KR100585231B1 - Method for routing of mobile ad-hoc network - Google Patents

Abstract

The present invention relates to a path searching method in a mobile Ad-hoc network.

In the path discovery method in the mobile ad-hoc network, the path explorer node that detects the change of network topology generates a path search message and transmits it to the neighbor node, and the neighbor node receives the path search message for the path through which the message has passed. Through this information, the route information for all nodes in the network can be recorded in its route table. In this way, the nodes in the mobile Ad-hoc network can find the path information for all nodes provided immediately through the path search message transmitted from the path explorer node, thereby reducing the path search delay and the periodic path information. There is no need to update the network, and the Ad-hoc gateway can participate in route search, thereby enabling Internet interworking of the mobile Ad-hoc network.

Mobile Ad-hoc Network, Route Explorer Node, Route Discovery Message, Receive Node, Route Table

Description

How to Navigate a Route in a Mobile Ade-ｈｏｃ Network {METHOD FOR ROUTING OF MOBILE AD-HOC NETWORK}

1 is a flowchart illustrating a path searching method in a mobile Ad-hoc network according to an embodiment of the present invention.

2 is a diagram illustrating a procedure for transmitting a message in a route explorer node according to an embodiment of the present invention.

3 illustrates a message transmission procedure at a receiving node according to an embodiment of the present invention.

The present invention relates to a path searching method in a mobile Ad-hoc network, and more particularly, to a path searching method in a mobile Ad-hoc network in which all nodes participating in the network can receive path information for all nodes.

Nodes constituting the mobile Ad-hoc network have a wireless interface, and are commonly referred to as mobile nodes because they satisfy a host having a mobile computing function and a router having an ad-hoc routing function at the same time.

The mobile node has a data propagation function as an intermediate node due to the limited propagation distance, and has a constant supply of energy because it uses a battery.

On the other hand, the mobile Ad-hoc network can be configured as a temporary or improvised network since the connection is established between the mobile nodes without a centralized coordinator such as a base station or an access point (AP).

Therefore, the mobile Ad-hoc network has a characteristic that the topology changes from time to time according to the movement pattern, traffic, link quality or power margin of the mobile node, and thus, path management for the mobile ad-hoc network is very difficult, thereby directly affecting the routing protocol.

In particular, Internet routing protocols such as Routing Information Protocol (RIP) or Open Shortest Path First (OSPF), which are used in existing networks, operate with periodic route table management in a stable, low-liquid network environment. This is a waste of bandwidth and does not respond quickly to dynamic changes in the network.

If the existing Internet routing protocol is applied to a mobile Ad-hoc network as it is, a lot of overhead is required, and a modification of the existing routing protocol or a new on-demand routing protocol is required.

The study of mobile Ad-hoc routing protocols has been the main research subject of mobile Ad-hoc networks. Each mobile node in the mobile Ad-hoc network has a limited wireless transmission distance so that information about the destination is determined by neighboring nodes or intermediate nodes on the data transfer path.

In a mobile ad-hoc network, a set or group of neighboring nodes capable of direct communication change together according to the movement patterns of the nodes, so that each node periodically broadcasts its existence to always maintain information of neighboring nodes or groups capable of direct communication. Should be.

Therefore, in the mobile Ad-hoc network, the route information is updated according to the information of the neighbor node. The route information is generated and managed by the routing protocol.

The routing protocol is currently being standardized by the Internet Engineering Task Force (IETF) Mobile Ad-hoc NETwork (MANET) Working Group, and is currently in the process of Ad-hoc On-demand Distance Vector (AODV), Dynamic Source Routing (DSR), and ZRP. (Zone Routing Protocol), Temporally-Ordered Routing Algorithm (TORA), and the like have been proposed as Internet drafts.

Routing protocols are divided into table-driven or proactive routing and on-demand or reactive routing.

Table routing is a method in which all nodes always keep the path information up to date by broadcasting the path information periodically or when the network topology changes. Routing protocols using a table method include routing protocols such as Destination Sequenced Distance Vector (DSDV), Wireless Routing Protocol (WRP), and Clusterhead Gateway Switching Routing (CGSR).

Since the above routing protocol always maintains the latest path information, communication can be performed without delay of path search when traffic occurs, while there is a problem in that the broadcasting overhead of control message for managing path information is too large.

Therefore, in the table routing method, research is being conducted to minimize the amount of control messages.

Request-based routing solves the control message overhead problem of table routing by searching for a route when traffic occurs.

