Aircraft low-altitude wireless network switching method and semi-physical simulation system

Abstract

The invention discloses an aircraft low-altitude wireless network switching method and a semi-physical simulation system, and relates to the technical field of wireless communication and control. According to the method, in a low-altitude aircraft communication scene, a source base station and a target base station are constructed to respectively transmit communication sensing integrated signals based on orthogonal frequency division multiplexing waveforms to an aircraft; according to an echo signal generated after interaction of the communication sensing integrated signal and the aircraft, the sensing distance between the aircraft and the source base station and the sensing distance between the aircraft and the target base station are determined; establishing an intensity-distance double-measure switching criterion according to the reference signal receiving power and the sensing distance; and when the reference signal receiving power or the sensing distance meets the strength-distance double-measure switching criterion, triggering the target aircraft to switch the low-altitude wireless network. According to the invention, high-reliability and low-delay communication switching control of the aircraft in a low-altitude three-dimensional high-speed mobile scene can be realized.

Description

Technical Field

[0001] This application relates to the field of wireless communication and control technology, and in particular to a method for switching low-altitude wireless networks for aircraft and a hardware-in-the-loop simulation system. Background Technology

[0002] With the rapid development of the low-altitude economy and the information and communication industry, airspace communication has gradually become an important component of the country's new infrastructure. Emerging services such as drone logistics, aerial inspection, emergency rescue, and air travel place higher demands on the high reliability, low latency, and native sensing capabilities of wireless communication systems. Future low-altitude wireless networks not only need to achieve high-speed communication connections but also need to possess environmental self-sensing and dynamic decision-making capabilities to ensure the safe and stable communication of aircraft in complex airspace environments.

[0003] In traditional cellular network architectures, handover mechanisms are primarily based on communication quality parameters (such as reference signal received power or reception quality). This mechanism is suitable for mobile users in a two-dimensional ground plane, but its performance has significant limitations in three-dimensional airspace scenarios. On the one hand, the time-varying nature of channels is significantly enhanced when low-altitude aircraft move at high speeds, making traditional handover decisions based on reference signal received power susceptible to multipath fading, shadowing, and measurement lag, resulting in redundant handover, handover delays, or handover failures. On the other hand, although cooperative handover methods introduce geometric information or trajectory prediction, they are highly dependent on the accuracy of location information transmission, increasing system complexity and communication burden, and making it difficult to achieve real-time response. Summary of the Invention

[0004] The purpose of this application is to provide a method for low-altitude wireless network switching of aircraft and a hardware-in-the-loop simulation system, which can realize highly reliable and low-latency communication switching control of aircraft in low-altitude three-dimensional high-speed moving scenarios.

[0005] To achieve the above objectives, this application provides the following solution.

[0006] In a first aspect, this application provides a method for low-altitude wireless network handover for aircraft, comprising: In the communication scenario of low-altitude aircraft, a communication and sensing integrated signal based on orthogonal frequency division multiplexing waveform is transmitted from the source base station and the target base station to the aircraft respectively; Based on the echo signal generated after the integrated communication and sensing signal interacts with the aircraft, the sensing distance between the aircraft and the source base station and the target base station is determined respectively. Based on the reference signal received power from the source base station and the target base station measured by the aircraft, and the sensing distance between the aircraft and the source base station and the target base station respectively, a strength-distance dual-measure switching criterion is established. When the reference signal received power from the source base station and the target base station measured by the target aircraft, or the sensing distance between the target aircraft and the source base station and the target base station respectively, satisfies the strength-distance dual-measure switching criterion, the target aircraft is triggered to switch to the low-altitude wireless network.

[0007] Optionally, the expression for the integrated communication and sensing signal is: ; In the formula, Indicates that the base station is in the continuous time domain Internally transmitted integrated communication and sensing signals The number of symbols used in orthogonal frequency division multiplexing. Indicates the number of subcarriers. Indicates the first The power of each subcarrier, Indicates the first In the nth orthogonal frequency division multiplexing symbol Modulated data symbols or sensing pilot symbols on each subcarrier Indicates the carrier frequency. Indicates the subcarrier spacing. For rectangular window functions, Indicates the signal period. It represents the imaginary unit.

[0008] Optionally, based on the echo signal generated after the integrated communication and sensing signal interacts with the aircraft, the sensing distance between the aircraft and the source base station and the target base station are determined, specifically including: Perform a fast Fourier transform on the echo signal and extract the phase difference of each subcarrier; The propagation delay is determined based on the phase difference between each subcarrier; Based on the propagation delay, using the formula The sensing distances between the aircraft and the source base station and the target base station are obtained respectively; where, This indicates the sensing distance between the aircraft and the source or target base station. Represents the speed of light. Indicates the propagation delay.

