KR101011265B1 - Apparatus and method for detecting selfish node in MANET, and data replica allocation method using thereof - Google Patents

Abstract

The present invention relates to a data copy allocation technique in a mobile ad hoc network, wherein a selfish node detection apparatus in a mobile ad hoc network according to the present invention is based on the available data storage size and stored data type of the first node. A node information transceiving unit which transmits node information relating to a second node and receives node information regarding an available data storage size and a type of stored data of the second node; And a selfishness determining unit that determines selfishness of the second node in consideration of node information of the second node, network information including a distance of the second node and a number of communication connections with the second node. This provides an advantage of improving network efficiency and security.

Description

Apparatus and method for detecting selfish node in MANET, and data replica allocation method using

The present invention relates to a technique for allocating data copies in a mobile ad hoc network. In particular, when there is a mobile node with selfishness on the mobile ad hoc network, a self-governing node that improves network efficiency and security by detecting and removing the node. The present invention relates to a detection apparatus and a method and a data copy allocation method using the same.

Recently, due to the rapid development of mobile equipment and wireless communication technology, interest in mobile ad hoc network-related technology is rapidly increasing in various application fields such as emergency rescue, emergency meeting, and military network of battlefield.

Mobile Ad hoc Network (MANET) means that mobile nodes autonomously configure and maintain a network through a wireless link without the need for a separate infrastructure, such as a wired network, a base station, or an access point. It refers to an information transmission network that can deliver.

This MANET enables mobile nodes to act as hosts and routers simultaneously over the air interface, overcomes limitations on the communication distance of the air interface due to the multi-hop routing function, and the network topology is dynamic due to the mobility of the mobile node. There is a characteristic that changes. In addition, MANET can be completely standalone or can interoperate with an underlying network such as the Internet via an Internet gateway.

However, unlike fixed networks that are securely connected, MANET frequently disconnects mobile nodes due to mobility of mobile nodes. That is, in MANET, one network is easily divided into a plurality of networks as the mobile node moves, and information cannot be transmitted between the divided networks. Therefore, a node included in one divided network cannot access data of a node included in another network. As a result, MANET has a problem that data accessibility is significantly lower than that of fixed networks.

For this reason, the problem of improving data accessibility is an important issue in the ad hoc network technology field.

Accordingly, various approaches for improving data accessibility of ad hoc networks have been proposed, and one of these approaches is data copy allocation scheme. The data copy allocation scheme is a technique for improving accessibility of data by nodes in the same network creating and sharing a copy of original data before network partitioning.

Typical data copy allocation schemes include static access frequency (SAF), dynamic access frequency and neighborhood (DAFN), and dynamic connectivity based grouping (DCG). These techniques include data replication and nodes in neighboring nodes or data sharing groups. To allocate.

On the other hand, mobile nodes of MANET are limited in resources, so they may show a selfish tendency to use their resources for their own interests rather than for other nodes. In most peer-to-peer systems that share data with other hosts, nearly 70% of hosts only receive data and do not provide their data to other hosts (E. Adar and B). Huberman, "Free Riding on Gnutella," First Monday, Vol. 5, No. 10, Oct, 2000.). The same holds true for MANET, where resource-constrained mobile nodes attempt to conserve resources by using the resources of other nodes in their network. Indeed, in the case of MANET, about 40% of nodes in a network are selfish nodes (K. Balakrishnan, J. Deng and PK Varshney, "TWOACK: Preventing Selfishness in Mobile Ad Hoc Networks"). ", IEEE Communications Society, Wireless Communications and Networking (WCNC 2005), pp 2137-2142, 2005.).

These selfish nodes do not store even the data copies that are allocated as a result of performing the data copy allocation process to improve data accessibility of MANET. In addition, it does not attempt to use its resources for other nodes by ignoring other mobile nodes' requests for data copies they are storing.

However, the existing data copy allocation techniques have a problem in that they overlook the adverse effects of selfish nodes in MANET. In other words, the existing data copy allocation schemes are based on a MANET consisting of unselfish nodes only. It does not provide any solution to the deterioration of data accessibility and query processing performance of MANET caused by selfish nodes. There is a problem.

In addition, the existing data copy allocation schemes have a problem in that they are vulnerable in terms of data security because they cannot determine the reliability of nodes sharing data.

Accordingly, the first technical problem to be achieved by the present invention is to provide a self-contained node detection device that detects a self-contained node in a mobile ad hoc network and improves network efficiency as well as security.

A second technical problem to be achieved by the present invention is to provide a method for detecting a self-contained node that detects a self-contained node in a mobile ad hoc network to improve not only network efficiency but also security.

