Non-terrestrial network multi-user dynamic channel simulation method and apparatus based on time slots

Abstract

The application relates to a time-slot-based non-ground network multi-user dynamic channel simulation method and device. The method comprises the following steps: constructing a communication link between each ground terminal simulation node and a satellite simulation node; calculating the link characteristics of each communication link based on the same satellite motion state deduction result according to a coarse-grained time step, and generating a corresponding large-scale channel parameter sequence; taking a standard time slot of a target communication system as a timing reference, respectively performing interpolation processing on the large-scale channel parameter sequence of each communication link to obtain a time-slot-level channel parameter, and configuring a standardized multipath delay line channel model by using the time-slot-level channel parameter; performing channel fading processing on a baseband sending signal generated based on the standard time slot timing through the configured channel model, and then performing time delay calibration and amplitude calibration to generate a dynamic channel output signal corresponding to each communication link. The method can improve the precision and operation efficiency of channel simulation in a multi-user non-ground network scene.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a method and apparatus for simulating multi-user dynamic channels in non-terrestrial networks based on time slots. Background Technology

[0002] With the development of technologies in the convergence of satellite internet and mobile communications, non-terrestrial network communication systems are gradually maturing. Wide-area signal coverage is achieved through satellite platforms deployed in low Earth orbit, medium Earth orbit, and geostationary orbit, providing ubiquitous connectivity services to terrestrial users. Among these, low Earth orbit satellite constellations, with their advantages of low latency and high throughput, have become the mainstream development direction of the current satellite communication industry. To support the research and development and performance verification of various non-terrestrial network communication systems, channel simulation is the core means to reproduce satellite-to-ground transmission characteristics and verify link performance. Currently, the industry has developed multiple technical approaches, including statistical modeling, hierarchical modeling, and timing adaptation.

[0003] However, in engineering applications of multi-user channel simulation in non-terrestrial networks, matching the time slot granularity of standardized communication to support link-level simulation requires a significant increase in the frequency of satellite orbit extrapolation and channel parameter calculation. This leads to a sharp increase in computational overhead in multi-user parallel scenarios, making the engineering implementation of the solution difficult. If coarse-grained calculations are used to control computational overhead, channel parameters will fluctuate within the time slot interval, failing to reproduce the continuously time-varying real transmission characteristics of low-Earth orbit satellite channels. Furthermore, large-scale time-varying parameters are difficult to smoothly adapt to standardized small-scale multipath channel models, and the output channel data cannot directly meet the high-precision performance verification requirements under standard communication timing. Summary of the Invention

[0004] Therefore, it is necessary to provide a time-slot-based method and apparatus for simulating multi-user dynamic channels in non-terrestrial networks to address the aforementioned technical problems.

[0005] A time-slot-based multi-user dynamic channel simulation method for non-terrestrial networks, the method comprising: Establish communication links between ground terminal simulation nodes and satellite simulation nodes in various regions; Based on the preset coarse-grained time step, the link characteristics of each communication link are calculated in batches according to the simulation results of the same satellite motion state, and the corresponding large-scale channel parameter sequence is generated. Using the standard time slots of the target communication system as the timing reference, the large-scale channel parameter sequences of each communication link are interpolated to obtain time slot-level channel parameters. The time slot-level channel parameters are then used to configure a standardized multipath delay line channel model. Acquire the baseband transmission signal generated based on the standard time slot timing, and perform channel fading processing on the baseband transmission signal using the configured channel model; The signal that has undergone channel fading is calibrated for time delay and amplitude to generate dynamic channel output signals for each communication link.

[0006] A time-slot-based multi-user dynamic channel simulation device for non-terrestrial networks, the device comprising: The link simulation module is used to construct communication links between ground terminal simulation nodes and satellite simulation nodes. The state inference module is used to batch calculate the link characteristics of each communication link based on the motion state inference results of the same satellite according to a preset coarse-grained time step, and generate the corresponding large-scale channel parameter sequence. The time slot interpolation module is used to interpolate the large-scale channel parameter sequences of each communication link based on the standard time slot of the target communication system to obtain time slot-level channel parameters, and to configure a standardized multipath delay line channel model using the time slot-level channel parameters. The channel fading module is used to acquire the baseband transmission signal generated based on the standard time slot timing and to perform channel fading processing on the baseband transmission signal using the configured channel model. The result output module is used to perform time delay calibration and amplitude calibration on the signal after channel fading processing, and generate dynamic channel output signals corresponding to each communication link.

