KR20090069960A - Communication system and method for effective route repair in ad hoc network - Google Patents

Abstract

A communications system for an efficient path restoration using filtering operation in an AD hoc network and a communications method are provided to minimize the truncation of data transmission by reducing a delay time to a recovery of route. A message transceiver(201) receives and transmits a message of a routing request message and a route reply message. A filtering unit(202) filters path information corresponding to one message according to a specific filtering method. A route information storage unit(203) stores the filtered routing information. The specific filtering method allows the affirmation error of the single number and reduces the size of the filtering object data.

Description

COMMUNICATION SYSTEM AND METHOD FOR EFFECTIVE ROUTE REPAIR IN AD HOC NETWORK}

The present invention relates to a communication system and a communication method for efficient path recovery in an ad hoc network.

Due to the characteristics of the ad hoc network whose network structure changes dynamically, the routing protocol is a key technology for constructing the ad hoc network. In ad hoc networks, routing protocols can be classified into three types according to the routing method.The proactive routing protocol in which each node periodically updates and stores routing information, and a destination when data transmission is required There is a reactive routing protocol that obtains routing information up to and a hybrid routing protocol that combines both methods.

Reactive routing protocols are commonly used in ad hoc networks. Reactive routing protocols can quickly route to new destinations and do not require routing information for nodes that are not required to route. Nonetheless, it has an algorithm suitable for an ad hoc network composed of mobile nodes with limited performance.

The routing protocol can be divided into a path search procedure that executes data transmission when necessary and a path maintenance procedure that maintains a set path. The messages used at this time are a path request message, a path response message, and a path error message.

The route request message is used by the source node for route discovery to the destination node. The source node sends the route request message to other nodes in the ad hoc network in a broadcast manner. If the node receiving the route request message is a destination node to which data should be sent or an intermediate node having routing information to the destination node, the route response message is used in response to the route request message. The route response message is sent to the source node in a unicast manner. If the node that receives the route request message does not apply to the above-mentioned content, the routing information from the source node to the intermediate node received is stored, and then the route request message is transmitted to the neighbor node. The path error message is used by the parent node of the disconnected node to transmit the information of the disconnected path to the source node when the established routing path is disconnected.

The present invention reduces the delay time until the path is restored by searching for an alternative communication system based on the stored path information through the filtering when the path is disconnected in an ad hoc network. Provided is a communication system and method capable of minimizing data transmission disconnection.

The present invention provides a communication system and method that can reduce the load on the network and bandwidth by reducing the frequency of attempting to re-route the route without using periodic location messages.

According to an embodiment of the present invention, a communication system includes a message transceiver for transmitting and receiving at least one message of a path request message and a path response message, a filter for filtering path information corresponding to the one message, and the filtered part. It includes a route information storage for storing the route information.

According to an aspect of the invention, the filtering unit may filter the path information according to a filtering method that allows a certain number of false positives and reduces the size of the data to be filtered.

According to an aspect of the present invention, the filtering unit may separately filter the path information into blocks having a predetermined size, and convert the filtered path information into a single filter value by connecting the individually filtered blocks.

According to an aspect of the present invention, the communication system for searching in the path information storage for an alternative communication system including a path disconnect recognition unit for detecting a path disconnection to a destination communication system and path information to the destination communication system. It may further include an alternative communication system search unit. In this case, the alternative communication system search unit may search for the alternative communication system based on a filter value generated by filtering address information of the destination communication system and identifier information of a specific communication system included in the path request message.

According to an embodiment of the present invention, a communication system may include: a first filter value generator that generates a first filter value by filtering path information corresponding to a received message, address information of a destination communication system, and identifier information of a specific communication system; And a second filter value generator for filtering and generating a second filter value, and an alternative communication system checking unit for checking whether the specific communication system is an alternative communication system based on the first filter value and the second filter value.

