A dynamic mapping relationship intersatellite link compatibility simulation method, device and medium

Abstract

The present invention discloses a dynamic mapping relationship intersatellite link compatibility simulation method, device and medium, wherein the method includes: selecting an interfering system and an interfered system, obtaining satellite technical characteristic parameters and satellite orbit position parameters of the interfering system and the interfered system, calculating the visibility between satellites in the two systems at each simulation moment, and generating a visibility matrix between satellites; generating an intersatellite link mapping relationship table at each simulation moment; calculating the interference signal power of each satellite transmitting signal of the interfering system to each visible satellite of the interfered system at each simulation moment; obtaining an interference evaluation conclusion as a basis for judging the compatibility of intersatellite links. The present invention establishes intersatellite link establishment criteria through different satellite system orbit configurations and operation strategies, selects establishment satellites that meet the range of operation requirements by setting different establishment conditions, and reflects various establishment strategies and dynamic establishment situations through a dynamic intersatellite link mapping relationship table.

Description

Technical Field

[0001] The present invention relates to the technical field of dynamic mapping relationship inter-satellite link compatibility evaluation, and in particular to a dynamic mapping relationship inter-satellite link compatibility simulation method, device and medium. Background Art

[0002] There are two main links in satellite communications: satellite-to-ground links and inter-satellite links, which refer to the communication link between satellites and ground equipment and the radio signal transmission link between satellites. In recent years, with the growing demand for inter-satellite links in data relay, space-based measurement and control, navigation and ranging, constellation networking, and galaxy fusion, the use scenarios of inter-satellite links have become increasingly complex, and the frequency compatibility issue between inter-satellite links of different systems using the same frequency has become increasingly prominent.

[0003] In the process of evaluating the possible interference level between intersatellite links of different systems using the same frequency, it is necessary to conduct dynamic analysis on various possible ways of establishing intersatellite links to reflect the situation in which the interference signal strength changes due to dynamic changes in the pointing azimuth, signal propagation distance, etc. of the satellite antenna beam at the transmitting end of the intersatellite link at different times.

[0004] The current frequency compatibility simulation analysis method for intersatellite links is mainly aimed at intersatellite links with fixed mapping relationships, that is, the transmitting satellite and the receiving satellite for establishing the intersatellite link are fixed, including both the intersatellite links between satellites in the constellation system and the traditional relay satellites providing intersatellite link access services for their user satellites. However, with the development of large-scale constellation systems in recent years, the mapping relationship of intersatellite links is undergoing major changes, and there is gradually a need to dynamically establish links based on the status between satellites. The existing intersatellite link processing method for fixed mapping relationships is too simplified and cannot fully reflect the dynamic changes in the pointing direction between different intersatellite links under the same frequency sharing condition, resulting in the problem of low accuracy of the frequency sharing compatibility evaluation index obtained using the existing simulation method.

[0005] In reality, there is a lack of co-frequency interference assessment simulation methods for inter-satellite links with dynamic mapping relationships in the current inter-satellite communication field. It is necessary to propose a method to determine the dynamic link establishment criteria of inter-satellite links in real time through quantifiable indicators, and obtain interference assessment conclusions based on this, and carry out frequency compatibility assessment for satellite system design and operation units to analyze the interference degree between inter-satellite links operating at the same frequency and optimize system design. Summary of the invention

[0006] The purpose of the present invention is to provide a method, device and medium for simulating the compatibility of inter-satellite links with dynamic mapping relationships, which can establish an inter-satellite link model under a dynamic mapping relationship in large-scale, multi-orbit satellite system applications, and simulate and evaluate the frequency compatibility between co-frequency satellite systems.

[0007] The embodiment of the present invention provides a method, device and medium for simulating the compatibility of inter-satellite links with dynamic mapping relationships.

[0008] A first aspect: A dynamic mapping relationship intersatellite link compatibility simulation method, comprising:

[0009] S1. Selecting intersatellite link system A as the interference system and selecting intersatellite link system B as the interfered system, wherein there is frequency overlap between intersatellite link system A and intersatellite link system B;

[0010] S2. Obtain satellite technical characteristic parameters of the interfering system and the interfered system;

[0011] S3, simulating and running the interfered system and the interfering system in the simulation system, and obtaining the satellite orbit position parameters of the interfered system and the interfering system at each simulation moment;

[0012] S4, calculating the visibility between the satellites in the two systems at each simulation time according to the technical characteristic parameters of the satellites of the two systems and the orbital position parameters of the simulation operation of the two systems, and generating a visibility matrix between the satellites;

[0013] S5. According to the visibility matrix between satellites, different link establishment criteria are selected to generate an inter-satellite link mapping relationship table at each simulation time;

[0014] S6. Calculate the interference signal power of each satellite transmitting signal of the interference system reaching each visible satellite of the interfered system at each simulation moment according to the inter-satellite link mapping relationship table;

[0015] S7. Collect statistics on the interference exceeding the standard for each satellite in the interfered system and obtain the interference assessment conclusion as the basis for judging the compatibility of inter-satellite links.

