KR20090038984A - Method for searching gateway in multichannel hybrid ad-hoc network - Google Patents

Abstract

A method for searching gateway in multichannel hybrid ad-hoc network is provided to minimize a disconnection of a service and to increase efficiency for searching, even though the method is applied in a gateway using different channel. When a quality of communication with a gateway is decreased lower than a specific level, a setup timer is initiated(S200). A gateway request message is produced(S202). The generated gateway request-message as described above is broadcasted to an ad hoc node of each channel. When the setup timer is completed, a gateway advertisement request-message is generated(S210,S212). The generated gateway advertisement request-message as described above is broadcasted to the ad hoc node of each channel. A proxy gateway advertisement message including the gateway information obtained as described above is received from the ad hoc node of each channe(S216). A gateway of a channel with the smallest hop count is selected(S218). A connection with the gateway of the channel selected as described above is carried out. The address assignment and address duplication check are performed and a communication is performed(S218,S220).

Description

Gateway discovery in multichannel hybrid ad hoc network {Method for Searching Gateway in Multichannel Hybrid Ad-hoc Network}

The present invention relates to a gateway discovery method in an ad hoc network, and more particularly, to a gateway discovery method in a multichannel hybrid ad hoc network.

In general, a mobile communication system transmits and receives data between a mobile element and a base station. That is, the mobile station and the base station directly transmit and receive data without relaying other nodes. However, the ad hoc network may use another node when transferring data of the source node to the destination node.

Ad hoc networks are autonomous networks of mobile nodes. Since the ad hoc nodes are guaranteed mobility, the structure of the ad hoc network is very flexible. In the case of using an ad hoc network, communication between nodes is possible without the support of an existing mobile communication system, and there is an advantage that there is no distance limitation of communication with multi-hop support.

Unlike an infrastructure network, there are no routers that relay packets in and out of the ad hoc network, and each mobile node simultaneously acts as a host and a router. In an ad hoc network, the transmission range of radio waves of each node is limited, so that a packet cannot be directly transmitted from the source node to the destination node. In this case, the packet is delivered via a plurality of nodes serving as routers.

This scheme is called multihop, and the ad hoc network requires a routing protocol for implementing the multi-hop scheme.

As such, an ad hoc network is a network composed of ad hoc nodes that communicate in multiple hops without the aid of infrastructure.

Hybrid ad hoc network refers to a network structure in which ad hoc nodes connect to a backbone network through a gateway.

FIG. 1 is a diagram for explaining a process of setting a data transmission path to a gateway by a node constituting a hybrid ad hoc network.

The gateway request process (S10) is a process in which a node entering an ad hoc network requests a gateway location. Nodes need to know the location of the gateway to be able to send data to it. Thus, a node broadcasts a message containing information about its address and information requesting the gateway's address. The neighbor node receives the message from the node and broadcasts it again.

By sequentially performing this process, the message transmitted by the node is delivered to the gateway. The gateway uses the information contained in the forwarded message to recognize that the node requests a response.

The ad hoc network that performs the gateway request process performs a gateway response process (S20). The gateway response process (S20) is a process in which the gateway, which finally received the message transmitted by the node, transmits its address information to the node. Here, the address information includes the prefix information of the IP address or the IP address to be used in the node.

The gateway extracts the address information of the node from the message received in the gateway request process (S10). The gateway then sends a message containing its address information to the node with the extracted address information.

The nodes that receive the message sent by the gateway count the hops. That is, 1 is added to the number of hops included in the message received from the previous node and the sum of the hops is transmitted to the next node. The node requesting the location information of the gateway by performing the above process may know the location information of the gateway and the number of hops to the gateway.

If a gateway to transmit data is selected, the node transmits data using the established path (S30).

Conventional ad hoc node search method has a problem that can not be applied to the multi-channel hybrid ad hoc network is focused on the point to search the gateway of the same channel. Until now, the method of gateway discovery in single channel hybrid ad hoc network has been proposed, but the method of searching gateway in multi channel hybrid ad hoc network has not been announced.

In order to solve such a problem, the present invention is to provide a gateway discovery method in a multi-channel hybrid ad hoc network.

