KR100551634B1 - SYSTEM AND METHOD FOR CONTROLLING HELLO MESSAGE'S TIME TO LIVE OF Mobile Ad-hoc NETWORK - Google Patents

Abstract

The present invention relates to a routing message lifetime control method of a mobile Ad-hoc network.

Routing message life time control method of mobile Ad-hoc network, when receiving hello message periodically from intermediate node, analyzes hello message that is input during life time and periodically increases the lifetime to appropriately. By increasing the packet interval and reducing unnecessary RREQ (Route Request) transmissions, unnecessary overhead of the network can be avoided.If the intermediate node does not receive hello messages periodically, it can reduce the life time to quickly send RERR packets to the source node. Transmission can be suppressed from sending excessive RREQ and RERR packets to improve the overall performance of the routing protocol.

Mobile Ad-hoc Network, Routing Protocol, RREQ Packet, RRER Packet, Hello Message, Lifetime

Description

How to control the routing message life time of mobile AD-ｈｏｃ network {SYSTEM AND METHOD FOR CONTROLLING HELLO MESSAGE'S TIME TO LIVE OF Mobile Ad-hoc NETWORK}

1 is a flowchart illustrating a generation process of an RREQ packet of an AODV routing protocol of a mobile Ad-hoc network.

2 is a flowchart illustrating a process of generating an RREP packet of an AODV routing protocol of a mobile Ad-hoc network.

3 is a flowchart illustrating a routing message lifetime control method of a mobile Ad-hoc network according to an embodiment of the present invention.

The present invention relates to a routing message lifetime control method of a mobile Ad-hoc network, and more particularly, to a routing message lifetime control method of a mobile Ad-hoc network for increasing or decreasing a lifetime waiting for a hello message in a routing protocol. will be.

Ad-hoc On-Demand Distance Vector (AODV) routing protocol, a representative routing protocol of Mobile Ad-hoc Network (MANET), was proposed by C. Perkins of Nokia Research Center in 1999. .

Routing protocols in mobile ad-hoc networks are intended to provide a means of communication between computers over the air, such as Dynamic Destination-Sectioned Distance Vector (DSDV), Dynamic Source Routing (DSR), and Ad-Hoc On Demand Distance Vector. ) And TORA.

AODV routing protocol is basically a protocol that combines and solves the advantages of DSDV (Destination-Sequenced Distance-Vector) and DSR (Dynamic Source Routing) of request driving algorithm.

However, in the AODV routing protocol, the lifetime of the node has a minimum lifetime of ALLOWED_HELLO_LOSS * HELLO_INTERVAL, which has a value of 3000 ms. There is a problem that can not cope actively, and can produce inefficient results.

The technical problem to be achieved by the present invention is routing of a mobile Ad-hoc network to reduce the number of RERR packets and RREQ packets by changing the lifetime value waiting for a HELLO message informing its existence between each node. It is to provide a message lifetime control method.

In order to solve this problem, the present invention adjusts the amount of RREQ packet and RRER packet transmission by increasing or decreasing the lifetime waiting for a hello message in a routing protocol.

The routing message life time control method of a mobile Ad-hoc network according to an aspect of the present invention is a routing message life time control method of a mobile Ad-hoc network providing a communication path between a source node, an intermediate node, and a destination node. A) establishing, by the source node, a valid path to the destination node and transmitting data to the destination node; B) HELLO periodically during the lifetime generated by the intermediate node during the data transmission in step A) by a specific variable (a), hello message loss value (Allowed_Hello_Loss) and hello message generation period (Hello_INTERVAL). Checking whether a message has been received; And C) the source node if the B) if received the Hello message periodically in phase, the life time and increase contribute early summer to the particular variable (a) value, that is the Hello message is received periodically Sending a ROUTER ERROR (RRER) message to reduce the life time based on the value of the particular variable (a).

In the step C), when the intermediate node periodically receives the hello message, a hello message checker (HELLO_Msg_Checker) variable for checking the amount of the hello message is provided and the variable (a) according to the ratio of the hello message checker. It is desirable to increase the value).

