KR101439189B1 - Method of constructing path in wireless sensor network, method of updating path in wireless sensor network, wireless sensor network using the same and mobile system included in wireless sensor network - Google Patents

Abstract

In a method of generating a path based on a distributed event in a wireless sensor network including a plurality of sensor nodes, a first event node corresponding to a start point of a path among a plurality of sensor nodes, Select the event node. And generates a Voronoi diagram for the plurality of sensor nodes based on the first event node and the second event node. The first sensor node having the smallest sum of the first hop distance from the first event node and the second hop distance from the second event node among the plurality of sensor nodes is selected based on the Voronoi diagram. And establishes a path between the first event node and the second event node to include the first sensor node.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of generating a path in a wireless sensor network, a method of updating a path in a wireless sensor network, a wireless sensor network using the wireless sensor network, MOBILE SYSTEM INCLUDED IN WIRELESS SENSOR NETWORK}

The present invention relates to a wireless sensor network, and more particularly, to a path generation method in a wireless sensor network, a path update method in a wireless sensor network, a wireless sensor network using the methods, and a mobile device included in the wireless sensor network .

A wireless sensor network (WSN) is a type of sensor network, and a plurality of sensor nodes are connected by wireless communication to form a network. Unlike existing networks, WSN is mainly used for remote information collection and can be widely used for various applications. In recent years, a technique of using a WSN as an infrastructure for navigation, that is, a technique of providing a mobile route to a user in a WSN by combining a mobile device such as a smart phone and a tablet PC with the WSN is being studied.

However, conventional techniques have been implemented centering on the function of guiding the user to a fixed place (e.g., a safe place) when the sensor senses a certain condition (for example, a dangerous situation). In this case, location information is required to provide the route, and each sensor node has to have an expensive device such as GPS. In addition, since conventional technologies provide paths only for predicted situations, there has been a problem that it is difficult to provide a path for an event generated in a distributed manner in real time.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for efficiently generating a path without positional information based on a distributed event in a wireless sensor network.

It is another object of the present invention to provide a method for efficiently updating a route generated in a wireless sensor network without location information based on a distributed event.

It is still another object of the present invention to provide a wireless sensor network using the path generation method and the path update method, and a mobile device included in the wireless sensor network.

According to an aspect of the present invention, there is provided a method of generating a path based on a distributed event in a wireless sensor network including a plurality of sensor nodes according to embodiments of the present invention, A first event node corresponding to a starting point of the path and a second event node corresponding to an arrival point of the path are selected. And generates a Voronoi diagram for the plurality of sensor nodes based on the first event node and the second event node. A first sensor node having a smallest hop distance from the first event node and a second hop distance from the second event node among the plurality of sensor nodes based on the Voronoi diagram, . And establishes the path between the first event node and the second event node to include the first sensor node.

In generating the Voronoi diagram, it is possible to obtain, for each of the plurality of sensor nodes, information related to a nearest event node, a hop distance to the nearest event node, and a parent node. Based on the obtained information, each of the plurality of sensor nodes can be classified into a Voronoi cell, a Voronoi edge, or a Voronoi vertex. At least one Voronoi region may be set based on the sensor nodes classified into the Voronoi cells among the plurality of sensor nodes.

Wherein the first sensor node and the first sensor node connect first parent nodes associated with the first event node among parent nodes of the first sensor node and the first sensor node, , The second event node, and the second parent node associated with the second event node among the parent nodes of the first sensor node.

In one embodiment, a third event node that is not located on the path among the plurality of sensor nodes may be further selected. And reconfigure the path to include the third event node.

In re-establishing the path, a closest event node closest to the third event node of the first and second event nodes may be selected based on the Voronoi diagram. And update the Voronoi diagram for the plurality of sensor nodes based on the first event node, the second event node, and the third event node. And update the path based on the updated Voronoi diagram such that the third event node is directly connected to the nearest event node.

A first lower path that travels from the first event node to the second event node and a second lower path that travels from the second event node to the third event node when the second event node is selected as the closest event node, 2 < / RTI > sub-path. A third lower path from the first event node to the third event node and a third lower path from the third event node to the second event node when the first event node is selected as the closest event node, And update the path to include four sub-paths.

According to another aspect of the present invention, there is provided a wireless sensor network including a plurality of sensor nodes according to embodiments of the present invention. (N + 1) event nodes that are not disposed on the path among the plurality of sensor nodes are selected in the method of updating the generated path including the event nodes based on the distributed event . (N + 1) -th event node closest to the (n + 1) -th event node, based on a Voronoi diagram previously generated based on the first through the n-th event nodes Select the node. And updates the pre-generated Voronoi diagram based on the first through (n + 1) -th event nodes. And regenerates the path so that the (n + 1) th event node is directly connected to the nearest event node based on the updated Voronoi diagram.