[0016] Optionally: the satellite technical characteristic parameters of the interfered system and the interfering system obtained in S2 include: frequency, antenna characteristics, transmission power and bandwidth parameters.

[0017] Optionally, when simulating and running the interfered system and the interfering system in the simulation system in S3, the simulation system settings include: simulation step length, simulation start and end time, and initial parameters of each satellite orbit in the interfered system and the interfering system.

[0018] Optionally: the visibility matrix in S4 includes:

[0019] The visibility matrix of each satellite in the intersatellite link system A to other satellites in the system;

[0020] The visibility matrix of each satellite in the intersatellite link system B to other satellites in the system;

[0021] The visibility matrix of each satellite in inter-satellite link system A to all satellites in inter-satellite link system B.

[0022] Optionally: the link establishment criteria in S5 include: determining whether to establish a satellite link based on a visible inter-satellite communication distance range, a visible time range and / or an interference avoidance antenna sidelobe angle range.

[0023] Optionally, the determining whether to establish a satellite link according to the visible inter-satellite interference avoidance antenna sidelobe angle range includes:

[0024] A transmitting satellite and multiple receiving satellites are selected in the interfering system, and a disturbed satellite is selected in the interfered system. The angle between the intersatellite link formed by the transmitting satellite and each receiving satellite and the intersatellite link formed by the transmitting satellite and the disturbed satellite is calculated, and it is determined whether to establish a satellite link based on the angle.

[0025] Optionally: when establishing a satellite link, if there are multiple visible satellites that meet the link establishment criteria for selection, random selection is used to establish the link; when no visible satellite meets the selected link establishment criteria, no link is established at this moment.

[0026] A second aspect: An electronic device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method provided in the first aspect when executing the program.

[0027] A third aspect: A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that when the computer program is executed by a processor, the steps of the method provided in the first aspect are implemented.

[0028] Beneficial effects of the present invention:

[0029] 1. The present invention establishes inter-satellite link establishment criteria through different satellite system orbit configurations and operation strategies, selects satellites that meet the operating requirements by setting different link establishment conditions, and reflects various link establishment strategies and specific methods of dynamic link establishment situations through a dynamic inter-satellite link mapping relationship table.

[0030] 2. The mapping relationship of the inter-satellite links is highly dynamic, and the present invention performs refined simulation modeling on this highly dynamic link relationship, effectively improving the accuracy of compatibility evaluation indicators in frequency sharing scenarios with other systems.

[0031] 3. In view of the current situation in the field of inter-satellite communications where there is a lack of co-frequency interference assessment and simulation methods for inter-satellite links with dynamic mapping relationships, the present invention proposes a method and process for determining the dynamic link establishment criteria of inter-satellite links in real time through quantifiable indicators, and performing frequency compatibility simulation based on this. The method and process can be used by satellite system design and operation units to analyze the degree of interference between inter-satellite links operating at the same frequency, optimize system design, etc., and effectively improve the accuracy of compatibility assessment indicators in frequency sharing scenarios with other systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of a flow chart of a dynamic mapping relationship inter-satellite link compatibility simulation method of the present invention;

[0033] Figure 2 A schematic diagram of the principle structure of a dynamic mapping relationship inter-satellite link compatibility simulation method of the present invention;

[0034] Figure 3 A schematic diagram of determining whether to establish a satellite link based on the interference avoidance antenna side lobe angle range in the present invention;

[0035] Figure 4 It is a schematic diagram of the structure of the electronic device of the present invention. DETAILED DESCRIPTION

[0036] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar symbols throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0037] The current frequency compatibility simulation analysis method for intersatellite links is mainly aimed at intersatellite links with fixed mapping relationships, that is, the transmitting satellite and the receiving satellite for establishing the intersatellite link are fixed, including both the intersatellite links between satellites in the constellation system and the traditional relay satellites providing intersatellite link access services for their user satellites. However, with the development of large-scale constellation systems in recent years, the mapping relationship of intersatellite links is undergoing major changes, and there is gradually a need to dynamically establish links based on the status between satellites. The existing intersatellite link processing method for fixed mapping relationships is too simplified and cannot fully reflect the dynamic changes in the pointing direction between different intersatellite links under the same frequency sharing condition, resulting in the problem of low accuracy of the frequency sharing compatibility evaluation index obtained using the existing simulation method.