[0009] Optionally, the intensity-distance dual-measure switching criterion is: ; In the formula, This represents the received power of the reference signal from the target base station as measured by the aircraft. This represents the received power of the reference signal from the source base station as measured by the aircraft. Indicates the signal strength hysteresis threshold; This indicates the sensing distance between the aircraft and the source base station. This indicates the sensing distance between the aircraft and the target base station. Indicates the distance threshold.

[0010] Optionally, based on the reference signal received power from the source base station and the target base station measured by the aircraft, and the sensing distance between the aircraft and the source base station and the target base station respectively, a strength-range dual-measure handover criterion is established, which further includes: Based on the Clamer-Rao lower bound, determine the lower bound of the distance error; Based on the intensity-distance dual-measure switching criterion, using the formula Determine the handover activation probability based on signal strength; where, This represents the handover activation probability based on signal strength. This represents the tail function of a Gaussian distribution. Indicates the signal strength hysteresis threshold. This indicates the communication distance between the aircraft and the source base station. The path loss function at that time This indicates the communication distance between the aircraft and the target base station. The path loss function at that time The standard deviation of shadow fading; Based on the intensity-distance dual-measure switching criterion and the lower bound of distance error, using the formula... Determine the switching activation probability based on perceived distance; where, This represents the activation probability of switching based on perceived distance. Indicates the distance threshold. This indicates the communication distance between the aircraft and the source base station. The lower bound of the error, This indicates the communication distance between the aircraft and the target base station. The lower bound of the error; Based on the handover activation probability based on signal strength and the handover activation probability based on sensing distance, using the formula... The switching activation probability of the intensity-distance dual-measure switching criterion is obtained; where, This represents the switching activation probability of the intensity-distance dual-measure switching criterion.

[0011] Optionally, the expression for the lower bound of the distance error is: ; In the formula, Indicates distance The lower bound of the error, Represents the speed of light. Indicates the signal-to-noise ratio. Indicates the proportion of sensing pilot signals. The number of symbols used in orthogonal frequency division multiplexing. Indicates the number of subcarriers. This represents the total system bandwidth.

[0012] Secondly, this application provides a hardware-in-the-loop simulation system for low-altitude wireless network handover of an aircraft, including: an aircraft parameter configuration module, an ISAC (Integrated Sensing and Communication) signal transmission module, a dual-base station channel simulation module, and an echo reception and handover decision module; The aircraft parameter configuration module is used to simulate the aircraft's cross-base station flight and outputs the aircraft's position parameters to the dual-base station channel simulation module in real time. The ISAC signal transmission module is used to generate and transmit integrated communication and sensing signals based on the orthogonal frequency division multiplexing (OFDM) system. The dual-base station channel simulation module is used to simulate the dual-link communication and sensing integrated channel between the source base station and the target base station according to the position parameters of the aircraft, and to act on the communication and sensing integrated signal. The echo reception and handover decision module is used to acquire the echo signal generated after the integrated communication and sensing signal of the dual-link communication and sensing integrated channel interacts with the aircraft, as well as the reference signal received power measured by the aircraft from the source base station and the target base station; based on the echo signal, it determines the sensing distance between the aircraft and the source base station and the target base station respectively; when the reference signal received power measured by the aircraft from the source base station and the target base station, as well as the sensing distance between the aircraft and the source base station and the target base station respectively, satisfy the strength-distance dual-measure handover criterion, it triggers the handover of the aircraft's low-altitude wireless network.

[0013] Optionally, the ISAC signal transmission module is a first general-purpose software radio peripheral device; the dual-base station channel simulation module is a channel simulator.

[0014] Optionally, the echo reception and switching decision module includes: a second general-purpose software radio peripheral device, a third general-purpose software radio peripheral device, and a decision device; The second general-purpose software radio peripheral device is used to receive the echo signal generated after the source base station interacts with the aircraft through the integrated communication and sensing signal of the dual-link integrated communication and sensing channel, as well as the reference signal received power from the source base station measured by the aircraft. The third general-purpose software radio peripheral device is used to receive the echo signal generated after the target base station interacts with the aircraft through the dual-link communication and sensing integrated signal and the reference signal received power from the target base station as measured by the aircraft. The decision-making device is used to determine the sensing distance between the aircraft and the source base station based on the echo signal generated after the source base station interacts with the aircraft through the integrated communication and sensing signal of the dual-link integrated communication and sensing channel; and to determine the sensing distance between the aircraft and the target base station based on the echo signal generated after the target base station interacts with the aircraft through the integrated communication and sensing signal of the dual-link integrated communication and sensing channel; when the reference signal received power measured by the aircraft from the source base station and the target base station, and the sensing distance between the aircraft and the source base station and the target base station respectively, satisfy the strength-distance dual-measurement switching criterion, the aircraft's low-altitude wireless network handover is triggered.