In regenerating the path, a first comparison result may be generated by comparing a first hop distance and a reference hop distance between the nearest event node and the (n + 1) -th event node. A second hop distance between a previous event node preceding the nearest event node and the (n + 1) th event node among the first to nth event nodes, and a second hop distance between the The second hop distance between the next event node following the nearest event node and the (n + 1) th event node may be compared with the first hop distance. And connect the nearest event node and the (n + 1) th event node based on at least one of the first comparison result and the second comparison result.

(N + 1) th event node to the (n + 1) th event node when the first hop distance is smaller than the reference hop distance; It is possible to add a second lower path that goes to the neighbor node. Deletes a first previous lower path from the previous event node to the closest event node when the first hop distance is greater than the reference hop distance and the second hop distance is smaller than the third hop distance, And add the third lower path and the second lower path from the previous event node to the (n + 1) th event node. Deletes a second previous lower path from the closest event node to the next event node when the first hop distance is larger than the reference hop distance and the third hop distance is smaller than the second hop distance, And a fourth sub-path from the (n + 1) th event node to the next event node.

The first lower path may be added if the first hop distance is greater than the reference hop distance and the previous event node or the next event node is not present.

According to another aspect of the present invention, there is provided a wireless sensor network including a plurality of sensor nodes according to embodiments of the present invention. In a method of updating a generated path including event nodes based on a distributed event, at least one event node among the first to nth event nodes may be selected. The Voronoi diagram may be updated based on the first through the n-th event nodes, based on the event nodes other than the selected at least one event node. The path can be regenerated based on the updated Voronoi diagram.

In one embodiment, the wireless sensor network may further comprise a mobile device that communicates with the plurality of sensor nodes. And updates the pre-generated Voronoi diagram based on the second through n th event nodes when the mobile device moves from the first event node to the second event node along the path, Lt; RTI ID = 0.0 > Voronoi < / RTI > diagram.

According to another aspect of the present invention, there is provided a wireless sensor network including a plurality of sensor nodes according to embodiments of the present invention and generating and updating a path based on a distributed event, n is a natural number greater than or equal to 2) event nodes and a mobile device. The first to nth event nodes are selected among the plurality of sensor nodes and included in the path. The mobile device communicates with the plurality of sensor nodes and moves along the path. Generating a Voronoi diagram for the plurality of sensor nodes based on the first to nth event nodes and generating a Voronoi diagram based on the Voronoi diagram based on the Voronoi diagram, Event nodes are connected to each other to generate the path.

(N + 1) -th event node that is not disposed on the path among the plurality of sensor nodes, and selects the (n + 1) th event node based on the first to Update the diagram, and update the path based on the updated Voronoi diagram. In another embodiment, at least one event node of the first through nth event nodes is selected, and the Voronoi diagram is updated based on remaining event nodes other than the selected at least one event node, Lt; RTI ID = 0.0 > Voronoi < / RTI > diagram.

According to another aspect of the present invention, there is provided a wireless sensor network including a plurality of sensor nodes in accordance with embodiments of the present invention and generating and updating a path in a wireless sensor network based on a distributed event, The mobile device moving along the path includes a selection unit, a Voronoi diagram generation unit, and a path generation unit. The selection unit selects first to n-th (n is a natural number of 2 or more) event nodes included in the path among the plurality of sensor nodes. The Voronoi diagram generation unit generates a Voronoi diagram for the plurality of sensor nodes based on the first through nth event nodes. The path generation unit generates the path by connecting two adjacent event nodes among the first to nth event nodes based on the Voronoi diagram.

In the route generation / update method in the wireless sensor network according to the above-described embodiments of the present invention, the path for visiting the event nodes generated in real time in a distributed manner is determined based on the Voronoi diagram without the location information on the event nodes It is possible to implement a wireless sensor network without expensive devices such as a central server and a GPS, and it is possible to effectively generate a path for a mobile device to move.

