High fidelity handset direct satellite simulation method

Abstract

This invention discloses a high-fidelity mobile phone direct satellite simulation method, comprising the following steps: constructing a satellite constellation architecture model; constructing a satellite movement model; integrating the ns3 built-in LTE module and 3GPP NTN channel model; and setting up the simulator. This invention is implemented on the ns3 open-source platform, eliminating the need for external trajectory import using commercial software such as STK. All functional modules are integrated in native ns3 code, allowing users to flexibly adjust simulation conditions such as constellation configuration, orbital parameters, and channel scenarios through configuration files, significantly reducing the barrier to entry and deployment complexity.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication technology, and more specifically, relates to a high-fidelity mobile phone direct satellite connection simulation method. Background Technology

[0002] Low Earth Orbit (LEO) satellite constellations, with their unique advantages of low latency, high bandwidth, and global coverage, have become a strategic high ground for next-generation information infrastructure. Mega-constellation projects, exemplified by SpaceX's Starlink, have entered large-scale commercialization, validating their technological feasibility. Against this backdrop, China is also accelerating the development of its own controllable LEO constellation system, including national-level constellations coordinated by China's StarNet and commercial space projects represented by the Qianfan constellation. The rapid development of these projects presents unprecedented challenges to the design, optimization, and verification of satellite communication systems. Unlike geostationary Earth Orbit (GEO) satellites, which are relatively "stationary" relative to the ground, LEO satellites (orbital altitude approximately 500-2000 km) move at high speeds relative to ground users, with an orbital period of only about 90-120 minutes. This fundamental difference brings core design challenges such as frequent inter-satellite handovers, significant Doppler shifts, and dynamically changing channel environments. Therefore, verifying the architecture, protocols, and algorithms of LEO constellations through high-reliability network simulations before system design and deployment is a crucial step in reducing R&D risks and shortening the commercialization cycle. With its open-source, modular, and high-fidelity features, the ns3 network simulator has become one of the mainstream platforms for satellite network simulation in academia and industry.

[0003] Currently, existing technologies for LEO satellite network simulation based on the ns3 platform mainly include: satellite simulation based on trajectory data files or simple trajectory models. The former is usually for simulating a single satellite or a few satellites. For Walker- Constellations with large scale and regular geometric configurations lack the ability to generate parameters quickly. Manually configuring the orbital parameters of hundreds or even thousands of satellites is not only inefficient but also prone to errors, making it impossible to accurately simulate the Doppler frequency shift state changes caused by relative motion, and difficult to accurately calculate the real-time changes in signal propagation delay. This makes it difficult to verify physical layer and link layer algorithms that require precise time and frequency synchronization in simulations based on existing technologies; the latter typically involves defining detailed satellite orbital parameters in STK and using its high-precision propagation model to generate time series of satellite positions. Subsequently, interface scripts are written to parse these discrete trajectory data and inject them into the ns3 motion model to drive node motion. However, this approach breaks the simulation loop, making it impossible to achieve closed-loop real-time interaction between "orbit calculation and communication events." At the same time, relying on commercial software STK increases research costs and deployment difficulty, hindering the widespread dissemination and secondary development of the technology. In addition, some researchers have replaced the ns3 simulation platform with general-purpose scientific computing tools such as Matlab and Python for simulation analysis. These tools have advantages such as low entry barriers and short development cycles in algorithm prototype verification, link budget calculation, and visualization. However, when simulation requirements extend from physical layer algorithms to the complete communication protocol stack, their limitations become apparent; they are not designed for large-scale, high-fidelity network protocol simulation. When dealing with complex protocol interactions, dynamic network management, and cross-layer optimization verification, specialized network simulators like ns3 have irreplaceable advantages.

