting the method described in this embodiment, the satellite mobile communication system terminal can meet the interference protection limit after extrapolating the spacing of 3*ΔL.

[0067] In summary, the method for deciding the same-frequency isolation zone between satellite mobile communication and ground mobile communication system of the present invention determines the deployment information of the ground mobile communication system with the same frequency as the satellite mobile communication system according to the regional elements in the satellite visible area; obtains the radio frequency link parameters of the ground mobile communication system; points the center of the satellite beam to the regional center of the ground mobile communication system; statistically calculates the interference of the base station set of the ground mobile communication system; determines whether the interference exceeding limit time percentage of the base station set interference is less than the time percentage limit; if it is not less than the time percentage limit, then the satellite beam is subjected to hexagonal symmetric simulation, and the six same-frequency beams are obtained to leave the coverage area of ​​the mobile communication system at equal distances through the hexagonal symmetric simulation. After reaching the interference protection limit, a link can be established with the satellite mobile communication satellite. In this way, the present invention realizes the decision of the same-frequency isolation zone between satellite mobile communication and ground mobile communication system, and reduces the interference-to-noise ratio of the base station of the ground mobile communication system to the terminal of the satellite mobile communication system; through the hexagonal symmetric simulation, the interference of the terminal of the ground mobile communication system to the satellite mobile communication system meets the interference protection limit, and realizes the same-frequency sharing of the satellite mobile communication system and the ground mobile communication system.

[0068] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for determining the frequency isolation zone between satellite mobile communication and terrestrial mobile communication systems, characterized in that: include: Step S1, determining the deployment information of a ground mobile communication system with the same frequency as the satellite mobile communication system according to the regional elements in the satellite visible area; wherein the ground mobile communication system includes a plurality of ground mobile communication base stations, each of which evenly serves and covers three cellular areas, and the cellular areas are connected and extended outward in a hexagonal shape; the deployment information includes the number of cells, the cell radius, the base station spacing, and the number of base stations; Step S2, obtaining radio frequency link parameters of the ground mobile communication system; Step S3, directing the satellite beam center to the regional center of the ground mobile communication system; Step S4, calculating the base station set interference of the ground mobile communication system according to the radio frequency link parameter statistics; The base station set interference in step S4 is calculated based on the following formula: Where I is the base station set interference, P k is the transmission power of the kth ground mobile communication base station, G t (θ k ) is the transmitting antenna gain of the kth ground mobile communication base station pointing to the satellite terminal, θ k is the link relative to the main lobe angle of the transmitting antenna, Loss k is the path loss from the kth ground mobile communication base station to the satellite terminal, G r (a k ) is the receiving antenna gain of the satellite terminal, a k is the angle of the link relative to the main lobe of the receiving antenna; Step S5, determining whether the interference exceeding limit time percentage of the base station set interference is less than the time percentage limit; Step S6, if the interference exceeding limit time percentage is not less than the time percentage limit, six same-frequency beams with N times the preset distance moving outward from the center of the area at equal distances are obtained by performing hexagonal symmetry simulation on the satellite beam; and returning to step S4; wherein N is a positive integer; Whenever the loop enters step S6, the value of parameter N is adjusted and the process returns to step S4 until the interference exceeding limit time percentage is less than the time percentage limit.

2. The method for determining the co-frequency isolation zone of satellite mobile communication and terrestrial mobile communication systems according to claim 1, characterized in that: After step S5, the method further includes: Step S7: If the interference exceeding limit time percentage is less than the time percentage limit, the current shifting distance is obtained as the co-frequency isolation distance between the satellite mobile communication and the terrestrial mobile communication at the current longitude and latitude.

3. The method for determining the co-frequency isolation zone of satellite mobile communication and terrestrial mobile communication systems according to claim 1, characterized in that: The radio frequency link parameters include a base station antenna model, a base station antenna downtilt angle, and a base station transmit power.

4. The method for determining the co-frequency isolation zone of satellite mobile communication and terrestrial mobile communication systems according to claim 1, characterized in that: The regional elements include urban area and population density; the urban area is the sum of the areas of all the cellular areas, and the base station spacing in the deployment information is calculated based on the following formula: Wherein, D is the base station spacing, β is the coefficient, and ρ is the population density.

5. The method for determining the co-frequency isolation zone of satellite mobile communication and terrestrial mobile communication systems according to claim 1, characterized in that: The regional center of the ground mobile communication system is the cellular cluster center of the ground same-frequency mobile communication system.

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