KR20090043291A - Merge-split based group management and leader election in mobile ad-hoc networks - Google Patents

Abstract

The present invention relates to a method of group management of nodes in a mobile ad-hoc network. The present invention first selects each leader node based on a priority of each node included in at least one group. The elected leader node determines the size of the group to which it belongs, and can optimally perform mobile ad hoc network communication with each node in a group having the size and a predetermined maximum or minimum value, that is, a predetermined size. Compare the set size. According to the comparison result, the leader node divides the group to which the leader belongs to a predetermined number or merges with the group to which the other leader node belongs. Then, the leader node is re-elected among the nodes belonging to the divided or merged group to manage the newly created group as a whole. According to the present invention, a group is generated with an optimal size, thereby reducing the number of traffic by reducing the number of messages generated between nodes or groups, thereby enabling mobile ad hoc communication more effectively.

Mobile, ad hoc, priority, merger, split, node

Description

Merge-split based group management and leader election in mobile ad-hoc networks

The present invention relates to a wireless communication network, and more particularly, merges or divides by checking the size of a group used in a mobile ad-hoc network, and elects a leader node to manage the created group. The present invention relates to a group management method in a mobile ad hoc network.

In mobile ad hoc networks, nodes themselves form and route networks without infrastructure. One or more nodes in the mobile ad hoc network are attracting attention because they are increasingly smaller, more mobile, and have a wider range of applications.

However, since the network operates wirelessly and the nodes are mobile, a lot of traffic is used to perform data collection and information transfer of each node.

In the related art, nodes are managed in groups to reduce the amount of traffic described above. This is because the amount of traffic can be reduced by designating the nodes as a group and using the group instead of the communication between the nodes.

Hereinafter, a method of selecting a leader node from a plurality of nodes will be described with reference to FIGS. 1A to 1D.

1A to 1D are explanatory views illustrating a method of selecting a leader node in a mobile ad hoc network according to the prior art.

Referring to the drawings, 'node A', 'node B', 'node C', 'node D', and 'node E' are provided, and these nodes are included to form a group. Each node is given a priority in Arabic numerals. The higher the number, the higher the priority. That is, in the exemplary embodiment to be described, the priority of each node is in the order of "node B <node A <node C <node E <node D".

In order to elect a leader node from such a group, 'node A' first sends an election notification message for selecting a leader node to 'node B' or 'node E'. In the election notification message transmission, since nodes are connected in a tree structure in the drawing, transmission is performed according to the connection relationship. At this time, nodes such as 'node B' receive an election notification message from 'node A', which is a higher node, and transmit it to 'node D', which is a lower node, or 'node C', which is equally connected.

Once the election notification message is sent to all nodes, the 'node A' receives an acknowledgment message containing its priority information from other nodes. In this case, 'node E' may move. Then, 'Node C' detects the movement of 'Node E', breaks the relationship with 'Node E', and sends a response message to 'Node A' based on its information. In this case, the priority of each node is changed in the initial state. This state is FIG. 1B.

Next, referring to FIG. 1C, 'Node A' aggregates all the information, and selects 'Node C' having the highest priority as the leader node based on the priority information of each node received from Node B, Node C, and Node D). Elect. However, the node E moved in FIG. 1B may terminate the election independently and set itself as a leader node. On the other hand, when 'node E' is included as shown in FIG. 1d, 'node E' becomes the leader node because 'node E' has the highest priority.

However, the prior art as described above has the following problems.

That is, since individual nodes belonging to the group are all involved in elections for electing a leader node, the traffic volume is large, and the load of the leader is also large because a single leader is used.

In the case of performing the inter-node communication based on the conventional method described above, in particular, in a mobile ad hoc network in which a large number of nodes are moved, elections to select leader nodes within a group are frequently performed. Therefore, there is a problem that its efficiency is lowered.

In addition, conventionally, since the leader node is notified to other nodes without considering the movement of the general node other than the movement of the leader node, there is a problem in that the size and structure of the group are unknown.

Accordingly, the present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to efficiently perform group merging and splitting with reference to the group size and to reduce the traffic by selecting a leader node and to efficiently manage the group. It is to provide a group management method in a mobile ad hoc network to enable.