The gateway discovery method according to the characteristics of the present invention for achieving the technical problem is a proactive gateway discovery method in a hybrid ad hoc network, (a) if the communication quality with the currently communicating gateway falls below a certain level Adjacent ad hoc nodes for each channel by generating a gateway request message that starts a setup timer, switches channels, and obtains gateway information for each channel—the adjoining ad hoc node for each channel is configured to receive the respective gateway from each channel's gateway. Receiving gateway information of a channel; (b) generating a gateway advertisement request message for changing gateways and requesting gateway information obtained from the gateways of the respective channels when the set timer is completed and broadcasting them to adjacent ad hoc nodes of the respective channels; And (c) receiving a proxy gateway advertisement message including the obtained gateway information from adjacent ad hoc nodes of each channel to select a gateway of a channel having a minimum hop count, accessing the gateway of the selected channel, and assigning an address; Performing communication by performing an address duplication check.

The gateway discovery method according to an aspect of the present invention is a reactive gateway discovery method in a hybrid ad hoc network, comprising: (a) starting a setup timer and switching channels when communication with the gateway currently in communication is interrupted; Generating and broadcasting a gateway request message requesting gateway information to the gateway; (b) receiving a gateway advertisement message informing the gateway information from the gateway of each channel while switching channels until the setting timer is completed; And (c) analyzing the received gateway advertisement message to select a gateway of a channel having a minimum hop count, and accessing the gateway of the selected channel to perform communication by performing an address assignment and an address redundancy check. .

With the above-described configuration, the present invention can expect the effect of searching for a gateway in a multi-channel hybrid ad hoc network.

The present invention provides a method in which gateways using other channels can be searched efficiently with minimal interruption of service.

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, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise. In addition, the terms “… unit”, “… unit”, “module”, “block”, etc. described in the specification mean a unit that processes at least one function or operation, which is hardware or software or a combination of hardware and software. It can be implemented as.

2 is a diagram schematically illustrating a configuration of a multi-channel hybrid ad hoc network according to an embodiment of the present invention.

Multi-channel hybrid ad hoc networks use the same frequency channel in the same peer group and use different frequency channels between neighboring peer groups. Here, the peer group means a set of ad hoc nodes 100 connected to the backbone through the same gateway.

As shown in FIG. 2, only the case where there are two peer groups is shown, but it is applicable to the case where there are any number of peer groups.

An embodiment of the present invention is to solve the efficient backbone network access scheme of the ad hoc node 100 moving in a multi-channel hybrid ad hoc network, specifically, the moving ad hoc node 100 is a different channel for continuity of service It provides a method for searching and accessing the gateway (200, 300) using.

The multi-channel hybrid ad hoc network according to an embodiment of the present invention includes a plurality of ad hoc nodes 100 of each channel and gateways 200 and 300 of each channel.

A plurality of ad hoc nodes 100 of each channel performs ad hoc communication by transmitting packets received from other nodes between each ad hoc node 100 to another node close to the destination node.

Ad hoc node 100 according to an embodiment of the present invention to change the channel (that is, to change the transmission frequency), to request and receive the gateway information to the neighboring neighbor node 100 of each channel, of each received channel The gateway information is analyzed to select optimal gateways 200 and 300.

The gateways 200 and 300 of each channel serve to connect each ad hoc node 100 and the external Internet 300.

In addition, the gateways 200 and 300 of each channel perform an address assignment and address duplication check function for the ad hoc node 100.

In the multi-channel hybrid ad hoc network according to an embodiment of the present invention, when the mobile ad hoc node 100 searches for a new gateway 200 or 300 while switching channels, the service is not interrupted for a long time and another channel is used for continuity of the service. It provides a method for searching the gateway (200, 300) using.

Next, a method of searching for a reactive gateway in a multi-channel hybrid ad hoc network will be described in detail with reference to FIG. 3.

3 is a diagram illustrating a reactive gateway discovery method in a multi-channel hybrid ad hoc network according to an embodiment of the present invention.

When the communication with the gateway 110 that is currently communicating with the ad hoc node 100 is stopped, the ad hoc node 100 starts the timer T1, changes the channel, and generates and broadcasts a first gateway request message (GWSOL) (S100). . Here, the first gateway request message is a message broadcast by the ad hoc node 100 to request gateway information from the gateways 200 and 300 of each channel.

