FANET secure routing method based on network topology awareness

Abstract

The invention relates to an FANET secure routing method based on network topology awareness. A wireless ad hoc network is highly dynamic and unstable, so that communication nodes are easy to lose efficacy and are easy to attack and cheat, and a huge challenge is brought to reliable communication. On the basis of considering a communication network factor, a spatial position factor and an energy factor, the invention provides a multi-routing measurement link selection method fusing an ETX link evaluation method based on stable node constraint and a link effective survival time calculation method aiming at the high dynamic nature of a network and the recombination problem after failure. Furthermore, a security routing protocol P-AODV (Perception-AODV) based on network topology awareness is designed, so that the stability and the security of the network are improved.

Description

Technical Field

[0001] The invention relates to the field of wireless self-organizing networks, in particular to a FANET secure routing method and system based on network topology perception. Background Art

[0002] Flying Ad Hoc Network (FANET) is a multi-hop, autonomous, highly dynamic mobile ad hoc network (MANET) composed of a group of unmanned aerial vehicles. FANET aircraft nodes form their own network without relying on infrastructure. The multi-hop forwarding communication mode can effectively extend the communication distance and perception range of aircraft. In addition to relay communication, FANET can also be used in search and rescue, electronic countermeasures, ground target detection and tracking, disaster monitoring and prediction, remote sensing and other fields.

[0003] In FANET, due to the high-speed mobility and spatial mobility of aircraft nodes, the network topology changes frequently. The irregular movement of nodes in three-dimensional space, as well as the random mobility model, time-related mobility model, path planning-related mobility model, group mobility model or hybrid mobility model adopted by the node group according to task requirements, will cause the pre-established communication path between the source node and the destination node in the network to fail quickly, and the reliability of the link will be reduced, which seriously affects the communication efficiency of FANET.

[0004] In addition, FANET's open wireless channels and distributed structure make it more vulnerable to network attacks. Since FANET does not rely on basic communication facilities or centralized management centers, each node in the network is an equal mobile terminal and its energy is limited. This feature makes FANET more vulnerable to network security threats such as signal eavesdropping, replay attacks, spoofing attacks, black hole attacks, gray hole attacks, and data packet discard attacks than traditional wired networks. These attacks not only destroy the integrity and confidentiality of the communication link, but also interfere with data transmission by reducing network throughput, increasing data transmission delays, and even interrupting communications or stealing information. Therefore, ensuring the security and communication reliability of FANET is an important issue that needs to be solved urgently.

[0005] Since the classic AODV routing protocol adopts the shortest link mechanism (i.e., the least routing nodes in the link) in the route discovery phase and does not consider the link status, it is easy to select a path with unstable links, especially in the FANET environment where the network topology changes rapidly, when two communication nodes on the link have a large relative movement, the node will move outside the communication radius in a short time, causing the communication link established by the AODV routing protocol to be frequently disconnected. When the communication link is disconnected, the communication network will reconstruct the route through the AODV routing repair mechanism, but the route reconstruction using the classic AODV routing repair mechanism often cannot keep up with the speed of link interruption caused by network topology changes, thereby causing the entire network communication performance to drop sharply. The present invention proposes a FANET secure routing method based on network topology perception to improve the communication reliability and security of FANET. Summary of the invention

[0006] In view of the above problems, the purpose of the present invention is to provide a FANET secure routing method based on network topology perception. The method is based on the classic AODV routing protocol, combines the ETX link evaluation method based on stable node constraints and the calculation method of the effective generation time of the link, and proposes a link selection strategy based on multi-routing metrics. By taking the mobility characteristics of the node as a constraint, the optimal RREQ message forwarding cluster is selected, resource waste is reduced, the path discovery time is shortened, and the routing overhead and end-to-end delay are effectively reduced. At the same time, by evaluating the effective generation time of the link, a safe and stable communication link is selected, thereby improving the communication reliability and security of FANET.