The third technical problem to be achieved by the present invention is to provide a method for allocating data copies that detects and removes a self-contained node in a mobile ad hoc network, thereby improving network efficiency as well as security.

In order to solve the first technical problem as described above, the present invention provides a device for detecting a selfish node in a first node of a mobile ad hoc network, usable data of the first node. A node information transceiving unit which transmits node information on storage size and stored data type to a second node, and receives node information on usable data storage size and stored data type of the second node; And a selfishness determining unit that determines selfishness of the second node in consideration of node information of the second node, network information including a distance of the second node and a number of communication connections with the second node. An apparatus for detecting a selfish node in a mobile ad hoc network is provided.

In order to solve the second technical problem as described above, the present invention provides a method for detecting a selfish node at a first node of a mobile ad hoc network. A node information receiving step of requesting and receiving node information regarding available data storage size and stored data type from the second node; And determining selfishness of the second node by considering node information of the second node, network information including the distance of the second node and the number of communication connections with the second node. It provides a method for detecting a self-node node in a mobile ad hoc network comprising a self-determination step.

In order to solve the third technical problem as described above, the present invention provides a method for allocating a data replica in a mobile ad hoc network, wherein the first node allocates an unselfish node and a data replica. Forming a data sharing group for sharing data; And a data sharing group coordination step wherein the first node detects and removes a self-contained node from the data sharing group while executing a data copy allocation process with a node of the data sharing group. do.

In an embodiment, the data sharing group forming step may include: receiving node information by the first node requesting and receiving node information regarding an available data storage size and a storage data type of a second node from the second node; ; And determining selfishness of the second node in consideration of node information of the second node, network information including the distance of the second node and the number of communication connections with the second node. Selfishness determination step.

In an embodiment, the receiving of the node information may include requesting node information of the second node by transmitting node information regarding an available data storage size and a stored data type of the first node to the second node. ; And the first node is an unselfish node in consideration of network information including the distance of the first node and the number of communication connections with the first node and the node information of the first node. If the step of approving the request.

In one embodiment, the selfishness determining step may include: counting a number of communication connections with the second node; And calculating a self interest index indicating a self interest index of the second node in consideration of the node information of the second node and the network information reflecting the counting result of the counting step.

In one embodiment, the calculating of self interest index may include: an equation;

Calculates the Selfishness Index, where S is the available data storage size of the second node, K is the storage data type of the second node, and CC is communication with the second node. The number of connections and f (h) represent a weight function proportional to the distance of the second node.

In an embodiment, the data sharing group forming may include determining the second node as an unselfish node when the self interest index is less than a predetermined threshold and including the second node. Forming a step.

The data sharing group adjusting step may include determining that the data sharing group is an unselfish node in the data sharing group forming step and executing a data copy allocation process with the second node included in the data sharing group. Determining the selfishness of the second node by calculating a selfishness index indicating the degree of selfishness of the second node in consideration of the node information, the network information, and the number of successful data requests of the first node for the second node. to be.

In one embodiment, the step of coordinating data sharing groups may include: equation;

Calculates the Selfishness Index, where S is the available data storage size of the second node, K is the storage data type of the second node, and CC is communication with the second node. The number of connections, f (h), is a weight function proportional to the distance of the second node, K _C is the number of successful data requests, and a is an experimentally determined weight.

The data sharing group adjusting may include detecting the second node as a selfish node and removing it from the data sharing group when the selfishness index is greater than a predetermined threshold.

The present invention provides the advantage of improving data accessibility and query processing performance over existing techniques by detecting and removing selfish nodes in a mobile ad hoc network environment.

In addition, the present invention provides an advantage of improving the security of the mobile node by allowing the mobile node to share data only with nodes that it can trust through selfishness determination on other nodes.

In addition, the present invention is a vehicle ad hoc network (Vehicular Ad-hoc Network), which is likely to meet a self-contained node due to frequent connection with mobile nodes of unknown information as well as existing wireless communication devices (PDA, Mobile Phone, etc.) ; VANET) can be applied easily and efficiently.

Prior to the description of the specific content of the present invention will be described the technical outline of the present invention for ease of understanding.

1A-1C show an application of a data copy allocation process in a mobile ad hoc network (MANET) without a selfish node.

As shown in Figs. 1A to 1C, the MANET includes mobile nodes M ₁ to M ₆ , and each of the mobile nodes M ₁ to M ₆ has its own original data D ₁ to D. ₆ ) is being saved. In FIG. 1A to FIG. 1C, the data stored by the mobile nodes M ₁ to M ₆ are their original data D ₁ to D ₆ and assigned data copies.

FIG. 1A illustrates an example of applying SAF (Static Access Frequency) to a MANET.

