Network topology construction method based on information fusion

Abstract

The invention provides a network topology construction method based on information fusion. The method comprises the following steps: a node collects information through an acquisition module and updates a neighbor link table; when a node evaluation period arrives, the evaluation module calculates a broadcast mode according to the collected information; if the broadcast mode is a periodic mode, performing periodic broadcast; if the broadcast mode is an incremental mode, performing incremental broadcast; and the nodes perform information diffusion according to own broadcast modes and update the global topology table, and when the global topology table changes, the routing table is recalculated. The method has the beneficial effects that self-adaptive switching between a periodic broadcast mode and an incremental broadcast mode is carried out by utilizing the network dynamic degree calculated by the evaluation module, and link information is updated in real time in combination with an information fusion mode, so that the network topology is constructed more efficiently to flexibly cope with variable network scenes.

Description

Technical Field

[0001] The present invention belongs to the field of wireless ad hoc network communication, and particularly relates to a network topology construction method based on information fusion. Background Art

[0002] Wireless ad hoc networks do not rely on pre - established infrastructure and can achieve self - adaptation in the absence of a central control node, with characteristics such as high dynamicity, diverse structures, and flexible communication. Therefore, they are widely used in military, disaster relief, environmental monitoring and other fields. In a wireless ad hoc network, nodes can spontaneously form connections with other nodes, and the network can still maintain efficient and stable communication during the addition, departure, or movement of nodes. With the continuous change of environmental conditions and mission requirements, the network topology can be dynamically adjusted according to the actual situation to adapt to the changing network environment. However, this self - adaptability also brings higher network management complexity. Especially in large - scale and dynamic environments, how to effectively manage and optimize network performance has become a major challenge.

[0003] Network topology construction, as a key link in network communication, provides a basis for selecting the optimal routing path by collecting the structure and status information of the current network. According to the network topology information, the transmission efficiency and communication quality can be improved by selecting paths with fewer hops or avoiding unstable wireless channels. Since the network topology is dynamically changing, when constructing and maintaining the network topology, nodes need to continuously update the link information in the network, including dynamic information such as the connection relationship between nodes, the bandwidth, delay, and load of the link. The main ways for nodes to spread information are periodic broadcasting and incremental broadcasting: Periodic broadcasting refers to a communication method of sending information regularly at specific time intervals; Incremental broadcasting refers to broadcasting the changed link information instead of all information.

[0004] In a relatively stable network, periodic broadcasting of link information will spread redundant information multiple times, consuming a large amount of communication resources; while incremental broadcasting mainly broadcasts new link information only when the link changes, which can reduce the spread of redundant information in the network. In a network where the link changes frequently, incremental broadcasting generates new link information every time the link changes, but the intermediate link information is already outdated information, and the meaning of broadcasting it is not great, and it may also cause more invalid information to spread in the network; while periodic broadcasting only broadcasts link information when the period arrives, which can reduce the broadcasting of outdated information to a certain extent. Due to the high dynamicity in wireless ad hoc networks, the topology in the network may change at any time. Therefore, a flexible and efficient way is needed to construct and maintain the network topology to ensure the stable operation of the network. Summary of the Invention

[0005] In view of this, the present invention aims to propose a method for constructing a network topology based on information fusion to solve the problems of redundant information volume and lack of flexibility and efficiency in the prior art.

[0006] To achieve the above object, the technical solution of the present invention is realized as follows: A method for constructing a network topology based on information fusion, comprising the following steps: S1. Node acquisition module Collect information; S2. Determine whether the node evaluation period has arrived. If so, the evaluation module Calculates the broadcast mode according to the collected information and restarts the timer of the evaluation module. Otherwise, jump to the next step S3; S3. If the broadcast mode is a periodic mode, perform periodic broadcasting; S4. If the broadcast mode is an incremental mode, perform incremental broadcasting; S5. Determine whether the global topology table has changed. If so, update the routing table using the dijkstra algorithm , otherwise, jump to the next step S6; S6. Determine whether the system has ended. If so, end the work. Otherwise, jump to step S2 to continue working; In step S2, the evaluation module Calculates the broadcast mode according to the collected information, including: S21. The number of neighbor changes Is the sum of the number of disconnected and newly added nodes, S22. The evaluation module Measures the dynamic degree of the local network where the node is located according to the evaluation period and selects the current broadcast mode according to the calculation result: Calculate the average value of the absolute value of the speed difference between the node and its one-hop neighbors; Set the boundary value for distinguishing the mode , , the evaluation module of the node Uses the number of neighbor changes and the speed difference to calculate the evaluation value ; Let , The smaller the value, the lower the dynamic degree, that is, when, select incremental broadcasting, The larger the value, the greater the dynamic degree, that is, when, select periodic broadcasting.