1 is a flowchart illustrating a path generation method in a wireless sensor network according to embodiments of the present invention.
2A is a diagram of a wireless sensor network in accordance with embodiments of the present invention.
2B and 2C are block diagrams illustrating an example of a sensor node and a mobile device included in the wireless sensor network of FIG. 2A.
3 is a flowchart showing an example of step S200 of FIG.
4 is a diagram showing an example of a Voronoi diagram generated by the method of FIG.
5 is a diagram showing the path generated by the method of FIG.
6 is a flowchart illustrating a path generation method in a wireless sensor network according to embodiments of the present invention.
7 is a flowchart showing an example of step S600 of FIG.
Figures 8A, 8B and 8C are diagrams illustrating examples of paths set and reset by the method of Figure 7;
9 is a flowchart illustrating a path update method in a wireless sensor network according to embodiments of the present invention.
10 is a flowchart showing an example of step S1400 in FIG.
Figs. 11A, 11B, 11C, 11D, 12A and 12B are views showing examples of paths updated by the method of Figs. 9 and 10. Fig.
13 is a flowchart illustrating a path update method in a wireless sensor network according to embodiments of the present invention.
14A, 14B, 15A, and 15B are views showing examples of paths updated by the method of FIG.

For the embodiments of the invention disclosed herein, specific structural and functional descriptions are set forth for the purpose of describing an embodiment of the invention only, and it is to be understood that the embodiments of the invention may be practiced in various forms, The present invention should not be construed as limited to the embodiments described in Figs.

The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms may be used for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between. Other expressions that describe the relationship between components, such as "between" and "between" or "neighboring to" and "directly adjacent to" should be interpreted as well.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprise", "having", and the like are intended to specify the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, , Steps, operations, components, parts, or combinations thereof, as a matter of principle.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be construed as meaning consistent with meaning in the context of the relevant art and are not to be construed as ideal or overly formal in meaning unless expressly defined in the present application .

On the other hand, if an embodiment is otherwise feasible, the functions or operations specified in a particular block may occur differently from the order specified in the flowchart. For example, two consecutive blocks may actually be performed at substantially the same time, and depending on the associated function or operation, the blocks may be performed backwards.

1 is a flowchart illustrating a path generation method in a wireless sensor network according to embodiments of the present invention.

Referring to FIG. 1, in generating a path based on a distributed event in a wireless sensor network including a plurality of sensor nodes, a first event node (event) among the plurality of sensor nodes node and a second event node (step S100). The first event node corresponds to a source of the path and the second event node corresponds to a destination of the path.

A Voronoi diagram for the plurality of sensor nodes is generated based on the first event node and the second event node (step S200). The above-described step S200 will be described later with reference to Figs. 3 and 4.

And selects a first sensor node among the plurality of sensor nodes based on the Voronoi diagram (step S300). The first sensor node is a sensor node having a smallest sum of a first hop distance of the plurality of sensor nodes with the first event node and a second hop distance of the second event node. And sets the path between the first event node and the second event node to include the first sensor node (step S400). The steps S300 and S400 will be described later with reference to FIG.

2A is a diagram of a wireless sensor network in accordance with embodiments of the present invention. 2B and 2C are block diagrams illustrating an example of a sensor node and a mobile device included in the wireless sensor network of FIG. 2A.

2A, 2B, and 2C, a wireless sensor network 100 includes a plurality of sensor nodes 200 and a mobile device 300. [

The plurality of sensor nodes 200 exchange data with each other according to a wireless communication protocol such as 802.11, 802.15, and the like. Each of the sensor nodes 200 includes a processor 210 for performing specific calculations or tasks, a sensor module 220 for sensing various physical quantities such as temperature, displacement, etc., and communicating with other adjacent sensor nodes A memory 240 for storing data necessary for operation of the sensor node, and a battery 250 for supplying power necessary for operation of the sensor node.

The mobile device 300 may be any interactive communication device, such as a smart phone, a tablet PC, and the like. The mobile device 300 includes a selection unit 310 for selecting event nodes among the plurality of sensor nodes 200, a Voronoi diagram generation unit for generating a Voronoi diagram based on the selected event nodes 320), and a path generating unit 330 for generating a path based on the Voronoi diagram.

The wireless sensor network 100 including the mobile device 300 is able to access the event nodes that are generated in a distributed manner in real time without location information and without a central server (e.g., in an Ad-hoc environment) Can be generated. The mobile device 300 may visit the event nodes by moving along the path by a user (not shown) within the wireless sensor network 100. [ Depending on the embodiment, the event nodes may be selected by the user, or may be selected based on data received at the mobile device 300 outside the wireless sensor network 100.

Meanwhile, in the embodiments of the present invention, the number of the plurality of event nodes may be much smaller than the number of the plurality of sensor nodes. For example, in the embodiments of the present invention, a plurality of event nodes (for example, several hundreds or thousands) may be formed in a cluster of sensor nodes to generate the path by selecting a few event nodes.