[0007] The aforementioned time-slot-based multi-user dynamic channel simulation method and apparatus for non-terrestrial networks, by batch-calculating the characteristics of each communication link based on the same satellite motion state extrapolation results at a coarse-grained time step and generating a large-scale channel parameter sequence, can reduce the repetitive execution of high-complexity orbit extrapolation calculations, reduce the computational overhead of multi-user parallel simulation, and improve the operational efficiency of multi-link channel simulation. Using the standard time slot of the target communication system as a time-series reference, large-scale parameters are interpolated to obtain time-slot-level channel parameters, achieving temporal depth alignment between channel parameters and communication frame structure, ensuring continuous smoothness of time-slot dimension parameters, and outputting high-precision channel data conforming to protocol granularity. By configuring a standardized multipath delay line channel model using time-slot-level channel parameters and performing fading processing on the baseband signal, combined with delay and amplitude calibration, effective adaptation of large-scale time-varying characteristics and standard small-scale multipath effects can be achieved, restoring the true spatial signal transmission characteristics. This invention can balance the accuracy and computational efficiency of channel simulation in multi-user non-terrestrial network scenarios, outputting continuous dynamic channel results synchronized with time slots, and adapting to the engineering application requirements of link-level closed-loop simulation. Attached Figure Description

[0008] Figure 1 This is a flowchart illustrating a time-slot-based multi-user dynamic channel simulation method for non-terrestrial networks in one embodiment. Figure 2This is a flowchart of an NTN dynamic multi-user channel simulation method based on LEO ephemeris in one embodiment. Detailed Implementation

[0009] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0010] In one embodiment, such as Figure 1 As shown, a time-slot-based multi-user dynamic channel simulation method for non-terrestrial networks is provided, including the following steps: Step 102: Construct communication links between ground terminal simulation nodes and satellite simulation nodes.

[0011] Ground terminal simulation nodes and satellite simulation nodes are virtualized mappings of real ground communication terminals and satellites in the simulation system, respectively carrying simulation configuration attributes related to signal transmission and reception. The communication link between the two is a digital simulation mapping of the space signal transmission path between the satellite and the ground terminal, used to carry subsequent channel parameter calculations and signal processing.

[0012] Step 104: Based on the preset coarse-grained time step, calculate the link characteristics of each communication link in batches according to the simulation results of the same satellite motion state, and generate the corresponding large-scale channel parameter sequence.

[0013] Coarse-grained time steps are time sampling intervals set to be greater than the target communication time slot precision, used to reduce the frequency of high-complexity calculations. Satellite motion state simulation is a computational process based on satellite orbital parameters to calculate the satellite's position, velocity, and other motion attributes at each moment. Batch calculation means that the results of a single satellite state simulation are simultaneously applied to the parameter calculations of all links, eliminating the need to repeat the simulation calculations for each link. Link characteristics reflect the overall transmission attributes of the link; the corresponding large-scale channel parameter sequence is a discrete data set arranged in coarse-grained time order, containing propagation delay, Doppler shift, and path loss parameters.

[0014] It is understandable that this step can significantly reduce the number of times high-complexity orbit extrapolation calculations are performed, reduce the overall computing power overhead in multi-user scenarios, improve the running efficiency of multi-link simulation while ensuring the continuity of parameters over time, and help support channel simulation scenarios with large-scale terminals running in parallel.

[0015] Step 106: Using the standard time slot of the target communication system as the timing reference, interpolate the large-scale channel parameter sequences of each communication link to obtain time slot-level channel parameters, and use the time slot-level channel parameters to configure a standardized multipath delay line channel model.

[0016] The target communication system refers to the specific communication standard and protocol system adapted to and served by this channel simulation method. It is the underlying basis for defining standard time slot duration, frame structure, baseband signal format, and channel model specifications. The timing reference settings, channel parameter granularity, and signal processing rules throughout the simulation process must be consistent with the protocol standard of this system. In specific embodiments of this invention, the target communication system includes a 5G NR (5G New Radio) non-terrestrial network communication system, and can also be adapted to LTE mobile communication systems, next-generation 6G non-terrestrial communication systems, and other communication systems with standardized frame and time slot structures, depending on the simulation requirements.

[0017] A standard time slot is the smallest time scheduling unit defined by the target communication protocol and is the basic building block of the communication system's frame structure. The timing reference is the time alignment standard uniformly followed throughout the entire simulation process. Interpolation is a method of numerically fitting discrete, coarse-grained parameter points to obtain parameters at more concentrated time points. Time slot-level channel parameters are high-precision channel parameters that correspond one-to-one with the standard time slot times. The standardized multipath delay line channel model is a general channel model that conforms to industry standard definitions and simulates multipath fading effects through multiple signal paths with different delays.

[0018] It is understandable that this step can accurately map coarse-grained channel parameters to the standard time slot granularity of the communication protocol, ensure the continuous smoothness of parameters in the time slot dimension, achieve deep alignment between channel simulation timing and communication system frame structure, and facilitate the output of standardized channel data that can be directly used for link-level simulation.