In the step C), when the intermediate node does not receive the hello message periodically, it is preferable to set the variable value to a minimum value and multiply the life time in order to reduce the life time.

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. Like parts are designated by like reference numerals throughout the specification.

First, the AODV routing protocol of the mobile Ad-hoc network will be described with reference to FIGS. 1 and 2.

1 is a flowchart illustrating a generation process of an RREQ packet of an AODV routing protocol of a mobile Ad-hoc network.

As shown in FIG. 1, when data to be transmitted is generated, the AODV routing protocol searches for route information managed in its own routing table (S11).

As a result of the search of the routing table, it is checked whether the data to be transmitted has a path to the corresponding destination node (S12).

If a path exists for the data to be transmitted, it is examined whether the life time of the destination node of the data is completed (S13). If the life time is not completed, it is determined that the path information of the data is valid, and the procedure is separately obtained for obtaining the path. The data is transmitted through the corresponding path without expanding (S14).

However, when a path exists for data but the life time of the path information is completed, a procedure of acquiring path information of the corresponding destination node must be separately performed. In addition, a new route acquisition procedure must be performed even without route information of the corresponding destination node. (S15)

That is, the source node generates a Route Request (RREQ) message and performs the following procedure before broadcasting to neighboring nodes through floating.

First, the source node selects Type as 1 in the RREQ packet and changes the hop count to 0. The broadcast ID increments 1 by the current broadcast ID.

The destination IP address and the source IP address are the IP addresses of the destination node and the source node. The destination sequence number uses the destination sequence number of the corresponding destination node stored in the current routing table, which is the latest destination sequence number of the corresponding destination node, without change. The source sequence number is used by incrementing 1 to the source sequence number last used by the current source node (Source Sequence Number +1).

The determined RREQ packet is carried in the IP header, and at this time, the time-to-live (TTL) and the IP address of the transmitting node are also included in the IP header and transmitted to the destination node (S16).

AODV routing protocol basically manages routing packets as UDP packets. The routing packet does not need a separate reply and receives a RREP (Router Response) and treats it as a reply.

The routing packet does not use a separate reply packet because a mobile Ad-hoc network using a limited resource can seriously affect performance when using a separate reply packet.

The receiving node receiving the RREQ packet above searches for an IP header. The receiving node can know which node has transmitted or relayed the RREQ packet through the IP header.

At this time, the TTL contained in the IP header is searched to determine whether to transmit the RREQ. That is, if TTL is 0, it is discarded. If TTL is not 0, the RREQ packet is searched to determine whether the packet is a duplicate packet through the source IP address and the broadcast ID.

In the case of receiving a packet having the same source IP address and broadcast ID during the last broadcast recording time (Broadcast_Record_Time), since the currently received RREQ packet is the same packet, the receiving node discards the currently received RREQ packet.

However, if any of the source IP address and the broadcast ID of the RREQ packet is different, it is determined that the receiving node is different from the RREQ packet previously received.

The receiving node determines whether the destination node is the corresponding destination node through the next destination IP address information, and then searches for a valid route to the destination node in the routing table if the destination node is not the corresponding destination node.

As a result of searching for a valid path at the receiving node, a path exists to the corresponding destination, but if the destination sequence number of the path is larger than the destination sequence number of the RREQ packet, the corresponding path information cannot be valid path information. However, if the destination sequence number of the route in the routing table is larger than the destination sequence number of the RREQ packet, the route information in the routing table is valid route information.

The path information is used to determine whether the RREQ packet is valid for the corresponding path, and finally, whether the RREP packet is generated and whether the RREQ packet is relayed to the neighbor node is determined.

In the above, when the route information is valid, the receiving node receiving the RREQ packet no longer relays the packet, but generates a RREP packet and transmits it to the source node. However, if the route information is not valid, the receiving node selects its IP address in the IP header, decreases the TTL by one, increases the value in the hop count of the RREQ by one, and forwards the packet to the neighbor node.