[0007] Further, in step S1, the node acquisition module collects information, including: Acquisition module Collect information on the speed, link status, link quality, and the number of neighbor changes from neighbor nodes.

[0008] Further, in step S21, the number of neighbor changes has the following expression: ; In the formula, is the number of disconnected nodes, is the number of newly added nodes.

[0009] Further, in step S22, the average value of the absolute value of the speed difference between the node and its one-hop neighbors has the following expression: ; In the formula, is the neighbor set, is the number of neighbors, is the node speed, is the node and the average value of the absolute value of the speed difference from its one-hop neighbors.

[0010] Further, in step S22, the evaluation value , has the following expression: ; In the formula, , is a variable parameter, is the slope adjustment parameter, is the dynamic degree benchmark.

[0011] Further, in step S3, periodic broadcasting includes: S31. Calculate the broadcast period and start the periodic broadcast timer; S32. Determine whether the acquisition module detects changes in neighbor links. If so, update the neighbor link information table and the topology table to be determined , otherwise, jump to the next step S33; S33. Determine whether the link information from other nodes is more valid. If so, update the topology table to be determined , otherwise, jump to the next step S34; S34. Determine whether the broadcast period has arrived. If so, update the global topology table , otherwise, jump to step S32; S35. Broadcast the fused information and dynamically adjust the broadcast period And restart the periodic broadcast timer; S36. Clear the topology table to be determined .

[0012] Further, in steps S31 and S35, the broadcast period , including: The broadcast period has the following expression: ; In the formula, is the broadcast period of node , is the minimum number of hops required for the information of node to be obtained by any node in the network, is the maximum communication distance of the node, is the speed of light.

[0013] Further, in step S4, incremental broadcast, including: S41. When a node does not detect that the update countdown timer of any neighbor link reaches zero, if it detects a change in the neighbor link or receives a valid link from another node, restart the update countdown timer of the neighbor link and start the information collection countdown timer ; S42. Before the information collection countdown timer reaches zero, collect valid updated links and add them to the topology table to be determined , and when the information collection countdown timer reaches zero, broadcast the fused link information; S43. When it is detected that the update countdown timer of the neighbor link reaches zero, update the sequence number of the neighbor link and restart the update countdown timer , wait for the information collection and information fusion to be completed, and then broadcast the fused information in the topology table to be determined ; S44. Clear the topology table to be determined . S44. Clear the topology table to be determined .

[0014] Compared with the prior art, the method for constructing a network topology based on information fusion according to the present invention has the following beneficial effects: (1) By combining periodic broadcast and incremental broadcast, information fusion and iterative processing, information diffusion and network topology construction are more efficiently achieved.

[0015] (2) To optimize the broadcast efficiency, a periodic dynamic adjustment strategy is introduced in the periodic broadcast, and the broadcast period is dynamically adjusted using the network diameter and the maximum communication distance of the device.

[0016] (3) In the incremental broadcast, an update countdown timer for the neighbor link is set to more easily distinguish between the two states where the link information has not changed and the link has failed. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 is a schematic diagram of the scenario described in the embodiment of the present invention; Figure 2 is a schematic diagram of the overall process described in the embodiment of the present invention; Figure 3 is a schematic diagram of the periodic broadcast mode described in the embodiment of the present invention; Figure 4 is a schematic diagram of the incremental broadcast mode described in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0019] The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0020] As Figures 1 to 4 shown, a method for constructing a network topology based on information fusion includes the following steps: S1. Node acquisition module Collect information; S2. Determine whether the node evaluation period has arrived. If so, the evaluation module calculates the broadcast mode according to the collected information and restarts the evaluation module timer. Otherwise, jump to the next step S3; S3. If the broadcast mode is the periodic mode, perform periodic broadcast; S4. If the broadcast mode is the incremental mode, perform incremental broadcast; S5. Determine whether the global topology table has changed. If so, update the routing table using the dijkstra algorithm , otherwise, jump to the next step S6; S6. Determine whether the system has ended. If so, end the work. Otherwise, jump to step S2 to continue working.

