A Location-Based Unmanned Aerial Vehicle (UAV) Ad hoc Network MPR Selection Method

Abstract

This invention discloses a location-based method for selecting MPR nodes in an unmanned aerial vehicle (UAV) ad hoc network, relating to the field of UAV ad hoc networks. This method applies real-time UAV location information to MPR selection. First, in MPR selection, each two-hop neighbor node selects its nearest one-hop neighbor node as the MPR node, effectively improving network transmission performance. Second, all MPR nodes are evaluated sequentially in ascending order of the number of their selected two-hop neighbors. MPR nodes whose two-hop neighbors can all connect to other MPR nodes are removed from the MPR set, further reducing MPR node redundancy and saving routing protocol overhead.

Description

Technical Field

[0001] This invention belongs to the field of UAV ad hoc networks, specifically relating to a method for selecting MPR nodes in UAV ad hoc networks based on location information. Background Technology

[0002] Unmanned aerial vehicle (UAV) ad hoc networks, using UAVs as network nodes, are characterized by multi-hop, decentralization, and self-organization, and do not rely on ground-based communication infrastructure, thus attracting increasing attention in recent years. UAV ad hoc network services typically require low latency, high reliability, and fast response times; therefore, selecting a suitable routing protocol is crucial for network construction. Optimized Link State Routing (OLSR), a typical a priori routing protocol, offers advantages such as fast response and low latency. Furthermore, it employs a multi-point relay (MPR) mechanism to forward broadcast information, effectively reducing the repeated forwarding of identical control information and saving routing protocol overhead. Due to these advantages, the OLSR protocol can well meet the service requirements of UAV ad hoc networks.

[0003] In the OLSR protocol, the selection of the MPR set significantly impacts its performance. The general principle for MPR selection in OLSR is to minimize the MPR set while ensuring access to all two-hop nodes. A smaller MPR set results in lower control message overhead and better network performance. However, the minimum MPR set selection problem has been proven to be a non-deterministic polynomial (NP) complete problem, making it difficult to find an optimal solution. Only heuristic algorithms can be used to obtain approximate solutions. Currently, heuristic MPR selection methods only utilize network topology information and do not consider the real-time geographical location information of nodes within the network. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by providing a location-based method for selecting the MPR (Multi-hop Relationship) in an unmanned aerial vehicle (UAV) ad hoc network. This method fully utilizes the real-time location information obtained by the UAV through its GPS module to calculate mutual distances. In the MPR selection process, each two-hop neighbor node selects the nearest (i.e., the one with the best transmission performance) one-hop neighbor node as the MPR node, effectively improving network transmission performance. Furthermore, to reduce MPR node redundancy, MPR nodes with a small number of two-hop neighbors that can also be connected to other MPR nodes are removed from the MPR set.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A location-based method for selecting the MPR (Multi-Level Position) of an unmanned aerial vehicle (UAV) ad hoc network includes the following steps:

[0007] Step S1: Based on the location information of the UAV nodes, determine the one-hop neighbor node set N1(s) and the two-hop neighbor node set N2(s) of the network source node s; initialize the MPR set of the network source node s to be empty;

[0008] Step S2: For all two-hop neighbor nodes s2, calculate the distance between them and all nodes in the one-hop neighbor node set N1(s), select the nearest one-hop node s1 as the MPR node and add it to the MPR set, and at the same time add s2 to the MPR_Selected set of the selected s1.

[0009] Step S3: Count the number of MPR_Selected set nodes for each MPR node in the MPR set, and sort the MPR nodes in ascending order of the number of MPR_Selected set nodes;

[0010] Step S4: Select the i=1th node MPR in the sorted MPR set. i ;

[0011] Step S5: Determine MPR i Check if all nodes in the MPR_Selected set can connect to other MPR nodes; if they can, proceed to step S6; if there are nodes that cannot connect to other MPR nodes, jump to step S7.

[0012] Step S6: Remove MPR nodes from the MPR set i and the node MPR i The nodes in the MPR_Selected set are assigned to the nearest other MPR nodes, the MPR_Selected set of each node in the MPR set is updated, and the process jumps to step S3;

[0013] Step S7: Determine whether all nodes in the MPR set have been traversed; if there are still nodes that have not been traversed, increment the value of i by 1 and jump to step S5; if all MPR nodes have been traversed, the MPR selection of the network source node s ends.