3 is a flowchart showing an example of step S200 of FIG. 4 is a diagram showing an example of a Voronoi diagram generated by the method of FIG.

Referring to FIGS. 1, 3 and 4, in generating the Voronoi diagram (step S200), for each of the plurality of sensor nodes, the closest event node among the event nodes, the hop Distance and information related to the parent node (step S210). Each of the event nodes may have an identifier. The parent nodes may be tracked to find the nearest event node, and each of the plurality of sensor nodes may store an identifier of the nearest event node. The hops distance may correspond to the number of parent nodes disposed between the sensor node and the closest event node.

Based on the obtained information, each of the plurality of sensor nodes can be classified into a Voronoi cell, a Voronoi edge, or a Voronoi vertex (step S220). For example, when the closest event node is one, the sensor node is classified as the Voronoi cell, and when the closest event node is two or more than three, the sensor node is divided into the Voronoi edge or the Voronoi vertex Can be classified. The Voronoi edge and the Voronoi vertex may store two or more identifiers.

At least one Voronoi region can be set based on the sensor nodes classified into the Voronoi cells among the plurality of sensor nodes (Step S230). The number of Voronoi regions may correspond to the number of event nodes. For example, as shown in FIG. 4, a Voronoi diagram including seven Voronoi regions may be generated when there are seven event nodes. In Figure 4, the red squares represent event nodes, and the blue, yellow and green points represent sensor nodes corresponding to Voronoi cell, Voronoi edge, and Voronoi corners, respectively.

5 is a diagram showing the path generated by the method of FIG.

Referring to FIGS. 1 and 5, a first event node ENA and a second event node ENB among a plurality of sensor nodes are selected. A second Voronoi area VA associated with the first event node ENA and a second Voronoi area associated with the second event node ENB are defined as VB (VB) by forming a border along the sensor nodes classified as Voronoi edge, ) To generate the Voronoi diagram. And selects the first sensor node SN1 based on the Voronoi diagram. The first sensor node SN1 may correspond to a Voronoi edge (or a Voronoi corner). (PN1) associated with a first event node (ENA) among parent nodes of a first event node (ENA), a first sensor node (SN1) and a first sensor node (SN1) By connecting the second parent nodes PN2 associated with the second event node ENB among the parent nodes of the first sensor node SN1, the second event node ENB and the first sensor node SN1 to each other, The path P is set.

Meanwhile, the method of FIG. 1 may be extended even when a plurality of event nodes are selected, and may update an already generated path by additionally selecting an event node or excluding a previously selected event node.

6 is a flowchart illustrating a path generation method in a wireless sensor network according to embodiments of the present invention.

Referring to FIG. 6, steps S100, S200, S300, and S400 may be substantially the same as steps S100, S200, S300, and S400 of FIG. 1 in creating a path within a wireless sensor network.

A third event node that is not disposed on the path among the plurality of sensor nodes is selected (step S500), and the path is reset to include the third event node (step S600). As described above, the third event node can be selected in a distributed manner without any positional information in real time.

7 is a flowchart showing an example of step S600 of FIG. Figures 8A, 8B and 8C are diagrams illustrating examples of paths set and reset by the method of Figure 7;

Referring to Figures 6, 7, 8a, 8b and 8c, in re-establishing the path (step S600), it is determined, based on the Voronoi diagram, The nearest event node can be selected (step S610). The Voronoi diagram for the plurality of sensor nodes may be updated based on the first, second, and third event nodes (step S620). Based on the updated Voronoi diagram, the third event node may update the path to be directly connected to the nearest event node (step S630).

For example, a path may be formed between the first event node ENA and the second event node ENB as shown in FIG. 8A.

In one embodiment, if the third event node ENC is closer to the second event node ENB, i.e., if the second event node ENB is selected as the nearest event node ENB as shown in FIG. 8B , A first lower path from a first event node (ENA) to a second event node (ENB), and a second lower path from a second event node (ENB) to a third event node (ENC) You can update the path. In this case, the existing path is maintained and the path can be updated in such a way that the second lower path is added to the existing path.

In another embodiment, if the third event node ENC 'is closer to the first event node ENA, i.e., if the first event node ENA is selected as the nearest event node, as shown in FIG. 8C A third lower path from the first event node ENA to the third event node ENC 'and a fourth lower path from the third event node ENC' to the second event node ENB To update the path. In this case, the path may be updated in such a manner that the existing path is deleted and new third and fourth lower paths are newly created.