According to an embodiment of the present invention, a communication method includes receiving at least one message of a path request message and a path response message, filtering and storing path information corresponding to the received message, and receiving the message according to the received message. Transmitting the route request message or the route response message.

The communication method according to an embodiment of the present invention includes generating a first filter value by filtering path information corresponding to a received message, filtering address information of a destination communication system and identifier information of a specific communication system, and then filtering the second filter. Generating a value and determining whether the specific communication system is an alternative communication system based on the first filter value and the second filter value.

According to the present invention, when a path break occurs in an ad hoc network, the delay time until the path is restored by searching for an alternative communication system based on the stored path information and performing local recovery is performed. It can be reduced to minimize data transmission disconnection.

According to the present invention, it is possible to reduce the load on the network and bandwidth by reducing the frequency of attempting to re-route the path without using the periodic location message.

Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

1 is an example illustrating an overview of an ad hoc network. The ad hoc network 100 may be composed of a plurality of nodes, and may transmit a message to a target node through communication between neighboring nodes in one node. That is, as shown in FIG. 1, if the message is to be transmitted from the source node 'S' 101 to the destination node 'D' 102, the source node 'S' 101 first searches the route table. It checks whether a route to the destination node 'D' 102 exists and, if the route does not exist, transmits a route request message to a neighboring node.

In this case, the route request message may be transmitted by broadcast, and a node that is included in a transmission range and receives the route request message may be the neighboring node. That is, in the example of FIG. 1, it is assumed that the node 'A' 103 and the node 'B' 104 receive the route request message transmitted from the source node 'S' 101.

The node 'A' 103 and the node 'B' 104 which have received the route request message retransmit the route request message based on the information on the destination node 'D' 102 included in the route request message. Or send a path response message to the source node 'S' 101. For example, the node 'A' 103 transmits the route response message to the source node 'S' 101 when the destination of the route request message is itself or stores information about the destination. If it is not the destination or if the information on the destination is not stored, the route request message can be retransmitted to its neighbor node. In the case of FIG. 1, node 'B' 104 and node 'C' 105 are taken as examples of neighboring nodes of node 'A' 103.

That is, when there is a node storing information about the destination between the source node 'S' 101 and the destination node 'D' 102, the path from the node to the source node 'S' 101 is detected. If there is no node that transmits a response message and stores information on the destination, after receiving the route request message at the destination node 'D' 102, the route response message is sent to the source node 'S'. Send to 101. For example, if storing information about a route from node 'Y' 106 to destination node 'D' 102, node 'Y' 106 instead of resending the route request message, The route response message is transmitted to the source node 'S' 101.

At this time, when the node (node 'Y' 106 in the above example) or the destination node 'D' 102 wishes to transmit, the route response message is based on a route table recorded in the route request message. The optimal path to the node 'S' 101 may be identified and the path response message may be transmitted to the optimal path.

In this way, when the route response message is received at the source node 'S' 101, the route to the destination node 'D' 102 can be set, and to the destination node 'D' 102 via the route. The first intended message can be sent.

2 is a block diagram illustrating an internal configuration of a communication system according to an embodiment of the present invention. The communication system 200 illustrated in FIG. 2 is a system corresponding to one node that may be included in the ad hoc network 100 described with reference to FIG. 1 or a system that may be included in the node. The message transmission / reception unit 201 And a filtering unit 202, a path information storage unit 203, a message transmission control unit 204, a path disconnection recognition unit 205, and an alternative communication system search unit 206.

The message transceiver 201 transmits and receives at least one message of a path request message and a path response message. For example, the communication system 200 may transmit the route request message as a source node, receive the route response message or receive the route request message as a destination node in the ad hoc network 100 described with reference to FIG. 1. The path response message may be transmitted. Alternatively, the path request message and the path response message may be received and transmitted as an intermediate node between the source node and the destination node.