[0007] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: a FANET secure routing method based on network topology perception, comprising the following steps:

[0008] Start the route discovery process: add the node status information to the RREQ message to form an improved RREQ message, and broadcast the improved RREQ message to the surrounding neighbor nodes;

[0009] ETX link evaluation based on stable node constraints: A stable node selection method is adopted to select stable nodes to form a stable node cluster, and the floodable range of the ETX link is constrained by the stable nodes;

[0010] Calculate the effective lifetime of the link: evaluate the effective lifetime of each routing line that can reach the destination node through the relative movement speed between nodes;

[0011] Link selection based on multi-routing metrics: Combine communication network factors, spatial location factors and energy factors to perform link selection based on multi-routing metrics.

[0012] The status message is the position and speed of the node.

[0013] The stable node selection method performs node screening according to the relative movement speed and direction of the current node position and the previous node, and includes the following steps:

[0014] In the three-dimensional rectangular coordinate system, the coordinates of the node M are (p Mx ,p My ,p Mz ), speed v M The angle with the z-axis is θ M , the angle between the projection of the velocity on the xOy plane and the x-axis is φ M ;

[0015] The coordinates of node N are (p Nx ,p Ny ,p Nz ), speed v N The angle with the z-axis is θ N , the angle between the projection of velocity on the xOy plane and the x-axis is And node N receives the improved RREQ message sent by node M; determine whether node N is a stable node, as follows:

[0016] The distance D between node M and node N MN ≤pR, where R is the communication radius of the node and p is the reliability parameter. The distance conditions that a stable node needs to meet are as follows:

[0017] (p Mx -p Nx ) 2 +(p My -p Ny ) 2 +(p Mz -p Nz ) 2 ≤p 2 R 2 , 0.7≤p≤1

[0018] The speed conditions that a stable node needs to meet are as follows:

[0019]

[0020] When the relative motion speed between two nodes is greater than the relative motion threshold v max , then give up selecting the current node N as a stable node; where the relative movement speed between node M and node N The calculation formula is as follows:

[0021]

[0022] If the current node meets the distance condition and the speed condition, the current node N is a stable node, updates the improved RREQ message and continues to broadcast and forward data to the surroundings; otherwise, it is not a stable node and discards the improved RREQ message.

[0023] The method of constraining the floodable range of the ETX link by using a stable node includes the following steps:

[0024] When the communication link between the source node and the destination node is established, the ETX value in the node link is obtained by calculating the probability of successful forward transmission of the link and the probability of successful reverse retransmission:

[0025]

[0026] Where L represents the routing link between two stable nodes in the network, x represents a hop in the routing link L, φ(x) is the forwarding reception ratio; ρ(x) is the reverse reception ratio, that is, the probability that the corresponding ACK message is successfully received;

[0027] The link ETX value is represented by the expected number of transmissions required to send a packet including retransmissions on the link; the ETX value of link l can be expressed as:

[0028]

[0029] Among them, p f represents the probability of successful message transmission, p r represents the probability of receiving an ACK message successfully, then the probability of sending a message successfully and getting confirmation is p f ×p r , the metric of the route r from the source node to the destination node is the sum of the ETX values ​​of each link l in the route and can be expressed as:

[0030] ETX r =∑ l∈r ETX l .

[0031] The calculating of the effective link lifetime comprises the following steps:

[0032] Randomly select two neighbor nodes A and B from a route from the source node to the destination node. Nodes A and B are the two intermediate nodes that the destination node passes through for data transmission along the reverse link after generating the RREP message. The maximum communication radius of the node is R.

[0033] At a certain time t, in the three-dimensional rectangular coordinate system, the coordinates of node A are (p Ax ,p Ay ,p Az ), with a velocity of v A , the angle between it and the z-axis is θA , the angle between the projection of the velocity on the xOy plane and the x-axis is φ A ;

[0034] The coordinates of node B are (p Bx ,p By ,p Bz ), with a velocity of v B The angle with the z-axis is θ B , the angle between the projection of the velocity on the xOy plane and the x-axis is φ B ;

[0035] The distance between AB at time t is D AB , after T i After time, node A and node B move to A′(p′ Ax ,p′ Ay ,p′ Az ) and B′(p′ Bx ,p′ By ,p′ Bz ), the distance between nodes A and B becomes D′ AB ;

[0036] When D′ AB = R, at this moment, the two nodes have reached the critical position of inter-node communication and are about to move out of each other's communication range; the effective communication time between node A and node B is T i , i∈1,2,...n, n represents the number of link segments in the route; T i The calculation method is as follows:

[0037]

[0038] The effective lifetime of a route is the minimum time that all inter-node links on the route link maintain effective communication;

[0039] The calculation formula for the effective lifetime of the route from the source node to the destination node is:

[0040] T=min(T1,T2,T3,...,T n )

[0041] Among them, T1, T2, T3, ..., T n It is the effective lifetime of all inter-node links on the routing link.

