Low-latency UAV network handover method based on resource reservation

Abstract

This invention discloses a low-latency handover method for unmanned aerial vehicle (UAV) networks based on resource reservation, primarily addressing the problems of high base station deployment costs, long handover latency, and resource allocation conflicts in existing technologies. The implementation scheme is as follows: UAV flight areas are clustered according to a geographic grid; nodes report flight information to the cluster head based on pre-handover information and location information; the cluster head node generates inter-cluster interaction information based on the received flight information and sends it to each neighboring cluster; the cluster head nodes of neighboring clusters release redundant reserved resources based on the inter-cluster interaction information, reserve time slot resources for the pre-handover node, update the inter-cluster interaction information, and send it to each neighboring cluster; the pre-handover node detects the inter-cluster interaction information and stores the reserved resource information related to its own node; after a handover occurs, the pre-handover node immediately uses the reserved resources to work in the new cluster, completing the handover. This invention features low handover latency, requires no base station participation, has low deployment costs, and eliminates resource allocation conflicts, making it suitable for self-organizing UAV networks with rapidly moving nodes.

Description

Technical Field

[0001] This invention belongs to the field of communication technology, and further relates to a method for handover between regions in a drone network, which can be used in a self-organizing drone network with rapidly moving nodes under a geographic grid clustered distributed architecture. Background Technology

[0002] With the rapid development of drone technology, drone networks are attracting widespread attention as a promising technology, and drone logistics has become a new economic growth point. Multi-drone systems, through collaborative work, not only improve mission resilience but also adapt to more complex and large-scale application scenarios, demonstrating enormous potential. These multi-drone systems are widely used in real-time monitoring, transportation, search and rescue operations, covering both civilian and military applications, providing more flexible and efficient solutions for various missions.

[0003] In large-scale drone network environments, due to limited communication distance, multi-hop communication is required to achieve drone interconnection. Therefore, clustering technology is used to divide drone nodes into clusters, with each cluster containing several drone nodes. A node is selected as the cluster head to manage and coordinate the allocation of communication resources within and between clusters. In a clustered drone network, each cluster uses orthogonal spectrum resources for communication to avoid inter-cluster interference.

[0004] Because drone nodes move, they inevitably traverse multiple clusters, leading to handover. During handover, the processes of drone node accessing the new cluster and allocating communication resources to the drone node are required, both of which contribute to handover latency. Furthermore, due to a lack of communication resources, drone nodes cannot send flight safety-related messages during handover, compromising the flight safety of the traversing drone and its neighboring drones.

[0005] To avoid the aforementioned problems, optimized handover technology is needed to enable drones to move freely between different clusters and achieve stable communication throughout the network. Numerous studies on handover technology have been conducted in the present technology field.

[0006] Cellular soft handover is a mobile communication handover technology that allows mobile devices to switch from one cellular network to another without interrupting communication. This technology originates from relevant specifications in the 3GPP (3rd Generation Partnership Project) standards. Its handover mode involves simultaneously activating two network links and their corresponding data streams for a relatively long period until the transmission quality of the new base station meets the required specifications, at which point the connection with the original base station is disconnected. While this handover technology guarantees no communication interruption during the handover process, the mobile node needs to communicate with multiple base stations simultaneously, consuming more spectrum resources and reducing network spectrum efficiency. Furthermore, drone nodes do not support multi-mode operation and cannot communicate with multiple base stations simultaneously; therefore, this handover technology is not suitable for drone networks.

[0007] Patent document CN112272365A discloses a method for handover of vehicle-to-ground communication signals in rail transit. The train reports its real-time location and speed information to the source base station via a vehicle-to-ground wireless network. The source base station extracts the location and speed information from the measurement report and determines whether to initiate a pre-bearing process based on the received information. If the initiation conditions are met, the pre-bearing process is executed, sending a pre-bearing request to the target base station. The target base station prepares for handover in advance, pre-configuring various handover parameters and allocating the time and frequency resources required for handover. This method reduces latency during inter-cell handover by employing a target pre-bearing approach, which can reduce the probability of handover interruption and improve the handover success rate. However, because it treats the base station as the central node of the network, responsible for managing and scheduling the connection of mobile devices, it is difficult to deploy the base station in complex geographical environments, and the deployment cost is high.