According to a feature of the present invention for achieving the above object, the present invention comprises the steps of: electing each leader node based on the priority of each general node included in at least one group; Determining the size of the group to which the selected leader node belongs; As a result of the determination, comparing the group size with a preset maximum or minimum value for optimally performing wireless communication; Merging with a group to which the other leader node belongs or dividing the group to which the leader belongs to the predetermined number according to the comparison result; And electing a leader node of the merged or divided group.

In this case, the merging step may include: merging when the group size is smaller than the minimum value, and transmitting a merge invitation message to at least one other group neighboring by the leader node of the group; Receiving respective group size information from the leader node of the neighboring one or more other groups; And selecting a mergeable group based on the group size information, and performing merge.

On the other hand, the dividing step may be performed if the group size is larger than the maximum value, but the leader node transmits a split request message for dividing the group to one or more general nodes in the group; Receiving, by the leader node, a response message including subtree size information of each general node from general nodes; And dividing, by the leader node, the size of the group based on the subtree size information such that the size of the group is a predetermined number of total size information of the group.

In this case, the dividing divides the entire size of the group into 1/2, and the sizes of the divided dividing groups are the same or have different sizes.

If the general node does not receive a heartbeat message from the leader node within a predetermined time, it attempts to merge with a group other than the group to which the leader node belongs.

The leader node is divided into a normal state in which the leader node is before the merger or division and election of a group, and a busy state in which the leader node is currently performing merger or division and election.

At this time, the leader node changes to a busy state when a merger, division or election of a group is performed in a normal state.

Preferably, the leader node does not perform a request message for merging / dividing / election from another group or node in a busy state.

In the mobile ad hoc network according to the present invention as described above in detail the group management method can be expected the following effects.

That is, the present invention has the advantage of performing efficient wireless communication by reducing the number of messages exchanged between the individual nodes in order to select a leader node in the related art and thereby reducing the amount of traffic.

In addition, the present invention compares the size of the group managed by the leader node with the size range for performing the optimal mobile ad hoc communication, and manages the wireless network efficiently by merging and dividing with neighboring node groups. There is an advantage to doing this.

Hereinafter, a preferred embodiment of a group management method in a mobile ad hoc network according to the present invention as described above will be described in detail with reference to the accompanying drawings.

2 is a block diagram showing a node configuration for explaining a group management method in a mobile ad hoc network of the present invention.

2, at least one general node 200 and a leader node 100 managing the general node 200 are provided.

The leader node 100 has a normal state and a busy state. The normal state means a standby mode before the leader node merges or divides a group or performs an election, and the busy state indicates a performance mode in which the leader node performs merger, split, or election of a group.

Therefore, in the normal state, the leader node 100 may receive a message related to a merger or division request of a group or a request for election, and if the merger or division or election is performed according to the message, The current state is changed to busy.

In addition, when the leader node is busy, the merger or division is currently being conducted or the election is being held, so even if a request message for merger / division / election is generated from another group or node, it is ignored. That is, the request message can be received, but does not actually perform a function corresponding to the request message.

Meanwhile, the leader node 100 transmits a heartbeat message to the general nodes 200. The heart-beat message is transmitted by the leader node 100 to inform the general node 200 of its existence, and also uses this to detect the general node 200 moving in a group. .

If the reader node 100 receives the heartbeat message from the leader node of another group, the node change is performed from the leader node to the general node. In addition, the general node 200 periodically checks whether the heart-beat message is received from the leader node 100. If the heart-beat message is not received for a certain period of time, the corresponding general node determines that the leader node 100 has separated from the group to which the leader node 100 belongs and attempts to merge with the neighboring group.

Next, the group management method in the mobile ad hoc network according to the present invention will be described in detail with reference to the accompanying drawings.

In the present embodiment, the method of managing a group may selectively perform merge or split by adjusting the group size. Here, the value used for the scaling means a value when optimal nodes are accommodated in one group to perform mobile ad hoc communication, which is within a range of maximum and minimum values specified by the user. Therefore, when the group size is smaller than the minimum value, group merging is performed, whereas when the group size is larger than the maximum value, group splitting is performed. Accordingly, the maximum value and the minimum value become reference points for merging and dividing, and the maximum value is usually two to three times the minimum value.

