Method and system for optimizing mixed transmission capacity of v2x system with high-low altitude platform cooperation

Abstract

The application discloses a kind of high-low altitude platform cooperation's V2X system hybrid transmission capacity optimization method and system, belong to vehicle networking technical field.The method includes: considering the heterogeneous channel characteristics, spectrum resource multiplexing mechanism and LAP distribution characteristics, construct three-layer heterogeneous V2X communication system model, design the mixed transmission strategy based on scene perception;Combining direct connection and relay link scene, construct time-varying CSI estimation model based on least square criterion;Based on time-varying CSI estimation model, combined with Palm theory and Laplace transform, deduce LAP existence probability, relay link distance expected value and system successful transmission probability;Establish relay transmission and direct transmission double scene capacity analysis model, extend the capacity expression under variable V2X link distance is deduced.The application improves transmission capacity and reliability under complex dynamic scene, provides theoretical basis and technical support for the deployment and optimization of high-low altitude cooperative V2X system.

Description

Technical Field

[0001] This invention belongs to the field of vehicle networking technology, specifically relating to a method and system for optimizing the hybrid transmission capacity of a V2X system that involves cooperation between high and low altitude platforms. Background Technology

[0002] With the rapid development of intelligent transportation and the low-altitude economy, vehicle-to-everything (V2X) communication, enabling real-time communication between vehicles and between vehicles and infrastructure, has become a key technology for achieving intelligent and safe transportation. By deploying onboard sensors and roadside units, V2X systems can monitor traffic flow, environmental parameters, and potential hazards in real time, thereby achieving data-driven intelligent decision-making and resource optimization. However, existing terrestrial communication infrastructure faces significant challenges in complex physical environments. High-rise buildings in cities, complex terrain in mountainous areas, and damage to facilities in remote areas after disasters often severely disrupt signal propagation paths, leading to degraded communication performance between base stations and edge users, making it difficult to meet the demand for full coverage. Against this backdrop, utilizing aerial platforms as mobile relays or aerial base stations has become a crucial method for solving communication blind spots.

[0003] While the addition of airborne platforms significantly enhances the coverage of V2X networks, the system still faces many bottlenecks in mixed scenarios with high vehicle density and high movement speeds. These factors include limitations on data transmission volume, high sensitivity to transmission delays, and severe signal interference. To address these challenges, establishing a three-layer heterogeneous network with cooperation between high-altitude and low-altitude platforms offers a feasible solution. A flexible hybrid transmission mode is also introduced to address different link distances and communication quality requirements. When direct ground communication is obstructed, the system automatically switches to a link using a low-altitude platform (LAP) relay or a high-altitude platform (HAP) cooperative link. This scenario-aware cooperative transmission mechanism maximizes spectral efficiency and overall system capacity while ensuring equitable user access and effectively mitigating co-channel interference in high-density environments.

[0004] Existing technology 1 proposes an optimization algorithm for V2X communication transmission strategy based on a single-layer low-altitude platform. First, a mathematical model is constructed for the V2X scenario where the UAV acts as the sole airborne relay, establishing a joint optimization problem between the UAV flight trajectory and spectrum resource allocation with the objective of minimizing system transmission latency. Then, an alternating optimization framework is used to decouple the original problem into two sub-problems: trajectory planning and resource scheduling. A convex optimization method is used to iteratively update the UAV's 3D trajectory, and a graph-based coloring algorithm is employed to complete multi-user spectrum allocation.

[0005] Existing technology two focuses on channel state information (CSI) estimation and compensation techniques in V2X high-speed mobile scenarios. Specifically, addressing the Doppler frequency shift problem caused by high-speed vehicle movement, this technology proposes a pilot-assisted adaptive CSI estimation model. This model comprehensively considers vehicle speed, multipath propagation delay spread, and time-frequency resource block allocation strategies, and introduces a variable-step-size minimum mean square adaptive filtering algorithm. Furthermore, a channel prediction-based CSI update mechanism is designed, using historical channel data to train a Long Short-Term Memory (LSTM) neural network to predict the channel state of future time slots, effectively mitigating the lag in CSI acquisition.

[0006] Existing technology three applies stochastic geometry theory to the performance analysis of air-to-ground integrated V2X communication networks. Specifically, a heterogeneous network model including ground base stations and UAV relays is constructed, modeling the spatial distribution of UAVs as a Poisson point process (PPP) and vehicle users as a Poisson line process (PLP). By deriving the probability density function of signal-to-interference-plus-noise ratio (SINR), closed-form expressions for system outage probability and coverage probability are obtained using Laplace transform. To improve spectral efficiency, this technology also introduces non-orthogonal multiple access (NOMA) technology and designs a distance-based user power allocation scheme.

[0007] However, the problem with existing technologies is: First, while existing technology one can optimize V2X transmission latency through a single low-altitude platform, it does not incorporate the wide-area collaborative capabilities of a high-altitude platform, resulting in limitations in its network architecture. Relying solely on a single low-altitude platform for relaying, it is prone to relay resource saturation in high-density user scenarios and lacks a balanced design between coverage breadth and access capacity, making it difficult to adapt to extreme scenarios such as large-scale disasters or ground base station failures.

[0008] Secondly, existing technology 2 focuses on CSI estimation in high-speed mobile scenarios, but does not take into account the three-dimensional network characteristics of high- and low-altitude platform cooperation, thus limiting its applicability. It only designs compensation mechanisms for direct ground connections or single-layer relay links, without considering the channel differences of heterogeneous air-ground links, and does not theoretically model macroscopic performance indicators such as system transmission capacity, thus failing to provide support for overall network optimization.

[0009] Finally, while existing technology three quantifies network performance using stochastic geometry theory, its channel assumptions and transmission mechanism design do not meet the requirements of actual V2X scenarios. It assumes an ideal static or slow-fading channel model, neglecting the Doppler shift caused by high-speed vehicle movement and the time-varying characteristics of the channel. Furthermore, it lacks a scene-aware adaptive transmission mode, leading to discrepancies between the theoretical derivations of outage and coverage probabilities and the actual system performance. This makes it difficult to cope with scenarios involving both complex obstructions and high-speed movement.

[0010] The difficulty in solving the above technical problems: First, addressing the limitations of single-layer low-altitude platform network architectures, existing technologies only optimize the resources and trajectories of a single low-altitude platform. A three-dimensional V2X network architecture coordinating high and low-altitude platforms is needed. This requires simultaneously considering the heterogeneous characteristics of wide-area coverage at high altitudes and short-range access at low altitudes, establishing a multi-objective optimization model for coverage breadth, access capacity, and transmission latency. This involves real-time perception and distributed decision-making of dynamic topologies across multiple platforms, presenting significant challenges in both theoretical modeling and engineering implementation of collaborative network resource allocation.

[0011] Secondly, addressing the issue that CSI estimation techniques are not adapted to heterogeneous three-dimensional networks, existing technologies only design channel compensation schemes for single links. It is necessary to integrate the fading differences between high- and low-altitude links with the Doppler frequency shift caused by high-speed vehicle movement to establish a joint estimation and prediction model for non-stationary time-varying channels. Simultaneously, it is necessary to balance channel estimation accuracy with computational complexity and to couple the microscopic channel state with macroscopic indicators such as system transmission capacity in the modeling, increasing the complexity of theoretical analysis.

[0012] Finally, addressing the issue that channel assumptions and transmission mechanisms do not align with real-world V2X scenarios, existing technologies derive performance metrics based on ideal static or slow-fading channels. It is necessary to break through the traditional static framework of stochastic geometry, introduce dynamic channel characteristics arising from high-speed movement and complex obstructions, and construct a unified performance analysis model that integrates dynamic fading. Designing scene-aware adaptive transmission modes is crucial to resolving the discrepancy between theoretical derivations and actual performance in scenarios involving high-speed movement and complex obstructions, placing stringent demands on interdisciplinary theoretical integration and real-time decision-making.