The filtering unit 202 filters the path information corresponding to the one message. In this case, the filtering unit 202 may filter the path information according to a filtering method that allows a certain number of false positives and reduces the size of the filtering target data. In addition, in order to reduce the false positives, the filtering unit 202 may divide the path information into blocks having a predetermined size and filter them individually, and then connect the individually filtered blocks to convert one filter value. A method of filtering the path information will be described in more detail with reference to FIG. 3.

The route information storage unit 203 stores the filtered route information. That is, the size of the stored data may be greatly reduced by converting and storing the filtered path information whose size is reduced through the filtering into one filter value without storing all the path information.

The message transmission control unit 204 controls retransmission of the route request message or transmission of the route response message according to the one message. In this case, when the communication system 200 is the destination communication system or stores the information of the destination communication system based on the identifier or address of the destination communication system included in the route request message, the message transmission control unit 204 The route response message may be controlled to be transmitted to the source communication system. On the other hand, if the communication system 200 is not the destination communication system and does not store the information, the path request message can be controlled to be transmitted back to its neighboring communication system.

The path disconnection recognition unit 205 recognizes a path disconnection to the destination communication system. In this case, when the path disconnection recognition unit 205 recognizes the path disconnection, the communication system 200 determines whether the communication system 200 is closer to the destination communication system or the source communication system, and is closer to the source communication system. In addition, the route error message may be transmitted to the source communication system so that the route re-search is started in the source communication system. On the other hand, if the communication system 200 is closer to the destination communication system, the communication system 200 performs local recovery. The local recovery is to recover the path disconnection and recover the path disconnection using the alternative communication system searched by the alternative communication system search unit 206 described below.

The alternate communication system search unit 206 searches the route information storage unit 203 for an alternate communication system including route information to the destination communication system. In this case, the alternative communication system searching unit 206 may search the alternative communication system based on the filter value generated by filtering the address information of the destination communication system and the identifier information of the specific communication system included in the route request message. have. Here, the filter value may be generated by dividing the address information and the identifier information into blocks having a predetermined size and separately filtering the divided blocks, and the alternative communication system search unit 206 may include a path information storage unit. If there is filtered path information that matches all of the filtered blocks among the filtered path information included in 203, the specific communication system may be searched as the alternative communication system. As described above, a method of searching for the alternative communication system will be described in more detail with reference to FIG. 5.

As described above, the communication system according to an embodiment of the present invention identifies an alternative communication system including information on a path to a destination communication system by using the stored path information through filtering when the path is disconnected, and the alternative communication. By performing local recovery using the system, it is possible to minimize the data transmission interruption by reducing the delay before the path is restored. In addition, it can reduce the load on network traffic and bandwidth by reducing the frequency of attempting to re-route the route without using periodic positioning messages.

3 is an example of a method of filtering route information. Here, the route information 301 may include route table information set by the route request message and the route response message. 4 is an example of route table information set according to a route request message. FIG. 4 shows the route table at each node 'A', 'B', 'C', 'X' and 'Y' receiving the route request message in the example of the ad hoc network 100 described in FIG. An example of information is shown. That is, each time the path request message and the path response message are received, a very large storage space is required to set and store all of the path table information. However, nodes in an ad hoc network generally have limited resources. Therefore, the communication system according to an embodiment of the present invention provides a method of filtering and storing the route table information.

In this case, a method using a bloom filter may be used as the filtering method. The bloom filter allows a small number of false positives to significantly reduce the size of the data. That is, the bloom filter reduces the size of data by using a plurality of hash functions. The size of the output data is constant regardless of the size of the input data. In addition, the ratio of false positives is reduced by the size of the output data and the number of hash functions. Another characteristic of the bloom filter is that it is possible to make several input data into one output data, and that no false negative occurs.

That is, the predetermined number of blocks 302 are generated by dividing the route information 301 into blocks having a predetermined size, and each of the predetermined number of blocks 302 is filtered using the bloom filter to each of the blocks. Filter values for the The filter values may be connected to each other and stored as one filter value 303.