[0004] In summary, existing technologies for LEO satellite network simulation, especially on the ns3 platform, suffer from several drawbacks. These include a difficulty in balancing model accuracy and simulation efficiency, insufficient support for large-scale parametric deployment of constellations, and a lack of intrinsic support for complex physical effects caused by high-speed movement (such as precise Doppler and dynamic delay). The root of these problems lies in the fact that existing methods either sacrifice simulation efficiency and flexibility in pursuit of accuracy (e.g., STK co-simulation) or discard key physical characteristics (e.g., simple movement models) to simplify implementation. This makes it difficult to meet the urgent needs of current and future large-scale, highly dynamic LEO constellation system designs for a high-fidelity, scalable, and integrated simulation platform. Therefore, there is a pressing need for a satellite modeling and link simulation tool that can achieve high-precision, parametric simulation and support for complex link effects within the ns3 platform to overcome the shortcomings of existing technologies. Summary of the Invention

[0005] To address the aforementioned issues, this invention proposes a high-fidelity mobile phone direct satellite communication simulation method. By integrating a high-precision parameterized satellite motion model and link simulation module within the ns3, it achieves integrated and accurate modeling of satellite orbital motion, Doppler effect, and dynamic delay. It also supports rapid parameterized deployment and efficient protocol simulation for large-scale constellations, thereby providing a high-fidelity and scalable simulation platform for the design and verification of mobile phone direct satellite communication systems.

[0006] To solve at least one of the aforementioned technical problems, according to one aspect of the present invention, a high-fidelity mobile phone direct satellite connection simulation method is provided, comprising the following steps:

[0007] Constructing a Satellite Constellation Architecture Model: To build a simulation platform that closely reflects actual operating conditions, this invention first establishes a geometric kinematic model of a low Earth orbit (LEO) satellite constellation, using the International Terrestrial Reference Frame (ITRF) as a unified spatiotemporal reference. In this model, the Earth is simplified as a sphere with a radius of R = 6371 km, with the Earth's center as the origin of the coordinate system. The X-axis lies in the equatorial plane and points towards the vernal equinox; the Z-axis coincides with the Earth's rotation axis and points towards the North Pole; and the Y-axis is perpendicular to the XOZ plane. These three axes together form a right-handed Cartesian coordinate system. This invention assumes that all satellites orbit in circular orbits. The spatial orientation of each orbital plane is characterized by two key parameters: orbital inclination, defining the angle between the orbital plane and the Earth's equatorial plane; and the right ascension of the ascending node (RAAN), specifying the initial orientation of the orbital plane in space. Satellites are uniformly distributed within each orbital plane, and the relative phase between satellites on adjacent orbital planes is controlled by a phase factor. For Walker-based satellites, such as Starlink... The constellation configuration introduces a phase factor F to adjust the phase offset between planes: when F=0, satellites on all orbital planes are in phase; when F=1, a more uniform global coverage distribution is produced. By adjusting the above key constellation parameters, this invention can flexibly reproduce various mainstream and customized LEO constellation architectures.

[0008] Constructing a Satellite Motion Model: To accurately describe the satellite's spatial position at any given time, this invention further constructs a satellite motion model based on vector rotation. This model uses the International Earth Reference System as a reference and assumes the satellite moves at a constant speed along a circular orbit. Its motion state is uniquely determined by the orbital velocity vector, instantaneous position vector, initial position vector, and the unit normal vector of the orbital plane. The initial position vector and normal vector can be pre-calculated based on the aforementioned orbital parameters such as orbital inclination and right ascension of the ascending node, representing the satellite's spatial coordinates and the spatial orientation of the orbital plane at time zero, respectively. The satellite's motion in its orbit is manifested as a uniform rotation of its position vector around the normal vector, with the rotation angle being the mean anomaly angle, which increases over time. To calculate the instantaneous position vector after rotating by any angle (mean anomaly angle) from the initial position vector, this model employs the Rodrigues rotation formula, which can rigorously realize the three-dimensional rotation of a vector around any spatial axis. Specifically, the instantaneous position vector is obtained by rotating the initial position vector by a certain angle (real-time mean anomaly angle) along the unit normal vector of the orbital plane. This model enables the simulator to generate the Cartesian coordinates of each satellite at any simulation moment in real time with high accuracy. This supports subsequent key simulation steps such as Doppler shift calculation, propagation delay estimation, inter-satellite link topology updates, and user terminal handover decisions. This motion model not only ensures the physical realism of the orbital motion but also boasts extremely high computational efficiency due to its analytical expression, making it suitable for large-scale constellation simulations involving thousands of satellites.