The ad hoc node 100 receives a gateway advertisement message (GWADV) while switching channels until the timer T1 expires from the gateways 200 and 300 that have received the first gateway request message (S102). Here, the gateway advertisement message is a message in which the gateways 200 and 300 inform their ad hoc node 100 and includes prefix information of the IP address of the gateway.

The ad hoc node 100 receives the gateway advertisement message from the plurality of channels and the plurality of gateways 200 and 300, and then selects the gateways 200 and 300 of the optimal channel at step S104. Here, the metric is defined as a survey value for selecting the optimal gateway 200, 300 in the embodiment of the present invention. The optimal metric in the embodiment of the present invention is that the delay time is minimal when the hop count is minimum, when the signal strength strength with the neighboring ad hoc node is maximum, and when the signal-to-noise ratio with the neighboring ad hoc node is maximum. And the like.

In the embodiment of the present invention, a case in which the hop count is minimum is illustrated as an optimal metric for convenience of description.

The ad hoc node 100 connects to the gateways 200 and 300 of the selected channel to perform address assignment and address duplication check (S106).

Next, a method of discovering a proactive gateway in a multi-channel hybrid ad hoc network will be described in detail with reference to FIG. 4.

FIG. 4 is a diagram illustrating a proactive gateway discovery method in a multi-channel hybrid ad hoc network according to an embodiment of the present invention.

When the ad hoc node 100 loses the communication quality with the gateway 110 currently being communicated below a certain level (when the hop count exceeds a reference value) (S200), the ad hoc node 100 suspends the communication to change the channel and the second gateway request message. After generating (Gateway Solicitation Request: GWSOL_REQ) and broadcasting it to the neighbor node 120 of each channel (S202), the timer T2 is started and communication is resumed again (S204). Here, the second gateway request message is a message broadcasted by the ad hoc node 100 to request the neighbor node 120 of each channel to obtain gateway information, and is a time to live (TTL) field. By setting the value to 1, unnecessary routing overhead is suppressed by preventing the message from being broadcast over the adjacent ad hoc node 120.

The neighbor node 120 receiving the second gateway request message generates a proxy gateway solicitation (PR_GWSOL) including the address of the ad hoc node 100 in the requester address field. It transmits to its gateway 140 that is connected to 120 (S206). Here, the proxy gateway request message is a message that the neighbor node 120 of each channel broadcasts to its gateway 140 to request gateway information.

Upon receiving the proxy gateway request message, the gateway 140 checks the redundancy of the proxy gateway request message based on the sequence number and the requester address field. Here, the sequence number is used to indicate uniqueness at that time in the proxy gateway request message of the neighbor node 120, and the requester address field is generated at a specific time in the neighbor node 120 as the address of the neighbor node 120. It is used to identify it. Here, the redundancy check is to check whether the sequence number and requester address fields match the sequence number and requester address fields of the message which has already been answered.

Subsequently, when the proxy gateway message does not have redundancy, the gateway 140 generates a proxy gateway advertisement message (PR_GWADV) and transmits the generated gateway gateway message to the neighboring node 120 (S208). The neighbor node 120 that receives the proxy gateway advertisement message is referred to as proxy node 130. Here, the proxy gateway advertisement message is a message informing the node that the gateway 140 has transmitted its proxy gateway request message, and includes the prefix information of the IP address or the IP address to be used in the ad hoc node 100. .

When timer T2 of the ad hoc node 100 in communication expires (S210), the ad hoc node 100 suspends communication, switches channels for all channels, and sends a Gateway Advertisment Request message (GWADV_REQ). It generates and broadcasts to the neighbor node 120 of each channel (S212), and receives a proxy gateway advertisement message from the proxy node 130 of each channel (S214). Here, the gateway advertisement request message is a message broadcasted to request to transmit the gateway information obtained from the neighboring node 120.

The aforementioned timer T2 is determined in consideration of the time when the ad hoc node 100 broadcasts the gateway request message and the neighbor node 120 of each channel receives the proxy gateway advertisement message from the gateway 140 of each channel.

Subsequently, the ad hoc node 100 receiving the proxy gateway advertisement message generates a proxy gateway advertisement acknowledgment message indicating that the proxy gateway advertisement message has been received and transmits it to the proxy node 130 of each channel (S216).

