Unmanned aerial vehicle dynamic access system for low-altitude air route supervision

Abstract

The application relates to the technical field of wireless communication resource allocation, and discloses a dynamic access system of a unmanned aerial vehicle (UAV) for low-altitude air route supervision, which comprises an airspace grid mapping unit, a trajectory vector conversion unit, a resource pre-judgment unit and an access control unit; the airspace grid mapping unit divides a base station coverage airspace into a three-dimensional grid, and establishes a mapping relationship between a grid boundary and a resource index; the trajectory vector conversion unit projects an UAV speed vector to generate a directed trajectory; the resource pre-judgment unit extracts an intersection resource index of the directed trajectory and a grid unit, and generates a phase bias characteristic value based on a Doppler frequency shift; and the access control unit issues an authorization instruction containing the phase bias characteristic value; the application implements access signal code domain isolation by triggering a physical layer orthogonal phase sequence, suppresses signaling congestion induced by preamble code collision, and guarantees the system stability of the low-altitude supervision link.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication resource allocation technology, and in particular relates to a dynamic access system for unmanned aerial vehicles (UAVs) for monitoring low-altitude flight paths. Background Technology

[0002] Current mobile data communication systems typically employ a contention-based random access mechanism when providing access services to terminals. This mechanism allocates time-frequency resource blocks within a specific physical random access channel to obtain uplink synchronization. Based on the assumption that the terminal is moving at low speed in the plane, the system triggers access requests by monitoring predefined signaling timing sequences. The base station scheduler demodulates the access preamble sequence sent by the terminal according to its time-domain location and sends a random access response on the downlink control channel.

[0003] For low-altitude flight path surveillance scenarios, drones exhibit three-dimensional maneuvering characteristics at altitudes of 0 to 1000 meters, resulting in severe Doppler shift and channel fading, increasing the difficulty of signaling demodulation at the wireless air interface. Due to the dimensional mismatch between the drone's spatial displacement and the one-dimensional time-axis scheduling architecture, arrival time drift occurs when physical displacement is converted to the time axis, leading to polarized idleness or sudden congestion of reserved resource blocks. In areas with densely intersecting flight paths, massive concurrent access requests cause frequent collisions of preamble sequences, resulting in overload of base station schedulers and large-scale terminal disconnections. Existing technologies attempt to address this by increasing base station deployment density. Extending the random access window may alleviate resource conflicts, but this results in excessively high construction costs and reduced wireless resource utilization. Even if physical coverage quality is improved at the hardware level, without a deep decoupling between the air interface access protocol and the three-dimensional spatial topology, the resource allocation logic at the software level is difficult to adapt to the highly dynamic changes of UAVs. For example, Chinese invention patent application CN121523393A discloses a method for tracking and predicting the dynamic trajectory of low-altitude UAVs based on multi-base station collaboration. It generates multimodal position predictions through multi-base station collaborative observation data and uses a generative model to smooth the trajectory.

[0004] Therefore, how to establish a mechanism for converting physical displacement features into wireless resource maps, eliminate error accumulation when three-dimensional trajectories are mapped to one-dimensional time axes, and improve scheduling stability in high-density access environments has become the technical problem to be solved by this invention. Summary of the Invention

[0005] This invention provides a dynamic access system for unmanned aerial vehicles (UAVs) for monitoring low-altitude flight paths, comprising:

[0006] The spatial grid mapping unit is used to divide the physical spatial domain covered by the base station from 0m to 1000m into a three-dimensional grid, and to establish a deterministic hash mapping association between the geometric boundary dataset of each grid unit and the resource block index of the media access control layer.

[0007] The trajectory vector transformation unit is used to obtain the three-dimensional velocity vector fed back by the UAV and project the three-dimensional velocity vector onto the physical airspace coordinate system to generate a directed predicted trajectory;

[0008] The resource prediction unit is used to calculate the intersection path between the directed predicted trajectory and the bounding box of the grid in the 3D mesh, extract the resource block index covered by the intersection path, and generate phase offset feature values ​​based on the radial Doppler frequency shift of the UAV relative to the base station.

[0009] The access control unit is used to generate access authorization instructions by combining resource block indexes and phase offset feature values, and issue them within a preset hysteresis window before the UAV reaches the corresponding grid boundary; wherein, the phase offset feature value is used to trigger the physical layer orthogonal phase offset sequence to isolate the code domain of random access preambles that occur concurrently in the same resource block group.