[0013] In summary, solving the above problems requires the comprehensive application of multidisciplinary methods such as network architecture design, time-varying channel modeling, stochastic geometric analysis, and intelligent optimization algorithms. It also requires consideration of the synergy of three-dimensional networks, the realism of channel modeling, and the dynamic adaptability of transmission strategies, as well as the rigor of theoretical analysis and the feasibility of engineering implementation. This places higher demands on the ability to integrate, innovate, and implement technologies. Summary of the Invention

[0014] The technical problem to be solved by the present invention is to provide a hybrid transmission capacity optimization method and system for V2X systems with high- and low-altitude platform cooperation, which addresses the shortcomings of the prior art. This method and system solves the technical problems of communication blind spots caused by complex physical environments, channel estimation failure caused by Doppler frequency shift due to high-speed vehicle movement, and system transmission capacity limitation caused by severe co-channel interference in air-ground integrated networks.

[0015] The present invention adopts the following technical solution: A method for optimizing the hybrid transmission capacity of a V2X system with high- and low-altitude platform collaboration includes the following steps: S1. Taking into account the channel characteristics, spectrum resource reuse mechanism, and static Poisson point process distribution characteristics of the links between the high-altitude platform (HAP) and ground users, the low-altitude platform (LAP) and ground users, and the links between ground users, a three-layer heterogeneous V2X communication system model is constructed, including HAP, multiple LAPs, and ground users. A scene-aware hybrid transmission strategy is designed. The hybrid transmission strategy adaptively selects direct transmission or LAP relay transmission mode according to the current channel state and LAP distribution. S2. Based on the three-layer heterogeneous V2X communication system model constructed in step S1, and combined with the direct link and relay link scenarios covered by the hybrid transmission strategy, a time-varying channel state information (CSI) estimation model based on the least squares criterion is constructed. S3. Based on the time-varying CSI estimation model obtained in step S2, and combined with the link selection probabilities corresponding to different transmission modes in the hybrid transmission strategy, the mathematical expressions for the LAP existence probability and the expected value of the relay link distance are derived using Palm theory and Laplace transform. Combined with co-channel interference analysis, the general form of the system's successful transmission probability is obtained. S4. Based on the LAP existence probability and successful transmission probability derived in step S3, and according to the decision mechanism of direct transmission and relay transmission in the hybrid transmission strategy, establish a transmission capacity analysis model for relay transmission and direct transmission scenarios in the underlying mode, and extend and derive the system transmission capacity expression under variable V2X link distance.

[0016] Preferably, in step S1, the specific process of constructing the three-layer heterogeneous V2X communication system model is as follows: The three-layer heterogeneous V2X communication system model is defined as including 1 HAP, M LAPs, and V ground users, with the horizontal coordinate of the HAP defined as follows: , No. m The horizontal coordinate of each LAP is , No. v The horizontal coordinates of the ground users are Configure coverage radius and transmission power for HAP and each LAP, set LAP to follow the static Poisson point process S-PPP distribution, and set terrestrial V2X users to follow the dynamic Poisson point process D-PPP distribution; set downlink relay links between terrestrial V2X users and LAP to share the same spectrum resources, and set HAP to use dedicated frequency bands to communicate with LAP and terrestrial V2X users.

[0017] Preferably, the specific process of designing a scene-aware hybrid transmission strategy is as follows: Establish line-of-sight Loss probability calculation formulas for HAP and ground users respectively. Non-line-of-sight (NLoS) probability calculation formula The formula for calculating the LosS probability of LAP and ground users NLoS probability calculation formula Path loss models and received power calculation models for links between HAP and ground users, LAP ground users, and ground users are established respectively. Based on the channel characteristics of each link and the availability of LAP relays, adaptive switching between direct ground connection, LAP relay, and HAP and LAP cooperative relay is realized.

[0018] Preferably, in step S2, the specific process of constructing the time-varying channel state information (CSI) estimation model based on the least squares criterion is as follows: Channel transmission characteristics of the direct link and the relay link are extracted separately, and observation models for CSI estimation are constructed for the two links respectively. ,in, For a moment i The received observation signal, For a moment i The known training sequence, It is additive white Gaussian noise. J This represents the number of sampling points; The CSI estimation problem is transformed using the least squares criterion. The objective function problem is solved by differentiating the objective function and setting the derivative to zero, thus obtaining the CSI least squares estimates for each of the two links. .

[0019] Preferably, the constructed time-varying channel state information (CSI) estimation model introduces a time-varying Doppler frequency shift positively correlated with vehicle speed into the Loss component of the CSI decomposition. ; is the superposition of NLoS components from CSI decomposition. N The time-varying Doppler frequency shift of each scattering path is used to complete the time-varying channel characteristic modeling of direct links and relay links.

[0020] Preferably, in step S3, the specific process of deriving the probability of LAP existence is as follows: Calculate the relay area between the V2X transmitter and receiver. Based on the hole probability characteristics of the S-PPP distribution of LAP, the probability of no LAP in the relay area is obtained. This leads to the derivation of the probability that at least one LAP exists within the relay region, i.e., the probability of LAP existence. Based on the uniform distribution characteristics of LAP in the relay area, the probability density function of horizontal distance is derived, and the expected value of relay link distance is obtained through integration. .

[0021] Preferably, the specific process of obtaining the general form of the system's successful transmission probability by combining co-channel interference analysis is as follows: Using the link selection probabilities of direct transmission and LAP relay transmission as weights, and ignoring thermal noise, the signal-to-interference ratio at a typical V2X receiver is derived. ;set up Minimum threshold Rayleigh fading coefficient based on terrestrial V2X links Following an exponential distribution with a unit mean, the probability of successful transmission is transformed into... Combining Laplace transform Decomposed into the Laplace transform product of V2X user and LAP accumulated interference. and This leads to the general form of the system's successful transmission probability, where, for, This represents the required transmission power of the transmitter.

[0022] Preferably, in step S4, the specific process of establishing the transmission capacity analysis models for both relay transmission and direct transmission scenarios under the underlying mode is as follows: For LAP relay transmission scenarios, a transmission capacity model is established based on the LAP existence probability Pexist and the system successful transmission probability obtained in step S3, combined with the ground V2X user distribution density λV2X. :

[0023] in, For the density of ground-based V2X user nodes, K Rice factor, The probability of LAP existence. and The probability of successful transmission from V2X to LAP and from LAP to V2X; For V2X direct transmission scenarios, establish a transmission capacity model. :

[0024] in, This represents the probability of successful V2X transmission via a direct link in the underlying mode. and The success probabilities of V2X to LAP and from LAP to V2X.

[0025] Preferably, in step S4, the specific process of extending and deriving the system transmission capacity expression under variable V2X link distance is as follows: Set the maximum transmission distance between the V2X transmitter and receiver. Minimum transmission distance Define V2X link distance exist The interval follows a uniform distribution, and its probability density function is: ; Assuming a sufficiently high potential LAP density, V2X communication will always receive LAP relay assistance, based on Compared to the LAP-assisted transmission capacity model in the underlying mode, the transmission capacity under variable V2X link distance is obtained through integral calculation. for:

[0026] in, It is the CDF of the standard normal distribution. and This is the core intermediate computational quantity in deriving the transmission capacity under variable V2X link distance. This represents the density of ground-based V2X user nodes.