At this time, the source sequence number of the RREQ packet is compared with the destination sequence number of the route information about the source node maintained in the routing table. If the source sequence number of the RREQ is greater than the destination sequence number in the routing table, the route of the routing table is older than the route generated by the received RREQ packet. Therefore, the route information of the source node is modified in the routing table. The source sequence number of the RREQ packet is copied to the routing sequence's destination sequence number in the routing table, and the process list must be modified.

2 is a flowchart illustrating a generation process of an RREP packet of an AODV routing protocol of a mobile Ad-hoc network.

As shown in Fig. 2, the RREP packet is generated by the following two conditions in the AODV routing protocol. The first is when the destination IP address of the RREQ packet is the IP address of the receiving node. The second is a RREP packet when there are enough valid paths to the destination node of the destination IP address in the routing table of the receiving node that received the RREQ packet. Create and send to the source node.

After receiving the RREQ packet, the receiving node checks whether the same RREQ packet is received, and then checks whether it is the destination node (S21).

If the receiving node is the destination node, the RREQ packet is no longer relayed and RREP is generated and transmitted to the source node (S22, S23, S24). However, although the receiving node is not the destination node, there is a valid path to the destination node in the routing table. If it is (S25), the RREP packet is generated using this route information and transmitted to the source node. (S26 to S30).

The generation procedure of the RREP packet is slightly different at the destination node and the intermediate node. The destination node stores the value of 1 in the last sequence number of the destination sequence number maintained by the node in the destination sequence number space in the RREP packet. The lifetime value of the RREP packet is copied to the value MY_ROUTE_TIMEOUT (= 2 * ACTIVE_ROUTE_TIMEOUT (3000ms)) maintained by each node.

The procedure for generating an RREP packet in a node having a valid path to a destination node is as follows.

Copies the destination sequence number of the destination to the destination sequence number space in the RREP packet. The hop count value in the RREP packet is obtained by adding the hop count from the current node to the current node plus the hop count from the source node to the current node obtained through the RREQ.

The lifetime value is obtained by subtracting the current time from the expiration of the path to the destination of the routing table. In this case, reducing the current time in the lifetime may use the current time in the case of storing the lifetime itself in the routing table, thereby reducing the current time and deleting the used time.

When generating the RREP packet in the intermediate node, it informs the destination node that the RREP packet is generated to solve the problem of performance degradation due to the characteristics of TCP. For this purpose, the intermediate node that generated the RREP packet delivers Gratuitous RREP to the destination node.

Select the "G" flag for the RREQ packet, the hop count uses the received RREQ packet, and the destination IP address uses the IP address that generated the RREQ packet.

The destination sequence number is created using the source sequence number of the received RREQ, and the source IP address uses the IP address of the destination node.

The RREP (RREQ) packet is unicast to the destination node. (S30) When the RREP packet is received at the node between the source node and the destination node (or even the intermediate node) that received the RREP packet, each node is collected. The route information is updated in the own routing table using the generated route information.

The receiving node receiving the RREP packet first compares the destination sequence number of its own destination node. If the destination sequence number is large in the RREP packet, the route information is corrected because it is more recent than the currently held route information.

If the destination sequence number is the same, the route information may not be valid. If the hop count value is different, the route information may be new. When delivering RREP packets, the hop count value is increased by one.

When route information is modified in the routing table, the lifetime is the current time plus the lifetime of the RREP packet.

Looking at the path management by the Router Error (RRER) packet, when the AODV routing protocol first joins the network, it periodically announces its presence to neighboring nodes using a hello message.

The interval for generating the hello message is HELLO_INTERVAL (= 1000 ms). At this time, TTL is set to 1 in the IP header so that the HELL0 message is not transmitted except the neighbor node.

If the hello message is not received during ALLOWED_HELLO_LOSS * HELLO_ INTERVAL, it is determined that the connection with the node is impossible.