As shown in FIG. 1A, SAF is a method in which each mobile node arranges request priorities for the corresponding data according to the frequency of access to each data, and receives a copy of the data having a high data request priority. However, when SAFs have similar access frequencies for each data, the data request priorities of the nodes become similar to each other, and thus the data copies assigned to each node become similar. Therefore, there is a problem in that data replicas stored in each node are duplicated with each other, so that data accessibility is not so improved.

FIG. 1B illustrates an example of applying DAFN (Dynamic Access Frequency and Neighborhood) to a MANET.

As shown in FIG. 1B, DAFN is designed as a method for solving the duplication of data copies, which is a disadvantage of SAF. The DAFN first assigns a copy of the data to each node using SAF. Each node then compares the data copy it is storing with the data copy it is storing at its neighbors, and if there is a duplicate data copy, each node has a relatively low access frequency. The branch is configured to minimize the duplication of the data copy by having a node allocate a copy of another data to replace the duplicate data copy.

FIG. 1C illustrates an example in which DCG (Dynamic Connectivity based Grouping) is applied to a MANET.

As illustrated in FIG. 1C, the DCG forms a data sharing group by using connection information of mobile nodes, and compares access frequencies among nodes in the sharing group to allocate data. That is, the DCG divides the data sharing group using a bi-connected component based on the connection information of the mobile nodes, and adds all data access frequencies of each node belonging to the same group. Then, the sum of the data access frequencies is sorted to allocate a replica of the data from the most frequently accessed data to the nodes with the most frequently accessed data in the group. In this way, DCG allows nodes in the same group to share data without data duplication, and shows improved data accessibility than the two methods mentioned above.

However, the data copy allocation schemes consider only the case where the communication connection is physically disconnected due to the mobility of the mobile nodes of the MANET. In other words, it does not consider any selfish nodes that exist in MANET and hinder the smooth network flow.

Regarding the routing protocol of MANET, the types of selfish nodes can be classified into three types as follows.

Type 1

Type 1 selfish nodes participate in the Dynamic Source Routing (DSR) routing path discovery and path maintenance phase, but refuse to deliver larger data packets (data packets are generally larger than routing control packets). .)

Type 2

Type 2 selfish nodes do not participate in data packet delivery, nor do they participate in finding a DSR routing path. Type 2 selfish nodes use their resources only for packet transmissions that benefit them.

Type 3

Type 3 selfish nodes behave differently considering their resource situation. Type 3 selfish nodes have an upper threshold T1 and a lower threshold T2 for the resource situation so that when their resource situation is between E, which is the best, and T1, the type 3 selfish nodes play their role appropriately in the network. However, when its resource situation is between T1 and T2, it behaves like Type 1, and when it is less than T2, it behaves like Type 2. (The relationship of E, T1, T2 is E> T1> T2. )

Among the three types, type 2 can easily detect and remove the self-contained node in the routing process, but type 1 and 3 are very difficult to detect the self-contained node in the routing process. The presence of self-contained nodes in MANET has a negative effect on data management beyond the network layer.

2A and 2B illustrate problems that occur when there are selfish nodes in a MANET.

As shown in FIG. 2A, when the first mobile node A transmits a data request to the second mobile node B via the selfish node S, the selfish node S uses a large amount of its own resources. Since the request packet is not used, the request of the first mobile node A arrives at the second mobile node B.

 Then, the second mobile node B, which is an unselfish node, sends a packet of data in response to the request of the first mobile node A. FIG. However, the selfish node S ignores the large data packet of the second mobile node B without passing it to the first mobile node A and ignores the first mobile node A to receive data. Do not let it. Of course, the selfish node S also ignores the request for data it has. As a result, the data accessible in the case of the first mobile node A are A, C, and D, and in the case of the second mobile node B, only B, G, and H, In this case, A, B, C, D, E, F, G, H, S all data can be accessed.

Thus, as shown in FIG. 2B, it can be seen that when there are no selfish nodes, when there are one, and when there are two, the data accessibility of the MANET is sequentially poor.

As such, selfish nodes adversely affect the accessibility of other nodes while accessing data of neighboring nodes in MANET. In addition, selfish nodes have the adverse effect of delaying query processing time by having other nodes requesting data continue to wait for the requested data.

Accordingly, the present invention newly defines the characteristics of the selfish node that can be applied to the data management step, apart from the three types of selfish nodes adapted to the routing protocol at the network level, in order to prevent the adverse effects of the selfish node described above. In order to detect and remove the selfish node in the MANET by calculating a selfishness index representing the degree of selfishness of neighboring nodes in consideration of the characteristics of the defined selfish node.