[0021] The specific implementation is as follows: As Figure 1 shown, each node deploys a collection module for collecting and managing neighbor information and an evaluation module for measuring the network dynamics and selecting the corresponding broadcast mode. Each node also dynamically maintains a neighbor link information table which records the real-time link information connected to the neighbors. The collection module receives information such as the status, address, and speed from neighbor nodes, and uses the processed information for updating the neighbor link information table and evaluation by the evaluation module ; the evaluation module uses the information processed by the collection module to output the measurement result of the dynamic degree and complete the mode selection of periodic broadcast and incremental broadcast, and records the selected mode result as . In addition, each node also maintains a global topology table and a to-be-determined topology table . When receiving link information from other nodes, the received valid link information is fused with local information to obtain new link information and filled into the to-be-determined topology table , and then the broadcast of the fused information and the update of the global topology table are completed according to the current mode. When it is detected that the global topology table has changed, the shortest paths to other nodes in the network are calculated using the dijkstra algorithm and the routing table is filled .

[0022] In the periodic broadcast mode, by dynamically adjusting the broadcast period , the transmission of information and the utilization of bandwidth are effectively managed. In addition, in the incremental broadcast mode, in order to more easily distinguish whether a link has not changed for a long time or the link has failed, each node introduces an update countdown timer for each neighbor link, and its initial value is recorded as . Each link information in the network carries or identifying the effective duration of the link. When other nodes receive a link information, they can know the starting value of the effective timer of the link. When the link effective countdown is 0, the link is regarded as an invalid link and the corresponding information in the global topology table is deleted.

[0023] Figure 2 is the overall flowchart of the present invention. The collection module collects and manages the information of neighbor nodes, including node speed, link status, link quality, the number of neighbor changes, etc. The number of neighbor changes It is defined as the sum of the number of disconnected nodes and the number of newly added nodes, and the formula is as follows: (1); Among them, the number of disconnected nodes , the number of newly added nodes .

[0024] When node does not detect the existence of neighbors, it periodically broadcasts its own information so that other nodes can discover in the network. Denote the neighbor set of as , the number of neighbors is expressed as , and its node speed is expressed as . When is not empty, the evaluation module measures the dynamic degree of the local network where the node is located according to the evaluation period , and selects its current mode as periodic broadcast or incremental broadcast according to the calculation result. The calculation model of the evaluation model is introduced below.

[0025] When , use the average value of the absolute value of the speed difference between node and its one-hop neighbors to measure the relative movement degree between the node and its neighbors, and the formula is as follows: (2); Set the demarcation value for distinguishing modes, generally . The evaluation module of uses and to calculate the evaluation value (3); Among them, is a variable parameter, and . , which is used to adjust the slope. is a rough benchmark for the dynamic degree, and can be dynamically adjusted according to different device sensitivities, different network environments (such as cities, villages or mountains), different network densities, etc. Let , The smaller it is, the lower the dynamic degree, that is, , select incremental broadcast; The larger it is, the greater the dynamic degree, that is, , select periodic broadcast.

[0026] Figure 3It is a flowchart of the periodic broadcast mode. When a node detects a change in the neighbor link, it updates the neighbor table and fills in the topology table to be determined. ; If the neighbor link does not change when the broadcast period is approaching, update the sequence number of this link and fill it into the topology table to be determined. Fill the valid link information received from other nodes before the broadcast period arrives into the topology table to be determined. Perform information fusion, and update the global topology table when the broadcast period arrives. And broadcast the fusion information, and finally clear the topology table to be determined. Node The minimum number of hops required for the information of to be obtained by any node in the network is denoted as , and the maximum communication distance of the node is expressed as . The broadcast period of can be adjusted according to the size of, and is defined as and the product of the ratio with the information propagation speed (the speed of light ), and the formula is as follows: (4); Among them, and The ratio of represents the maximum time required to communicate with one-hop neighbor nodes. In the initial stage of network formation, the information obtained by nodes is mainly the network status relatively close to themselves, and it will be considered that the number of hops required for the broadcast information to spread to the farthest nodes in the network is small. At this time, the smaller broadcast period enables the link information to be broadcast multiple times within a certain time, reducing the impact of network packet loss on network topology construction; but as the link information continues to spread, nodes gradually obtain the network status farther from themselves, and the minimum number of hops may increase. At this time, increasing the broadcast period can, to a certain extent, avoid network congestion caused by the spread of more redundant information.

[0027] Figure 4 It is a flowchart of the incremental broadcast mode. When the update countdown timer of any neighbor link detected by the node reaches 0, if it detects that the neighbor link changes or receives valid links from other nodes, restart the update countdown timer of the neighbor link and start the information collection countdown timer . Before reaches 0, collect more valid updated links and add them to the topology table to be determined , and when reaches 0, broadcast the fused link information. When it detects that the neighbor link of the When it reaches 0, update the neighbor link sequence number and restart , wait for the information collection and information fusion to complete, and then broadcast the topology table to be determined in the fusion information.