The corresponding value is 3000ms multiplied by the value 3 of ALLOWED_HELLO_LOSS and the value 1000ms of HELLO_INTERVAL. In this case, a RERR packet is generated to convey to the relevant node whether the link is in use.

Nodes that transmit data by managing paths through the above procedure do not have to repeat unnecessary path acquisition procedures.

In the embodiment of the present invention, as shown in Equation 1 below, the basic life time value ALLOWED_HELLO_LOSS is multiplied by HELLO_INTERVAL, and the multiplied value is multiplied by the variable a.

수명시간 =

Life time =

In Equation 1, the value of the variable a is 1 so that the life time maintains the basic minimum value.

3 is a flowchart illustrating a routing message lifetime control method of a mobile Ad-hoc network according to an embodiment of the present invention.

As shown in FIG. 3, in the method of controlling a routing message life time of a mobile Ad-hoc network according to an embodiment of the present invention, a source node may perform a path discovery process while several nodes communicating with an AODV routing protocol operate. After setting the path to the destination node, send the data to the destination node.

At this time, in a situation in which the destination node and the intermediate node are out of the communication reach range of the neighboring nodes or stop operation, the intermediate node periodically checks whether or not the hello message is received during the life time (S101).

When the hello message is received for the lifetime, the hello message checker (HELLO_Msg_checker) increases the check for the hello message (S102). Record in hours.

At this time, the magnitude of the increase amount of the hello message checker becomes a difference between the value previously recorded and the newly recorded value.

In the above Equation 1, the value of variable a is increased to multiply the value of the variable increased in life time to increase the life time.

At this time, in order to prevent the variable a value from being greater than a predetermined level and increasing the life time, the variable a value is periodically checked so that it does not become larger than the maximum value MAX extracted through simulation.

In order to prevent the life time from becoming too large, the increment value for the variable value to be multiplied by the lifetime is set to a real number less than 0, and the variable value to be multiplied by the lifetime is the minimum value of 1 plus the increase amount. If there is an existing specific value, it is a value obtained by adding an increment amount to a specific value. The lifetime value is increased by multiplying the variable value by the increase in the lifetime.

If the variable a value is less than or equal to the maximum value, the lifetime value is maintained by setting the variable a value to the maximum value. If the variable a value is greater than or equal to the maximum value, the lifetime value is set to an arbitrary maximum value so that the lifetime is not further increased. S104, S105)

In this case, the variable value that is multiplied by the life time less than the set maximum value is simulated by changing the source, recompiling by setting the maximum value to the AODV module source of any network simulator that has an open source structure. The result obtained is compared and analyzed, and the value judged to be the most appropriate value.

When the hello message is not received at the neighboring node for the lifetime, the variable a value is set to 1 to reduce the lifetime to the original minimum value (S106).

In this case, the reduction amount for the variable value multiplied by the lifetime is set to a real number less than 0, and the variable value to be multiplied by the lifetime value is the minimum value 1 plus the reduction amount. It is the sum of the reductions.

Subsequently, the lifetime value is decreased by decreasing the value of variable a (S107). If the value of variable a is greater than the minimum value, the RERR packet is immediately transmitted to the source node. If the value of variable a is not greater than the minimum value, the value of a is set to the minimum value of the RERR packet. Is transmitted to the source node (S108, S109, S110).

In other words, in order to prevent the life time from being less than or equal to the minimum value, the life time is maintained if the variable value is greater than or equal to the minimum value, but if the variable value is less than the minimum value, the life time is set to the minimum value so that the life time is not further reduced. Set to.

At this time, the variable value multiplied by the life time with the set minimum value can be obtained by simulating after recompiling by changing the source by setting various minimum values for the AODV module source of any network simulator having an open source structure. After comparing and analyzing the results, set the value to be the most appropriate value.

If you repeat the above operation periodically, the value of variable a keeps changing, so you can change its lifetime accordingly.

In this way, the AODV routing protocol changes the lifetime value for waiting for a hello message accordingly, so that a RREQ packet and a node used to acquire a route when the route to the corresponding destination node does not exist or are invalid. The transmission of RERR (Route Error) packet, which informs the relevant mobile terminal of the route information, can be controlled to prevent the use of the route because the communication becomes impossible due to the movement of the mobile terminal or the failure of the mobile terminal. have.

