KR101414973B1 - Apparatus and method for memory management in delay tolerant network - Google Patents

Abstract

A memory management device and method in a delay tolerant network is disclosed. The present invention determines a message to be deleted from the memory based on the number of message integrated transmissions calculated for each message, and deletes the determined message from the memory. According to the present invention, a message to be deleted from the memory is determined and deleted based on the number of message integrated transmissions calculated on a message-by-message basis, thereby leaving a message that has not yet spread widely in the network, To better meet the basic requirements of memory buffer management to improve overall message delivery.

Description

[0001] Apparatus and method for memory management in delay tolerant network [

The present invention relates to a memory management apparatus and method in a delay tolerant network, and more particularly, to a memory management apparatus and method in a delay tolerant network. More particularly, To a device and a method for deleting a message stored in a memory.

Recently, there has been actively studied a delay tolerant network (DTN) in which connection between a source node and a receiving node is not guaranteed. Since end-to-end connection is not guaranteed in DTN, existing routing protocols that set routing routes and perform routing in advance are not suitable, and new routing protocols based on Store-Carry-Forward are needed. In the DTN, each node stores a message to be transmitted in a buffer, and when it encounters another node, it forwards the message to the final destination by forwarding the stored message.

The DTN routing protocol is classified into a deterministic protocol applied in an environment that predicts changing network information and a dynamic protocol applied in an environment in which network information can not be predicted in advance. Among them, Dynamic protocol applied to general environment includes Epidemic protocol based on flooding method, PRoPHET protocol for performing probabilistic transmission using cumulative contact information of each node, Spray step for carrying out retransmission with redundancy in copy of message, And a Wait step that does not perform transmission until the destination node is used.

The Probabilistic Routing Protocol using History of Encounters and Transitivity (PRoPHET) protocol is based on the fact that nodes visit more often than visited at random based on previous movement patterns rather than randomly. In order to use this property, the PRoPHET protocol defines a delivery predictability P (a, b) having a value between 0 and 1 for all the destination nodes b at each node a as follows: .

는 이전에 저장된 전달 가능성을 나타낸다.

는 0과 1 사이의 값을 가지는 초기 확률값을 나타낸다.here,

Represents the previously stored delivery possibilities.

Represents an initial probability value having a value between 0 and 1.

If the node a and the node b do not contact each other for a long time, the possibility of the node a and the node b is reduced. Also, if a frequently contacts node b and node b frequently contacts node c, node a and node c are likely to be in frequent contact. Therefore, the possibility of transmission between the node a and the node c is expressed by the following equation (2).

는 0과 1 사이의 값을 가지는 스케일링 팩터(scaling factor)를 나타낸다.here,

Represents a scaling factor having a value between 0 and 1.

In the PRoPHET protocol, two nodes exchange a summary vector at the time of contact, exchanging the forwarding possibilities of each node. Each node uses this information to update its own transportability and deliver the message to nodes with greater transportability.

In the PRoPHET protocol, since the node has limited buffer memory, some messages stored in the buffer memory should be deleted if the buffer memory is insufficient. The PRoPHET protocol suggests various ways of deleting messages. One of them is the FIFO method, which removes the message stored in the buffer memory for the longest time. The other is the MOFO method, where each node manages the number of times a message is delivered to another node and removes the message with the highest value from the message first.

However, there is a problem that the FIFO scheme can not improve the message throughput by simply removing the message stored in the buffer memory for the longest time without considering the characteristics of the message. In addition, the MOFO scheme is able to generate a large deviation in each node even if the number of transmissions of each message managed by each node is the same, thereby eliminating the most widely distributed message from the overall network view, There is a problem in that the basic requirements of the buffer memory management to satisfy the basic requirements of the buffer memory can not be properly satisfied.

Patent Document 1 discloses a DTN routing method based on a social community. In Patent Document 1, in a source node in which a message to be transmitted in a queue exists, And determines whether forwarding is to be performed by comparing the destination cluster of the message with the contact node, controls message copy or forwarding according to whether forwarding is determined according to the cluster comparison, and transmits the message stored in the queue to the destination node The contents are disclosed. Patent Document 2 discloses an apparatus and method for supporting memory management in an off-load of network protocol processing. Patent Document 2 discloses an apparatus and method for supporting memory management in an off- Which allows grouping of DMA buffers that can be shared in a host system, and permits quick transmission of data to the host system and partial transmit and receive buffer operations that delay DMA requests so that they may be forwarded to the host system.

An object of the present invention is to provide a memory management apparatus in a delay-tolerant network that determines a message to be deleted from a memory based on the number of message integrated transmissions calculated for each message and deletes the determined message from the memory.

According to another aspect of the present invention, there is provided a method for managing a memory in a delay-allowed network for determining a message to be deleted from a memory based on the number of message integrated transmissions calculated for each message, There is provided a computer-readable recording medium on which a program is recorded.

According to another aspect of the present invention, there is provided a memory management apparatus in a delay-tolerant network, the apparatus comprising: a plurality of nodes, each of which includes a plurality of nodes, And storing the message in a memory, the method comprising: receiving a message delivery count list of the delivery node from the delivery node when a connection with the delivery node is detected; An information exchange unit transmitting the information to the delivery node; And a controller for obtaining a message delivery integration count using the message delivery count list received from the delivery node and the message delivery count list of the transmission node and deleting the message from the memory based on the message delivery integration count .