[0015] Optionally, the echo reception and switching decision module can display the reference signal reception power, sensing distance, and switching status of the aircraft's low-altitude wireless network in real time through a visual interface.

[0016] According to the specific embodiments provided in this application, this application has the following technical effects.

[0017] This application provides a method for low-altitude wireless network handover of aircraft and a hardware-in-the-loop simulation system. It constructs a communication and sensing integrated signal based on orthogonal frequency division multiplexing waveform that is transmitted from the source base station and the target base station to the aircraft. It fully leverages the sensing capability of the communication and sensing integrated system and establishes a strength-distance dual-measure handover criterion by jointly using two types of measurement parameters: sensing distance and reference signal received power. This enables high-reliability and low-latency handover decision-making for aircraft in low-altitude three-dimensional high-speed moving scenarios. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart illustrating a method for switching low-altitude wireless networks for aircraft, provided as an embodiment of this application.

[0020] Figure 2 This is a schematic diagram of a drone handover scenario with dual-base station ISAC transmission enabled, provided in an embodiment of this application.

[0021] Figure 3 This is a schematic diagram of the hardware-in-the-loop (HIL) system framework for switching between drones, provided in an embodiment of this application.

[0022] Figure 4 This is a schematic diagram comparing the handover activation probability under different handover distance threshold conditions provided in the embodiments of this application.

[0023] Figure 5 This is a schematic diagram comparing the switching activation probability under different sensing pilot ratios provided in the embodiments of this application.

[0024] Figure 6 This is a schematic diagram illustrating the overall process of the aircraft low-altitude wireless network switching method and hardware-in-the-loop simulation system provided in this application when applied to a drone. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] In one exemplary embodiment, such as Figure 1 As shown, a method for switching low-altitude wireless networks for aircraft is provided, including the following steps 101 to 104.

[0028] Step 101: In the low-altitude aircraft communication scenario, construct a source base station and a target base station to transmit integrated communication and sensing signals based on orthogonal frequency division multiplexing waveforms to the aircraft.

[0029] Step 102: Determine the sensing distance between the aircraft and the source base station and the target base station respectively based on the echo signal generated after the integrated communication and sensing signal interacts with the aircraft.

[0030] Step 103: Based on the reference signal received power from the source base station and the target base station measured by the aircraft, and the sensing distance between the aircraft and the source base station and the target base station respectively, establish the strength-distance dual-measure switching criterion.

[0031] Step 104: When the reference signal received power from the source base station and the target base station measured by the target aircraft, or the sensing distance between the target aircraft and the source base station and the target base station respectively, satisfies the strength-distance dual-measure switching criterion, the target aircraft is triggered to switch to the low-altitude wireless network.

[0032] By implementing steps 101 to 104 above, and by introducing the ISAC mechanism, the two types of measurement parameters, namely reference signal received power (communication signal strength) and sensing distance, are integrated to propose a strength-distance dual-measure switching criterion, thereby achieving highly reliable and low-latency switching decisions for aircraft (e.g., UAVs) in low-altitude three-dimensional scenarios.

[0033] In another exemplary embodiment of this application, the ground-to-air ISAC signal is constructed as follows: In a low-altitude aircraft communication scenario, a source base station (also known as a serving base station) and a target base station are configured to transmit ISAC signals based on the Orthogonal Frequency-Division Multiplexing (OFDM) system. The mathematical expression for the integrated communication and sensing signal based on the OFDM waveform is as follows: ; In the formula, Indicates that the base station is in the continuous time domain Internally transmitted integrated communication and sensing signals The number of symbols used in orthogonal frequency division multiplexing. Indicates the number of subcarriers. Indicates the carrier frequency. Indicates the signal period. Indicates the first The power of each subcarrier, , This represents the total transmission power. Indicates the first In the nth orthogonal frequency division multiplexing symbol The modulated data symbols or sensing pilot symbols on each subcarrier satisfy the normalization condition. , The expectation operator for random variables. Denotes the subcarrier spacing, and satisfies , This represents the total system bandwidth. This is a rectangular window function used to define the time-domain window for each OFDM symbol. It represents the imaginary unit.

