KR20070025321A - Method for topology management with pre-cluster in ad-hoc wireless network and record media recorded program for realizing the same - Google Patents

Abstract

A topology management method using reserve clusters in an Ad-hoc wireless network and a recording medium storing a program for realizing the same are provided to stably perform network topology management, despite of an unexpected session or absence of the cluster header, by making a reserve cluster header serve as the cluster header, without reconfiguring a new topology, in case the network topology is changed. If a cluster header is elected, the elected cluster header elects a node having the largest weight among the neighbor nodes located within its own single hop as a reserve cluster header(S500,S502). The cluster header broadcasts a hello message containing its own cluster ID and the ID of the reserve cluster header(S506). Each cluster member finds out a hop counter from the cluster header through the received hello message and determines a cluster having the smallest hop counter as its own cluster(S510).

Description

TECHNICAL FOR TOPOLOGY MANAGEMENT WITH PRE-CLUSTER IN AD-HOC WIRELESS NETWORK AND RECORD MEDIA RECORDED PROGRAM FOR REALIZING THE SAME}

1 is an exemplary diagram for explaining a conventional hierarchical single hop topology management method;

2 is a flowchart illustrating a conventional topology management method;

3 is a configuration diagram illustrating an ad hoc network system to which the present invention is applied;

4 is an exemplary view for explaining a topology management method using a spare cluster in an ad hoc wireless network of the present invention;

5 is a flowchart illustrating a topology management method using a spare cluster in an ad hoc wireless network according to the present invention;

FIG. 6 is a detailed flowchart illustrating an exemplary method for selecting a cluster header of FIG. 5;

FIG. 7 is an exemplary data format diagram illustrating a hello message broadcast in FIG. 5; FIG.

<Description of the symbols for the main parts of the drawings>

310 ~ 350: mobile node

The present invention relates to a method for managing a topology using a preliminary cluster in an ad hoc wireless network and a recording medium recording a program for implementing the same, and more particularly, for use in a mobile ad hoc network (MANET), The present invention relates to a topology management method using a spare cluster in an ad hoc wireless network, and a recording medium recording a program for implementing the same.

In general, a mobile ad hoc network is defined as a network in which mobile nodes autonomously communicate over multiple hops in the absence of an existing communication infrastructure. A mobile node of a mobile ad hoc network is itself a host or a router and can actively establish a connection, and has a characteristic of freely joining or leaving the network.

In addition, because of the characteristics of the device is operated by a battery, there is a characteristic that the topology of the network is frequently changed by the supply of energy sources and frequent environment changes according to the characteristics of the wireless network. Here, the topology is a physical form of a computer network, and a device is connected to each other, or a communication channel is connected to a communication network.

In such an ad hoc network, an algorithm that reliably manages a variety of changing topologies is needed, and this is the starting point of ad hoc network management.

As a conventional technique for stably managing such a topology, [T. Ohta, S. Inoue, Y. Kakuda: An adaptive multihop clustering scheme for highly mobile ad hoc networks. The Sixth International Symposium on Autonomous Decentralized Systems, pp. 293--300, 2003. (hereinafter referred to as 'Paper 1')] [Abhay K. Parekh: Selecting routers in ad-hoc wireless networks. In the Proceedings of ITS, 1994. (hereinafter referred to as 'Paper 2')], [M. Chatterjee, S. K. Sas, D. Trugut: An on-demand weighted clustering algorithm (WCA) for ad hoc networks. GLOBECOM '00. IEEE vol. 3, pp. 1697-1701, 2000. (hereinafter referred to as 'Paper 3')] and [A. Ephremides, J. E. Wieselthier, D. J. Baker: A design concept for reliable mobile radio networks with frequency hopping signaling. Proceedings of the IEEE Volume 75, pp. 56--73, 1987. (hereinafter referred to as 'Paper 4').

The paper 1 is a multi-hop scheduling, characterized in that re-clustering such as merging or splitting clusters based on the number of members belonging to one cluster.

The paper 2 is to perform single hop clustering with a unique identifier of a node as a clustering parameter. Reclustering and header re-election are performed when the new node has the lowest identifier.