[0042] The link selection based on multiple routing metrics comprises the following steps:

[0043]

[0044] Among them, M constancy For routing stability; ETXr For each link ETX in the route l The sum of the values; T is the effective lifetime of the route from the source node to the destination node; E is the initial energy of the node, E r is the residual energy; m1, m2 and m3 represent weights, where m1+m2+m3=1;

[0045] Routing stability M constancy The smaller it is, the higher the stability of the link is; select the routing stability M constancy The smallest link serves as the best data communication link.

[0046] The present invention has the following beneficial effects and advantages:

[0047] 1. The present invention is based on a network topology perception method, which ensures the connectivity of the network and realizes predictable network stability assurance; through a node trust estimation method, a trusted connection is established between highly dynamic FANET nodes, and trusted verification of nodes is realized in the process of network connectivity assurance, which effectively improves the communication reliability and security of FANET.

[0048] 2. Based on the classic AODV routing protocol, the present invention integrates the ETX link evaluation method based on stable node constraints and the calculation method of link effective generation time, and proposes a link selection strategy based on multi-routing metrics. Taking the mobility characteristics of the nodes as constraints, the optimal RREQ message forwarding cluster is selected, which reduces the resource waste caused by blind flooding broadcast, shortens the path discovery time, effectively reduces the routing overhead and end-to-end delay of the protocol, and selects a safe and stable communication link by evaluating the effective generation time of the link. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 Flow chart of the method of the present invention;

[0050] Figure 2 The mobile ad hoc network model of the present invention;

[0051] Figure 3 A stable node selection flow chart of the present invention. DETAILED DESCRIPTION

[0052] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0053] The present invention proposes a FANET secure routing method based on network topology perception. Aiming at the high dynamics of wireless self-organizing networks and the reorganization problem after network failure, the communication network factors, spatial location factors and energy factors are fully considered, and an ETX link evaluation method based on stable node constraints and a link effective generation time calculation method are integrated. A link selection method based on multi-routing metrics is proposed, and then a secure routing protocol P-AODV (Perception-AODV) based on network topology perception is designed.

[0054] See also Figure 1 , the method flow chart of the present invention specifically comprises the following steps:

[0055] Step 1: Start the route discovery process

[0056] In the FANET network, since the communication nodes can obtain real-time information such as position, flight speed, and flight attitude from the flight module, after the source node obtains its own position and speed information through GPS, it adds the position, speed, and trust information to the RREQ message to construct an improved RREQ message, and broadcasts the improved RREQ message to the surrounding neighbor nodes.

[0057] Establish a wireless ad hoc network communication model:

[0058] like Figure 2 As shown in Figure 1, a mobile ad hoc network can be modeled as an undirected graph G = (V, E), where V(G) and E(G) represent the set of nodes in the network and the set of links connecting the nodes, respectively. Assume that the nodes in the network have a uniform communication range R, and there is a link (u, v) ∈ E(G) between nodes u and v, d(u, v) ≤ R, where d(u, v) represents the geometric distance between u and v. The existence of a link between a pair of nodes means that they are neighbor nodes.

[0059] Step 2: ETX link evaluation algorithm based on stable node constraints:

[0060] like Figure 3 As shown in the figure, when RREQ reaches the neighbor node, the neighbor node first processes the RREQ message according to the classic AODV method. When the classic AODV routing algorithm determines that the node is an intermediate routing node, the location and speed information in the RREQ message is obtained and combined with the node's own location and speed information, and the stable node judgment mechanism is used to determine whether the routing node is a stable routing node. If it is, the RREQ message is updated and the data packets are broadcast and forwarded to the surrounding area. If it is not a stable routing node, the RREQ message is discarded.

