KR100584088B1 - Method for route searching of ad hoc network - Google Patents

Abstract

The present invention relates to a route search method in an ad hoc network.

The route search method in an ad hoc network stores an address of an internet node which frequently communicates with a node of an ad hoc network in a cache form at an internet gateway, and the internet gateway routes from a source node to a destination node. Receiving a Root Request (RREQ) message for discovery determines whether the destination node is located on the Internet based on the cache information it has and sends a Route Response (RREP) message to the source node according to the result of the determination. Can determine the location of the destination node according to the type of the route response (RREP) message received from the destination node or the Internet gateway.

This allows the source node to locate the destination node as quickly as possible, minimizing route traversal delays and control message overhead for external Internet nodes, thereby maximizing network performance and minimizing packet loss. .

Ad Hoc Network, Internet Gateway, Cache Information, Source Node, Destination Node, Internet Node

Description

Route search in ad hoc network {METHOD FOR ROUTE SEARCHING OF AD HOC NETWORK}

1 illustrates a structure of an ad hoc network interworking with a wired internet applied to the present invention.

FIG. 2 illustrates a request-based route search procedure for the Ad Hoc node of FIG. 1.

3 is a flowchart illustrating a route searching method in a temporary network according to a first embodiment of the present invention.

4 is a flowchart illustrating a route searching method in a temporary network according to a second embodiment of the present invention.

The present invention relates to a route search method in a temporary network for request-based route searching on a network in which the temporary network is interworked with the wired internet through an internet gateway.

An ad hoc network is an ad hoc network that is autonomously configured between nodes without the aid of an underlying network device such as a base station. Since Ad Hoc nodes communicate with each other using a radio interface, there is a limitation in transmission distance. Therefore, for communication between remote Ad Hoc nodes, a multi-hop communication method using intermediate nodes is used.

Therefore, Ad Hoc nodes include routing functions in addition to basic host functions.

The ad hoc network may exist completely independent of other existing networks, or may exist in the form of interworking with the existing wired network.

In order for an ad hoc network to interwork with a wired internet, at least one internet-gateway serving as a gateway to the wired internet must exist. The internet-gateway is a node belonging to both the ad hoc network and the wired internet, and performs the function of routing the packet between the ad hoc node and the internet node.

When the destination node exists in the external Internet, the Ad Hoc node forwards the data packet to the Internet-gateway, and the Internet-gateway forwards the data packet to the destination node by Internet routing.

To this end, it is first necessary to determine whether the destination node of the data packet exists inside the Ad Hoc network or outside the Ad Hoc network, that is, on the Internet. Such determination of the position of the target node and obtaining route information to the target node are performed by a route search procedure.

The prior art on-demand route search method broadcasts a Route Request (RREQ) message throughout the network to obtain the location of the target node and route information to the target node. After receiving the Route Reply message (RREP) before the route search timer expires, it is determined that the destination node exists in the Ad Hoc network.

On the other hand, if the route search fails because the RREP message is not received before the route search timer expires, the target node is determined to exist on the external Internet.

However, in this request-based route search method, if the destination node exists outside of the ad hoc network, i.e., if it is an external Internet node, the source node can locate the destination node only after the root search fails due to the expiration of the root search timer. You can judge. As a result, the request-based route search method causes a problem of control message overhead due to a large route search delay and an RREQ message broadcasted throughout the network.

In addition, most request-based route search methods retry the specified number of route searches if the first route search fails to improve the route search success rate. The problem becomes even worse.

As described above, the request-based route search method according to the related art has a problem in that the performance of the entire network is degraded due to the problem of route search delay or control message overhead, and the loss of data packets increases, which seriously affects stable communication.

 An object of the present invention is to provide a route discovery method in an ad hoc network to minimize route discovery delay and control message overhead for an external internet node in an ad hoc network interworking with a wired network.

In order to solve this problem, the present invention stores an address of an Internet node frequently communicated with a node of a temporary network in a cache form in an Internet gateway that interworks the temporary network with a wired Internet.

A route searching method in an ad hoc network according to a first aspect of the present invention is a route searching method in an ad hoc network in which an ad hoc network node communicates with an internet node located in a wired internet via an internet gateway, Managing, at the internet gateway, an address of an internet node frequently communicating with a node in the temporary network in a cache; B) When a route request (RREQ) message is broadcast from a source node in a temporary network to a destination node, the Internet gateway receives the route request (RREQ) message and sends the message in its cache information. Generating a route response (RREP) message according to whether an address of a destination node exists and unicasting to the source node; C) the source node receiving the RREP message of step B) determines whether the destination node is located on the wired Internet according to the type of the RREP message and whether or not the route search time is terminated; And in the step C), when the source node determines that the destination node is located on the wired internet, forwarding a data packet to the destination node through the internet gateway.

In step A), the address of the destination node included in the data packet routed from the temporary network to the wired network at the Internet gateway, and the address of the source node included in the packet routed from the wired network to the temporary network are cached. It is desirable to store and manage.