Such request-based routing protocols include Ad-hoc On-demand Distance Vector (AODV) or Dynamic Source Routing (DSR). Most of these routing protocols may be delayed due to path discovery. The problem is that priority is given to minimizing the path search time rather than searching the path of the path.

The technical problem to be achieved by the present invention is a path in a mobile Ad-hoc network in which information is updated according to a change in network topology by a request of a specific node, and all nodes participating in the network are provided with a path to the entire network. To provide a search method.

In order to solve this problem, the present invention allows all nodes participating in the network to receive a path to the entire network through a path discovery message generated by a request of a path explorer node that detects a phase change of the network.

A route searching method in a mobile Ad-hoc network according to the first aspect of the present invention includes a) a route explorer node that detects a change in the network--where the route explorer node is a node or schedule that wishes to participate in the network. Generating a path discovery message including message path information, and transmitting the generated path discovery message to the neighboring node within the predetermined distance, the node detecting the appearance of the new neighboring node in the state of losing the information about the neighboring node within the distance; And b) the neighbor node that has received the route discovery message in step a) updates its route table by extracting new information through the message route information of the route discovery message and updates its route table. Adding the address and transmitting the address back to the neighboring node within a certain distance;

The neighboring node may determine a path to the final destination by increasing the number of nodes in reverse order by one hop from the node corresponding to the last path in the message path information of the path discovery message.

In step b), if the neighbor node does not have a path to the destination in its path table, it is preferable to add a path to the destination.

In step b), if the neighbor node has a path to the destination in its path table, the number of hops of the path to the destination in the path table and the path to the destination of the path search message are determined. Comparing the number of hops of; b-2) according to the comparison result of b-1), it is preferable that the neighboring node includes the step of changing the route information with a smaller hop number of the route to the destination in its route table.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention.

First, a path searching method in a mobile Ad-hoc network according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

 All nodes in the network have the same subnet address and periodically exchange information about their neighbors, all nodes maintain their route information in the route table but do not update it periodically, and route discovery is a specific node that detects changes in the network. Only pathfinder nodes may initiate.

In the above, the route explorer node is restricted to only nodes newly participating in the AG or network that receive data from unidentified nodes in the same subnet.

The AG becomes a route navigator node whenever it wants to form an ad-hoc network in the initial state, or when a link is disconnected or receives data from an unidentified node on the same subnet.

In this way, the AG can participate in the path search in the same way as other nodes, and thus, the Internet can be interworked with the mobile Ad-hoc network according to the present invention.

In addition, a node that detects the appearance of a new neighbor node becomes a route explorer node when a new node participating in the network or a member of the network wants to become a member or loses information on a neighbor node.

1 is a flowchart illustrating a path searching method in a mobile Ad-hoc network according to an embodiment of the present invention, and FIG. 2 is a flowchart illustrating a setting procedure for transmitting a message in a path discoverer node according to an embodiment of the present invention. It is shown.

As shown in FIG. 1, according to an embodiment of the present invention, a path search method in a mobile Ad-hoc network includes a path searcher node detecting a change in topology of a network and a route search message (Route Search Message, RSM) is generated and transmitted to neighboring nodes of one hop distance.

At this time, the path discovery message, as shown in Figure 2, the source node (RSM.Source Address) of the source node has the address of the route probe node, the destination address of the message has a broadcast address of "255.255.255.255" For example, the TTL (Time To Live) value of a message is 1, which prevents propagation of more than one hop.

The g flag is set to 1 if the sender of the message is an AG so that nodes receiving it set the AG as the default router. The address length addr_length represents the number of nodes that the message passed through, and the address field addr field represents the address of the nodes that the message passed through. The sequence number seq_num of the message indicates the sequence number of the message transmitting node, and the route explorer node transmits the configured message RSM.

The node receiving the route search message from the route explorer node checks the sequence number of the message and immediately terminates without the message processing procedure when the sequence number of the currently received message is smaller than the sequence number of the recently received message. (S1, S2)

However, if the receiving node's sequence number is greater than that of the recently received message, the receiving node checks whether the sender address of the message and the first address of the address field are the same in order to determine whether to reset the route table (S3). ).

The receiving node deletes all previous information from its route table unless the sender address of the message is the same as the first address of the address field and a message has been returned via the previous one (S4, S5).

Thereafter, the receiving node sets the last address of the address field to Next and performs a route search until the address field ends (S7).

The receiving node searches for the destination node via Next in the reverse order of the address field (S8), and if the destination node is the same as the address of the receiving node, the previous node has already updated the information, and thus the path searching process ends after optimizing the path. (S10).