[0061] The present invention adopts the ETX mechanism to select the minimum propagation link of the propagation value, and monitors the expected number of data packets transmitted on the link through message probes. On the basis of the classic AODV-ETX routing protocol, the influence of the mobile characteristics in FANET on the routing stability is fully considered, and a mobile stable node selection method is proposed to select stable nodes, and then the best stable node cluster is obtained. The floodable range of ETX is constrained by the stable nodes, which reduces the resource waste caused by the blind flooding broadcast of the ETX mechanism, shortens the path discovery time, and effectively reduces the routing overhead and end-to-end delay of the protocol.

[0062] Stable node judgment mechanism:

[0063] Nodes are screened based on the relative movement speed and direction of the current node and the previous node. Let the coordinates of the node M be (p Mx ,p My ,p Mz ), with a velocity of v M The angle with the z-axis is θ M , the angle between the projection of the velocity on the xOy plane and the x-axis is φ M . Let the coordinates of node N be (p Nx ,p Ny ,p Nz ), with a velocity of v N The angle with the z-axis is θ N , the angle between the projection of the velocity on the xOy plane and the x-axis is φ N , and node N receives the improved RREQ message sent by node M. Considering the maximum communication radius and reliability requirements of the nodes, the distance between nodes M and N is D MN ≤pR, where R is the communication radius of the node and p is the reliability parameter. Therefore, the primary conditions that a stable routing node must meet are as follows:

[0064] (p Mx -p Nx ) 2 +(p My -p Ny ) 2 +(p Mz -p Nz ) 2 ≤p 2 R 2 , 0.7≤p≤1 (1)

[0065] After two nodes establish a communication link, if the two nodes have a large relative speed, the two nodes originally within the communication radius will move out of the communication radius in a short time, resulting in the disconnection of the communication link and making the entire communication network unstable. Therefore, the stable node should choose a node with a smaller relative movement speed than the node sending the RREQ. Assume that the maximum relative movement threshold is v max , that is, when the relative speed between the two nodes is greater than v max , then give up selecting the node as a stable node. The relative movement speed of node M and node N The calculation formula is as follows:

[0066]

[0067] Among them, i, j, and k are standard unit vectors, representing the directions of the x-axis, y-axis, and z-axis respectively;

[0068] When a node is determined to be an intermediate routing node through classic AODV screening, it is selected as a stable node if it satisfies equations (1) and (3).

[0069] The source node sends a RREQ packet to find the best path to the destination node, and selects nodes that may form a communication link through the stable node judgment method. When the communication link between the source node and the destination node is established, the ETX value in the node link is obtained by calculating the probability of successful forward transmission and reverse retransmission of the link:

[0070]

[0071] Where L represents the routing link between two stable nodes in the network, x represents a hop in the routing link L, φ(x) is the forwarding reception ratio, and ρ(x) is the reverse reception ratio, that is, the probability that the corresponding ACK message is successfully received.

[0072] The link ETX value should be expressed by the expected number of transmissions required to send a packet including retransmissions on the link. Then the ETX value of link l can be expressed as:

[0073]

[0074] p f represents the probability of successful message transmission, p r represents the probability of receiving an ACK message successfully, then the probability of sending a message successfully and getting confirmation is p f ×p r , the metric of route r is the sum of the ETX values ​​of each link l in the route:

[0075] ETX r =∑ l∈r ETXl (6)