5 is an example for explaining a method of searching for an alternative communication system. In the example of FIG. 5, each of the four blocks may be individually filtered in the path information 501 blocked with four blocks, and each filter value may be stored as one filter value 502.

Upon recognizing a path break in one communication system, the communication system can retrieve the alternate communication system containing the path information to the destination communication system using the one stored filter value 502 as described above.

First, the communication system may classify alternative communication system search data, which is address information of the destination communication system and identifier information of a specific communication system, included in the path request message into blocks of a predetermined size, wherein The size may be equally distinguished from each of the four blocks.

The communication system then filters each block of blocked alternate communication system search data 503 to produce a filter value 504, wherein a portion or all of one filter value 502 is associated with the entire filter value 504. By checking whether there is a match, it is possible to confirm whether the specific communication system knows route information to the destination communication system.

If one filter value 502 does not match the entire filter value 504, the same filtering and comparison process may be performed using an identifier of another communication system instead of the specific communication system or another stored filter value and filter. By comparing the value 504, an alternate communication system can be retrieved that includes route information for the destination communication system.

6 is a flowchart illustrating a communication method according to an embodiment of the present invention.

In step S601, the communication system receives at least one message of a path request message and a path response message. For example, the communication system may receive the route response message as a source node or the route request message as a destination node or an intermediate node in the ad hoc network 100 described with reference to FIG. 1.

In step S602, the communication system filters and stores path information corresponding to the received message. In this case, the communication system may filter the path information according to a filtering method that allows a certain number of false positives and reduces the size of the data to be filtered. In addition, in order to reduce the false positive, the communication system may divide the path information into blocks having a predetermined size and individually filter them, and connect the individually filtered blocks to convert one filter value.

In step S603, the communication system transmits the path request message or the path response message according to the received message. That is, the communication system may transmit the path request message or the path response message as the intermediate node in the ad hoc network 100, or transmit the path request message as the destination node.

In step S604, when the communication system recognizes the path disconnection of the path request message to the destination communication system, step S605 is performed. Here, steps S601 to S603 may be performed when the path request message or the path response message is received, and step S605 may be performed by disconnecting the path as in step S604 as described above. It may be performed when it is recognized.

That is, when the path disconnection is recognized, the communication system determines whether the communication system is closer to the destination communication system or the source communication system, and determines a path error message when the communication system is closer to the source communication system. Transmission to a source communication system may be such that the route re-search is started in the source communication system. On the other hand, when the communication system is closer to the destination communication system, local communication is performed in the communication system. The area recovery may be performed as step S605 described below to recover the path disconnection.

In step S605, the communication system searches for an alternative communication system including route information to the destination communication system. In this case, the communication system may search for the alternative communication system based on the filter value generated by filtering the address information of the destination communication system and the identifier information of the specific communication system included in the path request message and the filtered path information. Can be. In more detail, when the filtered path information includes all of the filter values, the communication system may search for the alternative communication system. It may be determined that the filter information filtered by the same filtering method and the filtered route information include both the identifier information and the address information when the filtered route information includes all of the filter values. This is because it is known that the specific communication system includes the address information.

7 is a block diagram illustrating an internal configuration of a communication system according to another embodiment of the present invention. Here, the communication system 700 includes a first filter value generator 701, a second filter value generator 702, and an alternative communication system searcher 703 as shown in FIG. 7.

The first filter value generator 701 filters the path information corresponding to the received message to generate a first filter value, and the second filter value generator 702 is configured to generate address information of the destination communication system and address information of the specific communication system. The second filter value is generated by filtering the identifier information. In this case, the first filter value generator 701 may divide the path information into blocks having a predetermined size and filter them separately, and connect the individually filtered blocks to generate the first filter value. The second filter value generator 702 may generate the second filter value by dividing the address information and the identifier information into blocks having the same size as the block and individually filtering them.