The paper 3 uses the density, mobility and residual power of the node as clustering parameters, and the reclustering period is present.

Finally, the paper 4 performs single hop clustering by calculating the density of nodes as clustering parameters. In the paper 4, reclustering and re-election of the cluster header are performed periodically, or whenever the density of neighboring nodes is changed.

However, the prior art as described above has a problem in that it cannot be properly applied in a multi-hop clustering structure, and in the case where the cluster header is absent, there is a problem that rapid response is impossible.

The present invention has been proposed to solve the above problems, and by pre-selecting a preliminary header among nodes located in a single hop neighbor using the density of the node and the weight of the residual power as a clustering parameter, even when the cluster header leaves or is absent. The purpose of the present invention is to provide a topology management method using a spare cluster in an ad hoc wireless network that enables stable network topology management, and a recording medium recording a program for implementing the same.

Another object of the present invention is to provide a method for managing a topology using a spare cluster in an ad hoc wireless network for supporting multi-hop clustering, and a recording medium recording a program for implementing the same.

In order to achieve the above object, according to a preferred embodiment of the present invention, a spare cluster in an ad hoc wireless network, for managing the ad hoc network to which a plurality of mobile nodes are wirelessly connected are divided into at least one cluster. A topology management method using: (a) selecting a mobile node having the largest clustering parameter as a cluster header; (B) selecting a mobile node having the largest clustering parameter among the single hop neighbor nodes except the cluster header as its spare cluster header; Broadcasting (c) the cluster header containing a hello message, the hop number including; And (d) determining, by the cluster member, the number of hops from the cluster header through the received hello message, and determining the cluster having the smallest number of hops as the cluster of its own node. Management methods are provided.

Here, step (a) may comprise: recognizing neighboring nodes within a single hop using a hello message each mobile node is periodically received; Setting clustering parameters of the own node; Broadcasting a hello message to the neighboring node, the hello message including the clustering parameter of the own node; And electing the mobile node with the largest clustering parameter as the cluster header within a single hop.

In this case, the hello message of step (c) may include a cluster identifier (ID), a preliminary cluster header ID, and a clustering parameter, wherein the clustering parameter is a ratio of the remaining power of the own node to the number of neighboring nodes. It may be a weight.

In addition, according to another embodiment of the present invention, in a topology management method using a spare cluster in an ad hoc wireless network for managing a topology of a cluster initially configured by the above method, the cluster header may determine the number of hello message-hops. Including-periodically broadcasting; And if a node having a larger clustering parameter exists in the same cluster, providing a topology management method using a spare cluster in an ad hoc wireless network, wherein the spare cluster header inherits the role of the header from the previous cluster header. The method may further include determining, by the cluster member, the number of hops from the cluster header through the received hello message, and determining the cluster having the smallest number of hops as the cluster of the own node.

In addition, according to another embodiment of the present invention, in a topology management method using a spare cluster in an ad hoc wireless network for managing a topology of a cluster initially configured by the method of claim 1 or 2, the cluster header is hello. Periodically broadcasting a message, including hop number; And if the clustering parameter of the cluster header is smaller than the threshold, providing a method for managing a topology using a spare cluster in an ad hoc wireless network, wherein the spare cluster header inherits the role of the header from the previous cluster header. The method may further include determining the hop number from the cluster header through the received hello message, and determining the cluster having the smallest hop number as the cluster of the own node.

In this case, the hello message may include a cluster identifier (ID), a preliminary cluster header ID, and a clustering parameter, and the clustering parameter may be a clustering weight that is a ratio of the remaining power of the own node to the number of neighboring nodes.

In addition, according to another embodiment of the present invention, a program of instructions that can perform a topology management method using a spare cluster in an ad hoc wireless network is tangibly implemented, and records a program that can be read by a digital processing device. A recording medium, comprising: selecting a mobile node having the largest clustering parameter as a cluster header; Selecting a mobile node having the largest clustering parameter among the single hop neighbor nodes except the cluster header as its spare cluster header; The cluster header broadcasting a hello message; And determining the number of hops from the cluster header through the hello message received by the cluster member, and determining the cluster having the smallest number of hops as the cluster of its own node.