[0076] Step 3: Calculation method of link effective lifetime

[0077] Calculate the effective lifetime T of the link between nodes i The calculation principle is as follows: some of the stable nodes in step 2 will form a link from the source node to the destination node, and then two neighboring nodes A and B are randomly selected from the middle of this link. That is, nodes A and B are the two intermediate nodes that the destination node passes through for data transmission along the reverse link after generating the RREP message. Their maximum communication radius is R. At a certain time t in the same three-dimensional rectangular coordinate system, the coordinates of node A are (p Ax ,p Ay ,p Az ), with a velocity of v A , the angle between it and the z-axis is θ A , the angle between the projection of the velocity on the xOy plane and the x-axis is φ A , the coordinates of node B are (p Bx ,p By ,p Bz ), with a velocity of v B The angle with the z-axis is θ B , the angle between the projection of the velocity on the xOy plane and the x-axis is φ B The distance between AB at time t is D AB , after T i After time, node A and node B move to A′(p′ Ax ,p′ Ay ,p′ Az ) and B′(p′ Bx ,p′ By ,p′ Bz ), the distance between nodes A and B becomes D′ AB If D AB Less than the communication radius R between nodes and at t+T i The distance between nodes A and B at the moment is given by D AB Increase to D' AB ,when' AB = R, at this moment, the two nodes have reached the critical position of inter-node communication and are about to move out of each other's communication range. Therefore, the effective communication time between node A and node B is T i , i∈1,2,...n (assuming there are n links in the route), T i The calculation method is as follows:

[0078]

[0079]

[0080] Since the routing link needs to ensure smooth communication between all nodes on the entire link, if the link between a node and a node is disconnected, the entire route will fail. Therefore, the effective lifetime of the route is the minimum value of the effective communication time between the links of each node on the entire routing link. The calculation formula for the effective lifetime of the route from the source node to the destination node is:

[0081] T=min(T1,T2,T3,...,T n ) (10)

[0082] Among them, T1, T2, T3, ..., T n is the effective lifetime of all links between nodes on the routing link. The effective lifetime of links between nodes is T i It can be calculated using formula (9), and the calculated T n Compare it with T stored in the RREP message. If the newly calculated T n If it is less than the T value in the RREP message, update T n The source node will know the effective lifetime T of the entire route based on the received RREP message. When the source node receives the RREP message returned on all routing lines, it can know the routing lifetime of each routing line based on the T information carried in the message.

[0083] Step 4: A link selection method based on multiple routing metrics

[0084] In order to evaluate the stability of the routing link, the following factors should be considered when selecting the routing link:

[0085] Communication network factors, the number of node expected transmissions: the more hops, the more likely each route is to fail, so the probability of route failure increases. However, in the classic AODV, the path is selected with the minimum number of hops, without considering the link status, which brings about link quality problems. Therefore, the ETX routing metric method is used to evaluate the node transmission capability level;

[0086] Spatial location factors, relative location of nodes: The less the relative location changes between nodes, the less likely the link failure is;

[0087] Energy factors, node residual energy: The less the node energy, the higher the possibility of node failure, which also affects the node survival time.

[0088] According to the above three factors, the routing stability M constancy It can be expressed as:

[0089]

[0090] Among them, M constancy ETX is a measure of routing stability; r For each link ETX in the route l The sum of the values; T is the effective lifetime of the route from the source node to the destination node; E is the initial energy of the node, E r is the residual energy. m1, m2 and m3 represent weights, where m1+m2+m3=1. In this protocol, the values ​​of m1, m2 and m3 are 0.3, 0.1 and 0.6 respectively, and the metric value M constancy The smaller it is, the more stable the link is.

Claims

1. A FANET secure routing method based on network topology perception, characterized in that: The following steps are involved: Start the route discovery process: add the node status information to the RREQ message to form an improved RREQ message, and broadcast the improved RREQ message to the surrounding neighbor nodes; ETX link evaluation based on stable node constraints: A stable node selection method is adopted to select stable nodes to form a stable node cluster, and the floodable range of the ETX link is constrained by the stable nodes; Calculate the effective lifetime of the link: evaluate the effective lifetime of each routing line that can reach the destination node through the relative movement speed between nodes; Link selection based on multi-routing metrics: Combine communication network factors, spatial location factors and energy factors to perform link selection based on multi-routing metrics.

2. A FANET secure routing method based on network topology perception according to claim 1, characterized in that: The status message is the position and speed of the node.