[0009] The ns3 platform integrates an LTE module and a 3GPP NTN channel model (several satellite communication-related functional modules have been integrated into the ns3 network simulation platform, providing some module complements for the development of this invention): The LTE module, as a widely used terrestrial cellular network simulation tool in the industry, fully implements the LTE protocol stack defined by 3GPP, including Radio Resource Control (RRC), Packet Data Convergence Protocol (PDCP), Radio Link Control (RLC), Media Access Control (MAC), and Physical Layer (PHY), and supports multi-user scheduling, handover management, and EPC core network simulation; the non-terrestrial network (NTN) channel model developed based on 3GPP standards is an important extension module added by ns3 in recent years. This module strictly adheres to the 3GPP TR 38.811 technical report, implementing channel simulation functions for aerospace nodes such as satellites, high-altitude platforms, and UAVs. Key features include: node localization in the geocentrically coupled map (ECEF) coordinate system; line-of-sight / non-line-of-sight probability models for different propagation scenarios (dense urban areas, urban areas, suburbs, and rural areas); free-space path loss; atmospheric absorption attenuation; ionospheric and tropospheric scintillation effects; shadowing fading; and clutter loss. It also supports S-band and Ka-band frequency configuration. Furthermore, the module provides a circular aperture antenna model to accurately simulate the radiation pattern of satellite antennas.

[0010] Simulator Setup: Based on the above analysis, this invention adopts a modular integration approach in its architecture design, fully reusing the existing mature functional modules of the ns3 platform, while making targeted extensions for the specific needs of mobile phone direct satellite connection scenarios. Specifically, this invention uses the LTE module built into ns3 as the protocol stack base, treating the user equipment (UE) in the terrestrial cellular network as the ground terminal in the mobile phone direct satellite connection scenario, and the base station (BS) as a satellite node operating in low Earth orbit. By attaching the aforementioned high-precision satellite mobility model to the BS node, the "base station in space" architecture design is achieved—an approach highly consistent with the 3GPP's proposed direction for spaceborne base station technology. Based on this, this invention deploys a large number of BS nodes in different orbital planes and orbital positions according to the parameterized configuration of a specified constellation configuration, constructing a large-scale low Earth orbit satellite constellation covering global or regional targets. Regarding the channel propagation model, this invention introduces a non-terrestrial network (NTN) channel model developed based on 3GPP standards to calculate physical layer propagation characteristics such as path loss, atmospheric absorption, scintillation effects, and Doppler shift in the satellite-to-ground link.

[0011] According to another aspect of the present invention, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps of the high-fidelity mobile phone direct satellite simulation method of the present invention.

[0012] According to another aspect of the present invention, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the high-fidelity mobile phone direct satellite simulation method of the present invention.

[0013] Compared with existing technologies, the beneficial effects of the above-described method of the present invention are as follows:

[0014] This invention achieves precise characterization of key parameters such as orbital inclination, right ascension of the ascending node, and phase factor by embedding a high-precision satellite motion model based on vector rotation. It can calculate the three-dimensional spatial position of the satellite at any time in real time and accurately reproduce the dynamic changes of physical effects such as Doppler shift and propagation delay, making the simulation results closer to the real satellite-to-ground link behavior.

[0015] This invention significantly improves constellation deployment efficiency. Addressing the problems of low deployment efficiency and difficulty in parameter adjustment caused by manually configuring satellite positions one by one or relying on externally imported trajectories via STK in existing technologies, this invention achieves Walker- The parameterized rapid generation of constellation configurations supports the one-click generation of large-scale constellations containing thousands of satellites with a small number of input parameters such as the number of orbital planes, the number of satellites per orbit, and phase factors, which greatly improves the simulation iteration efficiency of constellation configuration optimization and coverage analysis.

[0016] This invention achieves both completeness and realism in its protocol simulation. Addressing the shortcomings of existing tools like Matlab and Python, which lack standardized protocol stack implementations and cannot realistically simulate network layer behavior, this invention uses the ns3 built-in LTE module as the protocol foundation, fully preserving the complete protocol stack functions, including radio resource control, packet data aggregation protocol, radio link control, and media access control. Simultaneously, it introduces the NTN channel model to accurately characterize the propagation characteristics of the satellite-to-ground link, achieving for the first time on the ns3 platform the organic integration of a "complete protocol stack + high-precision channel," making the simulation conclusions valuable for engineering reference.