In addition, according to another embodiment of the present invention, in order to manage the topology of the cluster initially configured by the above method, a program of instructions capable of performing a topology management method using a spare cluster in an ad hoc wireless network is tangibly implemented. 16. A recording medium having a program recorded thereon, the program being readable by a digital processing apparatus, comprising: periodically broadcasting a cluster header including a hello message, the number of hops; And if a node having a larger clustering parameter exists in the same cluster, a recording medium for recording the program, wherein the preliminary cluster header performs the step of inheriting the role of the header from the previous cluster header.

In addition, according to another embodiment of the present invention, in order to manage the topology of the cluster initially configured by the above method, a program of instructions capable of performing a topology management method using a spare cluster in an ad hoc wireless network is tangibly implemented. 16. A recording medium having a program recorded thereon, the program being readable by a digital processing apparatus, comprising: periodically broadcasting a cluster header including a hello message, the number of hops; And if the clustering parameter of the cluster header is smaller than the threshold value, the preliminary cluster header performs the step of inheriting the role of the header from the previous cluster header.

Prior to the description of the present invention, a conventional method for managing a topology will be described first.

In general, a method for managing a topology in an ad hoc network can be divided into two types, which have a large plan management structure or a hierarchical management structure.

In relation to the characteristics of the ad hoc network described above, the planar management method in which all nodes participate in topology management, the entire mobile node maintains the entire topology information, so the routing for the destination node is quick and easy. There is an advantage that you can easily obtain the management functions and information necessary for management. However, since each node must maintain topology information of the entire network and collect network information through continuous information exchange, overall network overhead and traffic increase, and there is a problem of shortening the life of nodes. In addition, when the topology of the network is changed, it must be propagated throughout the network. Therefore, it takes a lot of time to maintain accurate topology information, and thus there is a problem that rapid adaptation due to the topology change is impossible.

On the other hand, the topology management method with hierarchical management structure through clustering requires network overhead and time required for electing the cluster header and configuring the cluster. The management reduces the overall network overhead, and the mobile node maintains its own single hop information, while the information about the cluster maintains the cluster header splitting the overall topology, reducing processing overhead for each node. In addition, if the topology is changed, the cluster header of the region can update information quickly, so that it can be quickly adapted to a dynamic environment.

Hierarchical topology management using clustering in mobile ad hoc nodes is divided into a series of clusters constituting the network, and cluster headers and cluster members, which are cluster managers constituting the cluster, and connected to other clusters to manage management information. It is divided into transmitting and receiving gateway nodes. The cluster header is a node managing the cluster. The cluster header manages the cluster by receiving information messages periodically transmitted from cluster members belonging to the cluster.

A typical method of topology management using clustering is a method of creating a hierarchical structure composed of a single hop using an identifier (hereinafter, referred to as' ID ') or density of a node. The former is called' Lowest_ID 'and the latter is' Highest_Degree 'method. 1 is a diagram illustrating a conventional hierarchical single hop topology management method and illustrates a Lowest_ID clustering scheme. In these schemes, the node with the lowest ID or the most neighboring nodes becomes the cluster header, and the cluster is formed from nodes in a single hop from the cluster header.

2 is a flowchart illustrating a conventional topology management method.

As shown in the figure, a conventional topology management method selects a cluster header using a clustering parameter (ID or density) (S200), and a node having a large clustering parameter (ID or density) exists in the same cluster. (S202), if the node is re-elected as a cluster header (S200), and if a node having a large clustering parameter (ID or density) does not exist in the same cluster (S202), information about the mobile ad hoc node is included. The hello message (HELLO MESSAGE) is transmitted to each node in the cluster (S204).

In step S204, each node in the cluster marks its own ID in the hello message and broadcasts it as a single hop, and neighboring nodes that receive it are compared with their IDs and have the smallest ID. If you have, in step 200 will declare that it is a cluster header.