Hereinafter, embodiments of the present invention will be described focusing on a configuration for updating (i.e., regenerating) a previously created path including a plurality of event nodes.

9 is a flowchart illustrating a path update method in a wireless sensor network according to embodiments of the present invention.

9, a path generated by including pre-selected first through n-th (n is a natural number of 2 or more) event nodes among the plurality of sensor nodes in a wireless sensor network including a plurality of sensor nodes, (N + 1) event nodes that are not disposed on the path among the plurality of sensor nodes (step S1100). Selects a closest event node closest to the (n + 1) th event node among the first to nth event nodes, based on the Voronoi diagram previously generated based on the first to nth event nodes (Step S1200). And updates the pre-generated Voronoi diagram based on the first through (n + 1) -th event nodes (step S1300). And regenerates the path so that the (n + 1) th event node is directly connected to the nearest event node based on the updated Voronoi diagram (step S1400).

10 is a flowchart showing an example of step S1400 in FIG.

Referring to FIGS. 9 and 10, in regenerating the path (step S1400), a first comparison result may be generated by comparing the first hop distance and the reference hop distance (step S1410). The first hop distance may represent a hop distance between the nearest event node and the (n + 1) th event node. In addition, the second comparison result may be generated by comparing the second hop distance and the third hop distance (step S1420). The second hop distance may represent a hop distance between a previous event node preceding the nearest event node and the (n + 1) th event node among the first through nth event nodes. The third hop distance may represent a hop distance between a next event node following the nearest event node and the (n + 1) th event node among the first through nth event nodes. The nearest event node and the (n + 1) th event node may be connected based on at least one of the first comparison result and the second comparison result (step S1430).

Specifically, when the first hop distance is smaller than the reference hop distance (step S1410: YES), the first lower path from the nearest event node to the (n + 1) n + 1) event node to the nearest event node (step S1432). If the first hop distance is greater than the reference hop distance (step S1410: No) and the second hop distance is smaller than the third hop distance (step S1420: YES), the nearest event node (Step S1434), and to add the third lower path and the second lower path from the previous event node to the (n + 1) th event node. If the first hop distance is greater than the reference hop distance (step S1410: No) and the third hop distance is less than the second hop distance (step S1420: NO), the next event node And to add a fourth lower path that proceeds from the first lower path and the (n + 1) th event node to the next event node.

Figs. 11A, 11B, 11C, 11D, 12A and 12B are views showing examples of paths updated by the method of Figs. 9 and 10. Fig.

Referring to FIG. 11A, paths including first through fifth event nodes EN1, EN2, EN3, EN4, and EN5 are generated. (ENN), which is a new event node that does not exist on the path, to update the path so that the sixth event node (ENN) is included in the path.

11B, the first through fifth Voronoi regions V1, V2, V3, V4, and V5 are arranged on the basis of the first through fifth event nodes EN1, EN2, EN3, EN4, The Voronoi diagram is included. And selects a nearest event node for the sixth event node (ENN) based on the Voronoi diagram. 11B, since the sixth event node ENN is included in the second Voronoi region V2, a second event node EN2 corresponding to the second Voronoi region V2 is allocated to the nearest event node EN2, .

Referring to FIG. 11C, the Voronoi diagram is updated based on the first through sixth event nodes EN1, EN2, EN3, EN4, EN5, and ENN. In this case, in order to include six Voronoi regions (V1, V2 ', V3', V4, V5, and VN) corresponding to six event nodes (EN1, EN2, EN3, EN4, EN5, Noi diagram is updated. In the example of Fig. 11C, the sixth Voronoi region VN is added and the second and third Voronoi regions V2 ', V3' adjacent to the sixth Voronoi region VN are changed.

Referring to FIG. 11D, the path is regenerated based on the updated Voronoi diagram. The example of FIG. 11D may correspond to step S1436 of FIG. That is, the sixth event node ENN is a certain distance from the nearest event node EN2 and the sixth event node ENN is next to the previous event node (i.e., EN1 preceded by EN2) , EN3 arranged after EN2), it is necessary to delete the previous lower path PP2 proceeding from the nearest event node EN2 to the next event node EN3 and to delete the sixth lower path PP2 from the nearest event node EN2, The path can be updated by adding a lower path P1 to the event node ENN and a lower path P4 from the sixth event node ENN to the next event node EN3.

