KR101294366B1 - Node apparatus in delay tolerant network and method for transferring message performing the node apparatus, and recording medium storing program for executing method of the same in computer - Google Patents

Abstract

Disclosed is a node apparatus for adaptively adjusting message transmission time in a delay-tolerant network composed of a plurality of nodes. The information confirmation unit checks the remaining energy and the number of remaining messages to be transmitted to other nodes. The calculator calculates the activity defined by the weighted sum of the energy ratio P _E and the message ratio P _L calculated based on the identified residual energy and the number of remaining messages. The interval setting unit sets the active section longer than the dormant section in one transmission period when the activity is higher than the preset reference value, and sleeps in the transmission section of one cycle if the activity is lower than the preset reference value. Set the interval longer than the active interval. The message transmitter transmits a message to another node in the set active period. According to the present invention, in order to reduce battery power consumption of each node constituting the delay-tolerant network, the node may periodically go to sleep to prolong the life of the node and increase the message spread to improve the message transmission probability.

Description

Node apparatus in delay tolerant network and method for transferring message performing the node apparatus, and recording medium storing program for executing method of the same in computer}

The present invention relates to a node device, a message transmission method performed by the node device, and a recording medium recording a program for executing the method on a computer. More particularly, the present invention relates to a power consumption in a delay-tolerant network composed of a plurality of nodes. The present invention relates to a node device for transmitting a message to another node with a minimum, a message transmission method performed by the node device, and a recording medium recording a program for executing the method on a computer.

A delay tolerant network (DTN) is a network that can transmit data using a store-carry-forward method even in an environment in which no end-to-end connection is provided.

The Epidemic protocol, the simplest delay-tolerant network protocol, exchanges messages that are not held by the peer by exchanging information of messages stored in buffers when nodes of the network connect. Because the transmission rate is high, the transmission success rate is high, but the traffic load is heavy and packet loss may occur due to the increased probability of collision.

Prophet protocol transmits a message to a node with a high probability of success, based on the probability of connection with the destination node when each node of the network connects with other nodes. The disadvantage is that it is not suitable for this irregular network.

In the spray and wait method, the first message generating node sets L, which is the maximum number of copies of the message, and transmits the message to the first access node. When a node receives a message, the node receives the message copy count within the range of L, which is the size of the message copy count, according to its own transmission policy. . At this time, the value of L, which is the size of the message copy count, which has been initially set, is not yet exhausted. The state of performing retransmission is called a 'spray stage'. The status of no retransmission until the destination node is met is called a 'weight phase'. Spray and wait (Spray and Wait) method has been conducted in a variety of research has been developed in various environments depending on how to control the number of L.

Binary spray and weight, the most basic spray and wait technique, always sends L / 2 copies, half of the maximum, to the nodes that connect. In the vehicle network environment, assuming that each node knows its mobility information, there is a technique of differentially transmitting L values by giving priority to a node moving in a different direction and a node far from the destination. There is a routing protocol for retransmitting the number of L efficiently according to the mobility model by recognizing the mobility model. The main purpose of these improvement techniques is to increase the message coverage by selecting an efficient retransmission node in consideration of the directionality or mobility model in the spray and weight method that performs retransmission by L.

In the message transfer protocol, a delay-tolerant network based on spray-and-weight method, when a node with L message copy times meets another node, transmits a copy of the message in proportion to the speed and remaining energy based on the speed and remaining energy of the two nodes. There is a protocol. In addition, to reduce power consumption of nodes that are always on in a delay-tolerant network, the states of nodes are defined as dormant and discovery states, and the node repeats sections consisting of dormant and discovery periods to save messages and reduce power. To promote

Looking at the related art in detail, Korean Laid-Open Publication No. 10-2010-0104931 (Energy-aware routing method and apparatus considering mobility in a sensor network) updates the routing information of a changed sensor node to delay energy depletion of the entire network. A routing method and apparatus are disclosed. This extends the life of the sensor network by considering only the amount of energy remaining in the sensor node. It does not consider the number of messages to be transmitted.