[0014] The beneficial effects of this invention are as follows:

[0015] 1. This invention uses the geographic location information of the UAV in the MPR selection. Two-hop neighbor nodes select the nearest one-hop neighbor node as the MPR node, which effectively improves network transmission performance.

[0016] 2. This invention sequentially removes MPR nodes that have fewer two-hop neighbor nodes and whose two-hop neighbor nodes can also be connected to other MPR nodes from the MPR set, thereby reducing MPR node redundancy and further saving routing protocol overhead.

[0017] 3. When the location of the UAV changes, the present invention can calculate the new MPR set faster than the traditional topology-based MPR selection method. Attached Figure Description

[0018] Figure 1 This is a flowchart of a location-information-based unmanned aerial vehicle (UAV) ad hoc network MPR selection method in an embodiment of the present invention.

[0019] Figure 2 This is a simulation intermediate process diagram of the MPR selection situation in an embodiment of the present invention.

[0020] Figure 3 This is a simulation result diagram of the MPR selection situation in an embodiment of the present invention.

[0021] Figure 4 The figure shows the simulation results of the MPR selection method using the standard OLSR protocol.

[0022] Figure 5 This is a schematic diagram of transmission without using any MPR node selection method. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0024] A location-based method for selecting the MPR (Multi-hop Relationship) in an ad hoc UAV network is proposed. This method applies real-time UAV location information to the MPR selection process. First, in the MPR selection, each two-hop neighbor node selects its nearest one-hop neighbor as the MPR node, effectively improving network transmission performance. Second, all MPR nodes are evaluated sequentially in ascending order of the number of their selected two-hop neighbors. MPR nodes whose two-hop neighbors can all connect to other MPR nodes are removed from the MPR set, further reducing MPR node redundancy and saving routing protocol overhead.

[0025] like Figure 1 As shown, the method includes the following steps:

[0026] Step S1: Based on the location information of the UAV node, determine the one-hop neighbor node set N1(s) and the two-hop neighbor node set N2(s) of the network source node s; initialize the MPR(s) set to empty.

[0027] The specific implementation of step S1 is as follows: Based on the UAV node location information, calculate the distance values ​​from the source node to all other nodes, and set the distance values ​​to be less than or equal to the UAV communication distance threshold d. thAll nodes are added to the one-hop neighbor set N1(s); nodes that do not belong to the one-hop neighbor set N1(s) but whose distance from a one-hop neighbor is less than or equal to d are removed. th The node is added to the two-hop neighbor set N2(s); the MPR(s) set is initialized to be empty.

[0028] Step S2: For all two-hop neighbor nodes s2, calculate their distance to all nodes in the one-hop neighbor node set N1(s). Each s2 selects the nearest one-hop node s1 and adds it to the MPR set; at the same time, it adds s2 to the MPR_Selected set of its selected s1. MPR nodes only forward information to their own MPR_Selected nodes.

[0029] Step S3: Count the number of MPR_Selected set nodes for each MPR node, and sort the MPR nodes in ascending order of the number of MPR_Selected set nodes.

[0030] Step S4: Select the i-th node MPR in the sorted MPR set. i Here, i = 1.

[0031] Step S5: Determine MPR i Check if all nodes in the MPR_Selected set can connect to other MPR nodes. If they can, proceed to step S6; if there are nodes that cannot connect to other MPR nodes, jump to step S7.

[0032] The specific implementation method of step S5 is as follows: First, select MPR i Any node in the MPR_Selected set k Calculate MPR_Selected k The distance value to all other MPR nodes, when other MPR nodes exist. j (j≠i) and MPR_Selected k The distance value is less than or equal to the UAV communication distance threshold d th At that time, it is considered that MPR_Selected k It can connect to other MPR nodes. If no other MPR node meets the conditions, proceed directly to step S7. Otherwise, continue to check the MPR. i Other nodes in the MPR_Selected set m (m≠k), repeat step S5 until MPR. i All nodes in the MPR_Selected set have been evaluated. At this point, MPR iAll nodes in the MPR_Selected set can be connected to other MPR nodes, so proceed to step S6.

[0033] Step S6: Remove the MPR node from the MPR set. i The nodes in the MPR_Selected set of the MPR node are assigned to the other MPR nodes that are closest to it, the MPR_Selected set of the MPR set nodes is updated, and the process jumps to step S3.