12A, another example of regenerating the path is shown. The example of FIG. 12A may correspond to step S1434 of FIG. That is, since the sixth event node ENN 'is somewhat separated from the nearest event node EN2 and the sixth event node ENN' is closer to the event node EN1 before the next event node EN3, A lower path P3 for deleting the previous lower path PP1 proceeding from the previous event node EN1 to the closest event node EN2 and proceeding from the previous event node EN1 to the sixth event node ENN ' The path can be updated by adding a lower path P2 from the sixth event node ENN 'to the nearest event node EN2.

Referring to FIG. 12B, another example of regenerating the path is shown. The example of FIG. 12B may correspond to step S1432 of FIG. That is, since the sixth event node ENN "is very close to the nearest event node EN2, it is difficult to update the Voronoi diagram by distinguishing the nearest event node EN2 and the sixth event node ENN" . Therefore, in this case, the previous sub-paths remain intact, and the child path P1 'and the sixth event node ENN " from the nearest event node EN2 to the sixth event node ENN " It is possible to update the path by adding a sub-path P2 'going to the node EN2, i.e. by adding a sub-path between the nearest event node EN2 and the sixth event node ENN " For example, the reference hop distance for distinguishing proximity between the nearest event node EN2 and the sixth event node ENN "may correspond to a distance of about one hop to about two hops.

Although not shown, the previous event node and / or the next event node may not be present according to the embodiment. In this case, step S1420 may be skipped, i.e., the path may be updated without generating the second comparison result. For example, if the previous event node does not exist, it is determined that the nearest event node is the start point of the path, and the nearest event node, the (n + 1) To update the path. If the next event node does not exist, it is determined that the nearest event node is an arrival point of the path, and the path can be updated by connecting the nearest event node and the (n + 1) have. And if the previous event node and the next event node do not exist, update the path by connecting the nearest event node and the (n + 1) -th event node.

Each of the event nodes may have a free state, a check state, or a lock state. For example, all event nodes (i.e., first through nth event nodes) may be initialized to the free state. If a new event node (i.e., (n + 1) event node) is selected, it may determine whether the nearest event node for the new event node is in the free state. If the nearest event node is not in the free state, waits until it becomes the free state, and if the nearest event node is in the free state, Or not. If the previous or next event node is in a free state, the previous or next event node may be changed to the locked state by the new event node. If the previous or next event node is in the check state and is checked by another node having a lower priority (i.e., having a lower identifier) than the closest event node, waiting for the other node and by the new event node The previous or next event node may be changed to the locked state. If the previous or next event node is in the check state and is checked by another node having a higher priority (i.e., having a higher identifier) than the closest event node, or if the previous or next event node is in the locked state , The new event node may be queued until the previous or next event node becomes the free state. When both the previous and next event nodes are in the locked state, the closest event node may be changed to the locked state. In the case of generating a path based on the above-described lock protocol, path generation may not be disturbed by other event nodes before the path is updated, and path generation may be efficiently performed even in a distributed event generation environment and / You can update it.

13 is a flowchart illustrating a path update method in a wireless sensor network according to embodiments of the present invention.

Referring to FIG. 13, in a wireless sensor network including a plurality of sensor nodes, paths generated by including pre-selected first through n-th (n is a natural number of 2 or more) event nodes among the plurality of sensor nodes, , At least one event node among the first to nth event nodes included in the path is selected (step S2100). The Voronoi diagram generated in advance based on the first through the n-th event nodes is updated based on the event nodes other than the selected at least one event node (step S2200). And regenerates the path based on the updated Voronoi diagram (step S2300).

14A, 14B, 15A, and 15B are views showing examples of paths updated by the method of FIG.

14A, the first through fifth Voronoi regions V6, V7, V8, V9, and V10 are set based on the first through fifth event nodes EN6, EN7, EN8, EN9, The Voronoi diagram is included.

14B, the second event node EN7 is selected and the Voronoi diagram is updated based on event nodes EN6, EN8, EN9, EN10 excluding the second event node EN7, And regenerates the path based on the updated Voronoi diagram. In this case, the Voronoi diagram is updated to include four Voronoi regions (V6 ', V8', V9, V10) corresponding to the four event nodes (EN6, EN8, EN9, EN10). In addition, by deleting the previous lower paths connected to the selected second event node EN7 and adding the lower path that directly connects the previous and next event nodes EN6 and EN8 for the second event node EN7 , The path can be updated.

Referring to FIG. 15A, the first to fifth event nodes EN6, EN7, EN8, EN9, and EN10 and the first through fifth Voronoi regions V6, V7, V8, V9, Noisy diagrams are generated, and mobile devices (MD) are included in the wireless sensor network. The mobile device MD communicates with the plurality of sensor nodes, moves along the path, and is located on the first event node EN6, which is the starting point of the path.