[0027] Secondly, embodiments of the present invention provide a hybrid transmission capacity optimization system for V2X systems with high- and low-altitude platform cooperation, comprising: The modeling module is used to comprehensively consider the channel characteristics, spectrum resource reuse mechanism, and static Poisson point process distribution characteristics of the links between HAP and ground users, LAP and ground users, and links between ground users, to construct a three-layer heterogeneous V2X communication system model that includes HAP, multiple LAPs, and ground users, and to design a scene-aware hybrid transmission strategy. The hybrid transmission strategy adaptively selects direct transmission or LAP relay transmission mode according to the current channel state and LAP distribution. The estimation module is used to construct a time-varying channel state information (CSI) estimation model based on the least squares criterion, based on the model built by the modeling module and combined with the direct link and relay link scenarios covered by the hybrid transmission strategy. The derivation module is used to derive the mathematical expressions for the probability of LAP existence and the expected value of relay link distance based on the time-varying CSI estimation model obtained by the estimation module, combined with the link selection probabilities corresponding to different transmission modes in the hybrid transmission strategy, using Palm theory and Laplace transform, and combined with co-channel interference analysis to obtain the general form of the system's successful transmission probability. The analysis module is used to establish transmission capacity analysis models for two scenarios, namely relay transmission and direct transmission, based on the LAP existence probability and successful transmission probability derived by the derivation module and the decision mechanism of direct transmission and relay transmission in the hybrid transmission strategy. It also extends and derives the system transmission capacity expression under variable V2X link distance.

[0028] Thirdly, a computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the above-described method for optimizing the hybrid transmission capacity of a V2X system for high- and low-altitude platform cooperation.

[0029] Fourthly, embodiments of the present invention provide a computer-readable storage medium including a computer program, which, when executed by a processor, implements the steps of the above-described method for optimizing the hybrid transmission capacity of a V2X system with high- and low-altitude platform cooperation.

[0030] Fifthly, a chip includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the above-described method for optimizing the hybrid transmission capacity of a V2X system with high- and low-altitude platform cooperation.

[0031] In a sixth aspect, embodiments of the present invention provide an electronic device, including a computer program, wherein when the computer program is executed by the electronic device, it implements the steps of the above-described method for optimizing the hybrid transmission capacity of a V2X system with high and low altitude platform cooperation.

[0032] Compared with the prior art, the present invention has at least the following beneficial effects: A hybrid transmission capacity optimization method for V2X systems with high-altitude and low-altitude platform collaboration is proposed. This method addresses the coverage blind spot problem of ground infrastructure in obstructed environments by introducing a heterogeneous architecture that combines wide-area coverage from high-altitude platforms (HAPs) with flexible relaying from low-altitude platforms (LAPs). The designed scene-aware hybrid transmission strategy adaptively switches between direct transmission and LAP relaying based on real-time channel conditions and LAP distribution. This avoids communication interruptions in traditional fixed-mode transmissions when no LAPs are available, or unnecessary relay overhead in short-distance direct connections. It not only encompasses static network topology but also lays a solid physical foundation for subsequent capacity optimization through a dynamic link selection mechanism, achieving efficient utilization of network resources.

[0033] Furthermore, LAP and ground users are modeled as S-PPP and D-PPP distributions respectively, which fits the dynamic characteristics of actual deployment scenarios; through differentiated allocation of spectrum resources, co-channel interference is effectively avoided; the quantitative definition of node parameters provides a clear calculation basis for subsequent channel modeling and probability derivation, ensuring the operability and repeatability of the technical solution.

[0034] Furthermore, by constructing LoS / NLoS probability models for HAP and LAP respectively, as well as path loss and received power models for each link, accurate quantification of channel status was achieved. Based on the adaptive switching logic of channel characteristics and LAP relay availability, the scientific nature of transmission mode selection was ensured—utilizing the low-loss advantage of direct ground connection for short distances, and switching to air relay for long distances or obstructed scenarios to maximize spectrum efficiency. At the same time, the HAP and LAP cooperative relay mode was incorporated, breaking through the coverage limitations of a single relay and adapting to extreme scenarios such as large-scale disasters and remote areas.

[0035] Furthermore, the least squares criterion is used to transform the estimation problem into a solution of the objective function. The algorithm has clear logic, controllable computational complexity, and is easy to implement in engineering. The CSI estimate is solved by operations on the known training sequence and the received signal, which ensures the real-time performance and accuracy of the estimation results.

[0036] Furthermore, by introducing vehicle speed-related time-varying Doppler frequency shifts into the LoS component and superimposing time-varying Doppler frequency shifts from multiple scattering paths onto the NLoS component, the time-varying channel effects caused by high-speed vehicle movement are fully captured. This modeling method breaks through the static or slow fading channel assumptions of existing technologies, making the CSI estimation model more consistent with actual V2X scenarios. The superposition modeling of multi-path Doppler frequency shifts improves the accuracy of channel estimation under complex scattering environments and provides an accurate basis for dynamic channel parameter compensation.

[0037] Furthermore, by calculating the relay area and deriving the horizontal distance probability density function, and combining integral operations, the expected value of the relay link distance is obtained, providing a quantitative reference for link loss assessment and resource allocation. The entire derivation process is based on stochastic geometry theory, with rigorous logic and universal results, applicable to scenarios with different deployment densities and coverage radii.

[0038] Furthermore, by using the link selection probability as a weight and combining it with co-channel interference analysis to derive the SIR expression, the differences in transmission modes and the cumulative effect of interference are fully considered. Based on the distribution characteristics of the Rayleigh fading coefficient, the probability of successful transmission is transformed into a mathematical expectation solution, ensuring the theoretical rigor of the probability calculation. The cumulative interference is decomposed into the product of independent components using the Laplace transform, simplifying the computational complexity and realizing a closed-form expression of the probability of successful transmission.

[0039] Furthermore, by combining the LAP existence probability, successful transmission probability, and user density, capacity models for relay transmission and direct transmission were constructed respectively, enabling differentiated capacity assessment under different scenarios. The models incorporate the segmented successful transmission probabilities from V2X to LAP and from LAP to V2X, accurately reflecting the transmission characteristics of relay links.

[0040] Furthermore, by defining a uniform distribution and probability density function for link distance, the dynamic changes in link distance caused by vehicle movement in actual V2X scenarios are closely aligned. Based on the integral operation of the probability density function and the LAP-assisted capacity model, a capacity expression under variable link distance is derived, breaking through the limitations of existing technologies that focus on fixed link distance. Assuming that potential high-density LAPs guarantee relay availability, the analysis focuses on the impact of link distance changes on capacity, making the analysis more targeted.

[0041] It is understood that the beneficial effects of the second to sixth aspects mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here.

[0042] In summary, this invention solves the problems of coverage blind spots and interference in complex environments by constructing a high- and low-altitude heterogeneous network and scene perception strategy. By utilizing time-varying channel estimation and stochastic geometry theory, it achieves accurate quantification and dynamic optimization of transmission capacity, significantly improving the communication capacity and robustness of vehicle-to-everything (V2X) networks in high-speed movement and obstructed scenarios.

[0043] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0044] Figure 1 This is a flowchart of the method of the present invention; Figure 2 A schematic diagram of a V2X communication system for high- and low-altitude platform cooperation provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the relay area for LAPs assisting V2X users provided in an embodiment of the present invention; Figure 4 The present invention provides a curve showing the change in transmission capacity with LAP deployment density under different LAP deployment densities. Figure 5 The present invention provides a curve showing the transmission capacity as a function of V2X user density under different V2X user densities. Figure 6 The present invention provides a curve showing the change in transmission capacity with V2X link distance under different V2X link distances. Figure 7 The curves showing the change in transmission capacity with LoS probability provided in the embodiments of the present invention under different LoS probabilities; Figure 8 The present invention provides a curve showing the change in transmission capacity with vehicle speed under different vehicle speed conditions. Figure 9The curves showing the transmission capacity as a function of Loss probability provided by the embodiments of the present invention at different LAP flight altitudes are shown. Figure 10 The curves showing the transmission capacity as a function of LAP deployment density in this embodiment of the invention under different LAP coverage radii are shown. Figure 11 The curves showing how the transmission capacity changes with CSI estimation accuracy under different vehicle speeds are provided in the embodiments of the present invention. Figure 12 A schematic diagram of a computer device provided in an embodiment of the present invention; Figure 13 This is a block diagram of a chip provided according to an embodiment of the present invention.

