KR20100116884A - Method for searching file based peer-2-peer in mobile ad-hoc network - Google Patents

Abstract

PURPOSE: A method for file searching based on peer-2-peer in a mobile ad-hoc network is provided to prevent large network load on ad-hoc network. CONSTITUTION: A subscription group is decided based on the number of child nodes connected to a signal strength of file information message received from each group and parent node of each group(S3). The subscription node is decided based on the number of child nodes connected to the signal strength and parent node of the file information message received from the parent node or the child node or the number of grandchild nodes connected to the child node of the subscription group decided as described above(S5). The file information of the node subscribed to the subscription node decided as described above is transmitted(S7).

Description

Method for searching file based peer-2-peer in mobile ad-hoc network}

The present invention relates to a file retrieval method for data transmission and reception in a peer-to-peer (P2P) manner in a mobile ad-hook network. More specifically, the present invention relates to a plurality of nodes constituting an ad-hook network. Grouping by dividing into groups, and to search for files in a peer-to-peer manner by group.

 Recently, due to the development of the CPU and the storage device, many kinds of mobile terminals, for example, mobile phones, PDAs, netbooks, PMPs, etc. have been developed. Therefore, research on the mobile terminal technology is actively being conducted. In particular, research related to P2B in the mobile environment has received a lot of attention recently.

P2P communication is a distributed computing paradigm in which each terminal participating in the network shares resources such as shared content and files among individual terminals, unlike a conventional client / server network in which each terminal participating in the network depends on a small number of some central servers. do. In peer-to-peer communication, all the terminals constituting the network participate in the network with equal status, and provide their own resources to the other node or route files transmitted and received on the peer-to-peer network.

Looking at an example of the ad-hook network in more detail with reference to Figure 1, the ad-hook network is composed of a plurality of mobile nodes (C1 to C18) having mobility, the mobile nodes (C1 to C18) Equally autonomous, ad-hoc networks are formed. Mobile node C1 is responsible for sending a data message or a file retrieval message to neighboring mobile nodes of mobile node C1 in order to send data to the neighboring mobile node in the ad-hook network or to retrieve a file owned by the neighboring mobile node. Cast. In order to receive a data message or retrieval data at mobile node C8, the data message or retrieval data is broached through a number of peripheral mobile nodes existing between mobile node C1 and mobile node C8 to be mobile node. Is received at C8.

Since the existing P2P communication method has been studied for the wired environment, it is not suitable for the current mobile network, especially the ad-hook network, which has a limited communication range. Ad-hook networks have been studied for the purpose of temporarily constructing networks in areas where there is no infrastructure or where it is not easy to deploy a network based on an infrastructure. Mobile nodes present in the ad-hook network are capable of peer-to-peer communication between mobile nodes using an air interface. However, the P2P communication method is a communication technology originally used for a wired network, and when the conventional P2P communication method is applied in an ad-hook network, the following problems occur due to the characteristics of the ad-hook network.

First, the network topology changes dynamically as the node moves. Changes in the network topology cause frequent update of the route information, which complicates the management of the route information, and the routing control message for this acts as network overhead.

Second, since the mobile nodes constituting the ad-hook network participate in the network with the same status, when the file is searched in the ad-hook network by peer-to-peer communication, the ad-hook network is transmitted in the process of transmitting the search message for the file search. The problem occurs that a heavy load is placed on the ad-hook network by broadcasting the same search message to all the nodes constituting the node.

Third, mobile nodes use a limited amount of battery, which is why energy use is limited.

In order to solve these problems, an optimized optimized routing independent network (ORION) protocol has been developed and used. ORION manages two routing tables, the route routing table and the file routing table, by integrating the query message of the application layer and the query layer of the network layer in order to efficiently retrieve a file through the peer-to-peer communication method in the ad-hook network. The file routing table maintains path information for the desired files, reducing traffic on the ad-hook network and improving network reliability with accurate file retrieval.