The step B) includes: i) the internet gateway receiving the RREQ message and checking whether an address of a destination node included in the RREQ message is stored in its cache; Ii) if the check result of step iii) is YES, unicasting a Deterministic Proxy (DP) -RREP message containing the address of the Internet gateway to the source node; And iii) if the check result of step iii) is no, unicasts a Non-Deterministic Proxy (NDP) -RREP message including the address of the Internet gateway to the source node, and sends the RREQ message to a neighbor node. It is preferable to include the step of broadcasting to.

In step C), if the source node receives the DP-RREP message before the route search time expires, stop the route search time and route information to the Internet gateway included in the DP-RREP message. Recording in the root table; And ii) when the step iii) is completed, determining the destination node as a node of an external wired network, and forwarding a data packet through a route to the internet gateway.

Step C) includes: i) recording the route information to the Internet gateway included in the NDP-RREP message in a route table when the source node receives the NDP-RREP message; And ii) determining that the destination node is a node of an external wired network when the source node has not received an RREP message other than an NDP-RREP message before the route search time expires when the step iii) is completed. ; And iii) forwarding the data packet through the route to the internet gateway according to the determination result of step ii).

The step C) includes: i) when the source node receives the RREP message before the route search time expires, ending the route search time and recording route information to the destination node in a route table; And ii) when the step iii) is completed, the source node determines the destination node as a node of the temporary network, and forwards the data packet through a route to the corresponding destination node.

DETAILED DESCRIPTION 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.

1 illustrates a structure of an ad hoc network interworking with a wired internet applied to the present invention.

As shown in FIG. 1, an Ad Hoc network 100 interworking with a wired Internet is autonomously constructed from multiple Ad Hoc nodes, such as Node-A, Node-B, and Node-C, each Ad-Hoc The nodes communicate with each other using the air interface 101.

Direct communication is possible between nodes located within each other's radio transmission area, such as Node-A and Node-B, that is, located at 1-hop radio transmission distance, and located outside the radio transmission area of each other, such as Node-A and Node-C. That is, nodes located at a radio transmission distance of two or more hops communicate with each other by a routing function of an intermediate node located between two nodes, such as Node-B.

In order for an Ad Hoc node to communicate with an Internet node located in the wired Internet 110, at least one Internet-gateway node 103 must exist within the Ad Hoc network. The Internet-gateway node 103 has a wired interface 105 for communication with the wired Internet in addition to the air interface 101 for communication with the Ad Hoc node, thus serving as a gateway between the Ad Hoc network and the wired Internet. do.

Therefore, data packets between Ad Hoc nodes and the Internet are always delivered to each other through the Internet gateway.

FIG. 2 illustrates a request-based route search procedure for the Ad Hoc node of FIG. 1.

As shown in FIG. 2, the request-based route search procedure for an Ad-Hoc node requires a source node S to transmit a data packet, but does not receive route information for a destination node D. If not in the root table, the source node S generates an RREQ message 1, broadcasts it to its neighbors, and starts the root search timer.

When the intermediate node I receives the RREQ message, it records the route information to the source node in its root table, and then broadcasts the received RREQ message to its neighbor node again.

When the destination node (D) receives the RREQ message, it writes the route information to the source node in its own root table, and then unicasts a Route Reply (RREP) message to the source node (4), When the intermediate node I receives the RREP message, it records the route information to the destination node in its own root table and then unicasts the received RREP message to the source node (5).

If the source node receives the RREP message before the root search timer expires, it stops the root search timer after writing the route information to the destination node in its root table. The target node determines that the target node exists in the ad hoc network, and transmits the data packet to the target node through the route to the discovered target node (6).

Based on the structure of the Ad-Hoc network interworking with the above-described wired Internet, a route search method and in a temporary network according to an embodiment of the present invention will be described in detail.

3 is a flowchart illustrating a route searching method in a temporary network according to a first embodiment of the present invention.

As shown in FIG. 3, in the procedure for the route search method in the temporary network according to the first embodiment of the present invention, first, route information about the destination node D to which the source node S intends to transmit a data packet. Suppose you don't have a in the root table, and the Internet gateway stores the address of the destination node in the cache.

The source node S generates and broadcasts an RREQ message to the neighbor node (11) and starts the route search timer (12).

When the intermediate node (I) located between the source node (S) and the destination node (D) receives the RREQ message, it writes the route information to the source node (S) in its own root table and writes the RREQ message received from the source node. Broadcast to its neighbor node (13).

When the Internet gateway 105 receives the RREQ message, it records the route information to the source node in its root table, and then searches its cache to see if the address of the destination node exists in the cache.

If the destination node's address is in the cache, the Internet gateway 105 generates a Deterministic Proxy-RREP (DP-RREP) message (hereinafter also referred to as a first reply message) containing its address and unicasts it to the source node. (14).

