KR100625659B1 - Peer to Peer File Searching Method between Mobile Communication Terminals in Wireless Environment - Google Patents

Abstract

The present invention relates to a peer-to-peer file retrieval method between mobile communication terminals in a wireless environment.

A peer-to-peer file search method of the present invention includes a first step of a search mobile communication terminal, which is a search requester, recognizing a searchable terminal according to signal strength to form a file search group; Generating, by the search mobile communication terminal, a file search list consisting of some nodes in the group for file search in the formed search group; A third step of, by the search mobile communication terminal, transmitting a search request signal to each node in the file search list; And a fourth step of receiving the search request data from the searched mobile communication terminal of the node which has received the search request signal.

File Search Group, File Search List, Group Search Delegate Elect Server

Description

Peer to Peer File Searching Method between Mobile Communication Terminals in Wireless Environment}

1 is a conceptual diagram illustrating a file search method using a conventional chord method;

2 is a conceptual diagram illustrating a group forming method of a file searching method according to an embodiment of the present invention;

3 is a conceptual diagram illustrating a file searching method within a group of a file searching method according to an embodiment of the present invention;

4 is a conceptual diagram illustrating a group movement search method of a file search method according to an embodiment of the present invention;

5 is a flowchart illustrating a file searching process in a list of a file searching method according to an embodiment of the present invention;

6 is a flowchart illustrating a file searching process when a node leaves in a file searching method according to an embodiment of the present invention;

7 is a flowchart illustrating a group movement search process of a file search method according to an embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

100: search mobile communication terminal

101, 201: base station

110 ~ 140: searched mobile communication terminal

200: group search delegate mobile communication terminal

300: group search delegate election server

The present invention relates to a peer-to-peer file retrieval method between mobile communication terminals in a wireless environment, and more particularly, to a peer-to-peer file retrieval method for enabling information retrieval between mobile communication terminals in a wireless environment or a wireless ad hoc environment. It is about.

Peer-to-peer service, called peer-to-peer (P2P), is a service that connects computers directly and shares files and information without a server.

As a representative technology of peer-to-peer services in the existing wired Internet environment, the Napster method, the Gnutella method, and the code method are as follows.

In the Napster method, a search server with an index exists in the center, and a user connects to the search server to exchange files and share files. In the case of a service that shares music files, the user uses a singer name and a song name. The server connects to the central server and searches, and the server locates the appropriate music file.

This Napster method has the advantage of having a large number of clients that can search because of the existence of a central search server, a very fast search speed, and a wide range of applications accordingly. Can be aborted, and all searches rely solely on the central server, which can overload the server if there are a large number of queries, ie file existence questions between computers.

The Gnutella method is a structure in which each node is a server and a client, and each peer is directly connected. In other words, the program installed in the user's PC itself has a built-in peer-to-peer search function, which means that the program is directly connected to the computer that holds the specific file.

For example, if user A requests user B to retrieve a specific file name, B's peer-to-peer program looks for the relevant file in its own index, sends data to A if it exists, or another user C Forward the search request to.

Since the Gnutella method does not use a central search server, the server load problem can be solved. However, the Gnutella method has a disadvantage of high network overload and long search time due to unnecessary large number of search requests.

Next, the code method is a peer-to-peer file search method that compensates for the shortcomings of the Napster method and the Gnutella method, and uses Gnutella's distributed file search to solve a long search time which is a disadvantage of the distributed search method. One way.

Referring to the code method, each node joining the file search group is given a virtual ID, thereby forming an ID space which is a virtual file search group. Nodes in each ID space are numbered and are mapped to the smallest of the nodes whose IDs are greater than or equal to itself. This node is called a pointer.

To implement the pointer function, all nodes maintain a routing table of m-entries, which contain information about other nodes in the system. The entry has a node ID and a network address (IP address, port number), and the nodes with the entry form a searcher table by a pointer function. This searcher table consists of only a few nodes in the group.

Therefore, when a search request is requested, only a few nodes in the list are searched, and nodes receiving the search request a relay search requesting search to other nodes, thereby reducing the search time.

Referring to FIG. 1 as an example, in order for node 1 to find the data of key 7, the node 1 does not make a search request to the node with key 7, but rather to pointer nodes of its own searcher table. After requesting a search, if there is no data, node 6 requests the other nodes to search using the searcher table of node 6 as shown in FIG.

In FIG. 1, the size of the ID space is set to 8 (0 to 7), and only four nodes (0,1,2,6) actually exist among the designated ID spaces. By hashing function of the Chord algorithm, each of the four nodes is given a respective ID (0, 1, 2, 6), and also generates a Successor Table.

As shown in Fig. 1, the searcher table is composed of [i (0,1,2) / finger (id + 2i) / successor], and the finger and searcher are values between 0 and 7. Where the searcher is specified as the smallest value of the existing node ID equal to or greater than the finger.