[0019] Step 108: Obtain the baseband transmission signal generated based on the standard time slot timing, and perform channel fading processing on the baseband transmission signal using the configured channel model.

[0020] The baseband transmitted signal is the raw transmitted data signal conforming to the time slot format of the communication protocol. Channel fading processing is the signal processing procedure that addresses the amplitude, phase, and time delay changes of analog signals during spatial transmission due to effects such as multipath propagation and Doppler shift.

[0021] It is understandable that this step enables the synchronous loading of time-slot aligned signals and channel parameters, which can realistically reproduce the signal transmission fading characteristics in non-terrestrial network environments and is conducive to outputting channel simulation signals that conform to the laws of real space propagation.

[0022] Step 110: Perform time delay calibration and amplitude calibration on the signal processed by channel fading to generate dynamic channel output signals corresponding to each communication link.

[0023] Delay calibration is the process of compensating for and correcting the propagation delay caused by signal transmission in space, ensuring that the signal timing matches the system's timing requirements. Amplitude calibration is the process of matching and adjusting path loss during signal transmission, restoring the true signal attenuation level. The dynamic channel output signal is the final output signal corresponding to a single communication link after all channel effect simulations have been completed.

[0024] It is understandable that this step can accurately match the transmission delay and attenuation characteristics of different links, and can output dynamic channel simulation results that are synchronized with the time slot timing and whose parameters change continuously, which is beneficial for direct access to the subsequent baseband link-level simulation verification process.

[0025] In the aforementioned time-slot-based multi-user dynamic channel simulation method for non-terrestrial networks, the characteristics of each communication link are batch-calculated based on the same satellite motion state extrapolation results at a coarse-grained time step, generating a large-scale channel parameter sequence. This reduces the repetitive execution of highly complex orbit extrapolation calculations, lowers the computational overhead of multi-user parallel simulation, and improves the operational efficiency of multi-link channel simulation. Using the standard time slot of the target communication system as a time-series reference, large-scale parameters are interpolated to obtain time-slot-level channel parameters. This achieves temporal depth alignment between channel parameters and communication frame structure, ensuring continuous smoothness of time-slot-dimensional parameters and outputting high-precision channel data conforming to protocol granularity. By configuring a standardized multipath delay line channel model using time-slot-level channel parameters and performing fading processing on the baseband signal, combined with delay and amplitude calibration, effective adaptation of large-scale time-varying characteristics and standard small-scale multipath effects can be achieved, restoring the true spatial signal transmission characteristics. This embodiment of the invention can balance the accuracy and computational efficiency of channel simulation in multi-user non-terrestrial network scenarios, outputting continuous dynamic channel results synchronized with time slots, and adapting to the engineering application requirements of link-level closed-loop simulation.

[0026] In one embodiment, constructing communication links between ground terminal simulation nodes and satellite simulation nodes includes: constructing satellite simulation nodes based on pre-set satellite orbit parameters; constructing corresponding ground terminal simulation nodes based on the location parameters of multiple ground terminals; and mapping each ground terminal simulation node to a satellite simulation node to generate a corresponding communication link. In this embodiment, by constructing satellite simulation nodes and multiple ground terminal simulation nodes and completing link mapping, a multi-terminal parallel simulation topology can be built. This provides a standardized node and link foundation for subsequent unified batch parameter calculation across the entire link, supports simulation scenarios with parallel access from multiple geographically located terminals, improves the dynamic adaptation capability of multi-user, multi-link systems, and the solution has good scalability, adapting to the simulation needs of large-scale multi-user non-terrestrial networks.

[0027] In one embodiment, the process of batch calculating the link characteristics of each communication link based on the same satellite motion state simulation results according to a preset coarse-grained time step, and generating the corresponding large-scale channel parameter sequence, includes: simulating the satellite motion state based on the satellite orbit parameters used to construct the communication link, and performing a satellite motion state simulation calculation once at each coarse-grained time step; for the current coarse-grained time step, calculating the propagation delay, Doppler shift, and path loss parameters of each communication link in batches based on the satellite motion state obtained from the same simulation; and arranging the calculation results of each communication link at all coarse-grained time steps in the order of the coarse-grained time steps to generate the large-scale channel parameter sequence corresponding to each communication link.

[0028] In this embodiment, by performing satellite motion state simulation only once at each coarse-grained time step, and calculating the link characteristic parameters of all communication links in batches based on the same simulation result, the number of repeated executions of high-complexity orbit simulation calculations can be significantly reduced, reducing the computational overhead of multi-user parallel simulation. This constitutes a coarse-grained computational layer with a two-level computational architecture of coarse-grained sampling and time slot-level high-precision interpolation, providing unified coarse-grained data support for subsequent differentiated interpolation and continuous evolution within time slots. This improves the running efficiency of multi-link simulation while ensuring the time continuity of parameters, and eliminates the need to perform orbit calculations independently for each user, thus supporting large-scale terminal parallel channel simulation scenarios.