In addition, the present invention is to form a data sharing group by reliable unselfish nodes to execute the data copy allocation process, and to detect and remove the self-contained node in the shared group again during execution of the data copy allocation process. Improve data accessibility and query latency performance in MANET.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to clarify the solutions of the technical problems of the present invention. However, in describing the present invention, when it is determined that the detailed description of the related known technology or configuration may make the gist of the present invention unclear, the detailed description thereof will be omitted. In addition, terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to intention or custom of a user, an operator, or the like. Therefore, the definition should be based on the contents throughout this specification.

3 is a block diagram showing an example of a self-node detection apparatus in a mobile ad hoc network according to the present invention.

4 is a flowchart illustrating an example of a method for detecting a selfish node in a mobile ad hoc network according to the present invention.

3 and 4, the selfishness detecting apparatus 300 according to the present invention is located in a mobile node of a mobile ad hoc network (MANET), and includes a node information transceiver 310 and a selfishness determiner 320. .

First, the node information transmission / reception unit 310 requests and receives node information, which is information for determining a selfishness of a second node to share data, with the second node (S410 to S432).

In order to define the node information received by the node information transceiver 310 for the selfishness determination of the second node, the characteristics of the selfish node defined in terms of data management should be considered.

In terms of data management, the characteristics of the selfish node can be defined as follows.

Attribute 1

The characteristics of the first selfish node try to minimize its resource usage. A selfish node with this characteristic only wants to receive data from other nodes, does not give its own data to other nodes, and uses its data storage only for itself.

In order to improve data accessibility, data replication and sharing must be performed smoothly, but if a selfish node with these characteristics is included in a shared group, data accessibility is impaired because it tries to use only its own data rather than giving an assigned copy of data.

Property 2

The characteristic of the second selfish node is that small packets, such as type 1 of the type of the selfish node related to routing, are transmitted because they do not have high energy consumption, but large data packets do not carry because their energy consumption is large. . As shown in FIG. 2A, the selfish node transmits a data request packet having a small packet size but ignores a packet having a large size including data.

This characteristic arises because the destination does not want its energy to be consumed when forwarding packets that are not itself to other nodes.

Attribute 3

The third nature of the selfish node is to join the data sharing group of the ad hoc network as much as possible to access and receive a lot of data, and if not, try to be included in the ad hoc network. Thus, selfish nodes want to join a network or data sharing group even by sending their own false information.

In consideration of the characteristics of the selfish node defined above, the node information for selfishness determination includes information on the available data storage size S of the target node and the type K of stored data stored in the target node.

Accordingly, the selfishness detecting apparatus 300 may use the available data storage size S1 of the first node in which it is located via the node information transceiver 310 and the data type K1 stored in the data storage 330. The node information of the first node is transmitted to the second node so as to request node information of the second node (S410).

Then, the second node determines selfishness of the first node by using node information of the first node (S420). If the first node corresponds to the selfish node (S422), the second node transmits a denial message to the first node (S430). On the other hand, if the first node does not correspond to a selfish node, that is, corresponds to an unselfish node (S422), the second node accepts the request of the first node and its available data storage size. Node information regarding the S2 and the stored data type K2 is transmitted to the first node (S432).

Through this process, the node information transceiver 310 receives the node information (S2, K2) of the second node.

Next, the selfishness determining unit 320, in the initial step (S410 to S450) of forming a data sharing group and the node information (S2, K2) of the second node, and the distance (h) of the second node The selfishness of the second node is determined in consideration of network information including the number of communication connections (CC) with the second node (S440).

On the other hand, as will be described again below, the selfishness determining unit 320 executes a data copy allocation process with nodes in the sharing group through the data transmitting / receiving unit 340 after the data sharing group is formed (S452 to S480). Further, the second node determines the selfishness by further considering whether the second node responds to the data request of the first node, that is, whether the first node succeeds in the data request.

For this selfishness determination, the selfishness determination unit 320 may include a counter unit 322 and a selfishness index calculator 324.

The counter unit 322 counts the number of times of communication connection with the second node (CC) and the number of successful data requests (K _C ) of the first node with respect to the second node.

In the initial stages S410 to S450, the self interest index calculator 324 reflects the node information S2 and K2 of the second node and the counting result of the counter unit 322. Taking into account CC), a Selfishness Index indicating the degree of selfishness of the second node may be calculated. In the execution steps S452 to S480, the selfishness index calculator 324 may calculate the selfishness index of the nodes of the data sharing group by further considering the number of successful data requests K _C.

In more detail, in the present invention, the self interest index indicating the degree of self interest of the mobile node is calculated in consideration of the characteristics of the self-defined node defined above. That is, in the initial steps (S410 to S450) the selfishness index (Selfishness Index) calculated by the selfishness index calculation unit 324 includes the asset factor (P) and risk factor (R), Selfishness Index = asset factor ( P) × risk factor (R) can be expressed as.