[0034] The above signals achieve joint multiplexing of communication and sensing: when When modulating data symbols (communication symbols), the signal is used for data transmission; when When sensing pilot symbols (pilot sequences), the signals are used for target detection and distance estimation, thereby achieving the integration of communication and sensing.

[0035] ISAC signals carry both communication data and sensing pilots. Based on orthogonal frequency division multiplexing waveforms, the integrated communication and sensing signal can transmit communication data and provide sensing pilots, realizing a unified waveform for communication and sensing.

[0036] In another exemplary embodiment of this application, sensing distance estimation in a dual-base station ISAC transmission enabled aircraft handover scenario: the ISAC signal emitted by the base station generates an echo signal after interacting with the aircraft. At the receiving end, the echo signal is first converted into a time-frequency domain signal via Fourier transform; then, after time-frequency synchronization, the time-frequency domain channel fading value is estimated based on the frequency domain pilot sequence; subsequently, the obtained time-frequency domain channel fading value is converted into a time-delay domain channel fading value via inverse Fourier transform; finally, based on the obtained time-delay domain channel fading value, the delay value of the multipath component closest to zero delay is extracted to obtain the propagation delay. The estimation results are used to estimate the sensing distance between the aircraft and the base station. (Distance equals the speed of light multiplied by time delay). Therefore, step 102 above can be replaced by the following steps 201 to 203.

[0037] Step 201: Perform a Fast Fourier Transform on the echo signal and extract the phase difference of each subcarrier.

[0038] Step 202: Determine the propagation delay based on the phase difference of each subcarrier.

[0039] Step 203: Based on the propagation delay, use the formula The sensing distances between the aircraft and the source base station and the target base station are obtained respectively.

[0040] In the formula, This indicates the sensing distance between the aircraft and the source or target base station. Represents the speed of light. Indicates the propagation delay.

[0041] For example, the sensing distance between the source base station and the target base station and the aircraft can be estimated separately.

[0042] Figure 2 This illustrates a drone handover scenario with dual-base station ISAC transmission enabled, centered at... of In the coordinate system, Represents the three-dimensional coordinates of the drone. In Indicates the horizontal coordinates of the drone. Indicates the drone's flight altitude. Indicates the antenna height of the base station. This represents the horizontal distance between the base station and the origin of the coordinate system. Figure 2 The area enclosed by the dashed line and the x and y axes represents the projected position of the drone on the ground. The light blue area represents the signal coverage range of the source base station, and the orange area represents the signal coverage range of the target base station.

[0043] The aircraft periodically measures the Reference Signal Received Power (RSRP) from the source and target base stations, and feeds back the RSRP and the obtained sensing distance to the source base station, forming a joint metric set of communication strength and sensing distance. Based on this joint metric set, a handover decision can be made using a strength-distance dual-metric handover criterion.

[0044] In another exemplary embodiment of this application, the strength-range dual-measure switching criterion is designed as follows: the aircraft periodically measures the received power of the reference signals from the source base station and the target base station, respectively denoted as... , Simultaneously, the source base station and the target base station estimate the sensing distance to the aircraft, denoted as [reference needed]. and The measurement results are all fed back to the source base station, forming a joint measurement set of communication strength and sensing distance.

[0045] This application introduces a sensing distance metric into the traditional handover method based on the RSRP criterion, and constructs a strength-distance dual-metric handover criterion as follows: ; In the formula, This represents the received power of the reference signal from the source base station as measured by the aircraft. This represents the received power of the reference signal from the target base station as measured by the aircraft. Indicates the signal strength hysteresis threshold; This indicates the sensing distance between the aircraft and the source base station. This indicates the sensing distance between the aircraft and the target base station. Indicates the distance threshold.

[0046] The strength-distance dual-metric handover criterion includes two conditions: (i) the RSRP of the target base station is higher than that of the source base station, and the difference is greater than a preset signal strength hysteresis threshold; (ii) the sensing distance between the aircraft and the target base station is less than the sensing distance with the source base station, and the difference is greater than a preset distance threshold. Handover is triggered when either of these conditions is met. The dual-metric criterion achieves multi-dimensional decision-making for low-altitude aircraft handover by fusing communication signal strength and sensing space information, thereby improving the handover success rate.

[0047] In another exemplary embodiment of this application, step 104 above performs a handover operation and the handover result is fed back by the receiving end to complete the reliable handover process.

[0048] In another exemplary embodiment of this application, a handover activation probability index is introduced to verify the handover triggering performance of the handover criteria. Following step 103 above, the method may further include steps 301 to 304.