[0010] Preferably, when the access control unit detects that multiple directed predicted trajectories point to the same grid bounding box, it assigns different physical layer orthogonal phase offset sequences based on the radial Doppler frequency shift difference of each UAV. The access control unit achieves logical decoupling of concurrent access requests by phase superposition on the same physical resource block based on the multipath Doppler characteristics of the wireless air interface, so as to suppress control plane signaling congestion induced by preamble collision.

[0011] Preferably, the spatial grid mapping unit includes a spatial model building component and an index binding component; the spatial model building component is used to build a three-dimensional grid; the index binding component is used to define the boundary of each grid cell in the three-dimensional grid as a radio resource trigger boundary and establish a monotonic mapping relationship between the radio resource trigger boundary and the corresponding resource block index.

[0012] Preferably, the access control unit includes a fault-tolerant control component; the fault-tolerant control component is used to configure a common backoff time slot to provide a short data recovery path when the UAV misses its dedicated access time window due to environmental disturbances, and to determine the yaw state of the UAV by monitoring the energy change trend of the uplink reference signal, wherein the yaw state is used to trigger the reduction of access frequency.

[0013] Preferably, the trajectory vector transformation unit includes a coordinate transformation component; the coordinate transformation component is used to convert the geographic coordinate system velocity components fed back by the UAV into three-dimensional vector parameters in the physical airspace coordinate system, and to establish the starting coordinates of the directed predicted trajectory based on the center position of the antenna array of the base station.

[0014] Preferably, when the resource prediction unit processes intersecting paths, it adopts a collision detection algorithm based on a hierarchical bounding box structure to calculate the geometric intersection of the directed predicted trajectory and the grid bounding box; the resource prediction unit determines the index of the first resource block to be allocated based on the starting position of the intersecting path, and reserves dedicated access resources for subsequent handover processes based on the penetration depth of the intersecting path.

[0015] Preferably, the opening duration of the preset hysteresis window is determined based on the ratio of the current flight speed of the UAV to the geometric radius of the grid cell, and the opening duration is set to be greater than or equal to the computation time of the resource prediction unit in processing intersecting paths.

[0016] Preferably, the geometric dimensions of the grid cells in the three-dimensional grid are dynamically adjusted according to the distribution density of UAVs within the base station coverage area; in areas where the UAV density exceeds a preset density threshold, the spatial grid mapping unit improves the spatial resolution of radio resource allocation by reducing the volume of the grid cells.

[0017] Preferably, the system further includes a parameter feedback module; the parameter feedback module sends an access authorization command containing phase offset characteristic values ​​to the UAV via the physical layer downlink control channel, so that the UAV can adjust the initial phase of its uplink access signal according to the phase offset characteristic values.

[0018] Compared with existing technologies, the UAV dynamic access system for low-altitude flight path monitoring of this invention has the following advantages:

[0019] 1. In the UAV dynamic access system, by dividing the available frequency bands of the wireless carrier into a virtual resource map isomorphic to the segments of the physical flight path, and combining the hard-coded binding relationship between the three-dimensional spatial voxel grid and the resource block index of the media access control layer, the access authorization for UAVs is transformed from one-dimensional time axis prediction to three-dimensional spatial topology retrieval. This cross-domain mapping mechanism avoids the arrival time deviation caused by aerodynamic wind deviation or obstacle avoidance in three-dimensional flight of highly dynamic UAVs, and eliminates the resource block polarization idleness or sudden congestion caused by dimension mismatch when traditional mobile communication systems deal with three-dimensional highly maneuverable objects. When the UAV deviates from the predetermined trajectory, the system directly extracts the resource block index attached to the intersecting voxels according to the through path generated by its three-dimensional velocity vector in the geometric model, ensuring real-time synchronization between wireless resource allocation and physical displacement characteristics.