In addition, Korean Laid-Open Publication No. 10-2011-0103610 (a method for establishing a routing path considering mobility and an ad hoc network using the same) includes reliable routing for transmitting source data by considering the mobility of nodes constituting the ad hoc network. A method of establishing a route is disclosed. This takes into account the connection time between each node when transmitting data from the source node to the destination node, and does not consider the amount of energy remaining and the number of messages to be transmitted.

SUMMARY OF THE INVENTION The present invention provides a node device that periodically transitions to a sleep state and a message transmission method performed by the node device in order to reduce battery power consumption of each node constituting a delay tolerant network. have.

Another technical problem to be achieved by the present invention is that the sleep state of each node is set according to the amount of remaining energy (battery power) and the number of remaining messages held by the node, thereby extending the lifetime of the node and increasing message spreading. A node device for improving a message transmission probability and a message transmission method performed by the node device are provided.

In the node device for adaptively adjusting the message transmission time in a delay-tolerant network composed of a plurality of nodes according to the present invention for achieving the above technical problem, the remaining energy and the number of remaining messages to be transmitted to another node Information confirmation unit to confirm; A calculation unit for calculating activity defined by a weighted sum of the energy ratio P _E and the message ratio P _L calculated based on the identified residual energy and the number of remaining messages; If the activity is higher than the preset reference value, the active period is set longer than the dormant period in one period of transmission, and if the activity is lower than the reference value, the dormant period is active within the transmission period of one cycle. A section setting unit that sets a length longer than that; And a message transmitter for transmitting a message to another node in the set active period.

A method for transmitting a message performed by a node apparatus for adaptively adjusting a message transmission time point in a delay-tolerant network composed of a plurality of nodes according to the present invention for achieving the above another technical problem, (a) held by the node apparatus Measuring remaining energy and number of remaining messages to be transmitted; (b) obtaining an activity defined by a weighted sum of the energy ratio P _E and the message ratio P _L calculated based on the measured residual energy and the number of residual messages; (c) If the activity is higher than a preset reference value, the active section is set longer than the dormant section in one period of transmission, and if the activity is lower than the reference value, the dormant section in the transmission section of one cycle Setting a length greater than an active period; And (d) transmitting a message to another node in the set active period.

According to the node device and the message transmission method performed by the node device according to the present invention, in order to reduce battery power consumption of each node constituting the delay-tolerant network, the node device periodically transitions to a sleep state to extend the life of the node. Increasing message spread can improve message transmission probability.

1 is a block diagram showing a node device according to the present invention;
2 is a block diagram showing the detailed configuration of an information confirmation unit constituting a node device according to the present invention;
3 is a block diagram showing a detailed configuration of a calculation unit constituting a node device according to the present invention;
4 is a flowchart illustrating a message transmission method according to the present invention, and
5 is a flowchart illustrating a message transmission method in detail according to the present invention.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the node device and the message transmission method performed by the node device according to the present invention.

1 is a block diagram showing a node device 100 according to the present invention. 2 is a block diagram showing the detailed configuration of the information confirmation unit 110 constituting the node device 100 according to the present invention. 3 is a block diagram showing a detailed configuration of the calculation unit 120 constituting the node device 100 according to the present invention.

Referring to FIG. 1, a node device 100 according to the present invention includes an information checking unit 110, a calculating unit 120, a section setting unit 130, and a message transmitting unit 140.

The information checking unit 110 checks the remaining energy possessed by the node and the number of remaining messages to be transmitted. Referring to FIG. 2, the information checking unit 110 includes an energy measuring unit 220 and a message number checking unit 230. The energy measuring unit 220 measures the amount of remaining energy consumed out of the total amount of energy initially owned by the node. In this case, the amount of energy held by the node may mean the amount of battery. The message number checking unit 230 checks the number of remaining messages already transmitted and remaining among the total messages to be transmitted by the node.