The asset element P may be represented as in Equation 1.

, (단, K≥1).

, Provided K≥1.

Included in the properties of the mobile nodes are the size (S) of the available data storage of each mobile node and the number of types (K) of data being stored.

5 shows a data store of a mobile node.

As shown in FIG. 5, the usable data storage size S of the mobile node may be represented by the difference between the total data storage size S _E and the storage size S _S that has already stored shared data. That is, if the total storage size of the mobile node is 7 and the storage size being used for storing shared data is 3, the size of the available data storage is 4 as S = 7-3.

Therefore, Equation 1 may be expressed as Equation 2.

, (단, S_E＞S_S, K≥1).

, Provided that S _E > S _S , K≥1.

As shown in Equations 1 and 2, the larger the size (S) of the available data storage, the smaller the value of the asset element (P), so the size of the self interest index is also smaller.

The type (K) of data stored in each mobile node is expressed as a number, and is basically larger than 1 since each mobile node has its own original data. As K increases, the value of the asset component P decreases, so the size of the self interest index decreases.

In Fig. 5, since K is 3, P = 1 / {(7-3) × K}, that is, 1/12.

The risk factor R may be expressed as in Equation 3.

, (단, CC≥1).

, Provided that CC≥1.

In order to calculate the selfishness index for each node, the risk factor must be included along with the asset factor P. Included in the risk of the mobile node is the number of communication connections (CC) with each node and the distance (f (h)) between the node.

The counter unit 322 counts the communication connection number CC. The counter unit may count and record the number of communication connections (CC) with each node through a connectivity table as shown in Table 1. Here, the communication connection means a connection in the network side.

In MANET, as the number of communication connections between mobile nodes increases, the probability that the two nodes are at a close distance is high, and the direction of movement is the same. The default value of the communication connection count (CC) is set to 1 and is increased by 1 whenever a connection is made with the corresponding node. As the number of times of the communication connection increases, the corresponding node may be determined to be in proximity, so the 1 / CC value is included in the risk factor R.

In addition, the longer the hop to the selfish determination target node is, the more easily the connection is broken and the reliability is less likely. Therefore, the distance of the target node is included in the risk factor (R). f (h) is a weight function that gives a weight in proportion to the distance of the target node.

6 is a graph illustrating a weight function proportional to the distance from the target node.

As shown in FIG. 6, the self interest index may be affected by the distance by applying a weight function that increases exponentially in proportion to the distance between the mobile nodes and uses the resultant value.

As a result, the self interest index in the initial steps (S410 to S450) can be calculated by the equation (4).

As shown in Equation 4, the larger the value of the self interest index is, the higher the probability is that the node is a selfish node.

The selfishness determining unit 320 determines the selfishness of the second node by comparing the selfishness index calculated by the selfishness index calculating unit 324 with a predetermined threshold (S440 and S442).

That is, when the calculated self interest index is greater than the threshold, the second node is determined to be a selfish node (S442), and the first node transmits a rejection message to the second node (S450).

On the other hand, when the calculated self interest index is smaller than the threshold, the second node is determined to be an unselfish node (S442), and allows the first node to share data including the second node ( data sharing group) and a data copy allocation process (S452).

Next, the selfishness determining unit 320 performs the data copy allocation process with the nodes in the sharing group after the data sharing group is formed, as described above, in step S452 to S480, the data of the first node. The self-interest of the second node is determined by further considering whether the second node has responded to the request, that is, whether the first node has successfully requested a data for the second node (S460 through S472).

That is, the counter unit 322 also counts the number of successful data requests K _C of the first node with respect to the second node included in the shared group during the execution of the data copy allocation process (S460).

The counter unit 322 increases 1 when the second node included in the data sharing group transmits data to the data request of the first node as shown in Equation 5, and decreases 1 when there is no response. .

The counter unit 322 may count the number of successful data requests of the first node for each node included in the sharing group using a table as shown in Table 2.

Then, the self interest index calculation unit 324, the node information (S2, K2) of the second node, the network information (h, CC) reflecting the counting result of the counter unit 322, and the first node The self interest index of the second node included in the data sharing group is calculated in consideration of the number of successful data requests K _C.

For example, the selfishness index calculator 324 may calculate the selfishness index by Equation 6 in the execution steps S452 to S480.

In Equation 6, K _C represents the number of successful data requests of the first node, and a represents an experimentally determined weight.

As shown in Equation 6, the larger the value of the self interest index is, the higher the probability is that the node is a selfish node.

The selfishness determining unit 320 determines the selfishness of the second node included in the data sharing group by comparing the selfishness index calculated by the selfishness index calculating unit 324 with a predetermined threshold. (S470, S472).