[0020] 2. By utilizing dual-source inputs of three-dimensional velocity vectors and service load identifiers, and combined with a physical layer phase offset sequence driven by Doppler frequency shift difference, the system achieves code domain decoupling of collision conflicts while ensuring high-density access capacity. Based on the frequency drift characteristics generated by the UAV's motion relative to the base station, the system superimposes mutually orthogonal phase offsets on access requests that collide within the same time-frequency resource block group, thereby achieving physical isolation of massive concurrent requests at the radio interface layer. This processing logic reduces the collision probability of random access preambles, suppresses control plane signaling storms induced by access failures, and ensures the systematic stability of the air traffic control data link in areas with dense intersections of low-altitude air routes.

[0021] 3. By combining the hysteresis-tolerant access micro-window in the directional access authorization command with the implicit resource reclamation mechanism based on energy attenuation gradient, the communication system's defense capability against interference from complex low-altitude physical environments is enhanced. When a UAV misses its dedicated access time window due to physical disturbances, the system provides a short data recovery path by configuring a shared backoff time slot, avoiding systemic delays caused by re-initiating the contention access process. At the same time, the scheduler autonomously determines the UAV's yaw state by monitoring the energy change trend of the uplink reference signal and triggers resource degradation logic, thereby improving the effective turnover rate of broadband wireless carrier resources. Attached Figure Description

[0022] Figure 1 This is a flowchart illustrating the core functional modules and control process of the UAV dynamic access system of this invention.

[0023] Figure 2 This is a diagram illustrating the hardware architecture and communication interaction of the drone, base station, and calibration server of this invention. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0025] It should be noted that all directional and positional terms used in this invention, such as: up, down, left, right, front, back, vertical, horizontal, inner, outer, top, bottom, transverse, longitudinal, center, etc., are only used to explain the relative positional relationship and connection between components in a specific state (as shown in the accompanying drawings). They are only for the convenience of describing this invention and do not require that this invention be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention. In addition, the descriptions of "first," "second," etc., in this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0026] In the description of this invention, unless otherwise explicitly specified and limited, the terms installation, connection, and linking should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to the internal connection of two components. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0027] In the description of this specification, references to the terms "an embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example, and the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0028] A dynamic access system for unmanned aerial vehicles (UAVs) for monitoring low-altitude flight paths, comprising:

[0029] The spatial grid mapping unit is used to divide the physical spatial domain covered by the base station from 0m to 1000m into a three-dimensional grid, and to establish a deterministic hash mapping association between the geometric boundary dataset of each grid unit and the resource block index of the media access control layer.

[0030] The trajectory vector transformation unit is used to obtain the three-dimensional velocity vector fed back by the UAV and project the three-dimensional velocity vector onto the physical airspace coordinate system to generate a directed predicted trajectory;

[0031] The resource prediction unit is used to calculate the intersection path between the directed predicted trajectory and the bounding box of the grid in the 3D mesh, extract the resource block index covered by the intersection path, and generate phase offset feature values ​​based on the radial Doppler frequency shift of the UAV relative to the base station.

[0032] The access control unit is used to generate access authorization instructions by combining resource block indexes and phase offset feature values, and issue them within a preset hysteresis window before the UAV reaches the corresponding grid boundary; wherein, the phase offset feature value is used to trigger the physical layer orthogonal phase offset sequence to isolate the code domain of random access preambles that occur concurrently in the same resource block group.

[0033] Preferably, when the access control unit detects that multiple directed predicted trajectories point to the same grid bounding box, it assigns different physical layer orthogonal phase offset sequences based on the radial Doppler frequency shift difference of each UAV. The access control unit achieves logical decoupling of concurrent access requests by phase superposition on the same physical resource block based on the multipath Doppler characteristics of the wireless air interface, so as to suppress control plane signaling congestion induced by preamble collision.

[0034] Preferably, the spatial grid mapping unit includes a spatial model building component and an index binding component; the spatial model building component is used to build a three-dimensional grid; the index binding component is used to define the boundary of each grid cell in the three-dimensional grid as a radio resource trigger boundary and establish a monotonic mapping relationship between the radio resource trigger boundary and the corresponding resource block index.

[0035] Preferably, the access control unit includes a fault-tolerant control component; the fault-tolerant control component is used to configure a common backoff time slot to provide a short data recovery path when the UAV misses its dedicated access time window due to environmental disturbances, and to determine the yaw state of the UAV by monitoring the energy change trend of the uplink reference signal, wherein the yaw state is used to trigger the reduction of access frequency.