[0029] In one embodiment, using the standard time slots of the target communication system as the timing reference, the large-scale channel parameter sequences of each communication link are interpolated to obtain time slot-level channel parameters, including: using the boundary times of each standard time slot of the target communication system as interpolation nodes, interpolating the Doppler frequency shift parameter to obtain the Doppler zero-order value corresponding to each time slot boundary, and solving the first-order and second-order rates of change based on the Doppler zero-order values ​​of adjacent time slots; interpolating the propagation delay parameter to obtain the total delay value corresponding to each time slot boundary, and interpolating the path loss parameter to obtain the path loss value corresponding to each time slot boundary; and using the Doppler zero-order value, first-order rate of change, second-order rate of change, total delay value, and path loss value as the time slot-level channel parameters corresponding to each communication link.

[0030] In this embodiment, the standard time slots of the target communication system are used as a unified timing reference. Linear interpolation is performed on the large-scale parameters of each link to obtain time slot-level channel parameters, forming a two-level computational architecture with a high-precision time slot mapping layer. The first and second order rates of change of the Doppler frequency shift parameters are solved, and combined with the interpolated propagation delay and path loss parameters to form a complete set of time slot-level channel parameters. This allows for precise mapping of coarse-grained channel parameters to the standard protocol time slot granularity, achieving deep and strong coupling between the channel model and the communication time slots. It reconstructs the timing reference for channel simulation, ensuring complete alignment between the channel simulation timing and the communication system frame structure and baseband signal processing timing. Simultaneously, linear interpolation guarantees the continuous smoothness of time slot-dimensional parameters, adapting to the parameter input requirements of the standard multipath delay line channel model, ensuring smooth evolution of multipath phase, and achieving effective decoupling between large-scale and small-scale parameters. The output is high-precision channel data that can be directly used for link-level closed-loop simulation.

[0031] In one embodiment, configuring a standardized multipath delay line channel model using time slot-level channel parameters includes: at the boundary time of each standard time slot, using the Doppler zero-order value, first-order rate of change, and second-order rate of change in the time slot-level channel parameters as global time-varying parameters, and loading them into all multipath taps of the standardized multipath delay line channel model.

[0032] In this embodiment, the zero-order Doppler value and the rate of change of each order at the time slot boundary are loaded as global time-varying parameters into all multipath taps of the standardized multipath delay line channel model. Simultaneously, the path loss value is configured as the gain normalization reference into the multipath tap gain coefficient. This approach is compatible with various multipath channel models defined by existing 3GPP standards, retains the mature framework of hierarchical modeling of large-scale time-varying parameters and small-scale multipath parameters, strictly ensures the hierarchical decoupling characteristics of large-scale parameters and small-scale multipath parameters, and achieves effective adaptation of large-scale time-varying characteristics and standard small-scale multipath effects. It can seamlessly connect with standard channel parameters in different scenarios, inheriting the advantages of hierarchical modeling while ensuring the compliance and realism of channel simulation, and has strong engineering applicability.

[0033] In one embodiment, obtaining a baseband transmission signal generated based on a standard time slot timing sequence includes: generating baseband transmission data according to the standard time slot timing sequence, using the standard time slot of the target communication system as the generation granularity; and performing modulation and upsampling processing on the baseband transmission data to obtain a baseband transmission signal aligned with the standard time slot timing sequence.

[0034] In this embodiment, baseband transmission data is generated at the standard time slot as the generation granularity, and a timing-aligned baseband transmission signal is obtained through modulation and upsampling. This ensures that the timing of the baseband transmission signal is completely consistent with the timing reference of the channel parameters, achieving time slot-level synchronization between the signal side and the channel side. This further strengthens the deep coupling between channel simulation and communication protocol timing, provides timing-aligned signal input for subsequent channel fading processing, ensures the timing consistency of the entire link-level simulation process, and can be directly adapted to the baseband processing flow of the communication system.

[0035] In one embodiment, channel fading processing of the baseband transmitted signal using a configured channel model includes: inputting the baseband transmitted signal into a configured standardized multipath delay line channel model; within a single time slot, continuously updating the phase characteristics of each multipath tap based on the loaded Doppler parameters, and simultaneously adjusting the gain amplitude of each multipath tap according to the second-order Doppler rate of change, performing time delay weighting and phase modulation on the input signal to obtain the output signal of each multipath tap; matching the corresponding power of the path noise according to the real-time gain amplitude of each multipath tap, and superimposing the path noise onto the output signal of the corresponding multipath tap; synthesizing the output signals of all multipath taps to obtain the multipath fading signal; and superimposing global complex Gaussian white noise onto the multipath fading signal to obtain the channel fading processed signal.