That is, when the calculated self interest index is greater than the threshold value, the second node is determined to be a selfish node (S472), and the first node removes the second node from the data sharing group and the second node. The process of allocating the data replica with the server is stopped (S480).

On the other hand, if the calculated self interest index is smaller than the threshold value, the second node is determined to be an unselfish node (S472), and if the network connection is maintained (S474), the first node causes the execution step ( S452 to S480) to repeat the process.

When a data copy allocation process is executed, the data transceiver 340 of the first node transmits a data copy corresponding to the original data of the first node to the data sharing group nodes, and the data of the data sharing group nodes. A copy is received and stored in the data store 330 of the first node.

The present invention may occur in the initial steps (S410 to S450) by continuously measuring K _C and reflecting it in the selfishness determination of the mobile node even while the data copy allocation process is executed through the execution steps (S452 to S480). This can prevent trickery of selfish nodes.

7 shows an example of a data copy allocation method in a mobile ad hoc network in accordance with the present invention.

Referring to FIG. 7, the method for allocating a data copy according to the present invention includes a data sharing group forming step (S710 and S720) and a data sharing group adjusting step (S730 to S760).

First, in the data sharing group forming step (S710, S720), the first node calculates a selfishness index (Selfishness Index) indicating the degree of selfishness of the mobile nodes (S710), and determines the selfishness (S710) In operation S720, a data sharing group for sharing data with unselfish nodes is formed.

The detailed processes corresponding to the initial steps (S410 to S450) of the method for detecting a selfish node according to the present invention described above are equally applicable to the calculation of the selfishness index and the selfishness determination process in the data sharing group forming steps (S710 and S720). Can be.

Next, in the data sharing group adjustment step (S730 to S760), the first node executes a data copy allocation process with the nodes in the data sharing group (S730), and the data sharing during the data copy allocation process is executed. In operation S740, a self interest index for the nodes in the data sharing group is calculated in consideration of the number of successful data requests of the first node for the nodes in the group. In operation S750, nodes included in the data sharing group are adjusted by detecting and removing the selfish node through the calculated selfish index.

The detailed processes corresponding to the execution steps S452 to S480 of the method for detecting a selfish node according to the present invention described above are equally applied to the calculation of the selfishness index and the selfishness determination process in the data sharing group adjustment steps S730 to S760. Can be.

While maintaining the network connection (S760), the first node repeats the data sharing group forming step (S710, S720) and the data sharing group adjusting step (S730 to S760) to continuously form and share the data sharing group. Adjust

As described above, the data copy allocation method according to the present invention allows any mobile node of the MANET to construct a self-centered friend tree (SCFT) around itself through the creation and coordination of data sharing groups. do.

8 shows an example of an SCFT configured by each mobile node by the data copy allocation method according to the present invention.

In FIG. 8, the SCFT is limited to 1 hope. As shown in FIG. 8, the mobile nodes M ₁ to M ₆ store the original data and the data copies of the respective destinations as a result of performing a data copy allocation process. M ₁ forms a shared group with M _2, and the selfish node M ₃ is determined to be a selfish node in the data sharing group forming steps S710 and S720 and is excluded from the sharing group. Since M ₂ has already established a trust group with M ₁ and formed a shared group, it is not necessary to form a group again, thus forming a shared group with M ₄ . In case of M ₄ , M ₅ is already formed with M _2. And a shared group with M ₆ , and other nodes perform the same process. M ₅ may be excluded from one or conclude a M ₆ and groups the selfishness index calculation formula is selfishness index value of the M ₆ obtained by the (Equation 4 or 6) does not form a covalent group if it exceeds a predetermined threshold value shared group Can be.

The invention can also be embodied as computer readable program code on a computer readable recording medium. When the present invention is executed through software, the constituent means of the present invention are code segments for performing necessary tasks. The program or code segments may be stored on a processor readable medium or transmitted by a computer data signal coupled with a carrier on a transmission medium or network.

The computer-readable recording medium includes all kinds of recording devices for storing data that can be read by a computer system. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disks, optical data storage devices, and the like. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

Hereinafter, the significant effects of the present invention are verified.

9A and 9B graphically show the results of a performance experiment of the present invention.

In order to evaluate the performance of the present invention, 40 mobile nodes were simulated in a space of 50 * 50 size, and mobile nodes M = {M1, ..., M40}, and data were D = {D1, .. ., D40}. Each mobile node Mi has data Di as original data. In addition, the mobile node can store up to C data, and the mobile node can move freely without placing any restrictions on the movement of the mobile node. Other variables of other mobile nodes are fixed as shown in Table 3.