The calculator 120 calculates an energy ratio P _E and a message ratio P _L of the node based on the remaining energy and the number of remaining messages checked by the information checking unit 110, and uses the activity ratio of the node. Obtain Referring to FIG. 3, the calculator 120 includes an energy ratio P _E calculator 330, a message ratio P _L calculator 340, and an activity calculator 350. The energy ratio P _E calculation unit 330 calculates by dividing the remaining energy held by the node by the total amount of energy initially owned by the node. The message ratio P _L calculator 340 calculates by dividing the number of remaining messages that the node should transmit to another neighboring node by the total number of messages that the node should transmit. Activity calculation unit 350, an energy ratio (P _E) calculation section 330, and the message ratio (P _L), the energy ratio (P _E) of the nodes calculated by the calculation unit 340 and the message ratio (P _L) Calculate the activity of the node by the following equation (1). In Equation 1, 'a' is a variable that varies depending on the situation, and may be given externally or set by the node itself.

Where A is the activity of the node, a is the weight (0 ≦ a ≦ 1), P _E is the energy ratio, and P _L is the message ratio.

The interval setting unit 130 sets the active interval longer than the dormant interval when the activity of the node obtained by Equation 1 is higher than a preset reference value (for example, 0.5), and the activity is set in advance. If it is lower than the value (for example, 0.5), the sleep interval is set longer than the active interval. This reference value is determined experimentally based on network traffic and message transmission volume of each node between 0 and 1. The message transmitter 140 transmits a message to another node when the node is in an active period. The active period of the node (R _a) and a sleep interval (R _n) is calculated by each of the following equation (2) and equation (3).

In Equations 2 and 3, R _a is an active period, R _n is a dormant period, T is a period of a node consisting of an active period and a dormant period, and A is the activity of the node.

Therefore, the node performs an operation for each set interval, and even if one period of the node elapses, the node repeats the operation again from the beginning to perform the operation in the next period. However, when the remaining energy of the node becomes '0' or transmits all remaining messages to be transmitted, all operations are terminated.

For example, suppose there are Node A and Node B that are part of a delay-tolerant network. Node A currently has 70% energy left, 5 remaining messages (10 total messages to send), Node B currently has 30% energy left, and 5 remaining messages (to send 10 messages total). In this case, the energy ratio P _E of node A is 0.7 and the message ratio P _L is 0.5. In addition, the energy ratio P _E of the node B is 0.3, and the message ratio P _L is 0.5. Based on this, if the activity of node A and node B (weight a is set to 0.6), the activity, active and dormant intervals of node A and node B are calculated as follows.

Activity on Node A = 0.6 * 0.7 + 0.4 * 0.5 = 0.42 + 0.20 = 0.62

Active interval of node A = 0.62 T

Sleep interval for node A = (1-0.62) * T = 0.38 T

Activity of Node B = 0.6 * 0.3 + 0.4 * 0.5 = 0.18 + 0.20 = 0.38

Active Interval for Node B = 0.38 T

Sleep interval for node B = (1-0.38) * T = 0.62 T

That is, node A and node B have the same number of remaining messages (five) and the message ratio (P _L ) is the same, the residual energy is different. In this case, Node A, which has higher residual energy, has a value of 0.62 with activity values greater than 0.5, so that the active period is set longer than the dormant period within one period of transmission, so that the message can be sent to another node. Have longer. On the other hand, Node B with low residual energy has a value of 0.36 whose activity value is less than 0.5, so that the sleep period is set longer than the active period in one transmission period, so that the sleep time for stopping message transmission is longer. do.

In addition, it is assumed that there are Node C and Node D constituting the delay tolerance network. Node C currently has 70% energy left, 7 remaining messages (10 total messages to send), node D currently has 70% energy left, and 3 remaining messages (to send 10 messages total). In this case, the energy ratio P _E of the node C is 0.7 and the message ratio P _L is 0.7. The energy ratio P _E of node D is 0.7 and the message ratio P _L is 0.3. Based on this, the activity of node C and node D (weight a is set to 0.6) is calculated, and the activity, active and sleep intervals of node C and node D are calculated as follows.