[0008] To address the handover access latency issue, in May 2023, Zhang Xiaokang proposed a preemptive resource pre-allocation mechanism in his research on message transmission strategies and resource allocation mechanisms for cellular vehicle-to-everything (V2X) applications. Vehicles determine channel resource occupancy by decoding the resource information of other vehicles, then record available and occupied resources. Resources are reserved for services through a resource selection window, and the vehicle determines its own priority based on whether it can obtain the reserved resource. When a vehicle generates a service, it checks if resources are reserved for that service. If reserved resources are available, they are used for transmission; otherwise, resource reselection is initiated to reallocate resources. However, this preemptive resource pre-allocation mechanism may disrupt the continuous transmission of periodic services due to higher-priority services preempting resources. Furthermore, in densely populated areas or resource-limited environments, this mechanism may lead to prolonged resource contention and conflicts. Additionally, the transmission of flight information in UAV networks must be conflict-free; therefore, this mechanism cannot be directly applied to UAV networks. Summary of the Invention

[0009] The purpose of this invention is to address the shortcomings of the prior art by proposing a low-latency UAV network handover method based on resource reservation. This method eliminates the dependence on base stations through autonomous UAV decision-making and resource allocation. By dividing the geographic grid into clusters and reserving resources in advance according to the services of each UAV node, it avoids flight safety issues caused by communication interruptions due to node handover latency.

[0010] To achieve the above objectives, the technical solution of the present invention is as follows:

[0011] (1) Initialization of UAV scene and time slot resources:

[0012] 1a) Divide the UAV flight area into clusters according to the geographic grid, and use orthogonal communication resources for communication in each cluster. Initialize the number of UAV nodes and make them work in the corresponding cluster C. i Each cluster selects a cluster head node M. i The cluster head node maintains the node information tables within the cluster and neighboring clusters, as well as the inter-cluster interaction information sent by the cluster.

[0013] 1b) Nodes within a cluster communicate using intra-cluster interaction time slots, while the heads of adjacent clusters communicate using inter-cluster interaction time slots.

[0014] (2) Ordinary nodes periodically generate node flight information and update it:

[0015] 2a) Ordinary nodes periodically generate node flight information based on parameters such as their own position, speed, flight direction, and current working cluster;

[0016] 2b) Ordinary nodes determine whether a pre-handover is needed based on flight information;

[0017] If a pre-switch has already occurred, proceed to step 2c);

[0018] If no pre-switch occurs, proceed to step (3);

[0019] 2c) The pre-switching ordinary node generates pre-switching request information and updates it to the node flight information, and executes step (3);

[0020] (3) Ordinary nodes use intra-cluster interaction time slot resources to send flight information to the head of the working cluster;

[0021] (4) The cluster head node updates the intra-cluster node information table and inter-cluster interaction information based on the received node flight information and uses the inter-cluster interaction time slot resources to send the inter-cluster interaction information to each neighboring cluster.

[0022] (5) After receiving the inter-cluster interaction information, the neighboring cluster head updates the inter-cluster interaction information:

[0023] 5a) After receiving the inter-cluster interaction information, the head node of the neighboring cluster determines whether it needs to release reserved resources based on the node information table in the received inter-cluster interaction information and the node information table within its own cluster:

[0024] If it is necessary to release reserved resources, then release and update the reserved intra-cluster interaction time slot resources, and then execute step 5b);

[0025] If there is no need to release reserved resources, proceed directly to step 5b).