[0045] Among them, 60. Computer equipment; 61. Processor; 62. Memory; 63. Computer program; 600. Electronic device; 610. Processing unit; 620. Storage unit; 6201. Random access memory unit; 6202. Cache memory unit; 6203. Read-only memory unit; 6204. Program / utility; 6205. Program module; 630. Bus; 640. Display unit; 650. Input / output interface; 660. Network adapter; 700. External device. Detailed Implementation

[0046] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0048] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0049] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this invention generally indicates that the preceding and following objects have an "or" relationship.

[0050] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0051] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0052] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0053] This invention provides a hybrid transmission capacity optimization method for V2X systems with high-altitude and low-altitude platform collaboration. First, the high-altitude platform (HAP) leverages its wide-area coverage to achieve communication control, while the low-altitude platform (LAP) uses a static Poisson point process distribution to complete flexible relaying. A scenario-aware hybrid transmission strategy is designed to achieve adaptive switching between ground direct connections and air relays. Then, addressing the Doppler shift problem caused by high-speed vehicle movement, a time-varying channel state information (CSI) estimation model based on the least squares (LS) criterion is constructed to accurately capture and compensate for dynamic channel parameters. Based on this, to comprehensively evaluate the system's theoretical performance, general expressions for the LAP existence probability, the expected value of the relay link distance, and the system's successful transmission probability are derived by combining Palm theory and Laplace transform. Simultaneously, system capacity analysis models for different transmission scenarios under the underlying mode are established, achieving precise optimization and quantitative performance analysis of V2X communication transmission capacity.

[0054] Please see Figure 1 The present invention discloses a method for optimizing the hybrid transmission capacity of a V2X system with high- and low-altitude platform cooperation, comprising the following steps: S1. Taking into account the channel characteristics, spectrum resource reuse mechanism, and static Poisson point process distribution characteristics of the links between HAP and ground users, LAP and ground users, and the links between ground users, a three-layer heterogeneous V2X communication system model including HAP, LAPs and ground users is constructed, and a scene-aware hybrid transmission strategy is designed. Please see Figure 2 , Figure 2 This is a schematic diagram of a V2X communication system for high- and low-altitude platform collaboration. Specifically, the system adopts a three-layer heterogeneous architecture, including one HAP and M LAPs (denoted as HAP). ) and V ground users (denoted as In this invention, the low-altitude platform is a quasi-fixed low-altitude platform, such as a quadcopter, balloon, or helicopter, and the ground users are vehicles and cellular users. Let the horizontal coordinate of the HAP be... Deployment height is , No. m The horizontal coordinate of each LAP is Deployment height is , No. v Horizontal coordinates of a ground user .

[0055] Each node is defined as follows: For a HAP node, the coverage radius is... Transmission power is For LAPs nodes, S-PPP is followed. This process is performed in a three-dimensional plane. The above is represented as Its density is The coverage radius is Transmission power is .

[0056] For terrestrial V2X user nodes, a dynamic Poisson point process (D-PPP) is followed. This process is performed in a three-dimensional plane. Represented as Its density is The horizontal distance between each V2X transmitter and its receiver on the ground is... Transmission power is It should be noted that the transmitting end of the V2X link is always a ground vehicle, while the receiving end can be other vehicles, pedestrians, or ground base stations. High-altitude and low-altitude platforms do not directly act as V2X nodes, but participate in communication as auxiliary relays or forwarders. When the distance between the LAP and both the V2X transmitter and receiver is less than... V2X communication can be relayed by one of the LAPs. If multiple LAPs are available, the transmitter will randomly select one for relaying. If data needs to be transmitted across regions, the signal can first be relayed from the LAP to the HAP, and then downlinked from the HAP to the LAP or ground node in the target area. It is assumed that the downlink relay links between ground V2X users and LAPs share the same spectrum resources. As a higher-layer relay node, the HAP will use a dedicated frequency band to communicate with both the LAP and ground V2X users, avoiding co-channel interference on their access links.

[0057] For ease of analysis, based on Palm theory, an arbitrary V2X receiver is selected from the system as a typical receiver and fixed at the origin of the three-dimensional coordinate system. This assumption does not change the statistical distribution of various types of nodes; it is merely to simplify the subsequent derivation of the probability of successful transmission and system capacity.

[0058] Because different types of links exhibit significant differences in line-of-sight probability, path loss models, and small-scale fading characteristics, these factors directly affect received signal power, interference accumulation effects, and signal-to-noise ratio distribution. Therefore, it is necessary to establish corresponding channel models for analysis to accurately reflect the propagation characteristics of various types of links.

[0059] Define separately and HAP and the first v The probability of Loss and the probability of non-line-of-sight (NLoS) among ground users.

[0060] Specifically, Represented as: (1) in, , and These are the basic occlusion coefficient, elevation angle sensitivity coefficient, and critical elevation angle threshold coefficient for HAP and ground users, respectively. For HAP and the first v The elevation angle between ground users is expressed as: (2) Define separately and HAP and the first v The path loss under the LoS probability and NLoS probability for each ground user is then... Represented as: (3) in, For carrier frequency, At the speed of light, and These are the additional loss factor and path loss exponent of HAP for ground links under the LoS probability, respectively. For HAP and the first v The Euclidean distance between ground users is expressed as: (4) Similarly, define and The first m The first LAP and the first v The Loss probability and NLoS probability among ground users are then Represented as: (5) in, , and The first m The LAP is related to the basic occlusion coefficient, elevation angle sensitivity coefficient, and critical elevation angle threshold coefficient of the ground user. For the first m The first LAP and the first v The elevation angle between ground users is expressed as: (6) Define separately and The first m The first LAP and the first v The path loss under the LoS probability and NLoS probability for each ground user is then... Represented as: (7) in, and These are the first and second probability values ​​under the Loss probability. m Each LAP has an additional loss factor and path loss index for ground links. For the first m The first LAP and the first v The Euclidean distance between ground users is expressed as: (8) In summary, HAP and the first v The received power of a ground user link is expressed as follows: (9) in, For HAP and the first v Transmission power of each ground user and HAP and the first-order HAP under LoS and NLoS probabilities respectively v The antenna gain of the first ground user, similarly, the antenna gain of the second ground user. m The first LAP and the first v The received power of a ground user link is expressed as follows: (10) in, For the first m The first LAP and the first v Transmission power of each ground user and The first and second digits under the LoS probability and NLoS probability respectively m The first LAP and the first v Antenna gain for each ground user.

[0061] Define separately and The first u The ground users to the first v The received power and transmitted power of each ground user, then Represented as: (11) in, and The first u The ground user and the first v Rayleigh fading coefficient and horizontal distance between ground users The path loss index for transmission links to ground users.

[0062] S2. Based on the obtained three-layer heterogeneous V2X communication system model, to address the Doppler frequency shift problem caused by high-speed vehicle movement, a time-varying channel state information (CSI) estimation model based on the least squares (LS) criterion is constructed. By accurately processing pilot signals, dynamic channel parameters are captured and compensated in real time. Because terrestrial V2X users are dynamically mobile, their high-speed movement introduces time-varying Doppler frequency shifts, which, combined with ground multipath scattering effects, cause channel characteristics to change rapidly over time, making it difficult to obtain CSI accurately in real time. To obtain CSI more accurately, a CSI estimation model is introduced. The least squares criterion is used to estimate the... e The transmitter and the first f CSI between receivers is represented as The estimation process is as follows: (12) in, K Rice factor, For the Loss component, The NLoS component follows a Rayleigh distribution.

[0063] Specifically, Affected by the speed of ground vehicles, Further expressed as:

[0064] in, For the initial phase, The frequency shift is time-varying and positively correlated with vehicle speed, specifically: ,in, For ground vehicles at time t Real-time movement speed, For the first e The transmitter to the first f Each receiver at time t The angle between the directions of signal propagation, The wavelength is the signal wavelength.

[0065] also, for N The superposition of scattering paths can be further expressed as:

[0066] in, N The number of scattering paths, For the first n The amplitude of each scattering path, For the first n The time-varying Doppler frequency shift of the scattering path is expressed as , For the first n The initial phase of the scattering path.