Based on this, hereinafter, the group merger and the group split will be described separately.

3 is a flowchart illustrating a group merging method according to a preferred embodiment of the present invention.

First, in step 300, the leader node determines the size of a group managed by the leader node.

Thereafter, in step 310, the leader node compares the group size to which the leader node belongs to a predefined minimum value. 3 illustrates only the merging process, so the comparison with the maximum value is omitted. However, the leader node first performs the process of comparing its group size with the maximum or minimum value. The division process according to the maximum value comparison is described below.

As a result of the comparison, when the group size is smaller than the minimum value as in step 320, in step 330, the leader node transmits a merge invitation message for merging with one or more neighboring groups.

Then, the other groups transmit a response message including their group size information to the leader node as a response message according to the merge invitation message.

In step 340, the leader node receives the response message, and in step 350, the leader node selects a group to be merged based on other group size information, and performs merge.

When the group is merged, the node having the highest priority among the nodes of the merged group is selected as the leader node. The elected leader node propagates the heart-beat message to the merged group to newly elect a leader node and completes the merge.

An embodiment of a merging process between each node group described above will be described in more detail with reference to the accompanying drawings.

3A and 3B are explanatory diagrams for explaining a process of merging nodes between nodes of the present invention.

In the present embodiment, 'node A' and 'node C' are assumed to be leader nodes, and 'node B' and 'node D' are assumed to be general nodes. The priority of each node is assumed to be "Node A> Node B> Node C> Node D".

The size of the group may change for reasons such as movement of nodes. In this state, when it is determined that the group size is small as shown in FIG. 3, 'Node B' sends a merge request message to the 'Node C' and the 'Node D' for merging.

The node C and the node D, which have received the merge request message, deliver the merge request message to the node A, the leader node of the group.

At this time, the node B, which has transmitted the merge request message, transmits a selection message for suggesting merger to node A having a higher priority than itself, and delivers a rejection message to node C.

In this case, 'Node B' merges with the group to which the leader node 'Node A' belongs.

Subsequently, the node A having the highest priority within the merged two groups is elected as the leader node. The node A selected as the leader node transmits the heartbeat message to the node B and node D, which are general nodes in the merged group.

On the other hand, if the priority of the 'node B' node is higher than the 'node A', the 'node B' does not transmit a selection message to the 'node A', the 'node A' and 'node D' By sending a heartbeat message, Node B becomes the leader node of the merged group.

As described above, the merger exchanges the merge request message and the response message between the leader nodes, and then selects the merge group and the new leader node in consideration of the priority.

Next, a group division method according to a preferred embodiment of the present invention will be described with reference to FIG. 5.

5 is a flowchart illustrating a group division method according to a preferred embodiment of the present invention.

First, in step 400, the leader node determines the size of a group managed by the leader node.

In step 410, the leader node compares the group size to which the leader node belongs to a predefined maximum value.

As a result of the comparison, when the group size is larger than the maximum value as in step 420, in step 430, the leader node transmits a split request message for dividing its own group to general nodes of its group.

Then, in step 440, the leader node receives a response message including subtree size information of each general node from general nodes belonging to its group.

In step 450, the leader node divides the size of the group so that the size of the group becomes a predetermined size, for example, 1/2, based on the total size information of the group. In this case, although the division size of the group may not be accurately divided according to the subtree, in this case, it is preferable to divide the size of the group based on an approximate value of about 1/2 of the total size information of the group.

When the group is divided, nodes having the highest priority among the divided groups of nodes are each elected as leader nodes. Each elected leader node propagates the heart-beat message to the general nodes of its group to inform the existence of the leader node and complete the partitioning.

Hereinafter, an embodiment of the above-described group division step will be described in detail with reference to FIGS. 6A and 6B.

6A and 6B are explanatory diagrams illustrating a group division process according to a preferred embodiment of the present invention.

Referring to the drawings, 'node B' and 'node C' based on the leader node 'node A'. Ten common nodes are included, such as 'node D', so a total of eleven nodes are formed in one group.

In this state, when it is determined that the group size is larger than the maximum value as described in FIG. 5, the node 'Node A', the leader node, transmits a split request message to the general nodes.

Then, the node B, node C, and node D, which have received the split request message, calculate their own subtree size and respond to the node A with the subtree size information. Send it.