As shown in Table 3, d represents the moving speed of the node and is set to 1. T refers to a period of calculating the initial steps (S410 to S450) of the method for detecting the selfish node or allocating data to each mobile node. That is, it represents the time taken until the next calculation after calculating the selfish index, and was set to 256 seconds. R represents the communication range of the mobile node and is set to 7. C represents the number of data that the mobile node can store and is set to 10. In fact, as a result of the experiment, it was judged that the change of R and C did not affect the experiment because it showed similar results. The weight a for calculating the self index was set to 0.6.

In order to evaluate the performance of the present invention, DCG, which is the most efficient of the existing data copy allocation schemes, is applied to remove the selfish node by applying the initial stage of the method of Selfish node detection according to the present invention, and the data copy is performed by DCG. We compared the performance of SD_DCG, which is allocated to SD_DCG, and SD_SCFT, which is a data copy allocation method according to the present invention.

9A shows a graph of data accessibility performance test results.

As shown in FIG. 9A, since the existing DCG is based on a stabilized MANET without a selfish node, data accessibility is drastically deteriorated as the number of mobile nodes having selfishness increases. The SD_DCG to which the present invention is partially applied does not show a significant improvement in data accessibility because the removal of the selfish node in the initial stage does not have a high probability of generating a stabilized data sharing group.

On the other hand, in the present invention (SD_SCFT), the data sharing group is formed and adjusted by removing the selfish node through the initial step and the execution step of the method for detecting the selfish node, thereby forming a stabilized data sharing group. The results show that data accessibility is improved by about 10%.

9B is a graph showing a query delay performance test result.

The query delay is the time when a mobile node of MANET makes a data request and a response to the request comes. As shown in FIG. 9B, it can be seen that the query delay increases as the number of selfish nodes increases on the MANET.

In the case of the existing DCG, since the selfish node discards the response packet having a large packet size, the time for which the requesting mobile node waits for the response increases exponentially to the query's life time. Both SD-DCG and the present invention (SD-SCFT) to which the present invention is partially applied show much lower query delay than DCG. The reason why the present invention (SD-SCFT) shows a higher query delay than the SD-DCG to which the present invention is partially applied is because the probability of success of the request is higher than that of the SD-DCG when the present invention (SD-SCFT) is applied. This is a trade-off between data accessibility and query latency.

As described above, the present invention provides an advantage of improving data accessibility and query processing performance over existing techniques by detecting and removing selfish nodes in a mobile ad hoc network environment. In addition, the present invention provides an advantage of improving the security of the mobile node by allowing the mobile node to share data only with nodes that it can trust through selfishness determination on other nodes.

In addition, the present invention is a vehicle ad hoc network (Vehicular Ad-hoc Network) that is likely to meet a self-contained node because of frequent connection with mobile nodes of unknown information as well as existing wireless communication devices (PDA, Mobile Phone, etc.) ; VANET) can be applied easily and efficiently.

So far, the present invention has been described with reference to the embodiments. However, one of ordinary skill in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential technical spirit of the present invention. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. That is, the true technical scope of the present invention is shown in the appended claims, and all differences within the equivalent scope will be construed as being included in the present invention.

1A to 1C are diagrams showing application examples of a data copy allocation process in a MANET without a self-node.

2A and 2B illustrate problems that occur when there are selfish nodes in a MANET.

3 is a block diagram showing an example of an apparatus for detecting a selfish node in a mobile ad hoc network according to the present invention;

4 is a flowchart illustrating an example of a method for detecting a selfish node in a mobile ad hoc network according to the present invention.

5 illustrates a data store of a mobile node.

6 is a graph illustrating a weighting function proportional to the distance from a target node.

7 is a flowchart illustrating an example of a method for allocating data copies in a mobile ad hoc network according to the present invention.

8 is a diagram showing an example of an SCFT configured by each mobile node by a data copy allocation method according to the present invention;

9A and 9B are graphs showing the results of a performance experiment of the present invention.

Claims (19)

