KR101694329B1 - Path establishing method for transmitting data in ad-hoc network - Google Patents

Abstract

The present invention defines, in an ad-hoc network composed of two or more nodes, a path searching method that can be used in determining through which path data should be transmitted, when one node transmits data to the other node. Each node can play a role of an intermediate node, and play a role of a relay node when transmitting data. When a node transmits data to a specific node, the node checks through which the data can be sent. If a node does not have a path (next hop), the node begins searching for a path. In searching for a path, a node that will transmit data broadcasts a path request message and all nodes receive the broadcast massage. The nodes receive the path request message, and when a node has a path (next hop) to a destination, the node transmits a path response message to a node that will transmit/receive data. If a node does not have a path (next hop), the node broadcasts the path request message again. Also, when a destination node receives a path request message, the destination node transmits a path response message to a source node that will transmit/receive data. In this case, the source node that will transmit/receive data receives the path response message, selects a value having the lowest routing cost, and sets a path (next hop).

Description

PATH ESTABLISHING METHOD FOR TRANSMITTING DATA IN AD-HOC NETWORK [0002]

The present invention relates to an ad hoc network, and more particularly, to a method for establishing a path for transmitting data in an ad hoc network capable of transmitting data while reducing excessive occurrence of a broadcast message in a wireless ah-hoc network.

Ad-hoc network is a network that is autonomously constructed between mobile nodes without the help of fixed network. It establishes a path by cooperating with surrounding nodes through communication with itself, to be. Also, ah-hoc network is mainly connected to a wireless network. In this case, since the propagation distance is limited, the source node (data transmission node) may not reach the destination node to which data is to be transmitted . Therefore, each node has the function of the role of the intermediate node, and when data is received, if the destination is not itself, it has a function of transmitting data toward the destination.

In addition, path management in ad hoc networks consists of table-driven, proactive, request-based (on-demand, reactive), and hybrid . The table management method is a method in which all nodes always maintain route information by periodically broadcasting route information. The request-based approach is to retrieve the path at the time the data is sent. The hybrid method is a method that combines the two methods and manages the route at the time of data transmission and manages the route information in the table. The timer has a timer, and when the timer expires, the path information is deleted from the table. After that, when the data is re-generated, the path is rediscovered and the path information is managed in the table.

The source node (data transfer node) checks to see if it has its own path (next hop) before sending the data to the destination node. If you have a route yourself, the source node (data transfer node) will send the data to that route. However, if you do not have a route, you can use the route search method to set the route and send the data.

Currently there are many types of path establishment methods in ad-hoc networks. The most commonly used path establishment method is as follows.

The source node (data transmission node) broadcasts the route request message if it does not have the route of the destination node (next hop). At this time, the neighboring nodes in the vicinity receive the broadcast message. Neighboring nodes that receive the message will broadcast the received broadcast message back to the neighboring node if it is not the destination itself. In addition, when a source node (data transmission node) receives a broadcast transmitted from neighboring nodes, it confirms that it is a route request message generated by itself, and discards the message.

When intermediate nodes other than the destination node receive the broadcast message, the same message can be received from multiple nodes due to the characteristics of the broadcast. In this case, the intermediate node compares the routing cost, selects the message with the lowest value, and broadcasts it to neighboring nodes again. Broadcast messages with high routing costs are discarded without further transmission.

The nodes receiving the message broadcast in this way transmit the path response message to the source node (data transmission node) in the reverse direction in which the path request message is transmitted in unicast, without broadcasting the message any more when the destination is the self .

Therefore, an excessive occurrence of the path request message may hinder the performance of the nodes, and at the same time, a broadcast message may be generated, resulting in a lost message. Since the path response message is received only from the destination, if the path response message is not received, the path request is retried.

Figure 1 depicts a route establishment method used in the prior art. The message generation and operation sequence is performed in the order of a -> b -> c -> d -> e -> f.

Referring to FIG. 1, a source node (data transmission node) 1 transmits a broadcast message to neighbor nodes (a). (B) Neighboring nodes 2 and 3 receive the broadcast message because the destination is not itself. Then, the neighbor nodes 4 and 5 receiving the broadcast message transmit the broadcast message again because the destination is not itself (c). Then, neighbor node 6 receives the broadcast message, node 6 determines that it is the destination itself, and then transmits the route response message in the reverse direction without further transmitting the broadcast message. The path response message is transmitted from node 6 to node 5 (d), from node 5 to node 2 (e), and from node 2 to node 1 (f).