However, in the conventional topology management method as described above, when a predetermined cluster header reaches its end of life or fails to function as a header, the header is elected again. The clustering parameter is used, which causes information loss and delay of the managed node.

That is, the above schemes require reconfiguration of the cluster as the topology changes, and as the size of the network increases, the number of clusters and the amount of traffic for management increase, resulting in a decrease in overall network performance and lifespan. . Therefore, various methods such as periodic ID change or weighting method have been proposed for allocating the role of cluster header. However, the problem of selecting an appropriate change cycle for load balancing is considered in relation to the performance of the network. It is in a trade-off relationship.

On the other hand, as described above, the general single hop clustering has a number of problems as follows.

First, there is a high possibility of cluster reconfiguration and cluster reconfiguration when topology changes due to node movement.

Second, according to the role of the cluster header, energy is consumed faster than other nodes. Therefore, the cluster header has to be re-elected to reconfigure the cluster.

In order to solve the problems of the general single hop clustering scheme, adaptive multi-hop clustering, which is a multi-hop structure, has been proposed. This method forms a cluster through the density of nodes and maintains the cluster by limiting the number of management of the cluster header.

However, the adaptive multi-hop clustering scheme as described above also has a problem of reselecting the cluster header because the cluster must be reconfigured when the topology changes.

As such, a common problem with hierarchical management structures such as single-hop clustering or multi-hop clustering is that the cluster header must be re-elected because the cluster must be reconfigured when the topology changes due to node movement and new node network participation. As a result, the processing overhead of the network and the election jitter are incurred. Therefore, the management structures that require frequent cluster reconfiguration in the clustering algorithm are unstable in the network topology. It will cause a loss.

Therefore, unstable topologies due to frequent cluster reconfigurations have a large impact on network performance, and also affect network lifetimes due to network overhead and processing overhead of each node.

In the present invention, to solve the problem of the re-election of the header according to the reconfiguration of the clustering, which has been presented as a problem of the prior art to solve by selecting the preliminary cluster header. Therefore, the present invention can improve the performance of the processing overhead and the election delay of the network, and can also improve the stability of the topology.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same components have the same number as much as possible even if displayed on different drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram illustrating an ad hoc network system to which the present invention is applied.

As shown in the figure, the present invention is applied to an ad hoc network in which a plurality of mobile nodes 310 to 350 are connected wirelessly, and when a plurality of nodes form an ad hoc network, management of nodes and overload of the network are performed. In order to reduce the head, nodes are divided hierarchically and clustered. The ad hoc node representing the cluster is called a cluster header. In FIG. 2, the mobile node '310' may be a cluster header.

The present invention is for efficient cluster configuration, header selection and management in a system in which an ad hoc network composed of a plurality of nodes is divided into several clusters and managed.

FIG. 4 is an exemplary view schematically illustrating a topology management method using a spare cluster in an ad hoc wireless network of the present invention, and shows a topology management structure.

The present invention is characterized by managing a multi-hop topology using a weight that combines the density and power of the node. The present invention selects a cluster header using a weight, not a node ID or density of neighboring nodes, and selects a spare cluster header among single hop neighbor nodes of the corresponding cluster header. In addition, by applying a certain threshold of weights in the role of the cluster header, the reserve cluster header acts as a substitute, and maintains the existing topology as appropriate without reconfiguring the cluster even if the topology changes due to dynamic environment. Set limit values to enable load balancing across nodes.

Therefore, the present invention is to reduce the overhead of the network that can occur by reconfiguring the topology according to the topology change, and to select an appropriate weight value to distribute the load appropriately to all nodes participating in the network.

5 is a flowchart illustrating a topology management method using a spare cluster in an ad hoc wireless network according to the present invention.

As shown in the figure, the topology management method of the present invention first selects a cluster header based on a clustering parameter (S500). This will be described in more detail with reference to FIG. 6.

6 is a detailed flowchart illustrating an embodiment of the method for selecting a cluster header of FIG. 5.