[0049] Step 301: Determine the lower bound of the distance error based on the Cramerlow lower bound.

[0050] To evaluate the theoretical accuracy of the distance estimation, this application is based on The lower bound (CRLB) is derived to explain the estimation error, and the result is as follows: ; in, Indicates distance The estimation error, Indicates distance The lower bound of the error, Represents the speed of light. This indicates the signal-to-noise ratio. Indicates the proportion of sensing pilot signals. By deriving CRLB, the minimum reachable error of the sensing distance can be obtained, thus providing a basis for accuracy constraints on the subsequent switching trigger threshold.

[0051] The expression for the lower bound of the distance error is: ; Step 302: Based on the intensity-distance dual-measure switching criterion, use the formula... Determine the switching activation probability based on signal strength.

[0052] In the formula, This represents the handover activation probability based on signal strength. Indicates the probability of switching activation. This represents the tail function of a Gaussian distribution. This indicates the communication distance between the drone and the source base station. The path loss function is used, and the path loss function adopts the 5G-NR UMa-AV LoS model: , Indicates the carrier frequency. This indicates the communication distance between the aircraft and the target base station. The path loss function at that time This represents the standard deviation of shadow fading, a large-scale fading phenomenon in wireless communication. These are empirical values ​​obtained based on statistical analysis of measured data.

[0053] Step 303: Based on the intensity-distance dual-measure switching criterion and the lower bound of distance error, use the formula... Determine the switching activation probability based on perceived distance.

[0054] In the formula, This represents the activation probability of switching based on perceived distance. This indicates the communication distance between the aircraft and the source base station. The lower bound of the error, This indicates the communication distance between the aircraft and the target base station. The lower bound of the error.

[0055] Step 304: Based on the handover activation probability based on signal strength and the handover activation probability based on sensing distance, use the formula... The switching activation probability of the intensity-distance dual-measure switching criterion is obtained. Where, This represents the switching activation probability of the intensity-distance dual-measure switching criterion.

[0056] This application proposes a reliable handover method for low-altitude networks based on integrated communication and sensing technology, which combines two types of measurement information: communication signal strength and sensing distance. The method achieves synchronous multiplexing of communication and sensing by constructing an OFDM-ISAC signal model, and is based on… The lower bound of the sensing distance estimation error is derived, thus providing high-precision spatial measurement support for the handover decision of low-altitude aircraft. Combined with a dual-measure joint decision mechanism, this application enables multi-dimensional sensing-driven handover decision optimization, significantly improving handover success rate and system robustness. Furthermore, the aircraft handover hardware-in-the-loop simulation platform developed in this application can verify performance under different signal-to-noise ratios, pilot overheads, and altitude conditions in a laboratory environment, supporting the engineering implementation and application promotion of the proposed method in real-world scenarios.

[0057] Based on the same inventive concept, this application also provides a hardware-in-the-loop simulation system for implementing the aforementioned aircraft low-altitude wireless network handover method. The solution provided by this system is similar to the implementation described in the above method. Therefore, the specific limitations of one or more hardware-in-the-loop simulation system embodiments for aircraft low-altitude wireless network handover provided below can be found in the limitations of the aircraft low-altitude wireless network handover method described above, and will not be repeated here.

[0058] In one exemplary embodiment, such as Figure 3 As shown, a hardware-in-the-loop simulation system for low-altitude wireless network handover of an aircraft is provided, including: an aircraft parameter configuration module, an ISAC signal transmission module, a dual-base station channel simulation module, and an echo reception and handover decision module.

[0059] The aircraft parameter configuration module simulates the aircraft's cross-base station flight and outputs the aircraft's position parameters to the dual-base station channel simulation module in real time. The ISAC signal transmission module generates and transmits an integrated communication and sensing signal based on orthogonal frequency division multiplexing (OFDM). The dual-base station channel simulation module simulates a dual-link integrated communication and sensing channel between the source and target base stations based on the aircraft's position parameters and applies this simulation to the integrated communication and sensing signal. The echo reception and handover decision module acquires the echo signal generated after the integrated communication and sensing signal interacts with the aircraft via the dual-link integrated communication and sensing channel, as well as the reference signal received power measured by the aircraft from the source and target base stations. Based on the echo signal, it determines the sensing distance between the aircraft and the source and target base stations, respectively. When the reference signal received power measured by the aircraft from the source and target base stations, and the sensing distance between the aircraft and the source and target base stations, respectively, satisfy the strength-distance dual-measure handover criterion, it triggers the handover of the aircraft's low-altitude wireless network.