[0026] 5b) The neighboring cluster head node obtains the time slot resource requirements of the nodes to be switched based on the pre-switching request information in the received inter-cluster interaction information, reserves intra-cluster interaction time slot resources for the nodes to be switched to this cluster, and updates the reserved time slot resources in the inter-cluster interaction information.

[0027] (6) The cluster head node of a neighboring cluster uses the inter-cluster interaction time slot resource to send inter-cluster interaction information to each of its neighboring clusters;

[0028] (7) After a normal node in a cluster undergoing pre-switching detects the inter-cluster interaction information sent by the target switching neighboring cluster, it stores the time slot resource information reserved for this node in this node.

[0029] (8) The pre-switched ordinary nodes periodically determine whether they have undergone inter-area handover based on flight information;

[0030] If no handover has occurred, meaning the node is still flying within the current cluster, it will wait for the next handover decision.

[0031] If a handover occurs, i.e., the node flies to the boundary of the cluster and enters the neighboring cluster, it uses the intra-cluster interaction time slot resources obtained in step (7) to communicate with the new cluster head, and the handover process ends.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] First, in traditional handover processes, nodes rely on base stations for handover decisions and resource allocation. This invention eliminates this reliance on base stations by enabling autonomous decision-making and resource allocation by UAV nodes, making it suitable for operation in complex geographical environments and areas without base station deployments.

[0034] Second, in traditional handover, resources are only allocated to a node by the new cluster when a handover occurs, resulting in access latency. This invention predicts the arrival time of a node to a neighboring cluster by analyzing the node's flight information. When the node's arrival time is less than the pre-handover time threshold, resources are reserved for that node, reducing access latency and improving flight safety.

[0035] Third, the resource reservation mechanism of traditional cellular networks and vehicle-to-everything (V2X) networks does not allocate reserved resources to specific nodes; instead, resources are available to all nodes joining the network during handover. This invention, however, allocates reserved resources to specific nodes without base station management. By reserving resources for designated nodes, these nodes can immediately use the reserved resources for communication after handover. This avoids the resource conflicts caused by nodes joining the network simultaneously, as is common in traditional resource reservation methods. Attached Figure Description

[0036] Figure 1 This is a flowchart illustrating the implementation of the present invention;

[0037] Figure 2 This is a schematic diagram of the drone flight area division in this invention;

[0038] Figure 3 This is a diagram illustrating the pre-switching delay configuration of the present invention. Detailed Implementation

[0039] The present invention will now be further described with reference to the accompanying drawings.

[0040] Reference Figure 1 The implementation steps for this example are as follows:

[0041] Step 1: Initialize the drone scene and time slot resources.

[0042] (1.1) The range of the transceiver carried by the UAV is approximated as a 3n×3n rectangular area. Based on the fact that the range of the UAV node's transceiver covers all adjacent clusters in the geographic grid clustering, the area size of the geographic grid cluster is determined to be an n×n rectangular area.

[0043] (1.2) Divide the flight area into n×n clusters according to a geographic grid. Each cluster uses orthogonal communication resources for communication. Initialize a certain number of UAV nodes and make them work in the corresponding cluster C. i Each cluster has a cluster head node M. i With several ordinary nodes N i Initialize the node information tables of each cluster within and between each cluster, and have the cluster head node maintain the node information tables of each cluster within and between each cluster and the inter-cluster interaction information sent by this cluster;

[0044] The cluster head node and ordinary nodes within a cluster communicate using intra-cluster interaction time slots, while the cluster heads of adjacent clusters communicate using inter-cluster interaction time slots.

[0045] like Figure 2As shown, in this embodiment, the UAV's flight area is a 50×50 rectangular area, and the UAV's transceiver range is approximately a 30×30 rectangular area. The UAV's flight area is divided into 5×5 geographical grids according to geographic grid clustering, with each grid cluster approximately a 10×10 rectangular area. Several UAV nodes exist between (10,10) and (40,40), with cluster numbers C1 to C9, operating frequency bands f1 to f9, and cluster head nodes M1 to M9. A regular node N1 exists within cluster C4, located at (X... T ,Y T The velocity components V in the perpendicular directions of X and Y x and V y It will then fly into cluster C5. Based on the node's location, speed, and the working cluster it belongs to, a node information table for each cluster, including information on nodes within and adjacent clusters, is generated and maintained by the cluster head node.