[0036] In this embodiment, the baseband transmitted signal is processed using a standardized multipath delay line channel model. Continuous perturbations within the multipath gain time slot are driven by the second-order Doppler rate of change, achieving synchronous and smooth evolution of phase and amplitude. Delay-weighted and phase-modulated input signals are then applied to obtain the output signals for each path. A two-level superposition mechanism of path-level noise and global noise is employed, which better reflects the noise generation mechanism of a real receiving link. This allows for the realistic reproduction of spatial transmission characteristics such as multipath fading, time-varying Doppler, and noise interference in non-terrestrial network environments. Combined with time-slot aligned parameters and signal input, a channel simulation signal conforming to real propagation laws is output, further improving the physical realism and accuracy of the channel simulation results and supporting high-precision link-level performance verification.

[0037] In one embodiment, performing time delay calibration and amplitude calibration on the signal after channel fading processing to generate dynamic channel output signals corresponding to each communication link includes: performing propagation time delay calibration on the signal after channel fading processing to obtain a time delay calibration signal; performing amplitude calibration on the time delay calibration signal according to the path loss parameter in the time slot-level channel parameters to obtain an amplitude calibration signal; and outputting the amplitude calibration signal as the dynamic channel output signal of the corresponding communication link.

[0038] In this embodiment, the propagation delay and amplitude are calibrated sequentially on the fading signal. This accurately matches the transmission delay and attenuation characteristics of different communication links, outputting dynamic channel simulation results that are synchronized with the time slot timing and whose parameters change continuously. The calibration process is synchronized with the time slot-level channel parameters, ensuring the timing and amplitude accuracy of the output signal. This allows for direct integration into subsequent baseband link-level simulation verification processes, improving the engineering practicality of the solution.

[0039] In one embodiment, time delay calibration is achieved by cascading integer delay and fractional delay; the integer delay is achieved by shifting the signal sampling points; and the fractional delay is achieved by fractional delay filtering.

[0040] In this embodiment, delay calibration is achieved by cascading integer and fractional delays. Integer multiple delay adjustment is completed by shifting signal sampling points, and subsampling delay compensation is completed by fractional delay filtering. The total delay value at the time slot level obtained by interpolation is directly mapped to the delay decomposition process, achieving seamless connection between interpolation accuracy and calibration accuracy. This approach balances the computational efficiency and processing accuracy of delay calibration, accurately restores the propagation delay characteristics of the communication link, ensures the continuous smoothness of delay parameters in the time slot dimension, and further improves the accuracy and realism of channel simulation results.

[0041] In one specific embodiment, such as Figure 2 As shown, a flowchart of an NTN dynamic multi-user channel simulation method based on LEO ephemeris is presented, demonstrating the complete simulation architecture of the NTN dynamic channel. The method is divided into two main branches: parameter preprocessing and time-slot-level signal processing. The left side is the parameter preprocessing branch, which takes TLE ephemeris and multi-UE coordinates as input, and sequentially passes through satellite station construction, ground station UE construction, link establishment, communication link analysis, and channel data export stages to complete coarse-grained link characteristic calculation and parameter output. The right side is the signal processing branch, where the time-slot-based transmitted signal sequentially passes through the TDL channel module, noise module, delay module, and amplitude adjustment module. Simultaneously, it combines the channel parameters calculated based on the time slots to complete the full-link channel effect simulation, ultimately outputting the dynamic channel simulation results. Specifically, the following steps are included: Step S1: Model the satellite station and set up the receiver on the satellite station.

[0042] Import satellite data from the TLE file to create a low-Earth orbit satellite, denoted as LEO1, with an orbital altitude of 630 km. Set up a receiver on the satellite side. The main configuration parameters of the receiver include the receiving carrier frequency, antenna gain to system noise-temperature ratio, polarization, antenna pointing angle, and polarization isolation.

[0043] Step S2: Establish a ground station, i.e., UE, and set up a transmitter on the ground station.

[0044] To simulate communication link data between terminals in different geographical locations, terminal nodes are deployed at multiple ground locations and initiate communication with the satellite. The location of the first ground station is in region A {30.2186, 104.873, 0}, the location of the second ground station is in region B {39.9298, 116.388, 0}, and the location of the third ground station is in region C {31.1289, 117.533, 0}. Transmitters corresponding to the simulation requirements can be established at different ground stations. For example, the key configuration parameters of the transmitter are: carrier frequency 2 GHz, elevation angle range of 10 degrees to 90 degrees.