As shown in the figure, in the initial topology configuration method of the present invention, each node recognizes a neighboring node within a single hop using the received periodic hello message (S600). From this, each node may set the cluster weight as a clustering parameter in consideration of the number of recognized peripheral nodes and the remaining power of the battery remaining in the node (S602). In this case, the cluster weight is preferably a ratio of the remaining power and the number of neighboring nodes.

Thereafter, a hello message including its own weight is broadcast to the neighboring node (S604). As a result, each node can grasp the weight of the other node through the received hello message (S606), and the node having the largest weight is selected as the cluster header (S608).

Again, in FIG. 5, after the cluster header is selected (S608), the selected cluster header selects the node having the largest weight except for itself among the neighboring nodes located in its single hop as the 'prepared cluster header' ( S502).

Thereafter, the cluster header broadcasts a hello message including the ID of the cluster and the ID of the spare cluster header (S506), and the cluster member finds the hop counter from the cluster header through the received hello message. In operation S510, the cluster having the smallest number of hops is determined as its own cluster.

This completes the initial topology configuration.

According to the present invention, the cluster cluster has a selection procedure only at the time of initial topology configuration. Election of the cluster header is selected by comparing weights with neighboring nodes, and may serve as a header within a threshold value range of a predefined weight.

FIG. 7 is an exemplary data format diagram for describing a hello message broadcast in FIG. 5.

As shown in the figure, the hello message transmitted from the cluster header to the cluster member according to the present invention is at least 40 bytes of data, and has 8 bytes of node ID, 8 bytes of cluster ID, and 8 bytes of spare. It includes the cluster ID, the hop count of 6 bytes, the state of 2 bytes, and the weight of 8 bytes.

The cluster formed through the initial topology configuration step as described above periodically determines whether a node having a larger clustering parameter exists in the same cluster (S504), and periodically broadcasts a hello message when there is no larger node ( S506). If there is a larger node, the spare cluster header inherits the role of the header from the previous cluster header (S514). When the cluster header is changed as described above, the changed cluster header broadcasts a hello message (S516), and the cluster member node knows the hop counter from the cluster header through the hello message received from the newly changed cluster header. The cluster with the smallest hop count is determined as its own cluster (S518).

On the other hand, although not shown in the figure, if the weight of the cluster header is less than the threshold value, the preliminary cluster header will inherit the role of the header from the cluster header, and the subsequent steps will be the same as the steps S516 and S518.

In the cluster formed according to the present invention, when the network topology is changed, such as when the operation of the cluster header node is suddenly interrupted, the cluster may be maintained by performing a role of the cluster header as a spare cluster header without reconfiguring the topology. .

The method of the present invention as described above may be implemented as a program and stored in a computer-readable recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.).

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes can be made in the art without departing from the technical spirit of the present invention. It will be clear to those of ordinary knowledge.

As described above, the present invention allows a spare cluster header to act as a cluster header without reconfiguring the topology when the network topology changes, such as when the operation of the cluster header node is suddenly interrupted. In case of departure or absence, stable network topology management can be performed. Therefore, it is possible to efficiently solve delay of election due to re-election of cluster header, information loss due to reconfiguration, and load balancing of network.

According to the present invention, each mobile node for the hierarchical structure may have a structure that adapts well to the dynamic change of ad hoc network topology, so that the role of each mobile node can be automatically changed by the neighbor information of the node. It is effective.

In addition, the present invention has the effect that even if the topology of the ad hoc network is changed by the movement of the node, the role is automatically determined as a member of the existing cluster by the information of the node without newly reconfiguring the cluster.

In addition, according to the present invention, the overhead for the hierarchical management structure is reduced because the number of cluster members (cluster size) is almost the same, and the cluster header and the spare cluster header automatically share roles by the threshold, so that the overall There is an effect that load balancing of the network is achieved.