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

As described above, in the method of controlling a routing message life time of a mobile Ad-hoc network according to the present invention, if a hello message is periodically received, the hello message inputted during the life time is analyzed and the lifetime is appropriately periodically increased to appropriately increase the RERR packet interval. By reducing the number of unnecessary RREQ packets and reducing unnecessary overhead of the network, it is possible to improve the efficiency of the entire network.

In addition, the routing message life time control method of the mobile Ad-hoc network according to the present invention can reduce the life time and transmit the RERR packet quickly to the source node if the hello message is not periodically received, thereby improving performance as well as reliability. There is an effect that can be increased.

Thus, the routing message life time control method of the mobile Ad-hoc network according to the present invention has the effect of suppressing excessive RREQ and RERR packets to improve the overall performance of the protocol.

Claims (10)

A method for controlling routing message life time of a mobile Ad-hoc network providing a communication path between a source node, an intermediate node, and a destination node, A) the source node establishing a valid path to the destination node and transmitting data to the destination node; B) HELLO periodically during the lifetime generated by the intermediate node during the data transmission in step A) by a specific variable (a), hello message loss value (Allowed_Hello_Loss) and hello message generation period (Hello_INTERVAL). Checking whether a message has been received; And C) if the hello message is periodically received in step B), increase the life time based on the value of the specific variable (a), and if the hello message is not received periodically, route to the source node Sending an ROUTER ERROR (RRER) message to reduce the life time based on the value of the particular variable (a) Routing message life time control method of a mobile Ad-hoc network comprising a. The method of claim 1, Step C) is The life time is adjusted by increasing or decreasing the value of the variable (a), and the life time is calculated by multiplying the hello message loss value (Allowed_Hello_Loss), hello message generation period (Hello_INTERVAL) and the variable (a) value. Routing message life time control method of a mobile Ad-hoc network characterized in that it is adjusted. The method of claim 2, The variable value is The routing message life time control method of the mobile Ad-hoc network in which the maximum value is set in advance to prevent the life time from exceeding the predetermined maximum value. The method of claim 2, Step C) is In the case where the intermediate node periodically receives the hello message, a hello message checker (HELLO_Msg_Checker) variable is provided to check the amount of the hello message, so that the value of the variable (a) increases according to the ratio of the hello message checker. A method for controlling routing message lifetime in ad-hoc networks. The method of claim 4, wherein The hello message checker, The routing message life time control method of the mobile ad-hoc network to record the number of hello messages in units of time. The method of claim 4, wherein The variable (a) value is, A method for controlling routing message life time of a mobile Ad-hoc network in which an increase amount of the life time is set to a real number less than 0, the increase value is added to the variable value, and the added value is multiplied by the life time. . The method of claim 4, wherein The variable value is In order to prevent the life time from exceeding a predetermined maximum value, a maximum value is set in advance, and if the variable value is less than or equal to the maximum value, the life time is maintained, and if the variable value is greater than or equal to the maximum value, the increase in the life time is suppressed. A method for controlling routing message life time of mobile Ad-hoc networks. The method of claim 2, Step C) is If the intermediate node does not receive the hello message periodically, the routing message lifetime control method of a mobile Ad-hoc network to multiply the lifetime by setting the variable value to the minimum value to reduce the lifetime. The method of claim 8, The variable value is The reduction amount for the lifetime is set to a real number less than 0, the minimum value is added to a current variable value, and then the sum is multiplied by the lifetime to control the routing message life time of the mobile Ad-hoc network. The method of claim 8, The variable value is In order to prevent the life time from becoming below a predetermined minimum value, a minimum value is set in advance, and if the variable value is greater than or equal to the minimum value, the life time is maintained, and if the variable value is less than or equal to the minimum value, the moving Ad- How to control routing message lifetime in hoc network.

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