'Node A' receiving the response message divides the group size.

Here, the group division size will be described in more detail as follows.

That is, in FIG. 6A, the total size of the group is referred to as '11' corresponding to the number of nodes. At this time, the size to be divided should be set to '6' which is '1/2' of the size of the current group.

Accordingly, the 10 general nodes that receive the split request message each calculate the size of their own subtree, wherein 'node C' has a subtree size of '3' including 2 subnodes, 'Node D' has a subtree size of '6' including 5 subnodes.

Thus, when dividing the total size of the group '11' by '2', the actual division size should be '5.5'. It should be divided according to the size information, but referring to the subtree size information, it is eventually divided into a 'node A' group having a size of '5' and a 'node D' group having a size of '6'.

As described above, in the present embodiment, the size of the current group is examined according to the size information of the group, the merger or division is performed, and the leader node managing the created group is selected. The traffic associated with data transmission is reduced.

According to this embodiment, as a result of measuring the amount of messages generated when moving the node and comparing with the conventional method, the average message was reduced by 35%, the gap between the nodes was confirmed that the higher the density becomes larger. In addition, the average message savings was 67%.

On the other hand, the rights of the present invention is not limited to the embodiments described above, but is defined by the claims, and those skilled in the art can make various modifications and adaptations within the scope of the claims. It is self evident.

That is, group nodes can be configured as neighbors and a tree between nodes can be maintained to prevent additional traffic from hop communication when a leader node collects or propagates a message in an application such as a monitoring system. Therefore, the present embodiment is suitable for an application such as a monitoring system that periodically collects or propagates data of each node in a mobile ad hoc network, and an application of periodically collecting data of a sensor node in a sensor network, which is a similar environment. Applicable to

1A to 1D are explanatory views for explaining a method of selecting a leader in a mobile ad hoc network in the related art.

Figure 2 is a block diagram showing a node configuration for explaining a group management method in a mobile ad hoc network of the present invention.

3 is a flowchart of a group merging method according to a preferred embodiment of the present invention.

4A and 4B illustrate an exemplary embodiment of a group merging process of FIG. 3.

5 is a flowchart of a group partitioning method according to a preferred embodiment of the present invention.

6A and 6B are diagrams illustrating an embodiment of a group division process of FIG. 5.

Explanation of symbols on the main parts of the drawings

100: leader node 200: general node

Claims (8)

Electing a leader node based on a priority of each general node included in at least one group; Determining the size of the group to which the selected leader node belongs; As a result of the determination, comparing the group size with a preset maximum or minimum value for optimally performing wireless communication; Merging with a group to which the other leader node belongs or dividing the group to which the leader belongs to the predetermined number according to the comparison result; And, And electing a leader node of the merged or divided group. The method of claim 1, The merge step, If the group size is smaller than the minimum value, merge is performed. Sending, by a leader node of the group, a merge invitation message to one or more other groups that neighbor; Receiving respective group size information from the leader node of the neighboring one or more other groups; Selecting a mergeable group based on the group size information, and performing a merge; Group management method in a mobile ad hoc network characterized in that it comprises a. The method of claim 1, The dividing step, When the group size is larger than the maximum value, division is performed. The leader node sending a split request message for splitting a group to one or more general nodes in the group; Receiving, by the leader node, a response message including subtree size information of each general node from general nodes; And dividing, by the leader node, the size of the group based on the subtree size information so that the size of the group is a predetermined number of the total size information of the group. The method of claim 3, The dividing divides the entire size of the group by 1/2, The size of the divided divided group is the same or different size group management method in a mobile ad hoc network, characterized in that. The method of claim 1, And if the general node does not receive a heartbeat message from the leader node within a predetermined time, attempts to merge with a group other than the group to which the leader node belongs. The method according to any one of claims 1 to 3, The leader node, And the leader node is divided into a normal state before merger or division and election of a group, and a busy state currently performing merger or division and election. The method of claim 6, The leader node is a group management method in a mobile ad hoc network, characterized in that the state changes to a busy state when the merger, division or election of the group in the normal state. The method of claim 6, The leader node does not perform even if a request message for merging / dividing / election is generated from another group or node in a busy state.

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