Each node basically maintains index information for items (files) owned by itself, and maintains index information for items owned by searchers in its searcher table.

At this time, when node ID 1 of FIG. 1 attempts to search for item 7, first of all, the node ID 1 does not have item 7, and since the node ID 1 has the index information of the searcher, node 2 and node 6 that do not have item 7 do not have item 7 as well. It can be seen that.

Thus, when a search request for item 7 is delivered to searcher 6, there is a node 0 that owns item 7 among searchers in searcher node 6, so the search through searcher 6 is completed.

On the other hand, in the case of the conventional peer-to-peer service PCs as described above, the position of each peer (PC) is fixed because it communicates through a wired communication network, and sudden power off occurs because of the power line. rare.

However, in the wireless environment and the wireless ad hoc environment, since each peer (wireless terminal) uses a battery as a power source, it is highly likely that the power is suddenly turned off when the battery is exhausted. There is a high possibility of sudden departure from the communication area. In addition, since the handoff phenomenon between the base stations occurs essentially due to the nature of radio waves, there is a high possibility of temporarily leaving the peer-to-peer service.

Accordingly, as a result of applying the above-described peer-to-peer search methods in the wired environment to the mobile environment (wireless, wireless ad hoc environment), the file search was not successful. First, in the case of the code method, the probability of finding a successful message by sending a question message was less than 0.5, and the search time, which is an advantage of the code method, was not achieved in the mobile environment.

This is because, due to the mobility of the nodes in the mobile environment, if the intermediate node suddenly turns off or suddenly disappears by moving out of the propagation range, the search is no longer performed, the search may take an infinite search time, or the search may not be performed at all. Because. In other words, the existing peer-to-peer service is optimized for wired environments, so there is a limit to applying it to a mobile environment with high mobility.

Therefore, there is a demand for a file and information retrieval service between wireless terminals and related technologies in a wireless environment and a wireless ad hoc environment.

Accordingly, the present invention is to solve the above disadvantages and problems of the prior art, peer-to-peer between the mobile communication terminal in a wireless environment that enables the file search between the mobile communication terminal suitable for wireless environment and wireless ad hoc environment It is an object of the present invention to provide a file retrieval method.

The above object of the present invention is a peer-to-peer (P2P) file search method for information sharing and file exchange between mobile communication terminals in a wireless environment, wherein a search mobile communication terminal, which is a search requester, recognizes a searchable terminal according to a signal strength Forming a search group; Generating, by the search mobile communication terminal, a file search list consisting of some nodes in the group for file search in the formed search group; A third step of, by the search mobile communication terminal, transmitting a search request signal to each node in the file search list; And a fourth step of receiving search request data from a searched mobile communication terminal of the node that has received the search request signal.

In the present invention, a wireless ad hoc environment is a concept opposite to an infrastructure network, but a general mobile communication network communicates wirelessly between mobile communication terminals, but a base station is connected by wire and thus has a wired base. It refers to an environment in which terminals communicate wirelessly with each other by relaying signals.

Details of the above object and technical configuration of the present invention and the resulting effects thereof will be more clearly understood from the following detailed description based on the accompanying drawings.

The peer-to-peer file search method of the present invention provides a method for forming a file search group, a file search method when a node leaves a file search list, and a search method when a file search within a group fails. Conceptually described through the following.

First, FIG. 2 is a conceptual diagram illustrating a group forming method of a file retrieval method according to an embodiment of the present invention.

As illustrated, the file search group forming method in a wireless ad hoc environment is to identify the signal strengths of all the mobile communication terminals and form the mobile communication terminal as a file search group within a range that receives a response of a certain signal strength.

That is, the search mobile communication terminal 100 to search transmits a pilot signal previously used for initializing communication between the base station and the terminal to form a file search group to adjacent terminals 110 to 140 within a range of mutual propagation. Then, the searchable group is recognized according to the response signals from the plurality of searched mobile communication terminals 110 to 140 that receive the same.

The plurality of searched mobile communication terminals 110 to 140 receiving the pilot signal transmit a battery state together with the pilot signal as a response signal. In this case, the battery state may be calculated as the power of the terminal through a signal arrival sensitivity calculation function by the power of the battery.

The search mobile communication terminal 100 receiving the response signal measures the time from the time when the signal is transmitted to the time when the response signal is received, selects the mobile communication terminal which transmits the response signal within a predetermined time, and selects a search group. To form.

Next, FIG. 3 is a conceptual diagram illustrating a file searching method within a group of a file searching method according to an embodiment of the present invention.

As shown in FIG. 2, when the file search group (nodes 0 to 7) is formed as described with reference to FIG. 2, each node is composed of only a few nodes in the group by a pointer function as in the conventional code method. (Searcher Table: Succ Table) is formed.