At this time, when the intermediate node I receives the DP-RREP message, it records the route information to the Internet-gateway in its own route table and unicasts the DP-RREP message received from the Internet gateway 105 to the source node. (15).

When the source node receives the DP-RREP message, it logs the route information to the Internet-gateway in its route table and stops the route search timer. The source node S determines that the destination node exists in the external Internet and delivers the data packet to the Internet gateway through the route to the Internet gateway, and the Internet gateway delivers the data packet to the destination node by Internet routing. (16)

4 is a flowchart illustrating a route searching method in a temporary network according to a second embodiment of the present invention.

As shown in FIG. 4, the procedure for the route search method in the temporary network according to the second embodiment of the present invention is first a route to the destination node D to which the source node S intends to transmit data packets. Suppose you do not have information in the root table, and the address of the destination node is not stored in the cache of the Internet gateway.

In this case, the source node S generates an RREQ message, broadcasts it to the neighbor node, and starts the route search timer (21, 22). When the intermediate node I receives the RREQ message, the intermediate node I records the route information to the source node in its own root table, and then broadcasts the received RREQ message to its neighbor node (23).

When the Internet-gateway 105 receives the RREQ message, it searches its cache and, if the destination node's address does not exist in the cache, a Non-Deterministic Proxy-RREP (NDP-RREP) message containing its own address (hereinafter referred to as the second). Generate a response message, and unicast to the source node (24), and broadcast the RREQ message to its neighbor node (J) (25).

When the intermediate node receives the NDP-RREP message, the intermediate node records its route information to the Internet-gateway in its route table and unicasts the NDP-RREP message to the source node (26).

When the source node receives the NDP-RREP message, it records the route information to the Internet-gateway in its route table. If the source node does not receive the RREP or DP-RREP message until the route discovery timer expires, the source node determines that the destination node exists in the external Internet, and transmits the data packet through the route to the Internet gateway. Forwarding to the gateway, the Internet gateway forwards the data packet to the destination node by Internet routing (27).

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, the route search method in the temporary network according to the present invention can maximize network performance by minimizing route search delay and control message overhead for external Internet nodes in the temporary network interworking with the wired Internet, This has the effect of minimizing losses.

Claims (6)

In a route search method in an ad hoc network in which an ad hoc network communicates with an internet node located in a wired internet through an internet gateway, A) managing, by the Internet gateway, a node address in the temporary network and an address of an Internet node outside the temporary network in communication with a node in the temporary network, respectively in the form of a root table and a cash; B) When a route request message is broadcast from a source node in the temporary network to a destination node, the Internet gateway receives the route request message and the presence of the address of the destination node in its cache information. Generating a first route response message or a second route response message and unicasting to the source node depending on whether C) the source node receiving the route response message of step B) determines whether the target node is located on the wired Internet according to the type of the route response message or whether the route search timer is terminated; And D) when the source node determines that the destination node is located on a wired Internet in step C), forwarding a data packet to the destination node through the Internet gateway. Route discovery method in a temporary network comprising a. The method of claim 1, Step A) is Cache the address of the destination node included in the data packet routed from the temporary network to the wired network through the temporary network routing protocol, and the address of the source node included in the packet routed from the wired network to the temporary network. Route discovery in ad hoc networks that are stored and managed by a server. The method of claim 1, Step B) is Iii) the internet gateway receiving the route request message and confirming that the address of the destination node included in the route request message is stored in its cache; Ii) if a destination node address is stored in a cache, unicast a Deterministic Proxy (DP) -Root Response (RREP) message to the source node as a first response message containing the address of the Internet gateway; And Iii) if a destination node address is not stored in the cache, a Non-Deterministic Proxy (NDP) -Root Response (RREP) message is unicast to the source node as a second response message containing the address of the Internet gateway, and the root Broadcasting request message to neighboring node Route discovery method in a temporary network comprising a. The method of claim 3, Step C) is Iii) if the source node receives the first response message before the route discovery timer expires, stopping the route discovery timer and recording route information of the Internet gateway included in the first response message in a route table. step; And Ii) when step iii) is completed, determining the destination node as a node of a wired network existing outside the temporary network, and forwarding a data packet through a route to the Internet gateway. Route discovery method in a temporary network comprising a. The method of claim 3, Step C) is Iii) when the source node receives the second response message, recording route information of the Internet gateway included in the second response message in a route table; And Ii) after the step iii), if the source node receives only the second response message until the root search timer expires, determining the destination node as a node of a wired network outside the temporary network; And Iii) the source node forwarding the data packet via the route to the internet gateway according to the determination result of step ii) Route discovery method in a temporary network comprising a. The method of claim 1, Step C) is Iii) if the source node receives the response message before the route search timer expires, ending the route search and recording route information to the destination node in a route table; And Ii) upon completion of step iii), the source node determines the destination node as a node of a temporary network and forwards the data packet via a route to the destination node. Route discovery method in a temporary network comprising a.

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