[0017] This invention enables dynamic closed-loop simulation. Addressing the functional fragmentation of existing NTN channel modules, which focus solely on link budget analysis, and LTE modules, which are only applicable to static scenarios, this invention establishes a complete causal driving chain of "orbital motion → channel change → protocol response." Real-time updates to satellite positions drive dynamic changes in channel parameters, thereby triggering protocol behaviors in the LTE protocol stack such as measurement reporting, handover decisions, and power control. This achieves a realistic simulation of the interaction between the dynamic channel environment and adaptive protocol mechanisms in a mobile phone-to-satellite system, filling the gap in existing tools for simulating the linkage between the protocol and physical layers.

[0018] This invention offers the advantage of ease of use through integrated design. It is entirely based on the ns3 open-source platform, eliminating the need for external trajectory import using commercial software such as STK. All functional modules are integrated using native ns3 code, allowing users to flexibly adjust simulation conditions such as constellation configuration, orbital parameters, and channel scenarios through configuration files, significantly reducing the barrier to entry and deployment complexity. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention.

[0020] Figure 1 This is a schematic diagram of a satellite constellation architecture in the ITRF coordinate system according to a preferred embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram of an LTE network architecture according to a preferred embodiment of the present invention;

[0022] Figure 3 This is a schematic diagram of a satellite simulator architecture according to a preferred embodiment of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention.

[0024] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0025] Example 1:

[0026] like Figure 1-3 As shown, this invention provides a high-fidelity mobile phone direct satellite connection simulation method, which abstracts satellite nodes as "base stations in the sky", uses the LTE module as the protocol processing core, and uses the NTN channel model as the physical layer propagation calculation engine to build a complete end-to-end simulation link.

[0027] To address the lack of native support for satellite orbital motion in existing ns3 modules, this invention directly embeds a high-precision satellite motion model based on vector rotation into the mobility management framework of the BS node.

[0028] This invention enables rapid parameterized deployment of large-scale low-Earth orbit satellite constellations.

[0029] This invention establishes a complete causal chain of "orbital motion → channel change → protocol response".

[0030] like Figure 1 The International Earth Reference System (ITRF) shown serves as a unified spatiotemporal reference standard, constructing a right-handed Cartesian coordinate system with the Earth's center as the origin: the X-axis lies in the equatorial plane and points to the vernal equinox; the Z-axis coincides with the Earth's rotation axis and points to the North Pole; and the Y-axis is perpendicular to the XOZ plane. In this coordinate system, the Earth is simplified as a uniform sphere with a radius of R = 6371 km. This invention assumes that all satellites orbit in circular orbits. The spatial orientation of each orbital plane is uniquely determined by two key parameters: the orbital inclination I, defined as the angle between the orbital plane and the Earth's equatorial plane; and the right ascension of the ascending node (RAAN) Ω, defined as the initial azimuth of the orbital plane within the equatorial plane, with the vernal equinox as the 0° reference (e.g., ...). Figure 1 (As shown by the red dot in the middle). The right ascension Ω of the ascending node and the orbital inclination I together determine the orientation of each orbital plane in three-dimensional space. For large-scale constellations containing multiple orbital planes, this invention adopts a uniform orbital plane distribution design. Assuming the constellation has a total of M orbital planes, and each orbital plane has the same orbital inclination I, then the right ascension of the ascending node of the m-th orbital plane is... Distributed uniformly in the equatorial plane according to the following formula:

[0031]

[0032] where m is the orbital plane index. Through this formula, the right ascension of the ascending node of each orbital plane is evenly distributed within the range of 0° to 360°, achieving a uniform layout of the orbital planes in space. Inside each orbital plane, the satellites are evenly distributed at equal intervals along a circular orbit. Let each orbital plane contain N satellites, and the orbital height from the ground be h. Then the orbital period and operating angular velocity of a single satellite can be derived from the orbital height in combination with the Earth's gravitational constant. To achieve global continuous coverage and minimize the coverage gap, the present invention adopts the Walker- constellation configuration as the default layout mode, which is also the classic configuration adopted by giant constellations such as Starlink. In the Walker- constellation, it is necessary to further determine the relative phase relationship between the satellites on different orbital planes. Taking the orbital plane 0 coinciding with the XOZ plane as the reference, and setting the satellite 0 on this plane at the intersection of the orbital path and the Z-axis, then the initial position of the satellite n on the orbital plane m can be defined as the longitude offset between this satellite and the satellite 0 on the orbital plane 0. The expression of