[0067] By using the least squares criterion and considering noise interference in actual communication, the observation model for the estimation process is assumed to be: (13) in, For a moment i The received observation signal, For a moment i Given training sequences that satisfy , It is additive white Gaussian noise. J This represents the number of sampling points.

[0068] Therefore, the estimation problem can be expressed as: (14) Based on this, taking the derivative of the objective function and setting the derivative to 0, we obtain the LS estimate of CSI: (15) in, for The conjugate of complex numbers.

[0069] S3. Using a combination of Palm theory and Laplace transform, based on the time-varying CSI estimation model, we derive mathematical expressions for the probability of LAP existence and the expected value of relay link distance, and combine this with co-channel interference analysis to obtain the general form of the system's successful transmission probability. S301, LAP existence probability and expected value of relay link distance Please see Figure 3 , Figure 3 A schematic diagram of the relay area for LAPs assisting V2X users. The horizontal distance between the V2X transmitter and receiver is... Furthermore, there exists a LAP whose distance to both the V2X transmitter and receiver is less than [a certain value]. LAP can assist in relaying data. The area of ​​this relay zone... It can be calculated using standard geometric formulas as follows: (16) Because LAPs nodes follow a density... S-PPP, based on the hole probability characteristics of S-PPP, a region with an area of The probability that there are no LAP nodes in the region is: (17) Therefore, the probability that at least one LAP exists within this relay region is, i.e., the probability of the existence of an LAP. Represented as: (18) definition The horizontal distance between the V2X user and the ground projection of the relay LAP is defined as the distance between the V2X user and the ground projection of the relay LAP. s arc length with radius Cross the shaded area. Because LAP is in the relay area. If it is uniformly distributed, then s The probability density function (PDF) Represented as: (19) Therefore, the expected value of the relay link distance between V2X users and LAP. Represented as: (20) make Substitute it into equation (20). Further expressed as: (twenty one) Using integration by parts, we can simplify equation (21) to obtain: (twenty two) Utilizing the substitution law Substitute it into equation (22). Further expressed as: (twenty three) make The expected value of the relay link distance between the V2X user and the LAP is obtained. , is represented as: (twenty four) S302, General form of the probability of successful transmission To obtain the general form of the probability of successful transmission, interference from downlink relay links from other V2X transmitters and LAPs is considered. Since spectrum sharing between V2X users and LAPs is primarily considered, this means that interference across the entire network is limited, and thermal noise is negligible. A typical V2X receiver represents a V2X communication system with high- and low-altitude platform cooperation. The signal-to-interference ratio (SIR) is expressed as: (25) in, For the required transmitter transmission power, and These represent the Rayleigh fading coefficient and horizontal distance between the required transmitter and a typical V2X receiver, respectively. and The cumulative interference from other ground-based V2X users or LAPs are represented as follows: (26) and (27) Therefore, the SIR of a typical V2X receiver is further expressed as: (28) To ensure the reliability of V2X communication, the receiver's SIR must meet a minimum threshold. ,Right now Therefore, the general form of the probability of successful transmission satisfies: (29) Due to the Rayleigh fading coefficient of terrestrial V2X links It follows an exponential distribution with a unit mean, and its PDF is... The corresponding cumulative distribution function (CDF) is: Then we get .

[0070] Therefore, equation (29) can be further expressed as: (30) in, For random variables and The mathematical expectation. Since terrestrial V2X users and LAPs follow two independent PPPs, the interference they generate is also independent of each other, so equation (30) can be further expressed as: (31) in, and The Laplace transforms of the cumulative interference from V2X users and LAPs are respectively expressed as: (32) and (33) in, , For having Gamma function of the form.

[0071] Substituting equations (32) and (33) into equation (31), we get the general form of the probability of successful transmission. Further expressed as: (34) S4. Establish transmission capacity analysis models for two scenarios under the underlying mode: relay transmission and direct transmission. At the same time, extend and derive the system transmission capacity expression under variable V2X link distance to achieve comprehensive quantitative analysis of transmission capacity.

[0072] S401, V2X transmission capacity assisted by LAP in low-level mode; In the lowest-level mode, terrestrial V2X users and LAPs share the same spectrum resources for their downlink relay links. Therefore, V2X receivers or LAP relay nodes in the system are simultaneously subjected to co-channel interference from other V2X transmitters and LAPs' downlinks. High-altitude platform (HAP) uses a dedicated frequency band and does not generate co-channel interference. To analyze the impact of LAP relay assistance on V2X transmission capacity, LAP assistance is discussed in two cases: Scenario 1: LAP relay transmission In this scenario, V2X communication is initiated only when an available LAP exists within the relay area; therefore, V2X communication only... The probability of a successful transmission from V2X to LAP and from LAP to V2X is expressed as follows: (35) and (36) The V2X transmission capacity in Case 1 of the underlying mode is expressed as follows: (37) Scenario 2: Direct V2X transmission In this scenario, V2X communication prioritizes LAP relays. If no available LAP is available in the relay area, V2X users transmit signals via direct links. First, the probability of successful V2X transmission via direct links in the underlying mode is expressed as: (38) Furthermore, in the underlying mode, the success probabilities of Case 2, from V2X to LAP and from LAP to V2X, are expressed as follows: (39) and (40) The V2X transmission capacity in Case 2 of the underlying mode is expressed as follows: (41) S402, V2X transmission capacity gain assisted by LAP in low-level mode; When there is no LAP in the underlying mode, the probability of successful transmission of a V2X link is expressed as: (42) The V2X transmission capacity without LAP in the underlying mode is expressed as follows: (43) In the underlying mode, the V2X transmission capacity gain brought by LAP in Case 1 and Case 2 can be expressed as follows: and .if and A value greater than 1 indicates that LAPs can provide performance gains for V2X transmission; conversely, a value less than 1 indicates better performance for V2X transmission using direct links. Furthermore, the higher the V2X density, the more LAPs can assist V2X users in transmitting signals, and the greater their impact on the system.

[0073] S403, Relay Transmission Capacity under Variable V2X Link Distance In the preliminary analysis, the link distance for V2X transmission was considered. The distance is set to a fixed value. However, in actual V2X communication scenarios, the dynamic movement of vehicles means that the link distance between the V2X transmitter and receiver is not a fixed value, but varies randomly over time. To make the theoretical analysis more consistent with actual deployment scenarios, the relay transmission capacity with variable V2X link distances will be analyzed next. Meanwhile, considering the effectiveness of LAP relays, a potential LAP density is assumed. Large enough, that is V2X communication can always obtain LAP relay assistance. Define separately. and The maximum and minimum transmission distances between the V2X transmitter and receiver are given, and the distance is given. exist The distribution in the middle follows a uniform distribution. Therefore... The PDF is represented as: (44) When V2X link distance exist When the range follows a uniform distribution, the transmission capacity of V2X with LAP in the underlying mode is expressed as: (45) in, It is the CDF of the standard normal distribution, and and They are represented as follows: (46) and (47) In another embodiment of the present invention, a hybrid transmission capacity optimization system for V2X systems with high- and low-altitude platform cooperation is provided. This system can be used to implement the above-mentioned hybrid transmission capacity optimization method for V2X systems with high- and low-altitude platform cooperation. Specifically, the hybrid transmission capacity optimization system for V2X systems with high- and low-altitude platform cooperation includes a modeling module, an estimation module, a derivation module, and an analysis module.