[0038] In view of the above problems, the present invention provides a dynamic mapping relationship inter-satellite link compatibility simulation method. Figure 1 A schematic flow chart of a method for simulating the compatibility of intersatellite links with dynamic mapping relationships provided by an embodiment of the present invention, the method comprising:

[0039] S1. Select intersatellite link system A as the interference system and intersatellite link system B as the interfered system;

[0040] S2. Obtain satellite technical characteristic parameters of the interfering system and the interfered system;

[0041] S3, simulating and running the interfered system and the interfering system in the simulation system, and obtaining the satellite orbit position parameters of the interfered system and the interfering system at each simulation moment;

[0042] S4, calculating the visibility between the satellites in the two systems at each simulation time according to the technical characteristic parameters of the satellites of the two systems and the orbital position parameters of the simulation operation of the two systems, and generating a visibility matrix between the satellites;

[0043] S5. According to the visibility matrix between satellites, different link establishment criteria are selected to generate an inter-satellite link mapping relationship table at each simulation moment.

[0044] S6. Calculate the interference signal power of each satellite transmitting signal of the interference system reaching each visible satellite of the interfered system at each simulation moment according to the inter-satellite link mapping relationship table;

[0045] S7. Collect statistics on the interference exceeding the standard for each satellite in the interfered system and obtain the interference assessment conclusion as the basis for judging the compatibility of inter-satellite links.

[0046] like Figure 2 As shown, the intersatellite link system A of the cooperative organization can be set as the interference system, and the intersatellite link system B from the non-cooperative organization can be set as the interfered system technical characteristic parameters, and the satellite technical characteristic parameters of the A and B systems can be obtained respectively, mainly including the conventional parameters such as the frequency, antenna characteristics, transmission power and bandwidth used by each satellite equipment in the system. These parameters can be obtained through public data query, and these parameters can be used to calculate frequency compatibility. And determine whether the frequencies used by the two systems overlap, including complete overlap and partial overlap.

[0047] The simulation system is set up, including the simulation step size, simulation start and end time, initial parameters of each satellite orbit of intersatellite link system A and intersatellite link system B (constellation configuration and the number of six orbits of each satellite), etc.

[0048] By setting up the simulation system, the orbital parameters of each satellite of the interfered system and the interfering system can be obtained at each simulation moment.

[0049] According to the technical characteristic parameters of the satellites of the two systems and the orbital position parameters of the simulated operation of the two systems, the visibility between the satellites in the two systems at each simulation time is calculated to generate a visibility matrix between the satellites; the visibility between the satellites at each moment, that is, whether the line between the two satellites is blocked by the earth, is visible if there is no blockage. The visibility calculation includes:

[0050] The visibility matrix of each satellite in intersatellite link system A to other satellites in system A;

[0051] For example: there are five satellites in the intersatellite link system A, denoted as A1, A2...A5, then the visibility between A1 and A2, A3, A4, A5, the visibility between A2 and A3, A4, A5, the visibility between A3 and A4, A5, and the visibility between A4 and A5 are calculated respectively.

[0052] According to the above method, the visibility matrix of each satellite in the intersatellite link system B to other satellites in the B system is obtained; and the visibility matrix of each satellite in the intersatellite link system A to all satellites in the intersatellite link system B is obtained.

[0053] Different link building criteria are selected based on the visibility matrix between satellites. The link building criteria include:

[0054] According to the communication distance range between visible satellites, the communication distance range determines whether to establish a link based on the distance between two visible satellites. For example, you can set it to select the nearest satellite to establish a link, or you can set it to select a satellite with a distance of 1000-2000 kilometers to establish a link, etc.

[0055] After the communication distance range is selected as the intersatellite link establishment criterion, the communication distance between visible satellites can be calculated according to the satellite orbit parameters at the current moment, and visible satellites that meet the standards can be selected to establish the link. When multiple visible satellites meet the standards, they are randomly selected.

[0056] The visible time range between visible satellites. The visible time range determines whether to establish a link based on the visible time of the two satellites. For example, you can set it to select the two satellites with the longest continuous visible time to establish a link, or you can set it to select the two satellites with a continuous visible time of more than 20 seconds to establish a link, etc.

[0057] After the visible time range is selected as the intersatellite link establishment criterion, the continuous visibility time between each group of satellites is calculated according to the visibility matrix, and visible satellites that meet the criteria are selected to establish the link. When multiple visible satellites meet the criteria, they are randomly selected.