[0060] This hardware-in-the-loop simulation system was developed in a laboratory environment and can be used to verify the performance of the switching criteria, thus validating the performance and feasibility of the proposed intensity-distance dual-measure switching criteria.

[0061] As an optional implementation, the ISAC signal transmission module is a first general-purpose software radio peripheral device, and the dual-base station channel simulation module is a channel simulator.

[0062] As an optional implementation, the echo reception and switching decision module includes: a second general-purpose software radio peripheral device, a third general-purpose software radio peripheral device, and a decision device.

[0063] The second general-purpose software-defined radio peripheral device is used to receive the echo signal generated after the source base station interacts with the aircraft via the integrated communication and sensing signal through the dual-link communication and sensing channel, as well as the reference signal received power from the source base station measured by the aircraft.

[0064] The third general-purpose software-defined radio peripheral device is used to receive the echo signal generated after the target base station interacts with the aircraft through the dual-link communication-sensing integrated channel, as well as the reference signal received power from the target base station measured by the aircraft.

[0065] The decision-making device is used to determine the sensing distance between the aircraft and the source base station based on the echo signal generated after the source base station interacts with the aircraft through the integrated communication and sensing signal of the dual-link integrated communication and sensing channel; and to determine the sensing distance between the aircraft and the target base station based on the echo signal generated after the target base station interacts with the aircraft through the integrated communication and sensing signal of the dual-link integrated communication and sensing channel; when the reference signal received power measured by the aircraft from the source base station and the target base station, and the sensing distance between the aircraft and the source base station and the target base station respectively, satisfy the strength-distance dual-measurement switching criterion, the aircraft's low-altitude wireless network handover is triggered.

[0066] As an optional implementation, the echo reception and switching decision module displays the reference signal reception power, sensing distance, and the switching status of the aircraft's low-altitude wireless network in real time through a visual interface.

[0067] In summary, the hardware-in-the-loop simulation system of this application mainly includes the following four functional modules: The aircraft parameter configuration module simulates the physical state parameters such as trajectory, altitude and speed of the aircraft during cross-base station flight based on the MATLAB model, and outputs the dynamic position information to the channel simulator in real time to realize the controllable reproduction of motion scenarios. ISAC signal transmission module: Employs a high-performance ISAC signal source to transmit ISAC signals based on OFDM waveforms, supporting baseband signal processing, pilot insertion, and waveform generation to achieve unified transmission of communication and sensing signals; Dual-base station channel simulation module: It uses a channel simulator to reproduce the dual-link channel characteristics of the source base station and the target base station, and supports the configuration of multipath fading, delay spread and path loss parameters, so as to accurately simulate the channel changes of the aircraft during the handover process; Echo reception and handover decision module: This module uses a USRPB210 device to receive and sample composite signals. Through baseband demodulation and waveform feature analysis, it achieves joint estimation of the sensing distance and the received power of the reference signal. Based on the estimation results, this module performs a strength-distance dual-measure handover decision and displays performance indicators such as handover status, signal strength, and distance changes in real time through an HTML-based visual interface, enabling visualized monitoring of the entire process.

[0068] This hardware-in-the-loop simulation system can also be called a hardware-in-the-loop simulation platform. The platform is designed with the "signal-channel-reception-decision" end-to-end concept as its core, and comprehensively uses signal sources, channel simulators, and USRP devices to build a complete integrated sensory experimental environment. Among them, the signal source is used to simulate the transmission of signals from the aircraft, the channel simulator is used to reproduce the characteristics of the ISAC channel, and the USRP module is used to simulate the signal transmission and reception process between the source base station and the target base station.

[0069] The hardware-in-the-loop simulation system supports experimental configurations under multiple parameter conditions, including different signal-to-noise ratios, sensing pilot ratios, flight altitudes, and switching distance thresholds. Based on this hardware-in-the-loop simulation system, this application conducted multiple sets of measured performance analyses, such as... Figure 4 and Figure 5 As shown. Under extreme conditions of 6% sensing pilot overhead and a handover distance threshold of 100m, compared with the traditional single-measure handover criterion based on RSRP, the intensity-distance dual-measure handover criterion proposed in this application can still achieve faster convergence of the cumulative density distribution function of the handover activation probability, verifying its high reliability and robustness in complex low-altitude communication environments. Figure 4 and Figure 5 middle, This represents the simulated value of the switching activation probability based on signal strength. This represents a measurement of the handover activation probability based on signal strength. This represents the simulated value of the switching activation probability based on the intensity-distance dual-measure switching criterion. This represents the switching activation probability measurement of the intensity-distance dual-measure switching criterion.