[0074] The modeling module is used to comprehensively consider the channel characteristics, spectrum resource reuse mechanism, and static Poisson point process distribution characteristics of the links between HAP and ground users, LAP and ground users, and links between ground users, to construct a three-layer heterogeneous V2X communication system model that includes HAP, multiple LAPs, and ground users, and to design a scene-aware hybrid transmission strategy. The hybrid transmission strategy adaptively selects direct transmission or LAP relay transmission mode according to the current channel state and LAP distribution. The estimation module is used to construct a time-varying channel state information (CSI) estimation model based on the least squares criterion, based on the model built by the modeling module and combined with the direct link and relay link scenarios covered by the hybrid transmission strategy. The derivation module is used to derive the mathematical expressions for the probability of LAP existence and the expected value of relay link distance based on the time-varying CSI estimation model obtained by the estimation module, combined with the link selection probabilities corresponding to different transmission modes in the hybrid transmission strategy, using Palm theory and Laplace transform, and combined with co-channel interference analysis to obtain the general form of the system's successful transmission probability. The analysis module is used to establish transmission capacity analysis models for two scenarios, namely relay transmission and direct transmission, based on the LAP existence probability and successful transmission probability derived by the derivation module and the decision mechanism of direct transmission and relay transmission in the hybrid transmission strategy. It also extends and derives the system transmission capacity expression under variable V2X link distance.

[0075] This invention provides a terminal device comprising a processor and a memory. The memory stores a computer program, which includes program instructions. The processor executes the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or other general-purpose processors, graphics processing units (GPUs), tensor processing units (TPUs), digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing and control core of the terminal, suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions to achieve a corresponding method flow or function. The processor described in this embodiment can be used in the operation of a hybrid transmission capacity optimization method for V2X systems with high- and low-altitude platform collaboration, including: Considering the channel characteristics, spectrum resource reuse mechanisms, and static Poisson point process distribution characteristics of the links between high-altitude platform (HAP) and ground users, low-altitude platform (LAP) and ground users, and links between ground users, a three-layer heterogeneous V2X communication system model is constructed, including HAP, multiple LAPs, and ground users. A scenario-aware hybrid transmission strategy is designed. This hybrid transmission strategy adaptively selects either direct transmission or LAP relay transmission mode based on the current channel state and LAP distribution. Based on the constructed three-layer heterogeneous V2X communication system model, and combining the direct link and relay link scenarios covered by the hybrid transmission strategy, a time-varying signal based on the least squares criterion is constructed. A Channel Status Information (CSI) estimation model is developed. Based on the obtained time-varying CSI estimation model, and combined with the link selection probabilities corresponding to different transmission modes in the hybrid transmission strategy, Palm theory and Laplace transform are used to derive mathematical expressions for the LAP existence probability and the expected value of the relay link distance. Combined with co-channel interference analysis, the general form of the system's successful transmission probability is obtained. Based on the derived LAP existence probability and successful transmission probability, and according to the decision mechanism of direct transmission and relay transmission in the hybrid transmission strategy, a transmission capacity analysis model for relay transmission and direct transmission scenarios under the underlying mode is established, and the system transmission capacity expression under variable V2X link distance is further derived.

[0076] Please see Figure 12The terminal device is a computer device. In this embodiment, the computer device 60 includes a processor 61, a memory 62, and a computer program 63 stored in the memory 62 and executable on the processor 61. When executed by the processor 61, the computer program 63 implements the hybrid transmission capacity optimization method for V2X systems with high- and low-altitude platform cooperation in this embodiment. To avoid repetition, these details are not elaborated here. Alternatively, when executed by the processor 61, the computer program 63 implements the functions of each model / unit in the hybrid transmission capacity optimization system for V2X systems with high- and low-altitude platform cooperation in this embodiment. To avoid repetition, these details are not elaborated here.

[0077] Computer device 60 can be a desktop computer, laptop, handheld computer, cloud server, or other computing device. Computer device 60 may include, but is not limited to, a processor 61 and a memory 62. Those skilled in the art will understand that... Figure 12 This is merely an example of computer device 60 and does not constitute a limitation on computer device 60. It may include more or fewer components than shown, or combine certain components, or different components. For example, computer device may also include input / output devices, network access devices, buses, etc.

[0078] The processor 61 may be a Central Processing Unit (CPU), or other general-purpose processors, graphics processing units (GPUs), tensor processing units (TPUs), digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0079] The memory 62 can be an internal storage unit of the computer device 60, such as a hard disk or memory of the computer device 60. The memory 62 can also be an external storage device of the computer device 60, such as a plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, etc. equipped on the computer device 60.

[0080] Furthermore, the memory 62 may include both internal storage units of the computer device 60 and external storage devices. The memory 62 is used to store computer programs and other programs and data required by the computer device. The memory 62 can also be used to temporarily store data that has been output or will be output.

[0081] Please see Figure 13 The terminal device is an electronic device 600, which is manifested in the form of a general-purpose computing device. The components of the electronic device may include, but are not limited to: at least one processing unit 610, at least one storage unit 620, a bus 630 connecting different platform components (including storage unit 620 and processing unit 610), a display unit 640, etc.

[0082] The storage unit stores program code, which can be executed by the processing unit 610 to perform the steps described in the method section of this specification according to various exemplary embodiments of the present invention. For example, the processing unit 610 can perform actions such as... Figure 1 The steps are shown in the figure.

[0083] Storage unit 620 may include a readable medium in the form of a volatile storage unit, such as random access memory (RAM) 6201 and / or cache memory 6202, and may further include a read-only memory (ROM) 6203.

[0084] Storage unit 620 may also include a program / utility 6204 having a set (at least one) program module 6205, such program module 6205 including but not limited to: operating system, one or more application programs, other program modules and program data, each or some combination of these examples may include an implementation of a network environment.

[0085] Bus 630 can represent one or more of several types of bus structures, including a memory cell bus or memory cell controller, a peripheral bus, a graphics acceleration port, a processing unit, or a local bus using any of the multiple bus structures.

[0086] Electronic device 600 can also communicate with one or more external devices 700 (e.g., keyboard, pointing device, Bluetooth device, etc.), and with one or more devices that enable a user to interact with electronic device 600, and / or with any device that enables electronic device 600 to communicate with one or more other computing devices (e.g., router, modem). This communication can be performed via input / output interface 650. Furthermore, electronic device 600 can also communicate with one or more networks (e.g., local area network, wide area network, and / or public network, such as the Internet) via network adapter 660. Network adapter 660 can communicate with other modules of electronic device 600 via bus 630. It should be understood that, although not shown in the figures, other hardware and / or software modules can be used in conjunction with electronic device 600, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage platforms.

[0087] Example 4 This invention also provides a storage medium, specifically a computer-readable storage medium, which is a memory device in a terminal device for storing programs and data. It is understood that the computer-readable storage medium here can include both built-in storage media in the terminal device and extended storage media supported by the terminal device; it can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, the storage space also stores one or more instructions suitable for loading and execution by a processor, which can be one or more computer programs (including program code). More specific examples of the computer-readable storage medium include: an electrical connection with one or more wires, a portable disk, a hard disk, random access memory, read-only memory, erasable programmable read-only memory, optical fiber, portable compact disk read-only memory, optical storage device, magnetic storage device, or any suitable combination thereof.

[0088] Computer-readable storage media also include data signals propagated in baseband or as part of a carrier wave, carrying readable program code. Such propagated data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A readable storage medium can also be any readable medium other than a readable storage medium that can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the readable storage medium can be transmitted using any suitable medium, including but not limited to wireless, wired, optical fiber, radio frequency, etc., or any suitable combination thereof.

[0089] Program code for performing the operations of this invention can be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java and C++, and conventional procedural programming languages ​​such as C or similar languages. The program code can execute entirely on the user's computing device, partially on the user's computing device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server. In cases involving remote computing devices, the remote computing device can be connected to the user's computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0090] One or more instructions stored in a computer-readable storage medium can be loaded and executed by a processor to implement the corresponding steps of the hybrid transmission capacity optimization method for V2X systems with high- and low-altitude platform cooperation in the above embodiments; one or more instructions in the computer-readable storage medium are loaded and executed by the processor in the following steps: Considering the channel characteristics, spectrum resource reuse mechanisms, and static Poisson point process distribution characteristics of the links between high-altitude platform (HAP) and ground users, low-altitude platform (LAP) and ground users, and links between ground users, a three-layer heterogeneous V2X communication system model is constructed, including HAP, multiple LAPs, and ground users. A scenario-aware hybrid transmission strategy is designed. This hybrid transmission strategy adaptively selects either direct transmission or LAP relay transmission mode based on the current channel state and LAP distribution. Based on the constructed three-layer heterogeneous V2X communication system model, and combining the direct link and relay link scenarios covered by the hybrid transmission strategy, a time-varying signal based on the least squares criterion is constructed. A Channel Status Information (CSI) estimation model is developed. Based on the obtained time-varying CSI estimation model, and combined with the link selection probabilities corresponding to different transmission modes in the hybrid transmission strategy, Palm theory and Laplace transform are used to derive mathematical expressions for the LAP existence probability and the expected value of the relay link distance. Combined with co-channel interference analysis, the general form of the system's successful transmission probability is obtained. Based on the derived LAP existence probability and successful transmission probability, and according to the decision mechanism of direct transmission and relay transmission in the hybrid transmission strategy, a transmission capacity analysis model for relay transmission and direct transmission scenarios under the underlying mode is established, and the system transmission capacity expression under variable V2X link distance is further derived.