[0046] Communication within and between clusters uses the UDP / IP protocol. Ordinary node N1 uses intra-cluster interaction time slots to periodically send flight information within the cluster via radio broadcast. Cluster head node M4 and cluster head node M5 use inter-cluster interaction time slots to periodically send inter-cluster interaction information to neighboring clusters via radio broadcast.

[0047] Step 2: Ordinary nodes periodically generate and update node flight information.

[0048] (2.1) Ordinary nodes periodically generate node flight information based on parameters such as their own position, speed, flight direction, and current working cluster.

[0049] In this embodiment, the ordinary node N1 periodically updates its own position:

[0050] (X T ,Y T )=(X+V x ×T,Y+V y ×T)

[0051] Where (X, Y) represents the initial position information of ordinary node N1, based on the velocity components V in the vertical directions of ordinary node N1 in the X and Y directions. x and V y T is the time period for updating the node's position;

[0052] Update the position of ordinary node N1 according to time period T, and based on the position (X) of ordinary node N1. T ,Y T ), velocity components V in the vertical directions of X and Y x and V y And the flight information of the current working cluster C4 generation node;

[0053] (2.2) Ordinary nodes determine whether a pre-handover has occurred based on flight information:

[0054] (2.2.1) The pre-switching node determines the pre-switching time threshold T based on the time required to complete the reception and storage of the reserved time slot resources. th :

[0055] First, calculate the maximum value ΔT of the pre-switching delay ΔT. max :

[0056] In this embodiment, the node pre-switching delay is as follows: Figure 3 As shown, ΔT1 is the time delay from node pre-handover to node sending flight information to cluster head, ΔT2 is the time delay from working cluster head sending inter-cluster interaction information containing pre-handover request to target switching cluster head, and ΔT3 is the time delay from target switching cluster head sending inter-cluster interaction information containing reserved resource information. The maximum value of the pre-handover delay ΔT is ΔT. max for:

[0057] ΔT max =ΔT 1max +ΔT 2max +ΔT 3max

[0058] Where ΔT 1max The maximum value of ΔT1 is the time slot interval for the node to periodically transmit flight information. 2max With ΔT 3max These are the maximum values ​​of ΔT2 and ΔT3, respectively, which represent the time slot intervals for periodically transmitting inter-cluster interaction information;

[0059] Then, the pre-handover time threshold T is calculated based on the maximum pre-handover delay. th :

[0060] T th =ΔT max ×(1+x)

[0061] Where x is the time factor, the time factor is used to ensure T th Within the specified time, the pre-switched node can receive the reserved resources.

[0062] (2.2.2) Ordinary nodes periodically estimate the time T for reaching the cluster boundary based on flight information such as position, velocity, flight direction, and the current working cluster. hd With pre-switched cluster C hd :

[0063] In this embodiment, the ordinary node N1 is determined based on its own position (X). T ,Y TThe top-left and bottom-right coordinates of the current working cluster C4 are (10,20) and (20,30), respectively. The velocity components V in the vertical X and Y directions are... x and V y Estimated node arrival time T at the cluster boundary hd With pre-handover cell C hd The time T required for a normal node to reach the boundary of the working cluster hd The formula for calculating the minimum positive time to reach the four boundaries is as follows:

[0064]

[0065] In the above formula, the time to reach the left boundary is The time to reach the right boundary is The time to reach the upper boundary is The time to reach the lower boundary is By calculating the time required to reach these four boundaries, the time to reach the right boundary of the cluster is found to be the smallest positive time among the four boundaries, i.e., the pre-switching time is: Its pre-switching cluster is C5.