[0058] It can be seen that the side lobe angle range of the interference avoidance antenna between satellites. The side lobe angle range of the interference avoidance antenna is determined based on the size of the angle between the transmitting satellite and the receiving satellite to be linked, and the angle between the transmitting satellite and the interfered satellite of the interfered system.

[0059] After selecting the interference avoidance antenna sidelobe angle range as the intersatellite link establishment criterion, the link angle between each group of proposed intersatellite links and the satellites in the interfered system is calculated according to the orbital parameters and the antenna characteristic parameters in the satellite system technical parameters, and the visible satellites that meet the standards are selected to establish the link. When multiple visible satellites meet the standards, they are randomly selected.

[0060] like Figure 3 As shown, the intersatellite link system A is used as the interference system, and five satellites A1, A2, A3, A4 and A5 are selected, among which A1 is used as the transmitting satellite, A2, A3, A4 and A5 are used as the receiving satellites, the intersatellite link system B is used as the interfered system, and satellite B1 is selected as the interfered satellite.

[0061] Calculate the angle between the intersatellite link formed by the transmitting satellite and each receiving satellite and the intersatellite link formed by the transmitting satellite and the disturbed satellite. For example, the angle between the A1-A2 intersatellite link and A1-B1 is θ1=10 degrees, the angle between the A1-A3 intersatellite link and A1-B1 is θ2=15 degrees, the angle between the A1-A4 intersatellite link and A1-B1 is θ3=25 degrees, and the angle between the A1-A5 intersatellite link and A1-B1 is θ4=50 degrees.

[0062] When the set interference avoidance side lobe angle is the largest, A1-A5 is selected to establish a chain; when the set interference avoidance side lobe angle is greater than 3 degrees, A1-A2, A1-A3, A1-A4 and A1-A5 are randomly selected to establish a chain.

[0063] When the communication distance range and / or the visible time range and / or the interference avoidance antenna sidelobe angle range are selected as the link establishment criteria at the same time, the visible satellites that meet all the criteria are selected for link establishment. When multiple visible satellites meet the criteria, they are randomly selected. When no visible satellite meets the selected criteria at the same time, the inter-satellite link is not established at this moment.

[0064] According to the above-mentioned link establishment criteria and link establishment process, an inter-satellite link mapping relationship table can be generated at each simulation moment.

[0065] According to the inter-satellite link mapping relationship table, the interference signal power of each satellite of the interference system reaching each visible satellite of the interfered system at each simulation moment is calculated; when the same satellite of the interfered system simultaneously receives multiple inter-satellite link transmission signals of the interference system, the aggregate interference signal power of the satellite is calculated.

[0066] Then, according to the interference protection standard of the intersatellite link of the interfered system, the interference exceeding the standard for each satellite of the interfered system is statistically analyzed to obtain the interference assessment conclusion, which serves as the basis for judging the compatibility of the intersatellite link.

[0067] The present invention also provides an electronic device, Figure 4A schematic diagram of the structure of an electronic device provided by an embodiment of the present invention, such as Figure 4 As shown, the electronic device may include: a processor, a communications interface, a memory, and a communications bus, wherein the processor, the communications interface, and the memory communicate with each other via the communications bus. The processor may call the logic instructions in the memory and may execute the method provided in the above embodiment, for example:

[0068] S1. Selecting intersatellite link system A as the interference system and selecting intersatellite link system B as the interfered system, wherein there is frequency overlap between intersatellite link system A and intersatellite link system B;

[0069] S2. Obtain satellite technical characteristic parameters of the interfering system and the interfered system;

[0070] S3, simulating and running the interfered system and the interfering system in the simulation system, and obtaining the satellite orbit position parameters of the interfered system and the interfering system at each simulation moment;

[0071] S4, calculating the visibility between the satellites in the two systems at each simulation time according to the technical characteristic parameters of the satellites of the two systems and the orbital position parameters of the simulation operation of the two systems, and generating a visibility matrix between the satellites;

[0072] S5. According to the visibility matrix between satellites, different link establishment criteria are selected to generate an inter-satellite link mapping relationship table at each simulation moment.

[0073] S6. Calculate the interference signal power of each satellite transmitting signal of the interference system reaching each visible satellite of the interfered system at each simulation moment according to the inter-satellite link mapping relationship table;

[0074] S7. Collect statistics on the interference exceeding the standard for each satellite in the interfered system and obtain the interference assessment conclusion as the basis for judging the compatibility of inter-satellite links.