As shown in FIG. 1, each neighboring node (2, 3, 4, 5) knows that it transmits an unconditional broadcast message when it is not the destination node itself. According to the conventional method, since a broadcast route request message is excessively generated, the node is overloaded and a message may be lost. Since the route response message can be received only from the final destination node, If not, there is a problem of retrying the route request.

Registration No. 10-0999118 (Data transmission method in ad hoc network) Registration No. 10-0555749 (Apparatus and method for setting up a data transmission path in an ad hoc network) Patent No. 10-1013752 (Data transmission method of ad hoc network) Registration No. 10-1601181 (Ad hoc network node and its operation method and data transmission method of ad hoc network) Registration No. 10-1214532 (Multicast data transmission system and data transmission method using location information in a wireless ad hoc network) Japanese Patent Registration No. 10-1535633 (Data transmission method and apparatus and data transmission system in an ad hoc network)

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problem, and it is an object of the present invention to provide an ad hoc network which can reduce excessive occurrence of a broadcast message in an ad- Method.

The present invention also provides a method for establishing a path for transmitting data in an ad hoc network capable of reducing the occurrence of excessive broadcast messages and establishing a stable path by receiving a plurality of path response messages.

Specifically, the relay node (neighbor node) can also transmit the route response message, selects the value with the lowest routing cost among the plurality of route response messages, and transmits the data in the ad hoc network determining the route to the destination node And to provide a method for establishing a path for the user.

According to another aspect of the present invention, there is provided a method for establishing a path for transmitting data from a source node to a destination node in an ad-hoc network, the method comprising the steps of: Broadcasting a request message (a); When the destination of the message is not itself, the neighboring nodes that have received the broadcast message transmit the path response message to the source node in a unicast manner if the node itself has a route to the destination, (B) broadcasting the received broadcast message back to the neighboring nodes if it does not have the path for the neighboring nodes; (C) transmitting a route response message to a source node side in a unicast manner when a destination is itself among neighboring nodes that have received the broadcast message; And a step (d) of selecting a path having the smallest routing cost (routing cost) among the plurality of received path response messages and determining a path to the destination node.

In step (b), if the destination node is not the destination itself, the neighbor node receiving the broadcast message searches its route information table and if it has the route to the destination, the routing cost value of the destination node is transmitted to the route response message And can be transmitted to the source node in a unicast manner.

The routing cost value is a value obtained by checking the reception sensitivity of the node when the route request message or the route response message is received. The higher the reception sensitivity, the lower the routing cost value.

The source node can calculate the routing cost value by calculating the reception sensitivity at the time of receiving the route response message and calculate the final routing cost value by adding the routing cost value in the route response message to the calculated routing cost value .

In step (d), the source node receives a route response message from one or more neighbor nodes, receives a route response message from the destination node, selects a value with the smallest routing cost among a plurality of route response messages, Can be determined.

When the source node receives one or more route response messages from neighboring nodes other than the destination node, it waits until it receives a route response message from the destination node, and if a route response message is received at the destination node, And the lowest value can be selected by comparison.

If the path response message is not received from the destination node until the waiting time set in the source node is exceeded, a path with the lowest routing cost is selected from among the path response messages received from one or more neighboring nodes to determine a path to the destination node .

According to the present invention having the above-described configuration, the following effects can be achieved.

First, the present invention can prevent an excessive occurrence of a route request broadcast message in an ad-hoc network, thereby preventing each node from being overloaded due to message transmission and reception.

Since the source node (data transmission node) can receive not only the path response message from the final destination node but also the neighbor nodes, it can establish a stable path by receiving a plurality of path response messages.

That is, in the conventional method of receiving a single path response message, if a message is lost and can not be received, the path request message must be retransmitted in a broadcast manner and the path response message must be received again. Even if some messages are lost, there is no need to retransmit the route request message to establish the route.

1 is an exemplary diagram illustrating an operation procedure for a path establishment method in an ad hoc network according to the related art.
2 is a flowchart of a method for establishing a path for transmitting data in an ad hoc network according to an embodiment of the present invention.
3 is a diagram illustrating an overall operation of a path establishment method in an ad hoc network according to an exemplary embodiment of the present invention.
4 is an exemplary diagram illustrating an operation procedure assuming that node 5 does not have a next hop for a destination according to an embodiment of the present invention.
FIG. 5 is a diagram illustrating an example of a procedure in which actual data is transmitted after path establishment according to an embodiment of the present invention. Referring to FIG.
FIG. 6 is a diagram illustrating an example in which nodes generate a next hop for a source node (data transmission node) in a route information table after receiving a route request message according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and how to accomplish them, will become apparent by reference to the embodiments described in detail below with reference to the accompanying drawings.