[0091] The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0092] 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. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0093] This experiment simulates a hybrid transmission strategy and transmission capacity optimization method for collaborative V2X communication between high- and low-altitude platforms, as well as an existing mechanism based on the same network parameters, to verify the superiority of the method proposed in this invention. The specific steps are as follows: The key parameter settings are as follows: , , LAPs follow a density of 1 per km 2 S-PPP, , , Ground-based V2X users follow a density of 50 per km. 2 D-PPP, The horizontal distance between the transmitter and receiver on the ground follows a uniform distribution within the range of [200 m, 500 m]. , The system SIR threshold is set to 5 dB.

[0094] Please see Figure 4 and Figure 5 , Figure 4 The figure illustrates the trend of transmission capacity changing with LAP deployment density. As can be seen from the figure, the simulated transmission capacity curve of the proposed solution closely matches the theoretical curve, verifying the effectiveness of the theoretical analysis. With the increase of LAP deployment density, the transmission capacity of all solutions shows an upward trend. This is because the deployment of more LAPs increases the relay access probability. In particular, the proposed solution can fully utilize the advantages of line-of-sight transmission and multipath gain through high- and low-altitude cooperation, significantly increasing the capacity from approximately 62 bps / Hz to over 100 bps / Hz, consistently outperforming the comparative solutions. When the LAP density is low, the proposed solution can adaptively switch to a direct ground link to ensure basic capacity, while the comparative solutions are limited in performance due to insufficient relay resources. When the LAP density is high, the capacity growth rate of the proposed solution is significantly higher than that of solutions relying solely on ground links. Figure 5 The curves showing the change in transmission capacity with V2X user density further verify the advantages of the present invention in multi-user scenarios. As user density increases, the opportunities for multi-user diversity gain and spectrum reuse increase. The present invention effectively suppresses co-channel interference through high- and low-altitude cooperative architecture and accurate CSI estimation, and always maintains the highest transmission capacity. In contrast, the performance improvement of the comparison scheme is limited due to interference accumulation or relay resource saturation.

[0095] Please see Figure 6 and Figure 7 , Figure 6The data shows the trend of transmission capacity changing with V2X link distance. Since path loss increases significantly with distance, the transmission capacity of all schemes decreases, but the scheme of this invention maintains optimal performance. In short-distance scenarios, it can fully utilize the low-loss advantage of direct ground links to achieve high-capacity transmission; when the distance increases and ground link fading becomes severe, it can adaptively switch to LAP or HAP relay links, effectively overcoming signal blind spots and long-distance fading, exhibiting extremely strong robustness. In contrast, schemes relying solely on ground links experience a sharp decrease in capacity, while forced relay schemes perform worse than this invention in short-distance scenarios due to additional overhead. Figure 7 The curves showing the change in transmission capacity with LoS probability are presented. As the LoS probability increases, the capacity of all schemes increases. The scheme of this invention can not only take advantage of the high LoS probability of HAP and LAP, but also select the transmission path optimally through hybrid mode, and maximize beamforming gain by combining accurate CSI estimation, thus always maintaining the best performance. In contrast, the gain improvement of the ground link scheme is relatively slow due to the obstruction of obstacles.

[0096] Please see Figure 8 and Figure 9 , Figure 8 The diagram illustrates how transmission capacity changes with vehicle speed. As vehicle speed increases, the Doppler shift intensifies, leading to enhanced time-varying channel characteristics. While the transmission capacity of all schemes decreases, the scheme presented in this invention exhibits the most gradual decrease, demonstrating exceptional resilience against mobility challenges. This is because the time-varying CSI estimation model based on the LS criterion designed in this invention accurately captures Doppler shift and multipath scattering effects, effectively offsetting channel fluctuations caused by high-speed movement. In the comparison, the MIMO scheme relying on accurate CSI experiences a sharp capacity drop in high-speed scenarios, while the scheme relying solely on terrestrial links exhibits weak resistance to fast fading and the worst overall performance. Figure 9 The curves showing the transmission capacity as a function of Loss Probability at different LAP flight altitudes are presented. Under a fixed Loss probability, the lower the LAP flight altitude, the shorter the physical distance of the communication link, the smaller the path loss, and the higher the transmission capacity. The peak capacity of the scheme with the lower flight altitude can reach about 123 bps / Hz, while the peak capacity of the scheme with the higher altitude is only about 82 bps / Hz, revealing the nonlinear influence mechanism of LAP flight altitude on capacity.

[0097] Please see Figure 10 and Figure 11 , Figure 10The curves show the transmission capacity varying with LAP deployment density under different LAP coverage radii. In low-density LAP areas, a larger coverage radius expands the relay search range and increases the probability of LAP presence, thus the scheme with a larger coverage radius performs better. In high-density LAP areas, a smaller coverage radius shortens the link distance between V2X users and LAPs, reduces path loss, and improves the effective receive signal-to-noise ratio, thus the scheme with a smaller coverage radius performs better. Figure 11 The transmission capacity under different CSI estimation accuracies was compared. The capacity of the ideal CSI remained stable, while the capacity of the scheme without Doppler compensation dropped to 20 bps / Hz in high-speed scenarios. Although the transmission capacity of the proposed scheme decreased slightly with speed, it always closely followed the ideal CSI curve and was significantly better than the uncompensated scheme, which verified the effectiveness of the proposed LS criterion time-varying CSI estimation model.

[0098] In summary, this invention presents a hybrid transmission capacity optimization method and system for V2X systems involving high- and low-altitude platform collaboration. It constructs a three-layer heterogeneous network architecture and a scene-aware hybrid transmission strategy, designs a time-varying CSI estimation model based on the LS criterion, and derives general expressions for the LAP existence probability, the expected value of the relay link distance, and the probability of successful transmission by combining Palm theory and Laplace transform. Simulation verification shows that the proposed solution significantly outperforms existing solutions in transmission capacity under various scenarios such as LAP deployment density, user density, link distance, and vehicle speed, and can cope with complex dynamic environments through adaptive mechanisms and accurate channel estimation. This invention can provide theoretical basis and technical support for parameter configuration, resource scheduling, and practical deployment of high- and low-altitude collaborative V2X communication systems.

[0099] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0100] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0101] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed in this invention can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0102] In the embodiments provided by this invention, it should be understood that the disclosed devices / terminals and methods can be implemented in other ways. For example, the device / terminal embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0103] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0104] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0105] If the integrated module / unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random-access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0106] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus, and computer program products according to embodiments of this application. It will 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 apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0107] 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.

[0108] 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.