According to another aspect of the present invention, there is provided a method of managing a memory in a delay-tolerant network, the method comprising: transmitting a message to be transmitted to a receiving node to a transmitting node, And storing the message in a memory, the method comprising the steps of: receiving a message delivery count list of the delivery node from the delivery node when a connection with the delivery node is detected; Transmitting a list of counts to the forwarding node; And a step of acquiring a message delivery integration count using the list of message delivery counts received from the delivery node and the list of message delivery counts of the transmission node and deleting the message from the memory based on the message delivery integration count .

According to another aspect of the present invention, there is provided a computer readable medium storing a program for causing a computer to execute any one of the above methods.

According to the apparatus and method for managing a memory in the delay tolerant network according to the present invention, a message to be deleted from the memory is determined and deleted based on the number of message integrated transmissions calculated for each message, It is possible to better meet the basic requirements of memory buffer management, which is intended to increase the overall message delivery rate by first eliminating messages that have already been sufficiently spread over the network.

FIG. 1 is a block diagram illustrating a memory management apparatus in a delay-tolerant network according to a preferred embodiment of the present invention,
2 is a block diagram illustrating a memory management method in a delay-tolerant network according to a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a memory management apparatus and method in a delay tolerant network according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram for explaining a memory management apparatus in a delay tolerant network according to a preferred embodiment of the present invention.

Referring to FIG. 1, a memory management apparatus 100 (hereinafter, referred to as 'memory management apparatus') in a delay tolerant network is provided in a transmitting node of a network including a plurality of nodes, To a different delivery node so that the message finally reaches the receiving node.

In addition, the memory management device 100 stores the message in the memory. At this time, if the amount of memory is not sufficient to store the message, the memory management device 100 determines a message to be deleted from the memory based on the number of message integration transmissions calculated for each message, and deletes the determined message from the memory.

Meanwhile, the delay tolerant network according to the present invention operates with the Probabilistic Routing Protocol using History of Encounters and Transitivity (PRoPHET) protocol. In the PRoPHET protocol, since the node has limited buffer memory, some messages stored in the buffer memory should be deleted if the buffer memory is insufficient. The present invention relates to a method for deleting a message from a buffer memory when a buffer memory is insufficient to delete a message.

1, the memory management apparatus 100 includes a storage unit 110, an information exchange unit 130, a control unit 150, and a transfer unit 170.

The storage unit 110 includes a memory and stores programs and data necessary for the operation of the memory management apparatus 100 and data generated during operation of the memory management apparatus 100 in a memory. For example, the storage unit 110 stores a message, a message delivery count list, and the like in a memory.

When the connection with the forwarding node is detected, the information exchange unit 130 exchanges the message forwarding count list with the forwarding node. That is, the information exchange unit 130 receives the message delivery count list of the delivery node from the delivery node, and transmits the message delivery count list of the sending node to the delivery node.

Here, the message delivery count list is composed of the number of deliveries of messages per node. For example, the list of message delivery times for message m may be as shown in Table 1 below.

Node identification information (Node ID)

Number of messages sent
N-ID-1

NF (M-ID-m, N-ID-1)
N-ID-2

NF (M-ID-m, N-ID-2)
...

...
N-ID-n

NF (M-ID-m, N-ID-n)

Herein, N-ID-n represents unique information capable of identifying a node. M-ID-m indicates unique information capable of identifying a message. The NF (M-ID-m, N-ID-n) indicates the number of times that the message having the message identification information M-ID-m is transmitted to another node in the node having the node identification information N-ID-n, It increases by 1 each time it is delivered.

In the case where the amount of memory is insufficient, the transmitting node provided with the memory management apparatus 100 according to the present invention requires information on the number of message transmissions of other nodes in order to determine the memory to be deleted from the memory. Therefore, the information exchange unit 130 requests the forwarding node to provide a message delivery count list of the forwarding node. Also, the information exchange unit 130 receives the message delivery count list of the delivery node from the delivery node, and simultaneously provides the message delivery count list of the sending node to the delivery node.

That is, in the network where the memory management apparatus 100 according to the present invention is applied to each node, each node exchanges a message delivery count list when it contacts another node, and if there is a message to be transmitted to a specific node, The message to be deleted from the memory is determined based on the received message delivery count list.

The control unit 150 compares the message delivery count list of the delivery node and the list of message delivery counts of the transmission node transmitted through the information exchange unit 130 and updates the message delivery count list of the transmission node. That is, if the same node identification information exists in both the message delivery count list of the transmitting node and the message delivery count list of the forwarding node, the control unit 150 updates the message delivery count list of the transmitting node with a larger message transmission count.

In addition, the controller 150 acquires the message delivery integration count using the message delivery count list using the message delivery count list of the delivery node and the message delivery count list of the transmission node, .

That is, the control unit 150 calculates the number of message delivery times for each message as shown in the following Equation (3) using the message delivery count list of the delivery node and the message delivery count list of the transmission node.