FIG. 2 is a view for explaining an example of searching for a file in an ad-hook network using a conventional ORION protocol. Referring to FIG. 2, in detail, all mobile nodes constituting the ad-hook network have their own. Browsing retained file information to neighboring neighbor nodes. For example, mobile node B holds files "1", "2", mobile node C holds files "1", "2", "3", and mobile node D ) Holds files "2", "3", and "4". Each mobile node generates and manages a file routing table based on retained file information received from neighboring neighbor nodes. For example, mobile node B generates a file routing table such as a based on retained file information received from peripheral mobile nodes C and D. Meanwhile, the mobile node A generates a file routing table such as b based on the file information received from the neighboring mobile nodes B, C, and D and the file routing table information received from the neighboring mobile node B. FIG.

Mobile node A first sends a file request message to mobile node B, which holds file "4" in the file routing table, in order to request file "4" in the ad-hook network. In response to the file request message, the mobile node B searches for the file " 4 " requested by the mobile node A in the file routing table of the mobile node B, and sends the file request message to the mobile node D again. . Mobile node D sends file " 4 " to mobile node A in response to the file request message.

The conventional method of retrieving files in an ad-hook network using the ORION protocol is that neighboring mobile nodes update their file routing table based on the file routing table and file information received from neighboring mobile nodes. The problem is that it is difficult to retrieve the file correctly when moving.

In addition, in order to retrieve files in the ad-hook network using the ORION protocol, each mobile node must create and update a file routing table in advance. Each mobile node can provide file information to neighboring mobile nodes in order to create a file routing table. Or by casting the file routing table, there is still a problem that puts a heavy load on the ad-hook network.

An object of the present invention is to solve the problems of the ad-hook network described above, the present invention is to provide a file retrieval method that does not put a heavy load on the network when searching the file in the ad-hook network.

Another object of the present invention is to provide a method for retrieving a file without placing a heavy load on the network by grouping a plurality of mobile nodes constituting an ad-hook network into a plurality of groups.

Another object of the present invention is to provide a method for searching files in a fast and low cost in an ad-hook network.

According to the present invention, a method for searching a file in a peer-to-peer manner in a mobile ad-hoc network includes transmitting a file request message (FRM) containing information of a file requested from a child node to a parent node, and a file of the parent node. Determining whether the request file exists in the information table, and if the request file does not exist in the parent node's file information table, broadcasting a search message (FSM) for searching the request file to the neighboring parent node of the parent node; Determining whether a search file exists in the file information table of the neighboring parent node based on the broadcasted search message and searching if the search file exists in the file information table of at least one of the neighboring parent nodes Sending a response message (SRM) to the parent node.

Preferably, when the new node joins the parent node, the new node receives the file information message of the new node from the new node, and further updates the file information table of the parent node based on the received file information message.

Preferably, when a child node of the parent node leaves, the child node sends a leave message to the parent node, and the parent node deletes and updates the file information table of the parent node based on the leave message.

According to an embodiment of the present invention, a method of grouping nodes for searching a file in a peer-to-peer manner in a mobile ad-hoc network includes receiving a file information message transmitted from a plurality of parent nodes and measuring signal strength of the received file information message. Determining a joining group based on a signal strength of a file information message received from each group and the number of child nodes connected to a parent node of each group, and receiving from a parent node or a child node of the determined joining group. Determining the joining node based on the signal strength of the file information message and the number of child nodes connected to the parent node or the number of grandchild nodes connected to the child node, and the file information message of the node joined with the determined joining node. Transmitting a step.

According to the present invention, a method of searching a file in a P2P manner in a mobile ad-hoc network has various effects as follows.

First, the file retrieval method according to the present invention manages file information of neighboring mobile nodes using a file information table, thereby preventing a large amount of retrieval messages from being transmitted and received, thus not placing a heavy load on the network.

Second, the file search method according to the present invention manages a plurality of mobile nodes constituting the ad-hook network into a parent node and child nodes joined to the parent node, thereby managing a search message for searching for a specific file between the parent nodes. Sending and receiving only does not put a heavy load on the network.

Third, the file retrieval method according to the present invention manages a plurality of mobile nodes constituting an ad-hook network by grouping them into parent nodes and child nodes joined to the parent node, even when the child nodes move and leave the group. You can update the file routing table only from within to retrieve files accurately and easily.