The received message may include at least one message of a route request message and a route response message, and the route information may include route table information set by the route request message or the route response message. .

That is, when the communication system 700 receives the path request message or the path response message, the communication system 700 may generate the path information as the first filter value and cope with the path disconnection when the generated first filter value is generated. Can save for. Thereafter, the communication system 700 may allow the second filter value generator 702 to generate the second filter value in order to search for an alternative communication system when the path disconnection is recognized.

The alternative communication system searching unit 703 checks whether the specific communication system is an alternative communication system based on the first filter value and the second filter value. Here, when the first communication value includes all of the values corresponding to each of the filter values, the alternative communication system search unit 703 may identify the specific communication system as the alternative communication system. That is, the first filter value and the second filter value are generated using a filtering method that does not include a negative error and allows only a positive error, and confirms that the second filter value is included in the first filter value. The specific communication system may verify that the path information of the destination communication system is known.

8 is a flowchart illustrating a communication method according to another embodiment of the present invention.

In step S801, the communication system filters the path information corresponding to the received message to generate a first filter value. In this case, the communication system may filter the path information by dividing the path information into blocks having a predetermined size and connecting the individually filtered blocks to generate the first filter value.

In step S802, the communication system filters the address information of the destination communication system and the identifier information of the specific communication system to generate a second filter value. In this case, the communication system may generate the second filter value by separately dividing the address information and the identifier information into blocks having the same size as the block.

In step S803, the communication system checks whether the specific communication system is an alternative communication system based on the first filter value and the second filter value. In this case, when the first filter value includes all of the values corresponding to each of the filter values, the communication system may identify the specific communication system as the alternative communication system.

This step S803 may be performed when a path disconnection is recognized in the communication system. That is, the first filter value and the second filter value are generated using a filtering method that does not include a negative error and allows only a positive error, and confirms that the second filter value is included in the first filter value. The specific communication system may verify that the path information of the destination communication system is known.

As described above, when using a communication system or a communication method according to an embodiment of the present invention, when a path disconnection occurs in an ad hoc network, the path is found by searching for an alternative communication system based on the stored path information through filtering and performing local recovery. It can reduce the data transmission interruption by reducing the delay time to recover, and reduce the load on the network and bandwidth by reducing the frequency of attempting to rescan the path without using the periodic positioning message.

Embodiments according to the present invention can be implemented in the form of program instructions that can be executed by various computer means can be recorded on a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on the media may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

In the present invention as described above has been described by the specific embodiments, such as specific components and limited embodiments and drawings, but this is provided to help a more general understanding of the present invention, the present invention is not limited to the above embodiments. For those skilled in the art, various modifications and variations are possible from these descriptions.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and all the things that are equivalent to or equivalent to the claims as well as the following claims will belong to the scope of the present invention. .

1 is an example illustrating an overview of an ad hoc network.

2 is a block diagram illustrating an internal configuration of a communication system according to an embodiment of the present invention.

3 is an example of a method of filtering route information.

4 is an example of route table information set according to a route request message.

5 is an example for explaining a method of searching for an alternative communication system.

6 is a flowchart illustrating a communication method according to an embodiment of the present invention.

7 is a block diagram illustrating an internal configuration of a communication system according to another embodiment of the present invention.

8 is a flowchart illustrating a communication method according to another embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

200: communication system

201: message transceiver

202: filtering unit

203: path information storage unit

204: message transmission control unit

205: path disconnect recognition unit

206: alternative communication system search unit

Claims (20)