However, if the destination node is not the same as the address of the receiving node, the receiving node checks whether there is an identical path to the destination via NEXT in its route table and the message route information of the route discovery message.

The receiving node finds the hop count for its route in its route table if the same route is found and the hop count information in its route table for that route is less than the hop count information in the message route information in the route navigation message. (S12, S13)

If the same node is not found, the receiving node stores the new path information in its path table (S14).

When the receiving node updates information in its route table or stores new information, the next message transmission flag (send_flag) is set to TRUE and the index for the address field is decreased to check the next route (S15).

At this time, the route explorer node receives the route discovery message sent by itself, or if the node receiving the route discovery message does not obtain any new information from the message, the route discovery message is deleted and no longer transmitted.

3 illustrates a message transmission procedure at a receiving node according to an embodiment of the present invention.

As shown in FIG. 3, the receiving node checks the transmission flag (send_flag) of the route discovery message and if it is TRUE, checks whether the sender is the first sender of the message (S21, S22).

If the receiving node is not the first sender of the message, it adds its address at the end of the address field, increases the length of the address field, sets the TTL value in the IP header back to 1, and finally receives the receiving node. After updating the sequence number for the received message, the message is transmitted to the neighbor node within one hop distance (S3).

However, the receiving node terminates without further message transmission if the transmission flag is not set to TRUE or if it is the first sender of the path discovery message.

That is, the node receiving the route discovery message performs route discovery through the corresponding message to determine whether to send the message back to the neighbor node or discard it.

When the receiving node finds the new route information from the route discovery message and updates the information on the new route in its route table, the receiving node transmits the route discovery message in which its address is added to the message to the neighbor node again.

In addition, if the receiving node already has information for any node but the number of hops for that node is less than the route navigation message is in the route table, the receiving node updates its route table with the number of hops in the route discovery message, and Add the address of to the path search message and send it to the neighbor node.

However, the route explorer node no longer sends the route discovery message even if it finds new information from the route discovery message.

In this way, the receiving node can naturally recognize the message path information from the neighbor node through the information of the node through which the message passes, that is, the message path information. In this case, it is preferable that the route discovery message is propagated only to nodes of one hop distance.

As such, in the embodiment of the present invention, the nodes participating in the mobile Ad-hoc network through the path discovery message have information about all nodes on the network in their tables.

Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited thereto, and various other changes and modifications are possible.

As such, the route searching method in the mobile Ad-hoc network according to the present invention provides the route information for all nodes that are immediately provided through the route discovery message transmitted from the route explorer node to the nodes in the mobile Ad-hoc network. As a result, it is possible to reduce the delay of the path search while eliminating the need to periodically update the path information.

Claims (10)

a) a route discoverer node that detects a change in the network--where the route discoverer node detects the appearance of a new neighbor node in the state of losing information about a node that wishes to participate in the network or a neighboring node within a certain distance. Generating a route discovery message including message route information and transmitting the route discovery message to a neighboring node within the predetermined distance; And b) the neighbor node receiving the route discovery message in step a) extracts new information through the message route information of the route discovery message, updates its route table, and then adds its address to the route discovery message. Adding and transmitting back to neighboring nodes within a certain distance Route search method in a mobile Ad-hoc network comprising a. delete delete The method of claim 1, B), The neighboring node searches for a route in the mobile Ad-hoc network which determines the route to the final destination by increasing the number of nodes in reverse order by one hop from the node corresponding to the last route in the message route information of the route discovery message. Way. The method of claim 4, wherein B), If the neighbor node does not have a route to the destination in its route table, adds a route to the destination. The method of claim 4, wherein B), b-1) if the neighbor node has a route to the destination in its route table, comparing the hop count of the route to the destination in the route table with the hop count of the route to the destination of the route discovery message. step; b-2) according to the comparison result of b-1), the neighboring node changes to route information having a smaller hop count for the destination in its route table; Route search method in a mobile Ad-hoc network comprising a. The method of claim 1, B), And searching for a route through the route discovery message, if the neighbor node discovers its own address, stopping the route discovery process. The method of claim 1, The route explorer node in step a), A method for searching a route in a mobile Ad-hoc network, which is an Ad-hoc gateway that receives data from a node that initially participates in the network or an unidentified node of the same subnet in the network. The method of claim 8, The Ad-hoc gateway searches for a route in the mobile Ad-hoc network which becomes the route investigator node whenever it requests the configuration of the network in the initial state, disconnects a link, or receives data from an unidentified node of the same subnet. Way. delete

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