The proxy node 130 of each channel receives the gate advertisement request message from the ad hoc node 100 and transmits the proxy gateway advertisement message to the ad hoc node 100 in response to the related information about the proxy gateway advertisement message. Keep it.

The ad hoc node 100 analyzes the proxy gateway advertisement message received from the proxy node 130 of each channel, selects the gateway of the channel having the minimum hop count, and connects to the gateway of the selected channel to perform address assignment and address duplication. Start communication by performing (S218, S220).

The ad hoc node 100 may select one of a proactive gateway discovery method and a reactive gateway discovery method, but it is advantageous to use the proactive gateway discovery method for a real-time service that minimizes service interruption.

The embodiments of the present invention described above are not implemented only by the apparatus and / or method, but may be implemented through a program for realizing a function corresponding to the configuration of the embodiments of the present invention, a recording medium on which the program is recorded, and the like. Such implementations may be readily implemented by those skilled in the art from the description of the above-described embodiments.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

FIG. 1 is a diagram for explaining a process of setting a data transmission path to a gateway by a node constituting a hybrid ad hoc network.

2 is a diagram schematically illustrating a configuration of a multi-channel hybrid ad hoc network according to an embodiment of the present invention.

3 is a diagram illustrating a reactive gateway discovery method in a multi-channel hybrid ad hoc network according to an embodiment of the present invention.

FIG. 4 is a diagram illustrating a proactive gateway discovery method in a multi-channel hybrid ad hoc network according to an embodiment of the present invention.

Claims (7)

A method for discovering a proactive gateway in a hybrid ad hoc network, (a) When the communication quality with the gateway currently being communicated falls below a certain level, the adjacent ad hoc node of each channel is generated by generating a gateway request message requesting to start a setting timer, switch channels, and acquire gateway information of each channel. Broadcasting, wherein adjacent ad hoc nodes of each channel receive gateway information of each channel from a gateway of each channel; (b) generating a gateway advertisement request message for changing gateways and requesting gateway information obtained from the gateways of the respective channels when the set timer is completed and broadcasting them to adjacent ad hoc nodes of the respective channels; And (c) receiving a proxy gateway advertisement message including the obtained gateway information from the adjacent ad hoc node of each channel to select a gateway of a channel having a minimum hop count, and accessing the gateway of the selected channel to assign an address and address; Performing redundancy checks to communicate Gateway discovery method comprising a. According to claim 1, In step (a), And resuming communication by suspending communication with the currently communicating gateway, transmitting the gateway request message to an adjacent ad hoc node of each channel, and starting the set timer. According to claim 1, The setting timer is determined in consideration of the time to broadcast the gateway request message and the adjacent ad hoc node of each channel receives the proxy gateway advertisement message from the gateway of each channel. According to claim 1, In step (a), And setting a value of a time to live field of the gateway request message such that the gateway request message is not broadcasted to adjacent ad hoc nodes of the respective channels. According to claim 1, Between step (a) and step (b), (a1) A proxy gateway request message for neighboring ad hoc nodes of each channel to request gateway information from the gateway of each channel. The proxy gateway request message includes an address of a node that generated the gateway request message. Generating in a field (Requester Address)-and transmitting to a gateway of each channel; And (a2) checking redundancy of the proxy gateway request message based on the requester address field, and if there is no redundancy, generating the proxy gateway advertisement message and transmitting it to the adjacent ad hoc node of each channel; Gateway discovery method further comprising. According to claim 1, The ad hoc node of each channel maintains the information related to the proxy gateway advertisement message until the gateway advertisement request message is received and the proxy gateway advertisement message is transmitted in response thereto. In a reactive gateway discovery method in a hybrid ad hoc network, (a) starting a setup timer, switching channels, and generating and broadcasting a gateway request message requesting gateway information to a gateway of each channel when communication with the gateway currently in communication is interrupted; (b) receiving a gateway advertisement message informing the gateway information from the gateway of each channel while switching channels until the setting timer is completed; And (c) analyzing the received gateway advertisement message to select a gateway of a channel having a minimum hop count, and accessing the gateway of the selected channel to perform address assignment and address duplication check to perform communication; Gateway discovery method comprising a.

Images