In addition, each node basically maintains index information on a file owned by itself and index information on a file owned by each node in its file search list.

In this case, when node 1 of the search mobile communication terminal of FIG. 3 wants to search for item 7, first of all, it does not have item 7 and has index information of the searcher, so that node 2 and node 6, which are searchers, are searched. You can also see that it does not have item 7.

Thus, when a search request for item 7 is delivered to searcher 6, there is a node 0 that owns item 7 among searchers in searcher node 6, so the search through searcher 6 is completed.

However, according to the mobility of the wireless environment, when the node 6, which is the searcher who needs to perform the search completion, suddenly disappears, the search requester, which is the search requester, waits for a predetermined time, and then waits for a predetermined time, and then moves to the previous number node of the node 6 as a new search node. A search request is made to node 5, so that node 0 with item 7 can be found via node 7 through node 5's file search list.

If node 5 suddenly disappears as in the above case, node 1, which is the search mobile communication terminal, makes a new search request to node 4, which is the node immediately preceding, to form a relay search path.

On the other hand, if the search is not made by attempting a search in the group as described above, the present invention allows to perform a search through a group other than the group to which it belongs, as described with reference to FIG. .

4 is a conceptual diagram illustrating a group movement search method of a file search method according to an embodiment of the present invention.

As illustrated, when the search mobile communication terminal 100 fails to search for a file in Group A, which is a group to which the search mobile communication terminal 100 belongs, the search mobile communication terminal 100 transmits a search request signal to the base station 101.

The base station 101 transmits the search request signal to the group search delegate election server 300 that selects a search delegate mobile communication terminal 200 in another group for file search, and the group search delegate election server 300. ) Selects a group search delegate mobile communication terminal 200 according to a predetermined rule or arbitrarily, and transmits the group search delegate mobile communication terminal 200 to the group search delegate mobile communication terminal 200 through the base station 201 to which the group search delegate mobile communication terminal 200 belongs. Pass the search request signal.

As described above, the search agent mobile communication terminal 200 receiving the search request signal performs a file search in the group B to which the search mobile communication terminal 100 belongs, as in the file search process in the group to which the search mobile communication terminal 100 belongs. do.

Each file search process of the file search method of the present invention as described above will be described again sequentially through FIGS. 5 to 7 as follows.

First, FIG. 5 is a flowchart illustrating a file searching process in a list of a file searching method according to an embodiment of the present invention.

As shown, the search mobile communication terminal 100 determines the signal strength of each terminal to form a file search group (S101), and a file search composed of several nodes among the nodes in the formed file search group. A list is created (S102), and each node in the group creates and maintains its own file search list.

Next, for example, when there are three searcher nodes in the file search list, first, the search mobile communication terminal 100 requests a search to terminal 1 (node 1) in its own file search list (S103). Terminal 1 performs a sequential file search through its file search list (S104).

At this time, each terminal maintains the index information of the file owned by itself and the index information of the file owned by each terminal in its file search list, and performs file search by searching the index information of the file. .

When a file search is successfully performed through the search list of the terminal 1 or the terminal 1 (S105), the search mobile communication terminal 100 receives a file from the terminal that owns the file (S112).

If the file search is not performed through the search list of the terminal 1 or the terminal 1, the search mobile communication terminal 100 requests a search to the terminal 2 (node 2) in the list again (S106), and the terminal 2 itself. A sequential file search is performed through the file search list (S107).

When the file search is not performed through the search list of the terminal 2 or the terminal 2 (S108), the search mobile communication terminal 100 requests a search to the terminal 3 which is the last node in the list (S109). 3 performs a sequential file search through its file search list (S110).

On the other hand, when the search request is made to all nodes of the file search list maintained by the search mobile communication terminal 100 as described above (S111), the search mobile communication terminal 100 The file search list consisting of several nodes in the file search group may be recreated (S102), and the process may be repeated.

Next, FIG. 6 is a flowchart illustrating a file searching process when a node leaves in the file searching method according to an embodiment of the present invention, and describes a searching method when the specific node leaves when performing the file searching process as shown in FIG. 5.

As shown, the search mobile communication terminal 100 forms a file search group (S201), creates a file search list in the group (S202), and requests a search from the terminals in the list (S203).

At this time, if there is no response from the terminal requesting the search within a predetermined time (S204), the search mobile communication terminal 100 requests the search and sends a search request signal to the mobile communication terminal having the node number immediately preceding the terminal that has no response. It is transmitted (S205).

If the search is successfully performed through the terminal requesting the search (S206), the search mobile communication terminal 100 receives a file from the terminal requesting the search (S207).

Finally, FIG. 7 is a flowchart illustrating a group movement search process of a file search method according to an embodiment of the present invention.

As shown, the search mobile communication terminal 100 to request a search forms a file search group (S301), and again creates a file search list consisting of only a few nodes in the file search group (S302). As described with reference to FIG. 5 and FIG. 6, a file search in a group is performed through the file search list (S303).