A message transceiving unit configured to transmit and receive at least one message of a path request message and a path response message; A filtering unit to filter path information corresponding to the one message; And Route information storage unit for storing the filtered route information Communication system comprising a. The method of claim 1, The filtering unit, And the path information is filtered according to a filtering method that allows a certain number of false positives and reduces the size of data to be filtered. The method of claim 1, The filtering unit, And dividing the path information into blocks having a predetermined size and individually filtering them, and connecting the individually filtered blocks and converting them into one filter value. The method of claim 1, A path disconnect recognition unit for recognizing a path break to the destination communication system; And An alternative communication system searching unit for searching for an alternative communication system including path information to the destination communication system in the path information storage unit; Communication system further comprising. The method of claim 4, wherein The alternative communication system search unit, And searching for the alternative communication system based on a filter value generated by filtering address information of the destination communication system and identifier information of a specific communication system included in the route request message. The method of claim 5, The filter value is generated by dividing the address information and the identifier information into blocks having a predetermined size, and filtering the separated blocks individually. The alternative communication system search unit, And if there is filtered path information that matches all of the filtered blocks among the filtered path information included in the path information storage unit, searching for the specific communication system as the alternative communication system. The method of claim 1, A message transmission control unit controlling retransmission of the route request message or transmission of the route response message according to the received one message Communication system further comprising. A first filter value generator configured to filter path information corresponding to the received message to generate a first filter value; A second filter value generator configured to filter address information of the destination communication system and identifier information of a specific communication system to generate a second filter value; And An alternative communication system confirming unit confirming whether an alternative communication system of the specific communication system is based on the first filter value and the second filter value; Communication system comprising a. The method of claim 8, The first filter value generator, Dividing the path information into blocks having a predetermined size and individually filtering them, and connecting the individually filtered blocks to generate the first filter value, The second filter value generator, And dividing the address information and the identifier information into blocks having the same size as the block and individually filtering the second filter values. The method of claim 8, The second filter value includes respective filter values obtained by filtering the address information and the identifier information into at least one block. The alternative communication system confirmation unit, And when the first filter value includes all of the values corresponding to each of the filter values, confirming the specific communication system as the alternative communication system. The method of claim 8, The received message includes at least one message of a route request message and a route response message, The route information includes route table information set by the route request message or the route response message. Receiving at least one message of a route request message and a route response message; Filtering and storing route information corresponding to the received message; And Transmitting the route request message or the route response message according to the received message; Communication method comprising a. The method of claim 12, The filtering and storing the path information corresponding to the received message, And filtering the path information according to a filtering method that allows a certain number of false positives and reduces the size of the data to be filtered. The method of claim 12, The filtering and storing the path information corresponding to the received message, And dividing the path information into blocks having a predetermined size and individually filtering the concatenated blocks, and converting the individually filtered blocks into one filter value. The method of claim 12, Searching for an alternative communication system including path information to the destination communication system when recognizing the path disconnection of the path request message to the destination communication system; Communication method further comprising. The method of claim 15, The step of searching for an alternate communication system including route information to the destination communication system, And searching for the alternative communication system based on the filtered route information and the filter value generated by filtering the address information of the destination communication system and the identifier information of the specific communication system included in the route request message. Communication method. Generating first filter values by filtering path information corresponding to the received message; Generating a second filter value by filtering address information of a destination communication system and identifier information of a specific communication system; And Determining whether the specific communication system is an alternative communication system based on the first filter value and the second filter value; Communication method comprising a. The method of claim 17, The generating of the first filter value by filtering the route information corresponding to the received message may include: Dividing the path information into blocks having a predetermined size and individually filtering them, and connecting the individually filtered blocks to generate the first filter value; The step of filtering the address information of the destination communication system and the identifier information of the specific communication system to generate a second filter value, And dividing the address information and the identifier information into blocks having the same size as the block and individually filtering to generate the second filter value. The method of claim 17, The second filter value includes respective filter values obtained by filtering the address information and the identifier information into at least one block. The determining of whether the specific communication system is an alternative communication system based on the first filter value and the second filter value may include: And when the first filter value includes all of the values corresponding to each of the filter values, confirming the specific communication system as the alternative communication system. A computer-readable recording medium in which a program for executing the method of any one of claims 12 to 19 is recorded.

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