15B, when the mobile device MD moves along the path from the first event node EN6 to the second event node EN7, the event nodes other than the first event node EN6 Updates the Voronoi diagram based on the updated Voronoi diagram (EN7, EN8, EN9, EN10), and regenerates the path based on the updated Voronoi diagram. In this case, the Voronoi diagram is updated to include four Voronoi regions V7 ", V8, V9, V10 "corresponding to the four event nodes EN7, EN8, EN9 and EN10. In addition, the path can be updated by deleting the lower path between the first event node EN6 and the second event node EN7 corresponding to the movement path of the mobile device MD.

The wireless sensor network 100 shown in FIG. 2A and the mobile device 300 shown in FIG. 2C and included in the wireless sensor network can be used to route a route based on the methods described above with reference to FIGS. 1, 6, 9, Generated and / or updated.

Specifically, in the mobile device 300, the selection unit 310 selects first to n-th event nodes included in the path among the plurality of sensor nodes, and the Voronoi diagram generation unit 320 generates 1 to nth event nodes, and the path generating unit 330 generates a Voronoi diagram for the plurality of sensor nodes based on the Voronoi diagram, And connects the two event nodes to each other to generate the path. A wireless sensor network (100) including a plurality of sensor nodes (200) includes first to nth (n is a natural number of 2 or more) event nodes selected from the plurality of sensor nodes, and a mobile node And generating a Voronoi diagram for the plurality of sensor nodes based on the first to nth event nodes and generating the Voronoi diagram based on the Voronoi diagram, And connects the two adjacent event nodes among the nodes to generate the path.

In one embodiment, the wireless sensor network 100 and the mobile device 300 select an (n + 1) th event node that is not disposed on the path among the plurality of sensor nodes, and the first through updating the Voronoi diagram based on the (n + 1) th event nodes, and updating the path based on the updated Voronoi diagram. In another embodiment, at least one event node of the first through nth event nodes is selected, and the Voronoi diagram is updated based on remaining event nodes other than the selected at least one event node, Lt; RTI ID = 0.0 > Voronoi < / RTI > diagram.

While the present invention has been described with respect to embodiments in which a wireless sensor network includes one mobile device and one path is created and updated, a wireless sensor network includes a plurality of mobile devices, It will be understood that the present invention is also applied to the embodiments that simultaneously or sequentially generate and update the paths.

The present invention can be applied to various types of wireless sensor networks requiring path generation. Especially, it can be used in existing networks such as smart home and monitoring system, and it can be used in military systems such as cave, jungle, etc., which searches for areas where GPS is difficult to operate, and military training and detection .

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims. It will be understood.

Claims (15)