[0045] Step S3: Establish a communication link Based on the satellite station and ground station constructed in steps S1 and S2, transmission connections are established between the transmitting end of each ground station and the receiving end of the satellite station to form multiple communication links, which can be used to observe the dynamic access process between multiple satellite beams and multiple ground UEs.

[0046] Step S4: Communication link analysis.

[0047] For multiple communication links between the ground station transmitter and the satellite receiver, one link can be selected for analysis of the desired access range. Analysis parameters include propagation delay, propagation distance, Doppler shift, elevation angle, and free space loss. This yields the access details map for UE1-LEO1 in region A. Plotting the third access operation yields the characteristic curves of the Grach process.

[0048] Step S5: Export channel data.

[0049] For different access intervals, channel data at any time within the interval can be exported. It can be exported according to the elevation angle or the starting time period. The exported data types include propagation delay, propagation distance, Doppler frequency shift, elevation angle, and free space loss. The granularity of the exported data can be set to 0.01s.

[0050] Step S6: Channel parameter calculation.

[0051] This step generates slot-level Doppler parameters using linear interpolation. This selection is not a general interpolation scheme, but a specific design combining NTN-TDL channel model rules, LEO satellite motion characteristics, and 5G slot features. According to the 3GPPNTN-TDL model specification, the global Doppler frequency offset generated by satellite motion needs to be superimposed as a unified linear time-varying parameter on all multipath taps. In the short timescale of the 0.5ms standard slot in this embodiment, the radial velocity of the LEO satellite is approximately constant, and the Doppler frequency offset exhibits quasi-linear variation. Linear interpolation can accurately restore this physical characteristic, ensuring continuous evolution of multipath phase in the TDL model and effective decoupling of channel parameters at large and small scales. If other methods such as stepped values, high-order spline interpolation, or nonlinear interpolation are used, problems such as Doppler jumps, numerical oscillations, and model hierarchical failures will occur, failing to meet the standardized modeling requirements of NTN-TDL. At the same time, linear interpolation has low computational cost, adapting to the multi-user, high-precision, and high-efficiency simulation architecture of this embodiment.

[0052] This step performs time-slot-level interpolation calculations for Doppler parameters, TA characteristic parameters, and signal strength parameters. All parameters are updated based on the same time-slot boundary, as detailed below: 1) Calculation of Doppler parameters based on time slots.

[0053] Taking the start time t0 of the k-th 5G time slot as the expansion base point, for any time t∈[t0, t0+0.5ms] within the time slot, the Doppler frequency shift is expressed as: ; in: This is the Doppler frequency shift at the start of the time slot (zero-order term). This represents the first-order rate of change (slope) of the Doppler curve. This is the second-order Doppler rate of change (curvature).

[0054] The first and second rates of change mentioned above are calculated using the discrete central difference method: ; ; 2) Calculation of TA characteristic parameters based on time slots.

[0055] The frame length and time slot length settings are consistent with those in the Doppler parameter calculation section. The propagation delay data exported in step S5 is read, and linear interpolation is performed using the same time slot boundary time as interpolation nodes to obtain the total delay value corresponding to each time slot boundary. This value is then output to the delay calibration stage for delay decomposition. The communication start time can be set to 100.

[0056] 3) Signal strength parameters based on time slots The settings for frame length and time slot length remain consistent with the aforementioned sections. The path loss data exported in step S5 is read, and linear interpolation is performed using the same time slot boundary time as the interpolation node to obtain the path loss value corresponding to each time slot boundary. The communication start time can be set to 100. Using the same time slot reference and linear interpolation method as the time slot Doppler parameters, the time slot-level signal strength parameters arranged in time slot order are obtained.

[0057] Step S7: Signal generation.

[0058] Generate a time-slot-based 5G baseband transmission signal, with the signal's frame structure and time slot boundaries fully aligned with the timing reference of the channel parameters.

[0059] Step S8: NTN TDL Channel Module Combining the second-order Taylor expansion Doppler model from step S6, a complete calculation formula for multipath time-varying channels is constructed: ; in, For the first l The inherent multipath delay of the path, For the first l The real-time gain amplitude of the multipath is composed of the inherent gain of the standard multipath plus a time-slot perturbation term mapped by the second-order Doppler rate of change. The perturbation amplitude has a linear mapping relationship with the second-order Doppler rate of change. For the first l The corresponding path noise level, whose noise power matches the real-time gain amplitude of the path, is obtained from step S6. , , Substituting all values ​​into the above equation, parameter loading is completed at the time slot boundaries. Within the time slot, the phase and gain of each multipath tap are continuously updated to complete the NTN TDL channel simulation based on the second-order Doppler model. For the modeled channel, time slot-level Doppler correlation parameters obtained from the second-order Taylor expansion are injected. Among these, For the first l Path gain, For the first l Path delay.