[0033]

[0034] is: where [[ID=...]] is the observation time deviation factor, used to compensate for the constellation rotation effect introduced by different observation times. The default value in the present invention is 0°; n is the serial number of the satellite within its orbital plane, and the value range is 0 ≤ n < N; F is the phase factor, which is the core adjustment parameter of the Walker- constellation, used to determine the relative phase offset between the satellites on adjacent orbital planes. The physical meaning of the phase factor F is that when F = 0, the satellites on all orbital planes are in exactly the same phase position, that is, the satellites on each orbital plane are aligned in the longitude direction; when F = 1, there is a complete phase offset period between the satellites on adjacent orbital planes, making the satellites staggered in the longitude direction, so as to obtain a more uniform global coverage effect with the same number of satellites. In practical applications, an appropriate value of F can be selected according to the coverage requirements and constellation scale. When necessary, fractional values between 0 and 1 can also be taken to achieve specific coverage characteristics.

[0035] Through the above parametric definition, the present invention realizes the Walker- A complete mathematical description of the constellation configuration. During simulation configuration, users only need to input a few parameters such as the number of orbital planes M, the number of satellites per plane N, the orbital inclination I, the orbital altitude h, and the phase factor F to quickly generate a large-scale low-Earth orbit constellation containing thousands of satellites. The initial spatial positions of all satellites can be calculated using the above formulas, providing an accurate spatial reference for subsequent orbital motion simulations and link performance analysis.

[0036] like Figure 1 As shown, the orbital motion of a satellite can be fully described by the following physical quantity: orbital velocity vector. Instantaneous position vector Initial position vector and the unit normal vector of the orbital plane Among them, the initial position vector The unit normal vector represents the satellite's spatial coordinates at time zero. The orientation of the orbital plane in space is characterized by both the orbital plane and the orbital plane, which can be derived from the constellation configuration parameters (orbital inclination I, right ascension of the ascending node Ω, and orbital altitude h) defined in the previous section. First, the unit normal vector of the orbital plane... Perpendicular to the plane of the satellite's orbit, its direction is determined by the right-hand rule (i.e., consistent with the direction of the satellite's angular momentum). Based on the geometric relationship between the orbital inclination I and the right ascension Ω of the ascending node, The component in the international Earth reference frame can be expressed as:

[0037]

[0038] This formula guarantees ,and The angle between the satellite and the Z-axis is exactly the orbital inclination angle I, and its projection direction in the equatorial plane is determined by Ω. Secondly, the satellite's initial position vector... Defined as the satellite's position relative to the Earth's center at time zero. To simplify the model, this invention assumes that the first satellite deployed in each plane is positioned near the intersection of the orbital plane and the Z-axis. Specifically, for satellite 0 on orbital plane 0, its initial position is located at the intersection of the positive Z-axis (northeast direction) and the orbit. For satellite n on any orbital plane m, its initial position needs to be determined according to Walker- The phase relationships of the constellation are rotated, but here we first give the initial position vector expression of a single satellite in its own orbital plane (corresponding to the case of satellite 0 on plane 0):

[0039]

[0040] This formula can be obtained by first rotating the unit vector pointing from the Earth's center to the North Pole around the X-axis by an inclination angle I, and then rotating it around the Z-axis by the right ascension of the ascending node Ω. The satellite moves at a constant speed along a circular orbit, and its motion can be represented by the average anomaly angle. Description. The average anomaly angle is defined as the angle swept by a satellite after it has traveled for a time t from its initial position at a constant angular velocity. Let the satellite's orbital period be T and its orbital circumference be... Orbital speed magnitude Given that the Earth's gravitational constant GM = 39.8600436, the average anomaly angle is... It can be represented as:

[0041]

[0042] The above formula shows that, As time increases linearly, the satellite rotates at a constant speed in its orbit. To obtain the satellite's instantaneous position vector at any time t... The initial position vector needs to be... Normal vector around the orbital plane Rotation angle This invention employs Rodrigues' rotation formula to achieve this three-dimensional rotation. This formula can rotate any vector about a unit axis in space by a given angle, and its expression is:

[0043]

[0044] The above formula consists of three terms, the first of which is In the normal vector The projection component (along the axis) remains unchanged during rotation; the second term is... Perpendicular to The projection components in the plane, rotation After the corner Attenuation; the third term is perpendicular to and The components spanning the plane are produced by the cross product, and their magnitude is determined by... Modulation. The sum of the three terms is the new vector after rotation.