[0075] In addition, the logic instructions in the above-mentioned memory can be implemented in the form of software functional units and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on this understanding, the technical solution of the present invention can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0076] The embodiment of the present invention further provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the method provided in the above embodiment is implemented, for example, including:

[0077] S1. Selecting intersatellite link system A as the interference system and selecting intersatellite link system B as the interfered system, wherein there is frequency overlap between intersatellite link system A and intersatellite link system B;

[0078] S2. Obtain satellite technical characteristic parameters of the interfering system and the interfered system;

[0079] S3, simulating and running the interfered system and the interfering system in the simulation system, and obtaining the satellite orbit position parameters of the interfered system and the interfering system at each simulation moment;

[0080] S4, calculating the visibility between the satellites in the two systems at each simulation time according to the technical characteristic parameters of the satellites of the two systems and the orbital position parameters of the simulation operation of the two systems, and generating a visibility matrix between the satellites;

[0081] S5. According to the visibility matrix between satellites, different link establishment criteria are selected to generate an inter-satellite link mapping relationship table at each simulation moment.

[0082] S6. Calculate the interference signal power of each satellite transmitting signal of the interference system reaching each visible satellite of the interfered system at each simulation moment according to the inter-satellite link mapping relationship table;

[0083] S7. Collect statistics on the interference exceeding the standard for each satellite in the interfered system and obtain the interference assessment conclusion as the basis for judging the compatibility of inter-satellite links.

[0084] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0085] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dynamic mapping relationship intersatellite link compatibility simulation method, characterized in that: include: S1. Selecting intersatellite link system A as the interference system and selecting intersatellite link system B as the interfered system, wherein there is frequency overlap between intersatellite link system A and intersatellite link system B; S2. Obtain satellite technical characteristic parameters of the interfering system and the interfered system; S3, simulating and running the interfered system and the interfering system in the simulation system, and obtaining the satellite orbit position parameters of the interfered system and the interfering system at each simulation moment; S4, calculating the visibility between the satellites in the two systems at each simulation time according to the technical characteristic parameters of the satellites of the two systems and the orbital position parameters of the simulation operation of the two systems, and generating a visibility matrix between the satellites; S5. According to the visibility matrix between satellites, different link establishment criteria are selected to generate an inter-satellite link mapping relationship table at each simulation time; The link establishment criteria include: determining whether to establish a satellite link based on a visible inter-satellite communication distance range, a visible time range, and / or an interference avoidance antenna side lobe angle range; Wherein, determining whether to establish a satellite link according to the visible inter-satellite interference avoidance antenna sidelobe angle range includes: selecting a transmitting satellite and multiple receiving satellites in the interference system, selecting a disturbed satellite in the interfered system, calculating the angle between the inter-satellite link formed by the transmitting satellite and each receiving satellite and the inter-satellite link formed by the transmitting satellite and the disturbed satellite, and determining whether to establish the satellite link according to the angle; S6. Calculate the interference signal power of each satellite transmitting signal of the interference system reaching each visible satellite of the interfered system at each simulation moment according to the inter-satellite link mapping relationship table; S7. Collect statistics on the interference exceeding the standard for each satellite in the interfered system and obtain the interference assessment conclusion as the basis for judging the compatibility of inter-satellite links.

2. The method for simulating intersatellite link compatibility based on dynamic mapping relationship according to claim 1, characterized in that: The satellite technical characteristic parameters of the interfered system and the interfering system obtained in S2 include: frequency, antenna characteristics, transmission power and bandwidth parameters.

3. The method for simulating the compatibility of intersatellite links according to claim 1, characterized in that: When simulating and running the interfered system and the interfering system in the simulation system in S3, the simulation system settings include: simulation step length, simulation start and end time, and initial parameters of each satellite orbit in the interfered system and the interfering system.

4. The method for simulating the compatibility of intersatellite links according to claim 1, characterized in that: The visibility matrix in S4 includes: The visibility matrix of each satellite in the intersatellite link system A to other satellites in the system; The visibility matrix of each satellite in the intersatellite link system B to other satellites in the system; The visibility matrix of each satellite in inter-satellite link system A to all satellites in inter-satellite link system B.

5. The method for simulating intersatellite link compatibility based on dynamic mapping relationship according to claim 1, characterized in that: When establishing a satellite link, if there are multiple visible satellites that meet the link establishment criteria for selection, random selection is used to establish the link; if no visible satellite meets the selected link establishment criteria, no link is established at that moment.

6. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of a dynamic mapping relationship inter-satellite link compatibility simulation method according to any one of claims 1 to 5 are implemented.

7. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of a dynamic mapping relationship inter-satellite link compatibility simulation method as claimed in any one of claims 1 to 5 are implemented.

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