[0034] Step S7: Determine if all nodes in the MPR set have been traversed. If there are still untraversed nodes, increment the value of i by 1 and jump to step S5. If all MPR nodes have been traversed, the MPR selection of the network source node s ends.

[0035] The performance of the location-based UAV ad hoc network MPR selection method is verified using simulation. The UAV ad hoc network scenario is set to a size of 1km*1km, with 50 UAV nodes, randomly distributed, and a communication distance threshold d between UAVs. th The distance is 300 meters. Taking UAV node s as an example, the result after it completes steps S1-S2 of the location-based UAV ad hoc network MPR selection method is as follows: Figure 2 As shown. At this point, one-hop neighbor nodes a, b, d, e, g, and h are selected as MPR nodes, resulting in a total of 6 MPR nodes. This is in contrast to all 15 one-hop neighbor nodes broadcasting and forwarding information (such as...). Figure 5 By relying on only 6 MPR nodes to forward broadcast information, routing protocol overhead can be greatly reduced. In addition, all two-hop neighbor nodes communicate with their nearest one-hop neighbor, which can effectively improve transmission performance.

[0036] To further reduce MPR node redundancy, all steps of the location-based UAV ad hoc network MPR selection method are executed, and the MPR selection result is as follows: Figure 3 As shown in the diagram, since MPR node h has only one MPR_Selected node that can connect to MPR node g, this two-hop neighbor node is assigned to MPR node g, and node h is removed from the MPR set. At this point, the MPR set only includes one-hop neighbor nodes a, b, d, e, and g. Nodes a, b, d, e, and g were not removed, indicating that they have MPR_Selected nodes that can only connect to themselves. The number of MPR nodes is now only 5, further reducing routing overhead. The number of MPR nodes calculated in this scenario is also the minimum number of MPR nodes.

[0037] Figure 4This diagram shows the results of the MPR selection method using the standard OLSR protocol in this UAV ad hoc network scenario. First, one-hop neighbor nodes a, b, and d with isolated two-hop neighbors are added to the MPR set sequentially. Then, their connected two-hop neighbors are added to their respective MPR_Selected nodes, and these two-hop neighbors are no longer considered. The one-hop neighbor node f with the most remaining connected two-hop nodes is selected and added to the MPR set. At this point, one two-hop node remains unconnected to any MPR set node, so its connected node e is added to the MPR set. (Comparison) Figure 3 and Figure 4 It can be seen that, although both the standard OLSR protocol's MPR selection method and the method of this invention obtain the minimum MPR set in this scenario, the MPR nodes selected by the method of this invention have a more balanced connection of their two-hop neighbor nodes, and the two-hop neighbor nodes of this invention are closer to their connected MPR nodes. In summary, using the method of this invention can effectively improve network performance.

Claims

1. A method for selecting the MPR (Multi-Level Position) of an unmanned aerial vehicle (UAV) ad hoc network based on location information, characterized in that, Includes the following steps: Step S1: Determine the network source node based on the drone node location information. s One-hop neighbor node set N 1( s ) and the set of two-hop neighbor nodes N 2 ( s Initialize the network source node. s The MPR set is empty; Step S2: For all two-hop neighbor nodes s 2. Calculate its set of one-hop neighbor nodes. N 1( s The distance values ​​of all nodes in the array are used to select the node with the closest one-hop distance. s 1 is added to the MPR set as an MPR node, and at the same time... s 2. Add to its selected s 1 MPR_Selected set; Step S3: Count the number of MPR_Selected set nodes for each MPR node in the MPR set, and sort the MPR nodes in ascending order of the number of MPR_Selected set nodes; Step S4: Select the first [item] of the sorted MPR set. i =1 node MPR i ; Step S5: Determine MPR i Check if all nodes in the MPR_Selected set can connect to other MPR nodes; if they can, proceed to step S6; if there are nodes that cannot connect to other MPR nodes, jump to step S7. Step S6: Remove MPR nodes from the MPR set i and the node MPR i The nodes in the MPR_Selected set are assigned to the nearest other MPR nodes, the MPR_Selected set of each node in the MPR set is updated, and the process jumps to step S3; Step S7: Determine whether all nodes in the MPR set have been traversed; If there are still nodes that have not been traversed, then... i Increment the value by 1, then jump to step S5; If all MPR nodes have been traversed, then the network source node s The MPR selection process has ended.

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