[0109] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for optimizing the hybrid transmission capacity of a V2X system with high- and low-altitude platform cooperation, characterized in that, Includes the following steps: S1. Taking into account the channel characteristics, spectrum resource reuse mechanism, and static Poisson point process distribution characteristics of the links between the high-altitude platform (HAP) and ground users, the low-altitude platform (LAP) and ground users, and the links between ground users, a three-layer heterogeneous V2X communication system model is constructed, including HAP, multiple LAPs, and ground users. A scene-aware hybrid transmission strategy is designed. The hybrid transmission strategy adaptively selects direct transmission or LAP relay transmission mode according to the current channel state and LAP distribution. S2. Based on the three-layer heterogeneous V2X communication system model constructed in step S1, and combined with the direct link and relay link scenarios covered by the hybrid transmission strategy, a time-varying channel state information (CSI) estimation model based on the least squares criterion is constructed. S3. Based on the time-varying CSI estimation model obtained in step S2, and combined with the link selection probabilities corresponding to different transmission modes in the hybrid transmission strategy, the mathematical expressions for the LAP existence probability and the expected value of the relay link distance are derived using Palm theory and Laplace transform. Combined with co-channel interference analysis, the general form of the system's successful transmission probability is obtained. S4. Based on the LAP existence probability and successful transmission probability derived in step S3, and according to the decision mechanism of direct transmission and relay transmission in the hybrid transmission strategy, establish a transmission capacity analysis model for relay transmission and direct transmission scenarios in the underlying mode, and extend and derive the system transmission capacity expression under variable V2X link distance.

2. The method of claim 1, wherein, In step S1, the specific process of constructing the three-layer heterogeneous V2X communication system model is as follows: The three-layer heterogeneous V2X communication system model is defined as including 1 HAP, M LAPs, and V ground users, with the horizontal coordinate of the HAP defined as follows: , No. m The horizontal coordinate of each LAP is , No. v The horizontal coordinates of the ground users are Configure coverage radius and transmission power for HAP and each LAP, set LAP to follow the static Poisson point process S-PPP distribution, and set terrestrial V2X users to follow the dynamic Poisson point process D-PPP distribution; set downlink relay links between terrestrial V2X users and LAP to share the same spectrum resources, and set HAP to use dedicated frequency bands to communicate with LAP and terrestrial V2X users. 3.The method of claim 2, wherein, The specific process of designing a scene-aware hybrid transmission strategy is as follows: Establish line-of-sight Loss probability calculation formulas for HAP and ground users respectively. Non-line-of-sight (NLoS) probability calculation formula The formula for calculating the LosS probability of LAP and ground users NLoS probability calculation formula ; Path loss models and received power calculation models for links between HAP and ground users, LAP ground users, and ground users are established respectively. Based on the channel characteristics of each link and the availability of LAP relays, adaptive switching between direct ground connection, LAP relay, and HAP and LAP cooperative relay is realized.

4. The method for optimizing the hybrid transmission capacity of a V2X system with high- and low-altitude platform cooperation according to claim 1, characterized in that, In step S2, the specific process of constructing the time-varying channel state information (CSI) estimation model based on the least squares criterion is as follows: Channel transmission characteristics of the direct link and the relay link are extracted separately, and observation models for CSI estimation are constructed for the two links respectively. ,in, For a moment i The received observation signal, For a moment i The known training sequence, It is additive white Gaussian noise. J This represents the number of sampling points; The CSI estimation problem is converted into a target function solving problem of by using the least square criterion, the derivative of the target function is solved and the derivative is set to 0, and two link respective CSI least square estimation values are obtained.

5. The method for optimizing the hybrid transmission capacity of a V2X system with high- and low-altitude platform cooperation according to claim 4, characterized in that, The constructed time-varying channel state information (CSI) estimation model introduces a time-varying Doppler frequency shift positively correlated with vehicle speed into the LosS component of the CSI decomposition. ; is the superposition of NLoS components from CSI decomposition. N The time-varying Doppler frequency shift of each scattering path is used to complete the time-varying channel characteristic modeling of direct links and relay links.

6. The method for optimizing the hybrid transmission capacity of a V2X system with high- and low-altitude platform cooperation according to claim 1, characterized in that, In step S3, the specific process of deriving the probability of the existence of LAP is as follows: Calculate the relay area between the V2X transmitter and receiver. Based on the hole probability characteristics of the S-PPP distribution of LAP, the probability of no LAP in the relay area is obtained. This leads to the derivation of the probability that at least one LAP exists within the relay region, i.e., the probability of LAP existence. Based on the uniform distribution characteristics of LAP in the relay area, the probability density function of horizontal distance is derived, and the expected value of relay link distance is obtained through integration. .

7. The method for optimizing the hybrid transmission capacity of a V2X system with high- and low-altitude platform cooperation according to claim 6, characterized in that, The specific process of obtaining the general form of the system's successful transmission probability by combining co-channel interference analysis is as follows: Using the link selection probabilities of direct transmission and LAP relay transmission as weights, and ignoring thermal noise, the signal-to-interference ratio at a typical V2X receiver is derived. ;set up Minimum threshold Rayleigh fading coefficient based on terrestrial V2X links Following an exponential distribution with a unit mean, the probability of successful transmission is transformed into... Combining Laplace transform Decomposed into the Laplace transform product of V2X user and LAP accumulated interference. and This leads to the general form of the system's successful transmission probability, where, for, This represents the required transmission power of the transmitter.

8. The method for optimizing the hybrid transmission capacity of a V2X system with high- and low-altitude platform cooperation according to claim 1, characterized in that, In step S4, the specific process of establishing transmission capacity analysis models for both relay transmission and direct transmission scenarios under the underlying mode is as follows: For LAP relay transmission scenarios, a transmission capacity model is established based on the LAP existence probability Pexist and the system successful transmission probability obtained in step S3, combined with the ground V2X user distribution density λV2X. : in, For the density of ground-based V2X user nodes, K Rice factor, The probability of LAP existence. and The probability of successful transmission from V2X to LAP and from LAP to V2X; For V2X direct transmission scenarios, establish a transmission capacity model. : in, This represents the probability of successful V2X transmission via a direct link in the underlying mode. and The success probabilities of V2X to LAP and from LAP to V2X.

9. The method for optimizing the hybrid transmission capacity of a V2X system with high- and low-altitude platform cooperation according to claim 1, characterized in that, In step S4, the specific process of extending and deriving the system transmission capacity expression under variable V2X link distance is as follows: Set the maximum transmission distance between the V2X transmitter and receiver. Minimum transmission distance Define V2X link distance exist The interval follows a uniform distribution, and its probability density function is: ; Assuming a sufficiently high potential LAP density, V2X communication will always receive LAP relay assistance, based on Compared to the LAP-assisted transmission capacity model in the underlying mode, the transmission capacity under variable V2X link distance is obtained through integral calculation. for: in, It is the CDF of the standard normal distribution. and This is the core intermediate computational quantity in deriving the transmission capacity under variable V2X link distance. This represents the density of ground-based V2X user nodes.

10. A hybrid transmission capacity optimization system for V2X systems with high- and low-altitude platform cooperation, characterized in that, include: The modeling module is used to comprehensively consider the channel characteristics, spectrum resource reuse mechanism, and static Poisson point process distribution characteristics of the links between HAP and ground users, LAP and ground users, and links between ground users, to construct a three-layer heterogeneous V2X communication system model that includes HAP, multiple LAPs, and ground users, and to design a scene-aware hybrid transmission strategy. The hybrid transmission strategy adaptively selects direct transmission or LAP relay transmission mode according to the current channel state and LAP distribution. The estimation module is used to construct a time-varying channel state information (CSI) estimation model based on the least squares criterion, based on the model built by the modeling module and combined with the direct link and relay link scenarios covered by the hybrid transmission strategy. The derivation module is used to derive the mathematical expressions for the probability of LAP existence and the expected value of relay link distance based on the time-varying CSI estimation model obtained by the estimation module, combined with the link selection probabilities corresponding to different transmission modes in the hybrid transmission strategy, using Palm theory and Laplace transform, and combined with co-channel interference analysis to obtain the general form of the system's successful transmission probability. The analysis module is used to establish transmission capacity analysis models for two scenarios, namely relay transmission and direct transmission, based on the LAP existence probability and successful transmission probability derived by the derivation module and the decision mechanism of direct transmission and relay transmission in the hybrid transmission strategy. It also extends and derives the system transmission capacity expression under variable V2X link distance.

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