[0036] Preferably, the fault-tolerant control component includes a resource recovery sub-component; the resource recovery sub-component is used to calculate the energy decay gradient based on the energy change trend. and in the energy decay gradient When the resource level remains below a preset shutdown threshold, resource degradation logic is triggered by releasing the corresponding resource block index; the energy decay gradient is calculated as follows: ,in, For the energy decay gradient, This represents the energy value of the uplink reference signal monitored at the current moment. Δt represents the energy value of the uplink reference signal at the previous sampling time, and Δt represents the sampling time interval.

[0037] Preferably, the trajectory vector transformation unit includes a coordinate transformation component; the coordinate transformation component is used to convert the geographic coordinate system velocity components fed back by the UAV into three-dimensional vector parameters in the physical airspace coordinate system, and to establish the starting coordinates of the directed predicted trajectory based on the center position of the antenna array of the base station.

[0038] Preferably, when the resource prediction unit processes intersecting paths, it adopts a collision detection algorithm based on a hierarchical bounding box structure to calculate the geometric intersection of the directed predicted trajectory and the grid bounding box; the resource prediction unit determines the index of the first resource block to be allocated based on the starting position of the intersecting path, and reserves dedicated access resources for subsequent handover processes based on the penetration depth of the intersecting path.

[0039] Preferably, the opening duration of the preset hysteresis window is determined based on the ratio of the current flight speed of the UAV to the geometric radius of the grid cell, and the opening duration is set to be greater than or equal to the computation time of the resource prediction unit in processing intersecting paths.

[0040] Preferably, the geometric dimensions of the grid cells in the three-dimensional grid are dynamically adjusted according to the distribution density of UAVs within the base station coverage area; in areas where the UAV density exceeds a preset density threshold, the spatial grid mapping unit improves the spatial resolution of radio resource allocation by reducing the volume of the grid cells.

[0041] Preferably, the system further includes a parameter feedback module; the parameter feedback module sends an access authorization command containing phase offset characteristic values ​​to the UAV via the physical layer downlink control channel, so that the UAV can adjust the initial phase of its uplink access signal according to the phase offset characteristic values.

[0042] Example 1: When the system faces the situation of a low-altitude, high-density UAV swarm crossing the coverage boundary of an urban base station, multiple UAVs concurrently enter the 0m to 1000m physical airspace of the same base station with different three-dimensional velocity vectors. The terminals send access requests to the same medium access control layer channel in a concentrated manner, causing random access preamble sequence collisions and control plane signaling congestion. The airspace grid mapping unit divides the physical airspace covered by the base station into a three-dimensional grid and establishes a deterministic hash mapping association between the geometric boundary dataset of each grid cell and the resource block index of the medium access control layer. The trajectory vector conversion unit obtains the three-dimensional velocity vector fed back by the UAV and projects it into the physical airspace coordinate system to generate a directed predicted trajectory. The resource prediction unit calculates the intersection path between the directed predicted trajectory and the grid bounding box in the three-dimensional grid and extracts the resource block index covered by the intersection path.

[0043] When multiple directed predicted trajectories point to the same grid bounding box, the resource prediction unit generates distinct phase offset feature values ​​based on the radial Doppler frequency shift difference between each UAV and the base station. The access control unit generates an access authorization command by combining the resource block index and the phase offset feature values, and issues it within a preset hysteresis window before the UAV reaches the corresponding grid boundary. The opening duration of the preset hysteresis window is greater than or equal to the computation time for processing intersecting paths, and the fault-tolerant control component included in the access control unit configures a common backoff time slot after the time domain of the resource block group to provide a short data recovery path. The UAV receiving the access authorization command adjusts the initial phase of the uplink access signal according to the phase offset feature value, triggering a physical layer orthogonal phase offset sequence. Based on the multipath Doppler characteristics of the radio air interface, the base station scheduler decouples concurrent access requests on the same physical resource block through phase superposition. Random access preambles within the same time-frequency resource are isolated in the code domain dimension, eliminating control plane signaling congestion and matching the underlying radio resource block allocation logic with the geometric topological characteristics of low-altitude three-dimensional moving objects.