In this case, when a file search is successfully performed in the file search group to which the file belongs, the search mobile communication terminal 100 receives a file from the mobile communication terminal that owns the file and ends the file search process. S305).

However, if the file search is not successfully performed in the file search group to which it belongs (S304), the mobile communication terminal 100 transmits a file search request signal to the base station 101 (S306).

Upon receiving the file search request signal, the base station 101 transmits the file search request signal to a group search delegate selecting server 300 that selects a search delegate mobile communication terminal 200 capable of performing a search through another group. The group search delegate selecting server 300 selects the mobile communication terminal 200 forming another group as the file searching delegate terminal (S307).

Next, the file search delegate terminal 200 creates a file search list in the search group formed by itself, similarly to the search mobile communication terminal 100 performing a file search in its group (S308). In step S309, file search is performed within its own group.

As those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features, the embodiments described above should be understood as illustrative and not restrictive in all aspects. Should be. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

Therefore, the peer-to-peer file search method between mobile communication terminals in the wireless environment of the present invention enables mobile communication by enabling peer-to-peer file search in a wireless environment or a wireless ad-hoc environment. A user having a terminal can freely share information and files owned by other users, and the file sharing and information exchange between mobile communication terminals can be performed even where a signal of a wireless base station does not reach.

Claims (6)

A peer-to-peer (P2P) file retrieval method for information sharing and file exchange between mobile communication terminals in a wireless environment, A search mobile communication terminal, which is a search requester, transmits a pilot signal for forming a file search group, and forms a file search group including at least one searched mobile communication terminal that transmits a response pilot signal to the pilot signal; Step 1; The search mobile communication terminal searches for a file by designating at least one or more mobile communication terminals of a plurality of searched mobile communication terminals in the file search group according to a specified rule that each mobile communication terminal has in common for relay search. Creating a list; A third step of the search mobile communication terminal transmitting a search request signal to each node in the file search list; And Receiving a search request data from a searched mobile communication terminal of a node that has received the search request signal; Peer-to-peer file retrieval method between mobile communication terminals in a wireless environment, characterized in that comprises a. The method of claim 1, The first step, Transmitting, by the search mobile communication terminal, pilot signals to the plurality of nodes; Transmitting, by the plurality of nodes receiving the pilot signal, signal strength information and a pilot signal according to its battery state as a response signal to the search mobile communication terminal; The search mobile communication terminal that has received the response signals from the plurality of nodes measures the time from when it transmits the pilot signal to the time when it receives the response signal, and the search mobile communication terminal responds within a predetermined time according to the measurement result. Forming a plurality of nodes having transmitted the file as a file search group; It is made, including In the second step, The search mobile communication terminal forms a virtual file search group through an ID assigned to the user for file search and forms a file search list by using a specific pointer function. Peer-to-peer file retrieval method between mobile communication terminals in a wireless environment, characterized in that for creating a. The method of claim 1, The third step, Transmitting, by the search mobile communication terminal, a search request signal to any one of a plurality of nodes in the file search list; If the node that receives the search request signal fails by performing a sequential file search through each node in its file search list, the search request signal to other nodes in the file search list except for the node that previously transmitted the search request signal. Transmitting; A peer-to-peer file search method between mobile communication terminals in a wireless environment, comprising: performing a sequential file search through each node in the file search list. The method of claim 1, The third step, Transmitting, by the search mobile communication terminal, a search request signal to a node in the file search list; Transmitting a search request signal back to the mobile communication terminal having the previous node number of the node when a search response from the node receiving the search request signal is not received within a predetermined time; The peer-to-peer file retrieval method between mobile communication terminals in a wireless environment, characterized in that comprises a, performing a re-search in the group when the departure of a particular node. The method of claim 1, After the third step and before the fourth step, Transmitting, by the search mobile communication terminal, a search request signal to a base station to which the search mobile communication terminal belongs if the search in the group through the node in the file search list fails; Transmitting, by the base station, the search request signal to a group search representative election server that selects a group search representative; Selecting, by the server, a group search delegate and transmitting a search request signal to the group search delegate terminal through a base station to which the group search delegate terminal belongs; And Performing a file search by transmitting a search request signal to a node in a file search group to which a group search delegate terminal receiving the search request signal belongs; It further comprises a, peer to peer file search method between mobile communication terminals in a wireless environment, characterized in that for performing a search through a different group of terminals. The method of claim 1, After the third step and before the fourth step, If the search in the group through the node in the file search list fails, the second step of the search mobile communication terminal to create a file search list consisting of some nodes in the group for the file search in the formed search group A peer-to-peer file retrieval method between mobile communication terminals in a wireless environment, characterized by performing a file retrieval within a group by reconstructing a file retrieval list by feedback.

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