Here, the SNF (M-ID-m) represents the number of times of integration of the message having the M-ID-m message identification information.

Then, the control unit 150 deletes the message having the largest message delivery integration count from the memory. For example, if a message a, a message b, and a message c are stored in the memory, and the integration counts of the messages a, b, and c are 4, 8, and 3, do.

At this time, if the amount of memory is not enough to store a new message, the controller 150 deletes the message from the memory. On the other hand, if the amount of memory is sufficient to store a new message, the control unit 150 transmits a new message to the transfer node via the transfer unit 170 and stores the new message in the memory. The controller 150 exchanges a list of message delivery times with the delivery node, and updates the message delivery count list of the transmission node.

The transmitting unit 170 transmits a message to the forwarding node under the control of the controller 150. [ Thereafter, if the amount of memory is not sufficient in the forwarding node, the message stored in the memory is deleted based on the calculated message forwarding count based on the message forwarding count list according to the forwarding protocol defined by the present invention, Let the message be delivered.

2 is a block diagram illustrating a memory management method in a delay-tolerant network according to a preferred embodiment of the present invention.

The memory management apparatus 100 detects a connection with the transfer node (S210). When a connection with the forwarding node is detected, the memory management apparatus 100 exchanges a message delivery count list with the forwarding node (S220).

If the amount of memory to store a new message is insufficient (S230-N), the memory management device 100 deletes the message from the memory based on the number of message delivery integration times obtained from the message delivery count list (S240). That is, the memory management apparatus 100 calculates the message delivery integration count for each message using the message delivery count list of the delivery node and the message delivery count list of the transmission node, and deletes the message having the largest delivery integration count from the memory.

On the other hand, if there is enough memory to store the new message (S230-Y), the memory management device 100 transmits a new message to the delivery node and stores the new message in the memory (S250). Then, the memory management apparatus 100 exchanges a message delivery count list with the delivery node (S260), and updates the message delivery count list (S270).

In this manner, a message to be deleted from the memory is determined and deleted based on the number of message integrated transmissions calculated on a message-by-message basis, so that a message that has not been widely spread in the network is left in the buffer memory, It better meets the basic requirements of managing memory buffers to increase the overall message delivery rate.

However, the present invention is not limited thereto. The present invention can be applied to all delay tolerant network routing techniques for delivering a message to a destination through a plurality of message copies have.

The present invention can also be embodied as computer-readable codes on a computer-readable recording medium. A computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer apparatus is stored. Examples of the computer-readable recording medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like in the form of a carrier wave . In addition, the computer-readable recording medium may be distributed to computer devices connected to a wired / wireless communication network, and a computer-readable code may be stored and executed in a distributed manner.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the appended claims.

100: memory management device in a delay tolerant network,
110:
130: Information exchange part,
150:
170:

Claims (7)

There is provided a memory management apparatus provided in a transmission node of a network having a plurality of nodes for transmitting a message to be transmitted to a receiving node to a transmitting node different from the receiving node and storing the message in a memory,
An information exchange unit for receiving a message delivery count list of the delivery node from the delivery node when a connection with the delivery node is detected and transmitting a message delivery count list of the transmission node to the delivery node; And
And a controller for obtaining a message delivery integration count using the list of message delivery counts received from the delivery node and the list of message delivery counts of the transmission node and deleting the message from the memory based on the message delivery integration count Wherein the memory management device is in a delay tolerant network. The method according to claim 1,
The control unit calculates a message delivery integration count for each message using the message delivery count list received from the delivery node and the message delivery count list of the transmission node and deletes the message having the largest message delivery integration count from the memory Wherein the memory management device is in a delay tolerant network. The method according to claim 1,
Further comprising a transmitting unit for transmitting a message to the forwarding node,
Wherein the control unit deletes a message from the memory if the amount of the memory is insufficient to store a new message, and if the amount of the memory is sufficient to store the new message, Message to the forwarding node and updates the message delivery count list of the transmitting node. A memory management method of a memory management apparatus, which is provided in a transmission node of a network composed of a plurality of nodes, transmits a message to be transmitted to a reception node to a delivery node different from the reception node, and stores the message in a memory,
Receiving a message delivery count list of the delivery node from the delivery node when a connection to the delivery node is detected, and transmitting a message delivery count list of the transmission node to the delivery node; And
Obtaining a message delivery integration count using the message delivery count list received from the delivery node and the message delivery count list of the transmission node and deleting the message from the memory based on the message delivery integration count; Wherein the memory management method comprises: 5. The method of claim 4,
The message deletion step calculates a message delivery integration count for each message by using the message delivery count list received from the delivery node and the message delivery count list of the transmission node, Wherein the deletion is performed by the deletion permission unit. 6. The method of claim 5,
The message deletion step is performed if the amount of the memory is not sufficient to store a new message,
Further comprising: if the amount of memory is sufficient to store the new message, sending the new message to the forwarding node and updating the message delivery count list of the transmitting node. How to manage memory. A computer-readable recording medium storing a program for causing a computer to execute a memory management method in the delay permitting network according to any one of claims 4 to 6.

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