[0060] Step S9: Noise module.

[0061] Noise is generated in two levels: radial noise and global noise. Path level noise generation: Calculate the corresponding path level noise power based on the real-time gain amplitude of each multipath tap, generate complex Gaussian white noise with the corresponding power, and superimpose it onto the output signal of the corresponding multipath tap; the noise power of the l-th path is proportional to the square of the gain amplitude of that path.

[0062] Global noise generation: Calculate noise power based on the preset simulation signal-to-noise ratio. Where SNR is the signal-to-noise ratio set in the simulation. Where N is the FFT length, Nrb is the number of RBs (resource blocks), and S is the signal power. Let be the number of receiving antennas. Global complex Gaussian white noise is generated based on the calculated global noise power and superimposed on the channel output signal. The corresponding expression is: ; ; in This is the multipath fading signal synthesized from the output signals of all multipath taps. This is the signal after adding global noise.

[0063] Step S10: Delay module (integer delay and fractional delay).

[0064] To address the multipath delay characteristics of NTN-TDL channels, a joint modeling of integer and fractional delays is achieved by combining time slot timing. Let the total delay of a single multipath path be... With the system baseband sampling period Based on this, the total delay is decomposed as follows: ; in: For the first The radius integer delay represents the integer number of sampling points. For the first The decimal delay satisfies , This is the system baseband sampling period.

[0065] Integer delay is achieved by shifting the sampling points, corresponding to the expression: ; Subsampling-level time delay compensation is achieved using a fractional delay filter, as shown in the following expression: ; In the formula This represents a fractional delay filtering operation. The final time-delay signal is obtained by concatenating the integer delay and the fractional delay.

[0066] Step S11: Amplitude adjustment module.

[0067] set up For the first Each time slot corresponds to a comprehensive link amplitude attenuation coefficient, which integrates parameters such as free space loss, antenna gain, and link-added loss. Its core value is derived from the time slot-level path loss value obtained through interpolation in step S6. The adjusted output signal is denoted as... The formula for adjusting the amplitude is: ; Amplitude attenuation coefficient The signal amplitude is updated synchronously at each time slot boundary and kept constant within the time slot, eventually completing the signal amplitude calibration of the entire link and outputting it to the subsequent processing unit.

[0068] It should be understood that, although Figure 1 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figure 1 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0069] In one embodiment, a time-slot-based multi-user dynamic channel simulation device for non-terrestrial networks is provided, comprising: The link simulation module is used to construct communication links between ground terminal simulation nodes and satellite simulation nodes. The state inference module is used to batch calculate the link characteristics of each communication link based on the motion state inference results of the same satellite according to a preset coarse-grained time step, and generate the corresponding large-scale channel parameter sequence. The time slot interpolation module is used to interpolate the large-scale channel parameter sequences of each communication link based on the standard time slot of the target communication system to obtain time slot-level channel parameters. The time slot-level channel parameters are then used to configure a standardized multipath delay line channel model. The channel fading module is used to acquire the baseband transmission signal generated based on the standard time slot timing and to perform channel fading processing on the baseband transmission signal through the configured channel model. The result output module is used to perform time delay calibration and amplitude calibration on the signal after channel fading processing, and generate dynamic channel output signals corresponding to each communication link.

[0070] Specific limitations regarding the time-slot-based multi-user dynamic channel simulation device for non-terrestrial networks can be found in the limitations of the time-slot-based multi-user dynamic channel simulation method for non-terrestrial networks described above, and will not be repeated here. Each module in the aforementioned time-slot-based multi-user dynamic channel simulation device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in hardware or independently of the processor in a computer device, or stored in software in the memory of a computer device, so that the processor can call and execute the operations corresponding to each module.