Hereinafter, with reference to the accompanying drawings, a method of searching for a file in a P2P method in a mobile ad-hoc network will be described in more detail.

3 is a functional block diagram illustrating an ad-hook network according to an embodiment of the present invention.

Referring to FIG. 3, the ad-hook network includes a plurality of parent nodes PN and a plurality of child nodes CN. Each of the plurality of child nodes CN is joined to one parent node PN, and the plurality of child nodes CN and one parent node PN constitute one group. As shown in Fig. 3, parent node 1 (PN1) is joined with child nodes 1 through 4 (CN1, CN2, CN3, CN4), and parent node 1 (PN1) and child nodes 1 through child node. 4 (CN1, CN2, CN3, CN4) constitute group 1. On the other hand, child nodes 1 through 6 (CN1, CN2, CN3, CN4, CN5, CN6) are joined to parent node 2 (PN2), and parent node 2 (PN2) and child nodes 1 through 6 (CN1). , CN2, CN3, CN4, CN5, CN6) constitute Group 2. On the other hand, child nodes 1 through 3 (CN1, CN2, CN3) are joined to parent node 3 (PN3), and parent nodes 3 (PN3) and child nodes 1 through 3 (CN1, CN2, CN3) Configure group 3.

While the parent node of each group cannot move to the fixed node, the child nodes joined to the parent node can join or leave the parent node as the mobile node. When the mobile node joins a new parent node, the parent node and the mobile node have a relationship between the parent node and the child node, and the parent node is further updated by a group managing file information of the mobile node joined as the child node. Meanwhile, when a child node leaves a parent node to which a child node has previously joined, the parent node deletes and updates information on the child node that has left the group managed by the parent node.

Data communication between each group is performed only between the parent nodes managing each group. Therefore, when a child node joined to a group requests a specific file from a parent node, the parent node broadcasts a search message to each neighboring parent node of another group to request the search for a specific file. Peripheral parent nodes of the group send a search response message to the parent node in response to the search message.

That is, in the ad-hook network according to the present invention, a message for requesting a specific file is not broadcasted to a neighboring mobile node, but only transmitted to a parent node, and when a specific file does not exist in the group, the neighboring node is transmitted through the parent node. Search messages are only broadcast to the parent node.

4 is a flowchart illustrating a message transmitted and received between a child node and a parent node and a message transmitted and received between a parent node and a neighboring parent node according to an embodiment of the present invention.

Referring to FIG. 4, the child node transmits a file request message (FRM) for requesting a specific file only to the parent node of the group to which the child node is subscribed. When a parent node receives a file request message (FRM) from a child node, the parent node broadcasts a message (FSM: File Search Message) for requesting a file search to all neighboring parent nodes. Peripheral parent nodes determine whether a file to be searched for exists in the file information table, and if a search request file exists according to the determination result, transmits a search response message (SRM) to the parent node. When the parent node receives a search response message from the neighboring parent node 2, it sends a message (FRM) to request a file. In response to the file request message, the peripheral parent node 2 transmits to the parent node a file held by the child node owned by the child node that is owned or joined to the group managed by the peripheral parent node 2. The parent node receiving the file delivers the received file to the child node that requested the file.

5 is a flowchart illustrating a grouping method of a mobile node for searching for a file in a peer-to-peer manner in a mobile ad-hook network according to an embodiment of the present invention.

Referring to FIG. 5 in more detail, in order for a mobile node to join a parent node, the mobile node first receives a file information message transmitted from a plurality of parent nodes and measures the signal strength of the received file information message (S1). ). The file information message is a file information table held by a group managed by a parent node. The file information message includes an identifier for identifying a parent node, file information held by a parent node, an identifier of a child node joined to a group managed by the parent node, and a file information table. Contains file information held by child nodes. The joining group is determined based on the signal strength of the file information message received from the plurality of buno nodes and the number of child nodes joined to the group managed by the parent node (S3). The decision of the joining group is determined according to Equation (1) below.