[0044] Example 2: To verify the stability of the media access control layer access scheduling scheme based on spatial grid hash mapping and Doppler phase offset eigenvalues, this example builds a hardware-in-the-loop test platform including a low-altitude base station and a drone swarm simulator. The physical altitude range of the test airspace is set to 0m to 1000m, and the cell bounding box resolution of the three-dimensional grid is set to 50m×50m×50m. The media access control layer of the base station scheduler is configured with 100 concurrent physical resource blocks. The test group includes 150 logistics drones that concurrently enter the airspace. The three-dimensional velocity vector of each drone is set to a gradient distribution in the range of 10m / s to 30m / s to generate radial Doppler frequency shift physical characteristics.

[0045] The test process extracted control plane signaling call drop rate and random access preamble sequence collision rate as measurement indicators. In the mode of disabling Doppler phase offset feature generation, when the number of concurrent UAVs increased from 50 to 150, the signaling call drop rate increased from 12% to 68%, and the preamble sequence collision rate climbed from 15% to 82%. After enabling the spatial grid mapping and directed predicted trajectory intersection path calculation logic, and maintaining the preset hysteresis window opening duration of 15ms, when the number of concurrent UAVs was 50, the signaling call drop rate decreased to 0.5% and the collision rate decreased to 1.2%. When the number of concurrent UAVs reached 150, the signaling call drop rate stabilized at 1.8%, and the preamble sequence collision rate remained below 2.5%. Neither of the two data indicators deteriorated with the increase of the number of concurrent UAVs.

[0046] The gradient test data above shows that the resource prediction unit extracts phase offset feature values ​​based on the radial Doppler frequency shift difference between the UAV and the base station and triggers the physical layer orthogonal phase offset sequence. This enables the base station scheduler to complete the logical decoupling of access requests through phase superposition on the same physical resource block. It transforms the physical frequency shift parameters that cause radio signal interference into orthogonal isolation identifiers in the code domain dimension. This eliminates the control plane signaling congestion caused by concentrated access of three-dimensional mobile objects at the medium access control layer and makes the allocation of the underlying radio air interface resource block match the spatial geometric topology distribution of low-altitude mobile objects.

[0047] Example 3: When the system faces the on-site calibration of physical layer protocol parameters, the calibration component controls multiple test drones to fly at a gradient relative radial velocity. The resource prediction unit extracts the set of radial Doppler frequency shift differences from the test drones. The computation component uses the ratio of the maximum phase deflection limit allowed by the random access preamble to the maximum value in the set of radial Doppler frequency shift differences as the upper limit of the search. Within the closed interval from zero to the upper limit of the search, it generates a candidate sequence of constant mapping coefficients k in arithmetic steps. The resource prediction unit calls the candidate sequence to calculate the phase offset feature value. The base station scheduler applies the phase offset characteristic values. Demodulate concurrent uplink access signals and calculate the code domain crosstalk bit error rate; the calibration component extracts the target candidate value that minimizes the code domain crosstalk bit error rate, and writes the target candidate value into the physical register as the constant mapping coefficient k for actual operation.

[0048] The adaptive module within the fault-tolerant control component extracts the uplink reference signal energy envelope measured by the calibration component under disturbed wind fields, calculates the intersection of the distribution boundaries of the energy envelope time decay rate under normal flight path and yaw conditions, and sets the distribution boundary intersection as the initial preset decay threshold. When the system is running continuously, the adaptive module extracts actual channel fading samples, quantifies the baseline drift component caused by large-scale path loss, and updates the initial preset decay threshold by removing the baseline drift component from the real-time calculated time decay rate. The temporal backoff allocation logic of the underlying radio air interface resource block matches the spatial trajectory disturbance amount excited by the physical environment.

[0049] Example 4: When the system faces the field calibration conditions of grid mapping parameters for newly built low-altitude base stations and hysteresis window baseline pre-calibration, the calibration server instructs the calibration UAV equipped with a differential global positioning module to hover at the preset geometric boundary node of the covered airspace. The airspace grid mapping unit extracts the spatial coordinate sequence of the calibration UAV and converts the spatial coordinate sequence into a discrete dataset composed of three-dimensional coordinate points. The computing component calculates the absolute physical distance of each spatial coordinate sequence relative to the base station based on the physical coordinates of the phase center of the base station antenna array. The signal acquisition module records the absolute timestamp of the uplink detection reference signal emitted by the calibration UAV reaching the baseband processing hardware. The computing component divides the absolute physical distance by the measured propagation rate of electromagnetic waves in the current atmospheric environment to generate a spatial propagation delay reference value. The resource prediction unit measures the total number of logic gate flips from receiving the uplink detection reference signal to outputting the corresponding resource block index. The calibration server combines the spatial propagation delay reference value with the hardware processing time of the associated logic gate flips to generate the single-point hysteresis lower boundary of the base station grid coverage.