[0066] (2.2.3) Ordinary nodes are assigned based on their expected arrival time at the cluster boundary, T. hd With pre-switching time threshold T th Compare and determine whether a pre-switching has occurred:

[0067] If T hd ≤T th If a normal node undergoes a pre-switch, the target pre-switch cluster is C. hd Execute step (2.3);

[0068] If T hd >T th If no pre-switch occurs in a normal node, proceed to step three.

[0069] In this embodiment, the ordinary node N1 is based on the pre-switching time T. hd With pre-switching time threshold T th Determine T hd <T th This indicates that a pre-switch has occurred in ordinary node N1, and its pre-switch cluster is C5. Therefore, the pre-switch ordinary node N1 will execute step (2.3).

[0070] (2.3) The ordinary node to be switched generates a switch request information based on the node’s time slot resource requirements and the cluster number of the target to be switched, and updates it to the node’s flight information.

[0071] In this embodiment, when a pre-switching occurs in a normal node N1, the normal node N1 generates a pre-switching request information based on the time slot resource requirements of its flight information service and the cluster number C5 of the target switch, and updates it in the node flight information.

[0072] Step 3: Ordinary nodes use intra-cluster interaction time slot resources to send flight information to the working cluster head.

[0073] In this embodiment, ordinary node N1 uses the time slot resources occupied by its flight information service to send the node's flight information to the cluster head node M4 of the current working cluster C4.

[0074] Step 4: The cluster head node updates the intra-cluster node information table and inter-cluster interaction information based on the received node flight information, and uses the inter-cluster interaction time slot resources to send the inter-cluster interaction information to each neighboring cluster.

[0075] (4.1) After receiving the flight information of the nodes in the cluster, the cluster head node updates the node information table in the cluster according to the location information therein, and updates it to the inter-cluster interaction information sent to each neighboring cluster;

[0076] In this embodiment, the cluster head node M4 of cluster C4 updates the position information of ordinary node N1 in the cluster node information table according to the flight information of ordinary node N1 received in the cluster and the position information of ordinary node N1, and updates the inter-cluster interaction information sent by cluster C4 to each adjacent cluster according to the latest cluster node information table.

[0077] (4.2) The cluster head node determines whether a pre-handover has occurred within the cluster based on the received flight information of the nodes within the cluster:

[0078] If the node flight information contains node pre-switching request information, then proceed to step (4.3);

[0079] If the node flight information does not contain node pre-switching request information, then proceed to step (4.4);

[0080] (4.3) The cluster head node adds the node pre-switching request information to the inter-cluster interaction information sent from this cluster to the target pre-switching cluster according to the target pre-switching cluster number in the node pre-switching request information, and executes step (4.4);

[0081] (4.4) The cluster head node uses its inter-cluster interaction time slot resources with each neighboring cluster to send the corresponding inter-cluster interaction information.

[0082] In this embodiment, the flight information received by the cluster head node M4 of cluster C4 from the ordinary node N1 includes node pre-switching request information. Based on the target pre-switching cluster C5 in the pre-switching request information of the ordinary node N1, the cluster head node M4 adds the pre-switching request information of the ordinary node N1 to the inter-cluster interaction information sent to the neighboring cluster C5.

[0083] Cluster head node M4 uses the inter-cluster interaction time slot resources occupied by this cluster to send inter-cluster interaction information with neighboring cluster C5 via radio broadcast.

[0084] Step 5: After receiving the inter-cluster interaction information, the neighboring cluster head updates the inter-cluster interaction information.

[0085] (5.1) After receiving the inter-cluster interaction information, the head node of the neighboring cluster determines whether it needs to release the reserved resources based on the node information table in the received inter-cluster interaction information and the node information table within its own cluster:

[0086] (5.1.1) The cluster head node of a neighboring cluster determines whether it has reserved time slot resources for the node to be switched over:

[0087] If time slot resources have been reserved for the pre-switching node, proceed to step (5.1.2);

[0088] If no time slot resources are reserved for the pre-switching node, there is no need to release resources; proceed to step (5.2).