[0045] Using the above model, this invention can calculate the Cartesian coordinates of each satellite in real time at any simulation moment. Specifically, in implementation, the simulator first calculates the Cartesian coordinates of each satellite based on the constellation configuration parameters (…). Calculate the initial position vectors of all satellites. (Requires Walker-) (Phase offset), and store the normal vector of each orbital plane. Subsequently, at each simulation time step, the average perigee angle of each satellite is calculated based on the current time t. The system then updates the positions of the satellites using the Rodriguez formula. This process is entirely analytical and requires no numerical integration, thus offering extremely high computational efficiency and enabling simulations of ultra-large constellations containing tens of thousands of satellites.

[0046] like Figure 2 As shown, this invention uses the ns3 LTE protocol stack as its foundation, abstracting satellite nodes as base stations (BS) and user terminals (UE) as terrestrial mobile phone users. To achieve mobility modeling of satellite nodes and simulation of satellite-to-ground link propagation characteristics, this invention extends the LTE module... Figure 3 The three core custom modules shown are: SatellitePositionAllocator, SatelliteMobilityModel, and ThreeGppNTNPropagationLossModel based on 3GPPPNTN channel propagation modeling. Additionally, to support satellite handover functionality, this invention extends the LteNetDevice in the LTE module, implementing the handover process between the UE and the satellite via the X2 interface.

[0047] The satellite position allocator module, also known as the satellite constellation architecture model mentioned earlier, is responsible for configuring the initial orbital parameters and initial phase of all satellites according to the constellation configuration parameters. This module receives constellation parameters input by the user, including the total number of orbital planes M, the number of satellites N in each orbital plane, the orbital inclination I, the orbital altitude h, and the Walker-... The phase factor F of the constellation. Based on formulas (1) and (2) above, this module calculates the right ascension Ωm of the ascending node of each orbital plane and the initial phase Фm,n of each satellite, thereby determining the spatial position reference of all satellites at the start of the simulation. Through this module, users can flexibly configure various constellation configurations, such as Starlink, OneWeb, or custom constellations, to achieve rapid deployment of large-scale constellations.

[0048] The satellite motion model module is responsible for calculating the satellite's spatial position at any simulation moment in real time. This module first obtains the orbital parameters (I, Ω, h) of each satellite from the satellite position allocator, and calculates the unit normal vector of the orbital plane according to formulas (3) and (4). and initial position vector Subsequently, based on the current simulation time t and the orbital velocity v derived from the satellite's orbital altitude, the average perigee angle is calculated using formula (5). Finally, , and Substituting into the Rodriguez rotation formula (6), we obtain the instantaneous position vector after rotation. This process is executed once per simulation time step, thus accurately simulating the continuous motion of a satellite along a circular orbit. This module is entirely based on analytical calculations, avoiding the overhead of numerical integration, and can efficiently support large-scale constellation simulations involving thousands of satellites.

[0049] The satellite propagation model module focuses on simulating the propagation characteristics of satellite-to-ground links, particularly large-scale fading effects. Based on the non-terrestrial network (NTN) channel model defined in the 3GPP TR 38.811 standard, this module calculates propagation losses such as path loss, atmospheric absorption attenuation, and scintillation effects based on real-time distance between the satellite and the ground-based UE, carrier frequency, and elevation angle, thereby determining the received power. This module provides an accurate propagation environment for link-level simulation, enabling simulation results to truly reflect the physical layer characteristics of satellite-to-ground communication.