An apparatus for detecting a selfish node at a first node of a mobile ad hoc network, Node information transmission and reception of node information on the usable data storage size and storage data type of the first node and receiving node information on the usable data storage size and storage data type of the second node. part; And And a selfishness determining unit that determines selfishness of the second node in consideration of node information of the second node, network information including a distance from the second node and a number of communication connections with the second node. An apparatus for detecting self nodes in a mobile ad hoc network. The method of claim 1, The selfishness determining unit, when the first node is executing a data copy allocation process with the second node, further determines the selfishness of the second node by further considering whether the first node has successfully requested a data for the second node. An apparatus for detecting selfish nodes in a mobile ad hoc network. The method of claim 2, The selfish determination unit, A counter unit for counting the number of communication connections with the second node and the number of successful data requests of the first node; And And a selfishness index calculator for calculating a selfishness index indicating a degree of selfishness of the second node in consideration of node information of the second node, the network information reflecting a counting result of the counter, and the number of successful data requests. An apparatus for detecting self nodes in a mobile ad hoc network. The method of claim 3, And the selfishness determining unit determines the selfishness of the second node by comparing the selfishness index with a predetermined threshold. A method for detecting a selfish node at a first node of a mobile ad hoc network, A node information receiving step, in which a first node requests and receives node information regarding an available data storage size and a stored data type of a second node, from the second node; And Determine the selfishness of the second node by considering the node information of the second node, network information including the distance with the second node and the number of communication connections with the second node. A self-node detection method in a mobile ad hoc network comprising a self-determination step. The method of claim 5, The node information receiving step, Requesting node information of the second node by transmitting node information regarding the available data storage size and the stored data type of the first node to the second node; And The first node is an unselfish node in consideration of network information including a distance between the first node and the number of communication connections with the first node and node information of the first node. And approving the request if the self-node node in the mobile ad hoc network. The method of claim 5, The selfishness determining step, when the first node is executing a data copy allocation process with the second node, further determining the selfishness of the second node in consideration of whether the first node's data request success for the second node; Self-contained node detection method in a mobile ad hoc network, characterized in that the step of. The method of claim 7, wherein The selfish determination step, Counting the number of communication connections with the second node and the number of successful data requests of the first node; And And calculating a self interest index indicating a self interest index of the second node in consideration of node information of the second node, the network information reflecting the counting result of the counting step, and the number of successful data requests. A method for detecting selfish nodes in a mobile ad hoc network. The method of claim 8, The self-determination step of the self-adjustment node detection method in the mobile ad hoc network, characterized in that the step of determining the self-interest of the second node by comparing the self-exposure index with a predetermined threshold. In a method of allocating a copy of a data in a mobile ad hoc network, A first node assigning a data replica with an unselfish node to form a data sharing group for sharing data; And And a data sharing group coordination step wherein the first node detects and removes a selfish node from the data sharing group while executing a data copy allocation process with the nodes of the data sharing group. The method of claim 10, The data sharing group forming step, A node information receiving step, wherein the first node requests and receives node information regarding the available data storage size and the stored data type of the second node from the second node; And Determine the selfishness of the second node by considering the node information of the second node, network information including the distance with the second node and the number of communication connections with the second node. A method of allocating data replicas in a mobile ad hoc network comprising a selfish determination step. The method of claim 11, The node information receiving step, Requesting node information of the second node by transmitting node information regarding the available data storage size and the stored data type of the first node to the second node; And The first node is an unselfish node in consideration of network information including a distance between the first node and the number of communication connections with the first node and node information of the first node. And approving the request if the data copy allocation method in the mobile ad hoc network. The method of claim 11, The selfish determination step, Counting a number of communication connections with the second node; And A mobile ad hoc network calculating step of calculating a self index, which represents the degree of self interest of the second node in consideration of the node information of the second node and the network information reflecting the counting result of the counting step; How to Allocate a Replica of Data The method of claim 13, The step of calculating the self interest index, Equation 1;

Calculates the Selfishness Index, wherein, in Equation 1, S is the usable data storage size of the second node, K is the storage data type of the second node, and CC is the second node. And a number of communication connections in the network, and f (h) represents a weight function proportional to the distance to the second node. The method of claim 14, The forming of the data sharing group may include determining the second node as an unselfish node and forming the data sharing group including the second node when the selfishness index is smaller than a predetermined threshold. A method for allocating data replicas in a mobile ad hoc network. The method of claim 11, The data sharing group adjustment step may include determining node information of the second node and the network during a data copy allocation process with the second node included in the data sharing group determined as an unselfish node in the data sharing group forming step. Determining a selfishness of the second node by calculating a selfishness index indicating a degree of selfishness of the second node in consideration of information and the number of successful data requests of the first node for the second node. Method of allocating data replicas in a mobile ad hoc network. The method of claim 16, The data sharing group adjustment step, Equation 2;

Calculates the Selfishness Index by Equation 2, wherein S is the usable data storage size of the second node, K is the storage data type of the second node, and CC is the second node. Is a weight function proportional to the distance to the second node, K _C is the number of successful data requests, and a represents a weight for the number of successful data requests. A method for allocating data replicas in a mobile ad hoc network. The method of claim 17, The data sharing group adjusting step includes detecting the second node as a selfish node and removing it from the data sharing group when the selfishness index is greater than a predetermined threshold. Way. 19. A computer readable recording medium having recorded thereon a program for executing the method of any one of claims 5-18.

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