[0089] In this embodiment, since the cluster head node M5 of the neighboring cluster C5 has not yet reserved time slot resources, there is no need to release resources, and step (5.2) is executed.

[0090] (5.1.2) The cluster head node of a neighboring cluster determines whether a pre-handover node with reserved resources has undergone a handover based on the node information table in the received inter-cluster interaction information:

[0091] If the node information table sent by the original cluster still contains a pre-switching node with reserved resources, then no handover has occurred, there is no need to release the reserved resources, and step (5.2) is executed.

[0092] If the node information table sent by the original cluster does not contain a pre-switching node with reserved resources, then the pre-switching node with reserved resources will undergo a cross-cell handover, and step (5.1.3) will be executed.

[0093] (5.1.3) The cluster head node of a neighboring cluster determines whether nodes with reserved resources should switch to its own cluster based on the node information table within its own cluster:

[0094] If there is a pre-switch node with reserved resources in the node information table within this cluster, then the node has already switched to this cluster across regions and there is no need to release the reserved resources. Proceed to step (5.2).

[0095] If there is no pre-switching node with reserved resources in the node information table within this cluster, then the node has not switched to this cluster across regions and needs to release the reserved resources. In this case, step (5.1.4) is executed.

[0096] (5.1.4) The cluster head node releases and updates the reserved intra-cluster interaction time slot resources, and executes step (5.2);

[0097] (5.2) The neighboring cluster head node obtains the time slot resource requirements of the pre-switching node in the pre-switching request information in the received inter-cluster interaction information, reserves intra-cluster interaction time slot resources for the node pre-switching to this cluster, and updates the reserved time slot resources in the inter-cluster interaction information.

[0098] In this embodiment, the cluster head node M5 of neighboring cluster C5 obtains the pre-switching request information of node N1 from the pre-switching request information in the inter-cluster interaction information sent by cluster C4. Based on the time slot resource requirements of node N1 in its pre-switching request information, M5 reserves intra-cluster interaction time slot resources for node N1 and adds the reserved time slot resource information to the inter-cluster interaction information sent by cluster C5 to cluster C4.

[0099] Step 6: The cluster head node of a neighboring cluster uses the inter-cluster interaction time slot resource to send inter-cluster interaction information to each of its neighboring clusters.

[0100] In this embodiment, the cluster head node M5 of neighboring cluster C5 uses the inter-cluster interaction time slot resources occupied by cluster C4 to send inter-cluster interaction information containing reserved time slot resource information to cluster C4 via radio broadcast.

[0101] Step 7: Pre-switch ordinary nodes to store reserved resources and use the reserved resources to work after the handover.

[0102] (7.1) After a normal node in a cluster undergoing pre-switching detects the inter-cluster interaction information sent by the target switching neighboring cluster, it stores the time slot resource information reserved for this node into the node.

[0103] In this embodiment, after the pre-switching ordinary node N1 detects the inter-cluster interaction information sent from neighboring cluster C5 to cluster C4, node N1 reads the reserved time slot resource information therein and stores it as the time slot resource information reserved for this node.

[0104] (7.2) Based on flight information, the pre-handover ordinary node periodically determines whether it has undergone a handover:

[0105] If no handover has occurred, meaning the node is still flying within the current cluster, it will wait for the next handover decision.

[0106] If a handover occurs, i.e., the node flies to the boundary of a cluster and enters a neighboring cluster, it uses the reserved intra-cluster interaction time slot resources to communicate with the new cluster head, and the handover process ends.

[0107] In this embodiment, the pre-switched ordinary node N1 has flown to the boundary of working cluster C4 and entered the neighboring cluster C5. That is, the pre-switched ordinary node N1 has undergone a cross-cell handover. Node N1 uses the time slot resource information reserved in cluster C5 to work under cluster C5, and the cross-cell handover process ends.