[0028] Embodiment 1 is shown in the following table:

[0029] The beneficial effects of the present invention are as follows: (1) Through the combination of periodic broadcast and incremental broadcast, information fusion and iterative processing, information diffusion and network topology construction are realized more efficiently.

[0030] (2) In order to optimize the broadcast efficiency, a periodic dynamic adjustment strategy is introduced in the periodic broadcast, and the broadcast period is dynamically adjusted by using the network diameter and the maximum communication distance of the device.

[0031] (3) In the incremental broadcast, an update countdown timer for the neighbor link is set to more easily distinguish between the two states where the link information has not changed and the link has failed.

[0032] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for constructing a network topology based on information fusion, characterized in that: Including the following steps: S1. Node Acquisition Module Collect information; S2. Determine whether the node evaluation period has arrived. If so, the evaluation module calculates the broadcast mode based on the collected information and restarts the evaluation module timer. Otherwise, jump to the next step S3; S3. If the broadcast mode is the periodic mode, perform periodic broadcasting; S4. If the broadcast mode is the incremental mode, perform incremental broadcasting; S5. Judge the global topology table If it has changed, update the routing table using the Dijkstra algorithm Otherwise, jump to the next step S6; S6. Determine whether the system ends. If so, end the work; otherwise, jump to step S2 to continue the work; In step S2, the evaluation module calculates the broadcast mode based on the collected information, including: S21. Number of neighbor changes which is the sum of the number of nodes with disconnection and newly added nodes S22, Evaluation Module According to the evaluation period Measure the dynamic degree of the local network where the node is located, and select the current broadcast mode according to the calculation result: Computing node Average value of the absolute value of the speed difference with one-hop neighbors Set the boundary value for the discrimination mode , , the evaluation module of the node uses the number of neighbor changes and the speed difference to calculate the evaluation value ; Let , The smaller it is, the lower the degree of dynamics, that is When, select incremental broadcast The larger it is, the greater the degree of dynamics, that is When, select periodic broadcast 2. The network topology construction method based on information fusion according to claim 1, characterized in that: In step S1, the node acquisition module collects information, including: Collection module Collect information on the speed, link status, link quality, and the number of neighbor changes from neighboring nodes.

3. The network topology construction method based on information fusion according to claim 1, wherein: In step S21, the number of neighbor changes has the following expression: ； In the formula, is the number of disconnected nodes, is the number of newly added nodes.

4. A network topology construction method based on information fusion according to claim 1, characterized in that: In step S22, the node The average value of the absolute value of the speed difference from one-hop neighbors, and its expression is as follows: ； In the formula, is the neighbor set, is the number of neighbors, is the node speed, is the node average value of the absolute value of the speed difference between and one-hop neighbors.

5. A network topology construction method based on information fusion according to claim 1, characterized in that: In step S22, the evaluation value , and the expression is as follows: ； In the formula, , is a variable parameter, is a slope adjustment parameter, is a dynamic degree reference.

6. The network topology construction method based on information fusion according to claim 1, characterized in that: In step S3, the periodic broadcasting includes: S31. Calculate the broadcast period And start the periodic broadcast timer; S32. Determine the acquisition module Whether a change in the neighbor link is detected. If so, update the neighbor link information table and the topology table to be determined , otherwise, jump to the next step S33; S33. Determine whether the link information from other nodes is more effective. If so, update the topology table to be determined. , otherwise, jump to the next step S34; S34. Determine whether the broadcast period has arrived. If so, update the global topology table , otherwise, jump to step S32; S35. Broadcast the fusion information and dynamically adjust the broadcast period And restart the periodic broadcast timer; S36. Clear the topology table to be determined .

7. A network topology construction method based on information fusion according to claim 6, characterized in that: In steps S31 and S35, the broadcast period , includes: Broadcast period The expression is as follows: ； Wherein, is the broadcast period of the node , is the minimum number of hops required for the information of the node to be obtained by any node in the network, is the maximum communication distance of the node, is the speed of light.

8. A method for constructing a network topology based on information fusion according to claim 1, characterized in that: In step S4, the incremental broadcasting includes: S41. When the update countdown timer of any neighbor link is not detected to reach zero by the node, if a change in the neighbor link is detected or a valid link is received from another node, restart the update countdown timer of the neighbor link and start the information collection countdown timer of the neighbor link ; ; S42. Before the information collection countdown timer reaches zero, collect valid update links and add them to the topology table to be determined , and when the information collection countdown timer reaches zero, broadcast the fused link information; S43. When a neighbor link is detected whose update countdown timer reaches zero, update the sequence number of the neighbor link and restart the update countdown timer . After waiting for information collection and information fusion to complete, broadcast the fusion information in the topology table to be determined ; S44. Clear the topology table to be determined .

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