However, the present invention is not limited to the embodiments described below, but may be embodied in various other forms.

The present embodiments are provided so that the disclosure of the present invention is thoroughly disclosed and that those skilled in the art will fully understand the scope of the present invention.

And the present invention is only defined by the scope of the claims.

Thus, in some embodiments, well known components, well known operations, and well-known techniques are not specifically described to avoid an undesirable interpretation of the present invention.

In addition, throughout the specification, like reference numerals refer to like elements, and the terms (mentioned) used herein are intended to illustrate the embodiments and not to limit the invention.

In this specification, the singular forms include plural forms unless the context clearly dictates otherwise, and the constituents and acts referred to as " comprising (or having) " do not exclude the presence or addition of one or more other constituents and actions .

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs.

Also, commonly used predefined terms are not ideally or excessively interpreted unless they are defined.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

A path establishment method for transmitting data in an ad hoc network according to the present invention relates to a path establishment method for transmitting data from a source node (data transmission node) to a destination node in an ad-hoc network.

In the present invention, the source node and the data transfer node are used in the same sense. In the following embodiments, the source node (data transmission node) is assumed to be 1, and the final destination node is assumed to be 6. In addition, nodes 2 to 5 correspond to neighboring nodes that relay data transmission.

The present invention will be described with reference to Fig.

[Step a]

The source node (data transfer node) initially does not have a path to the destination node. The source node broadcasts a route request message (S10).

[Step b]

The neighbor nodes receive the route request message broadcasted by the source node (data transmission node) (S20).

The neighboring nodes that have received the broadcast message determine whether the destination of the message is itself (S30).

If the destination of the message is not itself, it is determined whether the neighboring node itself has a route to the destination (S50). The neighboring node searches its own path information table in the storage unit to determine whether it has a path to the destination.

If the node itself has a route to the destination, it transmits the route response message to the source node (data transmission node) in a unicast manner (S60). In a different aspect from the prior art, one or more of the neighboring nodes may send a route response message to the source node (data transmission node) if it has a route to the destination.

Specifically, when the destination node is not the destination itself, the neighbor node receiving the broadcast message searches its route information table and stores the routing cost value of the destination node in the route response message if the destination node has the route to the destination node To the source node in a unicast manner.

Routing cost is the value (routing cost) that a node receives when it receives a route request message or a route response message and checks the reception sensitivity from the neighbor node. The better the transmission and reception sensitivity, The routing cost is reduced. That is, the lower the routing cost, the more stable the routing. It is a matter of course that the source node (data transmission node), the neighboring node and the destination node constituting the ad hoc network have a configuration capable of checking the transmit and receive sensitivity and the transmit and receive sensitivity to transmit and receive data.

However, if it does not have the route to the destination, it broadcasts the received broadcast message to neighboring nodes again (S70). As a result, the neighboring nodes do not unconditionally broadcast the received message but broadcast the received route request message only when the neighboring node does not have the route to the destination.

Neighboring nodes that have received the broadcast message will repeat the above procedure to determine and perform.

[Step c]

The neighboring nodes that have received the broadcast message search their route information table to determine whether the destination of the message is itself (S30). If the destination is itself, the route response message is transmitted in a unicast manner to the source node Node) (S40).

[Step d]

As a result, the source node (data transmission node) receives a plurality of path response messages in a unicast manner from one or more neighbor nodes and the final destination node. A path having the smallest routing cost (routing cost) is selected from among the plurality of received route response messages and a route to the destination node is determined (S80). Since the path response message is received in this manner, it is possible to avoid the problem of requesting the path again due to message loss even if some path response messages are lost.

The source node calculates the routing cost value by calculating the reception sensitivity when receiving the route response message, and calculates the final routing cost value by adding the routing cost value in the route response message to the calculated routing cost value. The source node (data transmission node) can receive multiple route response messages, calculates the routing cost by calculating the reception sensitivity for each received route response message, adds the routing cost value in each route response message, You will get multiple cost values. Each routing cost value will be different, and the route cost to the destination node is selected by selecting the routing cost value that has the smallest routing cost value.

When the source node receives one or more route response messages from neighboring nodes other than the destination node, it waits until it receives a route response message from the destination node, and when a route response message is received from the destination node, To select the smallest value. Upon receiving the route response message, the source node can know from which node the message is transmitted. As a result, if the route response message is not received yet from the destination node, it waits until it receives it, and compares a plurality of routing cost values calculated after receiving from the destination node.