[Equation 1]

SPN = MAX (PN (i)), PN (i) = a × RSSI (i) + b × nc (i)

Here, SPN means the parent node of the determined joining group, PN (i) means the selection value of the parent node of each group, and a and b indicate that the RSSI of the file information message signal and each parent node It means the weight of the number (nc) of child nodes joined to the managing group. That is, the mobile node determines a group managed by the parent node having the largest selection value as a joining group. Preferably, the weight for the reception strength of the file information message signal is greater than the weight for the number nc of child nodes joined to the group managed by each parent node. When retrieving or transmitting data through a parent node in a mobile node, the most important thing is the actual distance between the parent node and the mobile node, and the reception strength (RSSI) of the file information message signal is inversely proportional to the distance between the parent node and the mobile node. do. Therefore, the larger the received strength (RSSI) value of the file information message signal, the closer the distance between the mobile node and the parent node.

When the group to which the mobile node intends to join is determined, it is determined whether the mobile node joins the group as a child node of the parent node or as a grandchild node to a child node previously subscribed to the parent node (S5). The decision of the joining node is made according to the following equation (2).

[Equation 2]

SJN = MAX (JN (i))

Here, SJN refers to the determined joining node, and JN (i) refers to a reception strength (RSSI) of a file information message signal received from a parent node or a child node existing in the determined joining group. That is, the file information message is received from the parent node or the child node existing in the determined group, and the child or grandchild node is subscribed to the node having the largest RSSI of the received file information message.

When the joining group and the joining node are determined, the mobile node sends a joining message to the joining node (S7). The subscription message includes an identifier of a mobile node to be subscribed to and information about a file held by the mobile node. The parent node or child node updates the file information table of the parent node or child node based on the subscription message received from the mobile node (S9). If the subscription node determined by the mobile node is the parent node, the parent node updates the file information table of the parent node based on the file information of the subscription message received from the mobile node. On the other hand, if the subscription node determined by the mobile node is a child node, the child node updates the file information table of the child node based on the file information of the subscription message received from the mobile node, and sends the updated file information table to the parent node. do. The parent node updates the file information table of the group managed by the parent node based on the file information table received from the child node.

On the other hand, when the child node leaves the parent node, the child node sends a leave message to the parent node, and the parent node updates the file information table of the parent node based on the leave message.

6 shows an example of a file information table of a parent node or a child node.

Referring to FIG. 6 (a), the file information table of the parent node is described in more detail. The file information table of the parent node includes an identifier (ID) of the parent node, a file held by the parent node, and a group managed by the parent node. It contains the identifiers of the child nodes joined and information about the files held by each child node. Parent node and child node address (0x00011, 0x0001101, 0x0001110, 0x0001111) can be used as identifier of parent node or child node, and file information held by parent node and child node is file name (1, 2, 3, 4). , 5, 7, 8) can be used.

Meanwhile, referring to FIG. 6 (b), the file information table of the child node will be described in more detail. In the file information table of the child node, the identifier (0x00011) of the parent node and the files (1, 2, 5) held by the child node are shown. ), When a grandchild node is joined to a child node, information about an identifier (0x000110101) of the grandchild node and files (9, 10, 12) held by the grandchild node is included.

FIG. 7 is a flowchart illustrating a method of searching for a file in a peer-to-peer manner in a mobile ad-hoc network according to an embodiment of the present invention.

Referring to FIG. 7 in more detail, when a parent node receives a file request message from one child node among child nodes joined to a group managed by the parent node (S11), the parent node receives file information of the parent node. Based on the table, it is determined whether the file requested by the child node is a file held by the parent node or another child node joined to the group managed by the parent node (S12). As a result of the determination in step S12, when the file requested by the child node is a file held by the parent node or another child node joined to the group managed by the parent node, the parent node holds the request file in the file information table. The file is requested to another child node and transmitted to the child node (S19). On the other hand, if the file requested by the child node is not a file owned by the parent node or another child node joined to the group managed by the parent node, the parent node receives a search message for searching for the request file. It generates and casts the surrounding parent node (S13). The peripheral parent node determines whether the request file is held in the group managed by the neighboring parent node based on the file information table of the neighboring parent node, in response to the broadcast message. If it is determined that the neighboring parent node holds the request file in the managing group, the neighboring parent node transmits a search response message for informing that the parent node holds the request file (S18).