[0070] The overall process of applying the method and system of this application to a drone is as follows: Figure 6 As shown, it includes: S1: Construction of ground-to-air ISAC signal; S2: Estimation of sensing distance and derivation of lower bound of error in UAV handover scenario with dual-base station ISAC transmission enabled; S3: Design of handover criterion with intensity-distance dual measure; S4: Modeling of handover criterion performance index; S5: Construction and verification of UAV handover hardware-in-the-loop simulation platform.

[0071] In summary, this application fully leverages the sensing capabilities of ISAC, jointly models sensing parameters and communication indicators, and realizes a reliable handover decision-making mechanism driven by multi-dimensional metric fusion. By fusing ISAC sensing distance parameters and communication strength measures, a strength-distance dual-metric handover criterion is constructed and verified on a hardware-in-the-loop simulation platform, achieving highly reliable, low-latency handover control for aircraft in highly dynamic airspace.

[0072] The method in this application achieves synchronous multiplexing of communication and sensing by constructing an OFDM-ISAC signal model; based on The lower bound of the sensing distance estimation error is derived, providing a theoretical basis for distance measurement. A joint decision mechanism based on both strength and distance measures is designed, achieving highly reliable and low-latency decision-making during handover between low-altitude aircraft and base stations. Furthermore, this application constructs a hardware-in-the-loop simulation platform for aircraft handover, completing performance verification under different parameter conditions. Results show that this method significantly improves handover success rate and system robustness. This application possesses high engineering feasibility and application value.

[0073] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0074] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for low-altitude wireless network handover in aircraft, characterized in that, include: In the communication scenario of low-altitude aircraft, a communication and sensing integrated signal based on orthogonal frequency division multiplexing waveform is transmitted from the source base station and the target base station to the aircraft respectively; Based on the echo signal generated after the integrated communication and sensing signal interacts with the aircraft, the sensing distance between the aircraft and the source base station and the target base station is determined respectively. Based on the reference signal received power from the source base station and the target base station measured by the aircraft, and the sensing distance between the aircraft and the source base station and the target base station respectively, a strength-distance dual-measure switching criterion is established. When the reference signal received power from the source base station and the target base station measured by the target aircraft, or the sensing distance between the target aircraft and the source base station and the target base station respectively, satisfies the strength-distance dual-measure switching criterion, the target aircraft is triggered to switch to the low-altitude wireless network.

2. The aircraft low-altitude wireless network handover method according to claim 1, characterized in that, The expression for the integrated communication and sensing signal is: ； In the formula, Indicates that the base station is in the continuous time domain Internally transmitted integrated communication and sensing signals The number of symbols used in orthogonal frequency division multiplexing. Indicates the number of subcarriers. Indicates the first The power of each subcarrier, Indicates the first In the nth orthogonal frequency division multiplexing symbol Modulated data symbols or sensing pilot symbols on each subcarrier Indicates the carrier frequency. Indicates the subcarrier spacing. For rectangular window functions, Indicates the signal period. It represents the imaginary unit.

3. The aircraft low-altitude wireless network handover method according to claim 1, characterized in that, Based on the echo signals generated after the integrated communication and sensing signal interacts with the aircraft, the sensing distances between the aircraft and the source base station and the target base station are determined, specifically including: Perform a fast Fourier transform on the echo signal and extract the phase difference of each subcarrier; The propagation delay is determined based on the phase difference between each subcarrier; Based on the propagation delay, using the formula The sensing distances between the aircraft and the source base station and the target base station are obtained respectively; where, This indicates the sensing distance between the aircraft and the source or target base station. Represents the speed of light. Indicates the propagation delay.

4. The aircraft low-altitude wireless network handover method according to claim 1, characterized in that, The intensity-distance dual-measure switching criterion is as follows: ； In the formula, This represents the received power of the reference signal from the target base station as measured by the aircraft. This represents the received power of the reference signal from the source base station as measured by the aircraft. Indicates the signal strength hysteresis threshold; This indicates the sensing distance between the aircraft and the source base station. This indicates the sensing distance between the aircraft and the target base station. Indicates the distance threshold.