1. A method for generating a path based on a distributed event in a wireless sensor network comprising a plurality of sensor nodes,
Selecting a first event node corresponding to a starting point of the path among the plurality of sensor nodes and a second event node corresponding to an arrival point of the path;
Generating a Voronoi diagram for the plurality of sensor nodes based on the first event node and the second event node;
A first sensor node having a smallest hop distance from the first event node and a second hop distance from the second event node among the plurality of sensor nodes based on the Voronoi diagram, ; And
Setting the path between the first event node and the second event node to include the first sensor node,
Wherein generating the Voronoi diagram comprises:
Obtaining, for each of the plurality of sensor nodes, information related to a nearest event node, a hop distance to the nearest event node, and a parent node;
Classifying each of the plurality of sensor nodes into a Voronoi cell, a Voronoi edge, or a Voronoi vertex based on the obtained information; And
And setting at least one Voronoi region based on sensor nodes classified as the Voronoi cell among the plurality of sensor nodes. delete 2. The method of claim 1, wherein setting the path further comprises:
The first sensor node, the first sensor node, and the first parent node associated with the first event node among the parent nodes of the first sensor node, and the first sensor node, the second event node, And connecting second parent nodes associated with the second event node among the parent nodes of the first sensor node to each other. The method according to claim 1,
Selecting a third event node that is not located on the path among the plurality of sensor nodes; And
≪ / RTI > further comprising the step of resetting the path to include the third event node. 5. The method of claim 4, wherein the step of re-
Selecting a closest event node closest to the third event node among the first and second event nodes based on the Voronoi diagram;
Updating the Voronoi diagram for the plurality of sensor nodes based on the first event node, the second event node, and the third event node; And
And updating the path so that the third event node is directly connected to the nearest event node based on the updated Voronoi diagram. 6. The method of claim 5,
A first lower path that travels from the first event node to the second event node and a second lower path that travels from the second event node to the third event node when the second event node is selected as the closest event node, Update the path to include two sub-paths,
A third lower path from the first event node to the third event node and a third lower path from the third event node to the second event node when the first event node is selected as the closest event node, And updating the path to include four sub-paths. In a wireless sensor network including a plurality of sensor nodes, a path generated by including pre-selected first through n-th (n is a natural number of 2 or more) event nodes among the plurality of sensor nodes A method for updating based on a distributed event,
Selecting an (n + 1) th event node that is not disposed on the path among the plurality of sensor nodes;
(N + 1) -th event node closest to the (n + 1) -th event node, based on a Voronoi diagram previously generated based on the first through the n-th event nodes Selecting a node;
Updating the pre-generated Voronoi diagram based on the first through (n + 1) -th event nodes; And
Regenerating the path so that the (n + 1) th event node is directly connected to the nearest event node based on the updated Voronoi diagram,
Regenerating the path further comprises:
Generating a first comparison result by comparing a first hop distance and a reference hop distance between the nearest event node and the (n + 1) th event node;
A second hop distance between a previous event node preceding the nearest event node and the (n + 1) th event node among the first to nth event nodes, and a second hop distance between the Generating a second comparison result by comparing a third hop distance between a next event node following the nearest event node and the (n + 1) th event node among the plurality of event nodes; And
And connecting the nearest event node and the (n + 1) th event node based on at least one of the first comparison result and the second comparison result. . delete 8. The method of claim 7,
(N + 1) th event node to the (n + 1) th event node when the first hop distance is smaller than the reference hop distance; Adding a second sub-path to the connected event node,
Deletes a first previous lower path from the previous event node to the closest event node when the first hop distance is greater than the reference hop distance and the second hop distance is smaller than the third hop distance, Adding a third lower path and a second lower path from the previous event node to the (n + 1) -th event node,
Deletes a second previous lower path from the closest event node to the next event node when the first hop distance is larger than the reference hop distance and the third hop distance is smaller than the second hop distance, And adding a fourth lower path from the (n + 1) th event node to the next event node. 10. The method of claim 9,
And adds the first lower path if the first hop distance is greater than the reference hop distance and the previous event node or the next event node is not present. delete delete 1. A wireless sensor network comprising a plurality of sensor nodes and generating and updating a path based on a distributed event,
First to nth (n is a natural number of 2 or more) event nodes selected from the plurality of sensor nodes and included in the path; And
A mobile device communicating with the plurality of sensor nodes and moving along the path,
Generating a Voronoi diagram for the plurality of sensor nodes based on the first to nth event nodes and generating a Voronoi diagram based on the Voronoi diagram based on the Voronoi diagram, The event nodes are connected to each other to generate the path,
Obtaining, for each of the plurality of sensor nodes, information related to a nearest event node, a hop distance to the nearest event node, and a parent node;
Classifying each of the plurality of sensor nodes into a Voronoi cell, a Voronoi edge, or a Voronoi vertex based on the obtained information; And
And configuring at least one Voronoi region based on sensor nodes classified as Voronoi cells among the plurality of sensor nodes to generate the Voronoi diagram. 14. The method of claim 13,
Selecting an (n + 1) th event node that is not disposed on the path among the plurality of sensor nodes, updating the Voronoi diagram based on the first through (n + 1) Updating the path based on the updated Voronoi diagram,
Selecting at least one event node among the first through nth event nodes and updating the Voronoi diagram based on the remaining event nodes except for the selected at least one event node, And updates the path based on the received information. A mobile device included in a wireless sensor network having a plurality of sensor nodes, generating and updating a path in a wireless sensor network based on a distributed event, and moving along the path,
A selection unit selecting first to n-th (n is a natural number of 2 or more) event nodes included in the path among the plurality of sensor nodes;
A Voronoi diagram generation unit for generating a Voronoi diagram for the plurality of sensor nodes based on the first to nth event nodes; And
And a path generator for generating the path by connecting two adjacent event nodes among the first to nth event nodes based on the Voronoi diagram,
Wherein the Voronoi diagram generation unit comprises:
Obtaining, for each of the plurality of sensor nodes, information related to a nearest event node, a hop distance to the nearest event node, and a parent node;
Classifying each of the plurality of sensor nodes into a Voronoi cell, a Voronoi edge, or a Voronoi vertex based on the obtained information; And
And configuring at least one Voronoi region based on sensor nodes classified as Voronoi cells among the plurality of sensor nodes to generate the Voronoi diagram.

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