Meanwhile, the above-described embodiments of the present invention can be written as a program that can be executed in a computer, and can be implemented in a general-purpose digital computer that operates the program using a computer-readable recording medium.

The computer-readable recording medium may be a magnetic storage medium (for example, a ROM, a floppy disk, a hard disk, etc.), an optical reading medium (for example, a CD-ROM, DVD, etc.) and a carrier wave (for example, the Internet). Storage medium).

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

1 is a functional block diagram illustrating an example of a conventional ad-hook network.

2 is a diagram illustrating an example of searching for a file in an ad-hook network using a conventional ORION protocol.

3 is a functional block diagram illustrating an ad-hook network according to an embodiment of the present invention.

4 is a flowchart illustrating a message transmitted and received between a child node and a parent node and a message transmitted and received between a parent node and a neighboring parent node according to an embodiment of the present invention.

5 is a flowchart illustrating a grouping method of a mobile node for searching for a file in a peer-to-peer manner in a mobile ad-hoc network according to an embodiment of the present invention.

6 shows an example of a file information table of a parent node or a child node.

FIG. 7 is a flowchart illustrating a method of searching for a file in a peer-to-peer manner in a mobile ad-hoc network according to an embodiment of the present invention.

Claims (9)

In the method of grouping nodes to retrieve files in a peer-to-peer manner in a mobile ad-hook network, (a) receiving a file information message each transmitted from a plurality of groups of parent nodes, and measuring signal strength of the received file information message; (b) determining a joining group based on the signal strength of the file information message received from each group and the number of child nodes connected to the parent node of each group; (c) subscribing nodes based on the signal strength of the file information message received from the parent node or child node of the determined joining group and the number of child nodes connected to the parent node or the number of grandchild nodes connected to the child node. Determining; And and (d) transmitting the file information of the node subscribed to the determined subscription node. The method of claim 1, wherein the determined joining node is a parent node. And updating the file information message of the parent node based on the file information of the subscribing node. The method of claim 1, wherein the determined joining node is a child node. Updating the file information message of the child node based on the file information of the subscribing node, and transmitting the file information message of the updated child node to the parent node; And And updating the file information message of the parent node based on the updated file information message of the child node. The method according to claim 2 or 3, And the file information message includes an identifier of a parent node, file information held, an ID of a child node, and file information held by the child node. According to claim 1, wherein the determination of the joining group is determined by the following equation (1), [Equation 1] SPN = MAX (PN (i)), PN (i) = a × RSSI (i) + b × nc (i) Here, SPN means the parent node of the determined joining group, PN (i) means the selection value of the parent node of each group, and a and b are the RSSI of the file information message signal and the number of child nodes, respectively. (nc) means a weighting group. The method of claim 1, wherein the determination of the joining node is determined by Equation (2) below. [Equation 2] SJN = MAX (JN (i)) Here, SJN means a determined joining node, and JN (i) refers to a reception strength (RSSI) of a file information message signal received from a parent node or a child node existing in the determined joining group. Way. In a method of searching a file in a peer-to-peer manner in a mobile ad-hook network, Sending a file request message (FRM) containing information of a file requested by a child node to a parent node; It is determined whether a request file exists in the file information table of the parent node, and if a request file does not exist in the file information table of the parent node, a search message (FSM) for searching for the request file is located around the parent node. Broadcasting to a parent node; Determining whether the search file exists in the file information table of the neighboring parent node based on the browsing casted search message; And And transmitting a search response message (SRM) to the parent node when the search file exists in the file information table of at least one neighboring parent node among the neighboring parent nodes. 8. The method of claim 7, wherein when a new node joins the parent node, Receiving a file information message of the new node from the new node, And updating the file information table of the parent node based on the received file information message. The method of claim 7, wherein when a child node of the parent node leaves The child node sends a leave message to the parent node, And the parent node deletes and updates the file information table of the parent node based on the withdrawal message.

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