[0050] The computational component extracts a set of spatial propagation delay reference values ​​corresponding to multiple uniformly distributed geometric boundary nodes within the same mesh bounding box, calculates the standard deviation of the temporal distribution of the spatial propagation delay reference value set, and calibrates the server according to the formula. A fixed trigger baseline value for the preset hysteresis window is determined. This fixed trigger baseline value is the sum of three factors: the spatial propagation delay reference value, the product of the total number of logic gate toggles and the system master clock cycle, and the product of a margin factor and the time distribution standard deviation. The system master clock cycle is set to 5.95ns, corresponding to a processor frequency of 168MHz. The total number of logic gate toggles is preset to 1200 instruction cycles. The margin factor is calibrated to 1.5. The time distribution standard deviation is obtained through real-time variance calculation based on the set of spatial propagation delay reference values ​​collected within the first 60 seconds. This margin factor of 1.5 was calibrated by testing the 10ms-level delay jitter generated by the UAV under simulated wind disturbance at 12m / s. Ultimately, this ensures that control commands are encoded, encapsulated, and sent to the physical layer driver 20ms in advance. This is a fixed trigger baseline value measured in microseconds. The mathematical median of the set of reference values ​​for spatial propagation delay in microseconds. This represents the total number of dimensionless logic gate flip cycles. The main clock period is the system's main frequency, measured in microseconds, and γ is a dimensionless margin factor. The standard deviation of the time distribution is expressed in microseconds. The product of the margin factor and the standard deviation of the time distribution absorbs the random propagation jitter component induced by space weather turbulence. The calibration server extracts the reference spatial index corresponding to the discrete dataset and subtracts it from the actual scheduled air interface physical resource block index to generate a difference sequence. The statistical mode of the difference sequence is selected and written into the hardware register of the medium access control layer as a linear offset for converting the spatial index into the resource block index. The resource mapping logic of the underlying wireless air interface achieves quantitative matching with the physical electromagnetic propagation characteristics and hardware delay attributes of a specific base station.

[0051] Example 5: When the system faces code domain conflict suppression conditions with high dynamic access requests, the resource prediction unit will calculate the phase offset characteristic value. As initial values ​​for the physical layer, they are injected into the pseudo-random sequence generator, which is based on... Generate an orthogonal phase bias sequence, where, The initial values ​​generated for the sequence, For phase offset eigenvalues, The physical layer cell identifier of the base station is used. The orthogonal phase offset sequence is applied to the carrier mapping operator of the uplink access signal, so that the access signals of different UAVs present uncorrelated rotating phases on the same time and frequency resource block.

[0052] After receiving the superimposed uplink access signals, the base station scheduler extracts the impulse response function of the radio interface and performs time-delay Doppler two-dimensional domain mapping. Utilizing the Doppler dimension differences generated by multipath propagation, it matches the rotation phase factor corresponding to each orthogonal phase offset sequence for coherent accumulation and extraction, thereby decoupling the independent random access preamble signaling stream. The calibration component adjusts the candidate mapping step size to ensure the generated phase offset eigenvalues ​​are accurate. The phase difference after physical layer mapping is greater than the phase noise floor of the wireless air interface, so that the code domain isolation is maintained at a quantization level of not less than 20dB, and the underlying wireless communication link achieves deterministic decoupling at the physical layer in dense burst access scenarios.

[0053] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit of this application and the scope of protection of this invention, and all of these forms are within the protection scope of this application.