3. A FANET secure routing method based on network topology perception according to claim 1, characterized in that: The stable node selection method performs node screening according to the relative movement speed and direction of the current node position and the previous node, and includes the following steps: In the three-dimensional rectangular coordinate system, the coordinates of the node M are (p Mx ,p My ,p Mz ), speed v M The angle with the z-axis is θ M , the angle between the projection of the velocity on the xOy plane and the x-axis is φ M ; The coordinates of node N are (p Nx ,p Ny ,p Nz ), speed v N The angle with the z-axis is θ N , the angle between the projection of velocity on the xOy plane and the x-axis is And node N receives the improved RREQ message sent by node M; determine whether node N is a stable node, as follows: The distance D between node M and node N MN ≤pR, where R is the communication radius of the node and p is the reliability parameter. The distance conditions that a stable node needs to meet are as follows: (p Mx -p Nx ) 2 +(p My -p Ny ) 2 +(p Mz -p Nz ) 2 ≤p 2 R 2 ,0.7≤p≤1 The speed conditions that a stable node needs to meet are as follows: When the relative motion speed between two nodes is greater than the relative motion threshold v max , then give up selecting the current node N as a stable node; where the relative movement speed between node M and node N The calculation formula is as follows: If the current node meets the distance condition and the speed condition, the current node N is a stable node, updates the improved RREQ message and continues to broadcast and forward data to the surroundings; otherwise, it is not a stable node and discards the improved RREQ message.

4. A FANET secure routing method based on network topology perception according to claim 1, characterized in that: The method of constraining the floodable range of the ETX link by using a stable node includes the following steps: When the communication link between the source node and the destination node is established, the ETX value in the node link is obtained by calculating the probability of successful forward transmission of the link and the probability of successful reverse retransmission: Where L represents the routing link between two stable nodes in the network, x represents a hop in the routing link L, φ(x) is the forwarding reception ratio; ρ(x) is the reverse reception ratio, that is, the probability that the corresponding ACK message is successfully received; The link ETX value is represented by the expected number of transmissions required to send a packet including retransmissions on the link; the ETX value of link l can be expressed as: Among them, p f represents the probability of successful message transmission, p r represents the probability of receiving an ACK message successfully, then the probability of sending a message successfully and getting confirmation is p f ×p r , the metric of the route r from the source node to the destination node is the sum of the ETX values ​​of each link l in the route and can be expressed as: ETX r =∑ l∈r ETX l 。 5. A FANET secure routing method based on network topology perception according to claim 1, characterized in that: The calculating of the effective link lifetime comprises the following steps: Randomly select two neighbor nodes A and B from a route from the source node to the destination node. Nodes A and B are the two intermediate nodes that the destination node passes through for data transmission along the reverse link after generating the RREP message. The maximum communication radius of the node is R. At a certain time t, in the three-dimensional rectangular coordinate system, the coordinates of node A are (p Ax ,p Ay ,p Az ), with a velocity of v A , the angle between it and the z-axis is θ A , the angle between the projection of the velocity on the xOy plane and the x-axis is φ A ; The coordinates of node B are (p Bx ,p By ,p Bz ), with a velocity of v B The angle with the z-axis is θ B , the angle between the projection of the velocity on the xOy plane and the x-axis is φ B ; The distance between AB at time t is D AB , after T i After time, node A and node B move to A′(p′ Ax ,p′ Ay ,p′ Az ) and B′(p′ Bx ,p′ By ,p′ Bz ), the distance between nodes A and B becomes D′ AB ; When D′ AB = R, at this moment, the two nodes have reached the critical position of inter-node communication and are about to move out of each other's communication range; the effective communication time between node A and node B is T i , i∈1,2,...n, n represents the number of link segments in the route; T i The calculation method is as follows: The effective lifetime of a route is the minimum time that all inter-node links on the route link maintain effective communication; The calculation formula for the effective lifetime of the route from the source node to the destination node is: T=min(T1,T2,T3,...,T n ) Among them, T1, T2, T3, ..., T n It is the effective lifetime of all inter-node links on the routing link.

6. A FANET secure routing method based on network topology perception according to claim 1, characterized in that: The link selection based on multiple routing metrics comprises the following steps: Among them, M constancy For routing stability; ETX r For each link ETX in the route l The sum of the values; T is the effective lifetime of the route from the source node to the destination node; E is the initial energy of the node, E r is the residual energy; m1, m2 and m3 represent weights, where m1+m2+m3=1; Routing stability M condtancy The smaller it is, the higher the stability of the link is; select the routing stability M constancy The smallest link serves as the best data communication link.

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