A waiting time may be set in the storage unit of the source node (data transmission node) until a route response message is received after transmitting a route request message. If the path response message is not received from the destination node until the waiting time exceeds the set waiting time, the route to the destination node is determined by selecting a value with the lowest routing cost among the route response messages received from one or more neighboring nodes. This is to prevent a time delay in establishing the path by waiting for the source node to wait for the loss of the path response message transmitted by the destination node.

3 to 6, a method of establishing a route to a source node (data transmission node) 1 up to a destination node 6 will be described. It is assumed that the source node (data transmission node) is 1 and the destination node is 6.

[Stage 1]

The source node (data transmission node) # 1 performs the process of determining the path to send data to the destination # 6. Accordingly, the source node (data transmission node) 1 broadcasts a route request message (FIG. 3, a). Neighbor nodes 2 and 3 receiving the broadcast message can store the route for node 1 in the route information table of the storage unit. A method of storing the route for node 1 after receiving the route request message is shown in FIG. The intermediate nodes can set the node to nexthop immediately before the Orientation (Data Transfer Node) of the received route request message.

In the case of FIG. 6, since the node 1 is received, the next hop (nexthop) is set to 1 for the destination 1 in the route information table. If the destination of the broadcasted message is not itself, it searches its route information table. If there is a next hop for destination 6, nodes 2 and 3 will send a route reply message to source node 1 (data transmission node).

In the case of FIG. 3, it is assumed that the second hop has the next hop for the destination 6 in the route information table, and the third hop does not have the next hop. In this case, since node 2 has the next hop (route), it sends the routing cost value for destination 6 to the route response message. The routing cost is a value calculated by checking the reception sensitivity when receiving the route request message or the route response message. The higher the reception sensitivity, the smaller the routing cost value. Here, routing cost refers to the value obtained when node 2 previously determined the next hop for destination 6.

Therefore, when node 2 sends this routing cost value to the source node (data transmission node) # 1 in the route response message, it calculates the routing sensitivity and the routing cost to calculate the routing cost. The final routing cost value can be calculated in addition to the routing cost value in the route response message. Thus, the source node (data transmission node) # 1 can obtain the route to the destination # 6 (FIG. 3, b1).

[Step 2]

While # 3 does not have the next hop for destination # 6. In addition, since the destination requested by the source node (data transmission node) # 1 that sent the route request message is not itself, the received route request message is broadcast to neighboring nodes again (FIG. 3, b2).

When node 3 broadcasts a route request message, nodes 1, 2, 4, and 5 in the neighbor node receive the route request message. The nodes 1, 2, 4, and 5, which have received the route request message, take each action.

Node 1 is discarded without taking any action because it is a route request message sent by itself. 2 is discarded because it has received a duplicate message because it is the route request message it received previously. 4 and 5 are route request messages received for the first time. The processing procedure is the same as the processing procedure that was performed when the above-mentioned nodes 2 and 3 received the route request message at the beginning.

If the node itself has the next hop for destination 6, it sends a route response message to node 1 (data transmission node) 1, just like node 2. The path response message sent from the node 5 is transmitted to the source node (data transmission node) 1 through the node 3 (FIG. 3, c 1). In this case, the node 3 receives the route response message, calculates the reception sensitivity when the node itself receives the route response message to the neighbor node 5, calculates the routing cost, adds the value to the routing cost value in the route response message And sends a path response message to Node # 1 again (FIG. 3, d).

Node 1 receives the path response message, detects that it is a response message of the path request message sent by itself, calculates the reception sensitivity when receiving the path response message, calculates the routing cost, The final routing cost value is calculated in addition to the routing cost value. Then, it compares with the final routing cost value of the route response message which comes in the first time from 2 times. If the routing cost is lower than its own value, the next hop for destination 6 is updated to node 3. If the routing cost is higher than its own value, this path response message is discarded.

[Step 3]

On the other hand, if node 5 receives the route request message from node 3 and does not have the next hop for node 6, it broadcasts a route request message as node 3 did. (Fig. 4, c1, c2).

At this time, nodes 2, 3, 4 and 6 receive the route request message. In this case, nodes 2, 3, 4, and 6 will perform their respective operations.

Node 2 is discarded because it is identical to the path request message it originally received. Node 3 is discarded because it is a route request message that it has received and sent itself again. Node 4 is also discarded because it is identical to the broadcast message it wants to process. On the other hand, the node 6 processes the route request message because it is the first received route request message. It can detect that the destination included in the route request message is itself and therefore searches for the route to itself.