5. The aircraft low-altitude wireless network handover method according to claim 1, characterized in that, Based on the reference signal received power from the source and target base stations measured by the aircraft, and the sensing distances between the aircraft and the source and target base stations respectively, a strength-range dual-measure handover criterion is established, which also includes: Based on the Clamer-Rao lower bound, determine the lower bound of the distance error; Based on the intensity-distance dual-measure switching criterion, using the formula Determine the handover activation probability based on signal strength; where, This represents the handover activation probability based on signal strength. This represents the tail function of a Gaussian distribution. Indicates the signal strength hysteresis threshold. This indicates the communication distance between the aircraft and the source base station. The path loss function at that time This indicates the communication distance between the aircraft and the target base station. The path loss function at that time The standard deviation of shadow fading; Based on the intensity-distance dual-measure switching criterion and the lower bound of distance error, the formula is used. Determine the switching activation probability based on perceived distance; where, This represents the activation probability of switching based on perceived distance. Indicates the distance threshold. This indicates the communication distance between the aircraft and the source base station. The lower bound of the error, This indicates the communication distance between the aircraft and the target base station. The lower bound of the error; Based on the handover activation probability based on signal strength and the handover activation probability based on sensing distance, using the formula... The switching activation probability of the intensity-distance dual-measure switching criterion is obtained; where, This represents the switching activation probability of the intensity-distance dual-measure switching criterion.

6. The aircraft low-altitude wireless network handover method according to claim 5, characterized in that, The expression for the lower bound of the distance error is: ； In the formula, Indicates distance The lower bound of the error, Represents the speed of light. Indicates the signal-to-noise ratio. Indicates the proportion of sensing pilot signals. The number of symbols used in orthogonal frequency division multiplexing. Indicates the number of subcarriers. This represents the total system bandwidth.

7. A hardware-in-the-loop simulation system for low-altitude wireless network switching of aircraft, characterized in that, include: The aircraft parameter configuration module, the ISAC signal transmission module, the dual base station channel simulation module, and the echo reception and handover decision module; The aircraft parameter configuration module is used to simulate the aircraft's cross-base station flight and outputs the aircraft's position parameters to the dual-base station channel simulation module in real time. The ISAC signal transmission module is used to generate and transmit integrated communication and sensing signals based on the orthogonal frequency division multiplexing (OFDM) system. The dual-base station channel simulation module is used to simulate the dual-link communication and sensing integrated channel between the source base station and the target base station according to the position parameters of the aircraft, and to act on the communication and sensing integrated signal. The echo reception and handover decision module is used to acquire the echo signal generated after the communication sensing integrated signal through the dual-link communication sensing integrated channel interacts with the aircraft, as well as the reference signal received power from the source base station and the target base station measured by the aircraft. Based on the echo signal, the sensing distance between the aircraft and the source base station and the target base station is determined respectively; when the reference signal received power from the source base station and the target base station measured by the aircraft, and the sensing distance between the aircraft and the source base station and the target base station respectively, satisfy the strength-distance dual-measurement switching criterion, the switching of the low-altitude wireless network of the aircraft is triggered.

8. The hardware-in-the-loop simulation system for low-altitude wireless network switching of aircraft according to claim 7, characterized in that, The ISAC signal transmitting module is a first general-purpose software radio peripheral device; The dual-base station channel simulation module is a channel simulator.

9. The hardware-in-the-loop simulation system for low-altitude wireless network switching of aircraft according to claim 7, characterized in that, The echo reception and switching decision module includes: a second general-purpose software radio peripheral device, a third general-purpose software radio peripheral device, and a decision device; The second general-purpose software radio peripheral device is used to receive the echo signal generated after the source base station interacts with the aircraft through the integrated communication and sensing signal of the dual-link integrated communication and sensing channel, as well as the reference signal received power from the source base station measured by the aircraft. The third general-purpose software radio peripheral device is used to receive the echo signal generated after the target base station interacts with the aircraft through the dual-link communication and sensing integrated signal and the reference signal received power from the target base station as measured by the aircraft. The decision-making device is used to determine the sensing distance between the aircraft and the source base station based on the echo signal generated after the source base station interacts with the aircraft through the integrated communication and sensing signal of the dual-link integrated communication and sensing channel; and to determine the sensing distance between the aircraft and the target base station based on the echo signal generated after the target base station interacts with the aircraft through the integrated communication and sensing signal of the dual-link integrated communication and sensing channel; when the reference signal received power measured by the aircraft from the source base station and the target base station, and the sensing distance between the aircraft and the source base station and the target base station respectively, satisfy the strength-distance dual-measurement switching criterion, the aircraft's low-altitude wireless network handover is triggered.

10. The hardware-in-the-loop simulation system for low-altitude wireless network switching of aircraft according to claim 7, characterized in that, The echo reception and switching decision module displays the reference signal reception power, sensing distance, and switching status of the aircraft's low-altitude wireless network in real time through a visual interface.

Images