[0050] In satellite networks, due to the high-speed movement of satellites relative to ground users, the coverage time of a single satellite over a specific ground area is typically only a few minutes. Therefore, handover management is crucial for ensuring communication continuity. This invention implements a Conditional Handover (CHO) mechanism based on the LTE protocol stack and integrates two classic handover strategies: Closest Satellite Handover (CSHO) and Maximum Visibility Handover (MVHO). In the CSHO strategy, the UE always selects the nearest satellite as the serving satellite; in the MVHO strategy, the UE selects the satellite with the longest remaining visibility time to reduce the handover frequency. Both strategies use dedicated monitoring functions to track the distance and visibility status between the satellite and the UE in real time. When a preset handover condition (such as the distance to the current serving satellite exceeding a threshold or the remaining visibility time falling below a threshold) is triggered, the simulator initiates a handover request through the LteHelper::HandoverRequest method. The request further invokes the source satellite's DoHandoverRequest method, which sends a handover signaling message (SendHandoverRequest) to the target satellite via the X2 interface from the source satellite's Radio Resource Control (RRC) layer, completing the UE's migration from the source satellite to the target satellite. This process fully simulates the handover signaling interaction process defined in the 3GPP standard, ensuring protocol consistency in the handover simulation.

[0051] On the service side, this invention deploys a UDP-based packet sender and receiver on the remote host and UE, respectively. The downlink data stream generated by the remote host is forwarded through the evolved packet core (EPC) to the satellite node acting as a base station, and then transmitted to the UE via the air interface. This end-to-end path allows the simulator to realistically evaluate performance metrics such as throughput, latency, and packet loss rate of downlink data transmission under a dynamic constellation topology.

[0052] Through the integration and expansion of the above modules, this invention achieves, for the first time, a full-chain simulation on the ns3 platform, encompassing constellation deployment, orbital motion, channel propagation, and protocol switching, providing a complete technical tool for the design and verification of mobile phone-to-satellite communication systems. Users can flexibly adjust constellation parameters, switching strategies, and service models through configuration files to conduct simulation experiments in various scenarios.

[0053] In summary, by deeply integrating the above modules with the high-precision satellite mobility model and parameterized constellation architecture generation module proposed in this invention, the present invention achieves the replacement and upgrade of the LTE module mobility framework and the protocol layer behavior driving of the NTN channel module. This constructs a comprehensive simulation platform that can simultaneously support large-scale constellation rapid deployment, high-precision orbital motion simulation, satellite-to-ground link dynamic propagation calculation, and complete LTE protocol stack simulation, providing complete toolchain support for the design and verification of mobile phone direct satellite communication systems.

[0054] Example 2:

[0055] The computer-readable storage medium of this embodiment stores a computer program that, when executed by a processor, implements the steps in the high-fidelity mobile phone direct satellite simulation method of Embodiment 1.

[0056] The computer-readable storage medium in this embodiment can be an internal storage unit of the terminal, such as the terminal's hard disk or memory; the computer-readable storage medium in this embodiment can also be an external storage device of the terminal, such as a plug-in hard disk, smart memory card, secure digital card, flash memory card, etc. equipped on the terminal; furthermore, the computer-readable storage medium can include both the terminal's internal storage unit and external storage devices.

[0057] The computer-readable storage medium of this embodiment is used to store computer programs and other programs and data required by the terminal. The computer-readable storage medium can also be used to temporarily store data that has been output or will be output.

[0058] Example 3:

[0059] The computer device of this embodiment includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps in the high-fidelity mobile phone direct satellite simulation method of Embodiment 1.

[0060] In this embodiment, the processor can be a central processing unit, or other general-purpose processors, digital signal processors, application-specific integrated circuits, off-the-shelf programmable gate arrays or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor, etc. The memory can include read-only memory and random access memory, and provides instructions and data to the processor. A portion of the memory can also include non-volatile random access memory. For example, the memory can also store device type information.

[0061] Those skilled in the art will understand that the content disclosed in the embodiments can be provided as a method, system, or computer program product. Therefore, this solution can take the form of a hardware embodiment, a software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this solution can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage and optical storage) containing computer-usable program code.

[0062] This solution is described with reference to flowchart illustrations and / or block diagrams of methods and computer program products according to embodiments of this solution. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing device, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0063] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0064] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0065] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0066] The examples described herein are merely preferred embodiments of the invention and are not intended to limit the concept and scope of the invention. Any modifications and improvements made by those skilled in the art to the technical solutions of the invention without departing from the design concept of the invention should fall within the protection scope of the invention.