[Step 4]

At this time, node 6 generates a path response message and sends a path response message to node 1, which firstly sends the path request message. The order in which the route response message is sent is transmitted through the node # 5 to the node # 3 and the node # 1 (FIG. 4, d, e, f). Node # 3 and Node # 1 receive the route request message and know the next hop for node # 1. Therefore, it is possible to transmit the route response message to the source node (data transmission node) # 1. Nodes 5 and 3 calculate the reception sensitivity obtained when the node itself receives the path response message when transmitting the path response message, calculate the routing cost value, and add the value to the path response message to be cumulatively transmitted.

Node # 1 that received the route response message confirms that it is the response message of the route request message sent by itself and processes the message. Calculates the reception sensitivity when receiving the path response message, calculates the routing cost, and adds the value to the routing cost value in the path response message to calculate the final routing cost value. Node 1 compares with the next hop for destination 1 that it has already own. In this case, the route is updated if the routing cost is lower than the routing cost of the next hop. If it is higher than the routing cost of the next hop, it discards the route response message. In this way, node 1 can set the path to destination 6.

[Step 5]

As shown in FIG. 3, when node 1 receives the path response message through node 2 for the first time, and assumes that it has received the node through node 3 after a while, node 1 compares the two path response messages . If the routing cost received from node 2 is low, the next hop for destination 6 becomes node 2. The source node (data transmission node) # 1 always sends data to destination # 6 when it sends data to destination # 6. At this time, the node 2 searches again the route information table it owns, and transmits the data to the node 5 if the next hop to the destination 6 is the node 5. In addition, node 5 transmits data to node 6 if the next hop for destination 6 is 6 times. With this procedure, the data will reach destination number 6 in the order of 1, 2, 5, 6.

FIG. 5 shows how a source node (data transmission node) that has established a path through the present invention transmits data to be actually transmitted to a destination via a certain path. Here, the assumption is made that the source node (data transmission node) is once and the destination is six times.

As shown in Fig. 3, the path establishment method is a -> b1, b2 -> c1, c2 -> d -> e -> f.

As described above, the present invention is an effective way to reduce a large amount of data in an ad-hoc network, and is a key to minimizing a broadcast message.

Advantages obtained by the present invention are as follows. First, unnecessary processing procedures of nodes disappear, a message caused by simultaneous broadcast messages is prevented from being lost, an optimal path can be established by receiving a plurality of path response messages There is purpose in there. In an ad-hoc network where a large number of messages are transmitted and received, there is a disadvantage that broadcast messages can affect other operations. Therefore, the present invention is suitable for forming a stable ad-hoc network by applying a simple and easy path establishment method.

It will be apparent to those skilled in the art that many other modifications and applications are possible within the scope of the basic technical idea of the present invention.

Claims (7)

In order to prevent the delay of establishing the path by waiting for the source node to wait in case the path response message transmitted by the destination node is lost, data is transmitted from the source node to the destination node in the ad- A method for establishing a path for establishing a path,
(A) broadcasting the route request message if the source node does not have the route of the destination node;
When the destination of the message is not itself, the neighboring nodes that have received the broadcast message transmit the path response message to the source node in a unicast manner if the node itself has a route to the destination, (B) broadcasting the received broadcast message back to the neighboring nodes if it does not have the path for the neighboring nodes;
(C) transmitting a route response message to a source node side in a unicast manner when a destination is itself among neighboring nodes that have received the broadcast message; And
(D) determining a route to a destination node by selecting a value having a lowest routing cost from a plurality of received route response messages,
In the step (b)
The neighbor node receiving the broadcast message searches the route information table of its own if the destination is not itself, and when the neighbor node has the route to the destination, it loads the routing cost value for the destination node into the route response message, Unicast method,
The routing cost value is a value obtained by checking the reception sensitivity of the node when the route request message or the route response message is received. The higher the reception sensitivity, the smaller the routing cost value.
The source node calculates a routing cost value by calculating a reception sensitivity at the time of receiving the route response message, calculates a final routing cost value by adding a routing cost value in the route response message to the calculated routing cost value,
In the step (d)
The source node receives a route response message from one or more neighbor nodes, receives a route response message from a destination node, determines a path to a destination node by selecting a value with the lowest routing cost from among a plurality of route response messages,
When the source node receives one or more route response messages from neighboring nodes other than the destination node, it waits until it receives a route response message from the destination node, and if a route response message is received at the destination node, The lowest value is selected by comparing,
If a route response message is not received from the destination node until the waiting time set in the source node is exceeded, a path with the lowest routing cost is selected from among the route response messages received from one or more neighboring nodes to determine a route to the destination node The storage unit of the source node sets a waiting time to wait until receiving the path response message after transmitting the path request message. delete delete delete delete delete delete

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