[0108] The above description is merely a specific example of the present invention and does not constitute any limitation on the present invention. Obviously, those skilled in the art, after understanding the content and principles of the present invention, may make various modifications and changes in form and details without departing from the principles and structure of the present invention. However, these modifications and changes based on the ideas of the present invention are still within the scope of protection of the claims of the present invention.

[0109] It should be noted that the step numbers in the specification and claims of this invention are only for the purpose of clearly describing the embodiments of this invention and facilitating understanding, and their order is not limited.

Claims

1. A low-latency UAV network handover method based on resource reservation, characterized in that, Includes the following steps: (1) Initialization of UAV scene and time slot resources: 1a) Divide the UAV flight area into clusters according to the geographic grid, and use orthogonal communication resources for communication in each cluster. Initialize the number of UAV nodes and make them work in the corresponding cluster C. i Each cluster selects a cluster head node M. i The cluster head node maintains the node information tables within the cluster and neighboring clusters, as well as the inter-cluster interaction information sent by the cluster. 1b) Nodes within a cluster communicate using intra-cluster interaction time slots, while the heads of adjacent clusters communicate using inter-cluster interaction time slots. (2) Ordinary nodes periodically generate node flight information and update it: 2a) Ordinary nodes periodically generate node flight information based on parameters such as their own position, speed, flight direction, and current working cluster; 2b) Ordinary nodes determine whether a pre-handover is needed based on flight information; If a pre-switch has already occurred, proceed to step 2c); If no pre-switch occurs, proceed to step (3); 2c) The pre-switching ordinary node generates pre-switching request information and updates it to the node flight information, and executes step (3); (3) Ordinary nodes use intra-cluster interaction time slot resources to send flight information to the head of the working cluster; (4) The cluster head node updates the intra-cluster node information table and inter-cluster interaction information based on the received node flight information and uses the inter-cluster interaction time slot resources to send the inter-cluster interaction information to each neighboring cluster. (5) After receiving the inter-cluster interaction information, the neighboring cluster head updates the inter-cluster interaction information: 5a) After receiving the inter-cluster interaction information, the head node of the neighboring cluster determines whether it needs to release reserved resources based on the node information table in the received inter-cluster interaction information and the node information table within its own cluster: If it is necessary to release reserved resources, then release and update the reserved intra-cluster interaction time slot resources, and then execute step 5b); If there is no need to release reserved resources, proceed directly to step 5b); 5b) The neighboring cluster head node obtains the time slot resource requirements of the nodes to be switched based on the pre-switching request information in the received inter-cluster interaction information, reserves intra-cluster interaction time slot resources for the nodes to be switched to this cluster, and updates the reserved time slot resources in the inter-cluster interaction information. (6) The cluster head node of a neighboring cluster uses the inter-cluster interaction time slot resource to send inter-cluster interaction information to each of its neighboring clusters; (7) After a normal node in a cluster undergoing pre-switching detects the inter-cluster interaction information sent by the target switching neighboring cluster, it stores the time slot resource information reserved for this node in this node. (8) The pre-switched ordinary nodes periodically determine whether they have undergone inter-area handover based on flight information; If no handover has occurred, meaning the node is still flying within the current cluster, it will wait for the next handover decision. If a handover occurs, i.e., the node flies to the boundary of the cluster and enters the neighboring cluster, it uses the intra-cluster interaction time slot resources obtained in step (7) to communicate with the new cluster head, and the handover process ends.

2. The method according to claim 1, characterized in that, The node information table within and between clusters in step 1a) includes the cluster number of each cluster and the location information of each node under that cluster.

3. The method according to claim 1, characterized in that, The inter-cluster interaction information sent by this cluster in step 1a) includes the node information table within this cluster, the pre-switching request information of the nodes within this cluster, and the time slot resource information reserved for the nodes in each neighboring cluster.