Claims (13)

In the topology management method using a spare cluster in an ad hoc wireless network for managing the ad hoc network in which a plurality of mobile nodes are connected wirelessly to at least one cluster, (A) selecting a mobile node having the largest clustering parameter as a cluster header; (B) selecting a mobile node having the largest clustering parameter among the single hop neighbor nodes except the cluster header as its spare cluster header; Broadcasting (c) the cluster header containing a hello message, the hop number including; And (D) determining, by the cluster member, the number of hops from the cluster header through the received hello message to determine the cluster having the smallest number of hops as the cluster of its own node (d) Topology management method using a spare cluster in an ad hoc wireless network comprising a. The method of claim 1, Step (a) is, Each mobile node recognizing neighboring nodes within a single hop using a hello message periodically received; Setting clustering parameters of the own node; Broadcasting a hello message to the neighboring node, the hello message including the clustering parameter of the own node; And A method for topology management using a spare cluster in an ad hoc wireless network, comprising selecting a mobile node having the largest clustering parameter as a cluster header within a single hop. The method of claim 1, The hello message of step (c) is A topology management method using a spare cluster in an ad hoc wireless network, comprising a cluster identifier (ID), a spare cluster header ID, and a clustering parameter. The method according to any one of claims 1 to 3, The clustering parameter is, A topology management method using a spare cluster in an ad hoc wireless network, characterized in that the clustering weighting is a ratio of the remaining power of the own node to the number of neighboring nodes. In the topology management method using a spare cluster in an ad hoc wireless network for managing the topology of the cluster initially configured by the method of claim 1 or 2, Periodically broadcasting a cluster message including a hello message, the number of hops; And If a node with a larger clustering parameter exists in the same cluster, the spare cluster header inherits the role of the header from the previous cluster header. Topology management method using a spare cluster in an ad hoc wireless network comprising a. The method of claim 5, The method further includes determining, by the cluster member, the number of hops from the cluster header through the received hello message, and determining the cluster having the smallest number of hops as the cluster of its own nodes. In the topology management method using a spare cluster in an ad hoc wireless network for managing the topology of the cluster initially configured by the method of claim 1 or 2, Periodically broadcasting a cluster message including a hello message, the number of hops; And If the clustering parameter of the cluster header is less than the threshold, the spare cluster header inherits the role of the header from the previous cluster header Topology management method using a spare cluster in an ad hoc wireless network comprising a. The method of claim 7, wherein The method further includes determining, by the cluster member, the number of hops from the cluster header through the received hello message, and determining the cluster having the smallest number of hops as the cluster of its own nodes. The method according to claim 5 or 7, The hello message, A topology management method using a spare cluster in an ad hoc wireless network, comprising a cluster identifier (ID), a spare cluster header ID, and a clustering parameter. The method according to claim 5 or 7, The clustering parameter is, A topology management method using a preliminary cluster in an ad hoc wireless network, wherein the clustering weight is a ratio of the remaining power of the own node to the number of neighbor nodes. In an ad hoc wireless network, a program of instructions capable of performing a topology management method using a spare cluster is tangibly implemented, and in a recording medium recording a program that can be read by a digital processing apparatus, Selecting a mobile node having the largest clustering parameter as a cluster header; Selecting a mobile node having the largest clustering parameter among single hop neighbor nodes except the cluster header as its spare cluster header; The cluster header broadcasting a hello message; And The cluster member finds the hop count from the cluster header through the received hello message, and determines the cluster having the smallest hop count as the cluster of its own node. Recording medium recording a program, characterized in that for performing. In order to manage the topology of the cluster initially configured by the method of claim 11, a program of instructions for performing a topology management method using a spare cluster in an ad hoc wireless network is tangibly implemented and read by a digital processing apparatus. In the recording medium which records the program, Periodically broadcasting a cluster message including a hello message, the number of hops; And If a node with a larger clustering parameter exists in the same cluster, the spare cluster header inherits the role of the header from the previous cluster header. Recording medium recording a program, characterized in that for performing. In order to manage the topology of the cluster initially configured by the method of claim 11, a program of instructions for performing a topology management method using a spare cluster in an ad hoc wireless network is tangibly implemented and read by a digital processing apparatus. In the recording medium which records the program, Periodically broadcasting a cluster message including a hello message, the number of hops; And If the clustering parameter of the cluster header is less than the threshold, the spare cluster header inherits the role of the header from the previous cluster header Recording medium recording a program, characterized in that for performing.

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