[0067] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the specific embodiments described above. The specific embodiments and descriptions in the specification are merely for further illustrating the principles of the invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the claims and their equivalents.

Claims

1. A high-fidelity mobile phone direct satellite connection simulation method, characterized in that, Includes the following steps: Construct a satellite constellation architecture model; Construct a satellite movement model; The ns3 integrates an LTE module and a 3GPP NTN channel model; The simulator is built using a modular integration architecture, with the LTE module built into the ns3 as the protocol stack base. User equipment in the terrestrial cellular network is regarded as a ground terminal in the scenario of direct connection between mobile phones and satellites, and base stations are regarded as satellite nodes operating in low Earth orbit. By attaching the aforementioned high-precision satellite motion model to the base station node, the architecture design of "base station in the sky" is realized.

2. The method as described in claim 1, characterized in that, The specific steps for constructing the satellite constellation architecture model are as follows: First, a geometric kinematic model of a low Earth orbit satellite constellation is established, using the International Earth Reference System as a unified spatiotemporal reference benchmark; the Earth is simplified as a sphere with a radius of R = 6371 km, with the Earth's center as the origin of the coordinate system; the X-axis lies in the equatorial plane and points to the vernal equinox, the Z-axis coincides with the Earth's rotation axis and points to the North Pole, and the Y-axis is perpendicular to the XOZ plane, together forming a right-handed Cartesian coordinate system; it is assumed that all satellites orbit along circular orbits, and the spatial orientation of each orbital plane is characterized by two key parameters: orbital inclination, defining the angle between the orbital plane and the Earth's equatorial plane; and the right ascension of the ascending node, specifying the initial orientation of the orbital plane in space; satellites are uniformly distributed within each orbital plane, and the relative phase between satellites on adjacent orbital planes is controlled by a phase factor; for Walker-based constellations represented by Starlink... The constellation configuration introduces a phase factor F to adjust the phase offset between planes: when F=0, the satellites on all orbital planes are in phase; when F=1, a more uniform global coverage distribution is generated; by adjusting the constellation parameters, various mainstream and customized LEO constellation architectures can be reproduced.

3. The method as described in claim 2, characterized in that, The specific steps for constructing the satellite movement model are as follows: A satellite motion model based on vector rotation is constructed. The satellite motion model based on vector rotation uses the international Earth reference frame as a reference and assumes that the satellite moves at a constant speed along a circular orbit. The motion state is uniquely determined by the orbital velocity vector, instantaneous position vector, initial position vector and unit normal vector of the orbital plane.

4. The method as described in claim 3, characterized in that, The initial position vector and normal vector can be pre-calculated based on constellation orbital parameters such as orbital inclination and right ascension of the ascending node, respectively representing the satellite's spatial coordinates and spatial orientation of the orbital plane at time zero. The motion of a satellite in its orbit is characterized by the uniform rotation of its position vector around its normal vector, with the rotation angle being the mean anomaly angle, which increases with time. To calculate the instantaneous position vector after rotating by any angle from the initial position vector, the Rodriguez rotation formula is used to achieve three-dimensional rotation of the vector around any axis in space.

5. The method as described in claim 4, characterized in that, The simulator setup is as follows: The architecture design adopts a modular integration approach. The LTE module built into ns3 serves as the protocol stack base, treating user equipment in the terrestrial cellular network as a ground terminal in a scenario where the mobile phone directly connects to the satellite, and the base station as a satellite node operating in low Earth orbit. By attaching the aforementioned high-precision satellite mobility model to the BS node, the "base station in the sky" architecture design is realized. According to the parameterized configuration of the specified constellation configuration, a large number of BS nodes are deployed in different orbital planes and orbital positions to build a large-scale low Earth orbit satellite constellation covering global or regional targets. In terms of channel propagation model, a non-terrestrial network channel model developed based on the 3GPP standard is introduced to calculate the physical layer propagation characteristics such as path loss, atmospheric absorption, scintillation effect, and Doppler shift in the satellite-to-ground link.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by the processor, it implements the steps in the high-fidelity mobile phone direct satellite simulation method as described in any one of claims 1 to 5.

7. A computer 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, it implements the steps in the high-fidelity mobile phone direct satellite simulation method as described in any one of claims 1 to 5.

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