Claims

1. A dynamic access system for unmanned aerial vehicles (UAVs) for monitoring low-altitude flight paths, characterized in that, include: The spatial grid mapping unit is used to divide the physical spatial domain covered by the base station from 0m to 1000m into a three-dimensional grid, and to establish a deterministic hash mapping association between the geometric boundary dataset of each grid unit and the resource block index of the media access control layer. The trajectory vector transformation unit is used to obtain the three-dimensional velocity vector fed back by the UAV and project the three-dimensional velocity vector onto the physical airspace coordinate system to generate a directed predicted trajectory; The resource prediction unit is used to calculate the intersection path between the directed predicted trajectory and the bounding box of the grid in the 3D mesh, extract the resource block index covered by the intersection path, and generate phase offset feature values ​​based on the radial Doppler frequency shift of the UAV relative to the base station. The access control unit is used to generate access authorization instructions by combining resource block indexes and phase offset feature values, and issue them within a preset hysteresis window before the UAV reaches the corresponding grid boundary; wherein, the phase offset feature value is used to trigger the physical layer orthogonal phase offset sequence to isolate the code domain of random access preambles that occur concurrently in the same resource block group.

2. The UAV dynamic access system for monitoring low-altitude flight paths according to claim 1, characterized in that, When the access control unit detects that multiple directional predicted trajectories point to the same grid bounding box, it assigns different physical layer orthogonal phase offset sequences based on the radial Doppler frequency shift difference of each UAV. Based on the multipath Doppler characteristics of the wireless air interface, the access control unit achieves logical decoupling of concurrent access requests on the same physical resource block through phase superposition, so as to suppress control plane signaling congestion induced by preamble collision.

3. The UAV dynamic access system for monitoring low-altitude flight paths according to claim 1, characterized in that, The spatial grid mapping unit includes a spatial model building component and an index binding component; the spatial model building component is used to build a three-dimensional grid; the index binding component is used to define the boundaries of each grid cell in the three-dimensional grid as radio resource trigger boundaries and establish a monotonic mapping relationship between the radio resource trigger boundaries and the corresponding resource block indexes.

4. The UAV dynamic access system for monitoring low-altitude flight paths according to claim 1, characterized in that, The access control unit includes a fault-tolerant control component; the fault-tolerant control component is used to configure a common backoff time slot to provide a short data recovery path when the UAV misses its dedicated access time window due to environmental disturbances, and to determine the yaw state of the UAV by monitoring the energy change trend of the uplink reference signal, wherein the yaw state is used to trigger the reduction of access frequency.

5. A dynamic access system for unmanned aerial vehicles (UAVs) for monitoring low-altitude flight paths according to claim 1, characterized in that, The trajectory vector transformation unit includes a coordinate transformation component; the coordinate transformation component is used to convert the geographic coordinate system velocity components fed back by the UAV into three-dimensional vector parameters in the physical airspace coordinate system, and to establish the starting coordinates of the directed predicted trajectory based on the center position of the base station's antenna array.

6. The UAV dynamic access system for monitoring low-altitude flight paths according to claim 1, characterized in that, When processing intersecting paths, the resource prediction unit uses a collision detection algorithm based on a hierarchical bounding box structure to calculate the geometric intersection of the directed predicted trajectory and the grid bounding box. The resource prediction unit determines the index of the first resource block to be allocated based on the starting position of the intersecting path and reserves dedicated access resources for subsequent handover processes based on the penetration depth of the intersecting path.

7. A dynamic access system for unmanned aerial vehicles (UAVs) for monitoring low-altitude flight paths according to claim 1, characterized in that, The opening duration of the preset hysteresis window is determined based on the ratio of the UAV's current flight speed to the geometric radius of the grid cell. The opening duration is set to be greater than or equal to the computation time taken by the resource prediction unit to process intersecting paths.

8. A dynamic access system for unmanned aerial vehicles (UAVs) for monitoring low-altitude flight paths according to claim 1, characterized in that, The geometric dimensions of the grid cells in the 3D grid are dynamically adjusted according to the distribution density of UAVs within the base station coverage area; in areas where the UAV density exceeds a preset density threshold, the spatial grid mapping unit reduces the volume of the grid cells to improve the spatial resolution of radio resource allocation.

9. A dynamic access system for unmanned aerial vehicles (UAVs) for monitoring low-altitude flight paths according to claim 1, characterized in that, The system also includes a parameter feedback module; the parameter feedback module sends an access authorization command containing phase offset characteristic values ​​to the UAV via the physical layer downlink control channel, so that the UAV can adjust the initial phase of its uplink access signal according to the phase offset characteristic values.

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