4. The method according to claim 1, characterized in that, In step 2b), ordinary nodes determine whether a pre-handover has occurred based on flight information, which is implemented as follows: 2b1) The pre-switching node determines the pre-switching time threshold T based on the time required to complete the reception and storage of the reserved time slot resources. th ; 2b2) Ordinary nodes periodically estimate the time T for reaching the cluster boundary based on flight information such as position, velocity, flight direction, and current working cluster. hd With pre-switched cluster C hd ; 2b3) Ordinary nodes are based on the expected arrival time T at the cluster boundary. hd With pre-switching time threshold T th Determine if a pre-switching has occurred: If T hd ≤T th If a normal node undergoes a pre-switch, the target pre-switch cluster is C. hd ; If T hd >T th In this case, no pre-switch occurs for ordinary nodes.

5. The method according to claim 1, characterized in that, In step 2c), the pre-switching ordinary node generates pre-switching request information and updates it to the node flight information. This is done by generating the pre-switching request information based on the node's time slot resource requirements and the cluster number of the target pre-switching node, and then adding the pre-switching request information to the node flight information.

6. The method according to claim 1, characterized in that, In step (4), the cluster head node updates the intra-cluster node information table and inter-cluster interaction information based on the received node flight information, and sends the inter-cluster interaction information to each neighboring cluster. The implementation is as follows: 4a) After receiving the flight information of the nodes in the cluster, the cluster head node updates the node information table in the cluster according to the position information therein and updates it to the inter-cluster interaction information sent to each neighboring cluster; 4b) The cluster head node determines whether a pre-handover has occurred within the cluster based on the received flight information of the nodes within the cluster: If the node flight information contains node pre-switching request information, then proceed to step 4c); If the node flight information does not contain node pre-switching request information, then proceed to step 4d); 4c) The cluster head node adds the node pre-switching request information to the inter-cluster interaction information sent from this cluster to the target pre-switching cluster based on the target pre-switching cluster number in the node pre-switching request information, and then executes step 4d). 4d) The cluster head node uses its inter-cluster interaction time slot resources with each neighboring cluster to send the corresponding inter-cluster interaction information.

7. The method according to claim 1, characterized in that, In step 5a), after the head node of the neighboring cluster receives the inter-cluster interaction information, it determines whether to release the reserved resources based on the node information table in the received inter-cluster interaction information and the node information table within its own cluster. The implementation is as follows: 5a1) The cluster head node of a neighboring cluster determines whether it has reserved time slot resources for the node to be switched over: If time slot resources have been reserved for the pre-switching node, then proceed to step 5a2); If no time slot resources have been reserved for the pre-switched node, then there is no need to release the resources; 5a2) The cluster head node of a neighboring cluster determines, based on the node information table in the received inter-cluster interaction information, whether a pre-handover node with reserved resources has undergone a handover: If the node information table sent by the original cluster still contains pre-switched nodes with reserved resources, then no handover has occurred and there is no need to release the reserved resources; If the node information table sent by the original cluster does not contain a pre-switched node with reserved resources, a handover will occur, and step 5a3 will be executed. 5a3) The cluster head node of a neighboring cluster determines whether a node with reserved resources should switch to its own cluster based on the node information table within its own cluster: If there is a pre-switch node with reserved resources in the node information table within this cluster, then the node has already switched to this cluster across regions and there is no need to release the reserved resources; If there is no pre-switch node with reserved resources in the node information table within this cluster, then the node has not switched to this cluster across regions and the reserved resources need to be released.

8. The method according to claim 1, characterized in that, In step (8), the pre-switched ordinary node periodically determines whether it has undergone a handover based on flight information. This determination is made based on whether the ordinary node is still flying within its original working cluster. If a normal node is still flying within its original working cluster, then no handover has occurred; If a normal node has crossed the working cluster boundary and entered the new cluster, a handover occurs.

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