[0071] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0072] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A time-slot-based multi-user dynamic channel simulation method for non-terrestrial networks, characterized in that, The method includes: Establish communication links between ground terminal simulation nodes and satellite simulation nodes in various regions; Based on the preset coarse-grained time step, the link characteristics of each communication link are calculated in batches according to the simulation results of the same satellite motion state, and the corresponding large-scale channel parameter sequence is generated. Using the standard time slots of the target communication system as the timing reference, the large-scale channel parameter sequences of each communication link are interpolated to obtain time slot-level channel parameters. The time slot-level channel parameters are then used to configure a standardized multipath delay line channel model. Acquire the baseband transmission signal generated based on the standard time slot timing, and perform channel fading processing on the baseband transmission signal using the configured channel model; The signal that has undergone channel fading is calibrated for time delay and amplitude to generate dynamic channel output signals for each communication link. The step of batch calculating the link characteristics of each communication link based on the simulation results of the same satellite motion state according to a preset coarse-grained time step, and generating the corresponding large-scale channel parameter sequence includes: The satellite motion state is deduced based on the satellite orbit parameters used to construct the communication link, and a satellite motion state deduction calculation is performed once at each coarse-grained time step; For the current coarse-grained time step, based on the satellite motion state obtained from the same simulation, the propagation delay, Doppler shift and path loss parameters of each communication link are calculated in batches; The calculation results of each communication link at all coarse-grained time steps are arranged in the order of the coarse-grained time steps to generate a large-scale channel parameter sequence corresponding to each communication link. The process of interpolating the large-scale channel parameter sequences of each communication link using the standard time slots of the target communication system as the timing reference yields time slot-level channel parameters, including: Using the standard time slot boundary times of the target communication system as interpolation nodes, the Doppler frequency shift parameter is interpolated to obtain the Doppler zero-order value corresponding to each time slot boundary, and the first-order and second-order rates of change are solved based on the Doppler zero-order values ​​of adjacent time slots. The total delay value corresponding to each time slot boundary is obtained by interpolating the propagation delay parameter, and the path loss value corresponding to each time slot boundary is obtained by interpolating the path loss parameter. The zero-order Doppler value, first-order rate of change, second-order rate of change, total delay value, and path loss value are used as the time slot-level channel parameters for each communication link. The configuration of the standardized multipath delay line channel model using the time slot-level channel parameters includes: At the boundary time of each standard time slot, the Doppler zero-order value, first-order rate of change and second-order rate of change in the time slot-level channel parameters are used as global time-varying parameters and loaded into all multipath taps of the standardized multipath delay line channel model. The process of performing channel fading processing on the baseband transmitted signal using the configured channel model includes: The baseband transmission signal is input into a standardized multipath delay line channel model that has been configured. Within a single time slot, the phase characteristics of each multipath tap are continuously updated based on the loaded Doppler parameters. At the same time, the gain amplitude of each multipath tap is continuously adjusted according to the second-order Doppler rate of change. The input signal is then subjected to time delay weighting and phase modulation to obtain the output signal of each multipath tap. Match the corresponding power level noise to the real-time gain amplitude of each multipath tap, and then superimpose the level noise onto the output signal of the corresponding multipath tap. The output signals of all multipath taps are synthesized to obtain the multipath fading signal; Global complex white Gaussian noise is superimposed on the multipath fading signal to obtain a signal that has undergone channel fading processing.

2. The method according to claim 1, characterized in that, The construction of communication links between ground terminal simulation nodes and satellite simulation nodes includes: Based on pre-set satellite orbit parameters, construct satellite simulation nodes; Based on the location parameters of multiple ground terminals, corresponding ground terminal simulation nodes are constructed respectively; Each ground terminal simulation node is linked to a satellite simulation node to generate a corresponding communication link.

3. The method according to claim 1, characterized in that, The acquisition of the baseband transmission signal generated based on the standard time slot timing includes: The baseband transmission data is generated according to the standard time slot sequence of the target communication system, using the standard time slot as the generation granularity. The baseband transmission data is modulated and upsampled to obtain a baseband transmission signal aligned with the standard time slot timing.

4. The method according to claim 1, characterized in that, The step of performing time delay calibration and amplitude calibration on the signal after channel fading processing to generate dynamic channel output signals corresponding to each communication link includes: The propagation delay is calibrated on the signal that has undergone channel fading processing to obtain a delay calibration signal; The delay calibration signal is amplitude-calibrated based on the path loss parameter in the time slot-level channel parameters to obtain the amplitude calibration signal. The amplitude calibration signal is output as the dynamic channel output signal of the corresponding communication link.

5. The method according to claim 1, characterized in that, The time delay calibration is achieved by cascading integer delay and fractional delay; the integer delay is achieved by shifting the signal sampling points; and the fractional delay is achieved by fractional delay filtering.

6. A time-slot-based multi-user dynamic channel simulation device for non-terrestrial networks applied to the method described in any one of claims 1-5, characterized in that, The device includes: The link simulation module is used to construct communication links between ground terminal simulation nodes and satellite simulation nodes. The state inference module is used to batch calculate the link characteristics of each communication link based on the motion state inference results of the same satellite according to a preset coarse-grained time step, and generate the corresponding large-scale channel parameter sequence. The time slot interpolation module is used to interpolate the large-scale channel parameter sequences of each communication link based on the standard time slot of the target communication system to obtain time slot-level channel parameters, and to configure a standardized multipath delay line channel model using the time slot-level channel parameters. The channel fading module is used to acquire the baseband transmission signal generated based on the standard time slot timing and to perform channel fading processing on the baseband transmission signal using the configured channel model. The result output module is used to perform time delay calibration and amplitude calibration on the signal after channel fading processing, and generate dynamic channel output signals corresponding to each communication link.

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