Activity of node C = 0.6 * 0.7 + 0.4 * 0.7 = 0.42 + 0.28 = 0.70

Active interval of node C = 0.70 T

Sleep interval for node C = (1-0.70) * T = 0.30 T

Activity of node D = 0.6 * 0.7 + 0.4 * 0.3 = 0.42 + 0.12 = 0.54

Active interval of node D = 0.54 T

Sleep interval for node D = (1-0.54) * T = 0.46 T

That is, node C and node D have the same residual energy amount (70%), so the energy ratio P _E is the same, and there is a difference in the number of remaining messages to be transmitted to other nodes. Both Node C and Node D have activity values greater than 0.5, but Node A, which has more residual messages to transmit, has a value of 0.7 with activity values greater than 0.5, so it is active within one period of transmission. The interval is set longer than the dormant interval, so that it has a longer time to send a message to another node.

4 is a flowchart illustrating a message transmission method according to the present invention.

Referring to FIG. 4, in the message transmission method performed by the node apparatus 100 that adaptively adjusts a message transmission time in a delay-tolerant network composed of a plurality of nodes, first, a residual energy possessed by a node and a message to be transmitted Measure the number of (S410). The activity of the node is calculated using the measured node information (S420). In this case, when the node has a large amount of remaining energy or a number of remaining messages to be delivered, the activity value also becomes large. Subsequently, by setting an active section and a dormant section of the node based on the calculated activity level (S430), the node performs an operation for each section (S440). If the activity of the node calculated in step S420 is greater than 0.5, the active section is set longer than the dormant section, and performs a message transmission operation for a long time, and in the case of the node whose activity is less than 0.5, the dormant section is longer than the active section. It will be set more time to stop sending messages. In this regard, we will look in more detail below.

5 is a flowchart illustrating a message transmission method in detail according to the present invention.

Referring to FIG. 5, the remaining energy possessed by the node and the number of remaining messages to be transmitted are measured (S510). The energy ratio P _E and the message ratio P _L of the node are calculated based on the measured node information (S520). At this time, the energy ratio is obtained by dividing the remaining energy held by the node by the total amount of energy initially held by the node. Say. Here, the high energy ratio of the node means that there is still a lot of energy remaining in the node, and the high message ratio of the node means that the node has a large number of remaining messages to be transmitted to other nodes in the future. The activity ratio of the node is calculated using the energy ratio and the message ratio of the node obtained in operation S520 (S530). The activity of the node is calculated by Equation 1 described above, and the higher the energy ratio and message ratio of the node, the higher the activity. The active section and the dormant section of the node are set based on the activity of the node thus obtained, and the active section and the dormant section are calculated and set by Equation 2 and Equation 3, respectively (S540). The node performs an operation for each section according to the set active section and the dormant section (S550). The node transmits a message to another node in the active section, and stops the message transmission in the dormant section. The node repeats again from step S510 even if one cycle 1T has elapsed. When all remaining message transmissions completed by the node are completed or all remaining energy is consumed (S560), all the operations are terminated.

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 system 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, and a carrier wave (transmission via the Internet). In addition, the computer-readable recording medium may be distributed to a computer system 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 clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation in the embodiment in which said invention is directed. It will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the appended claims.

100: node device 110: information confirmation unit
120: calculation unit 130: section setting unit
140: message transmission unit 220: energy measurement unit
230: number of messages check unit 330: energy ratio (P _E ) calculation unit
340: message ratio (P _L ) calculation unit 350: activity calculation unit

Claims (13)

In the node device for adaptively adjusting the message transmission time in a delay-tolerant network consisting of a plurality of nodes,
An information checking unit for checking the remaining energy and the number of remaining messages to be transmitted to another node;
A calculation unit for calculating activity defined by a weighted sum of the energy ratio P _E and the message ratio P _L calculated based on the identified residual energy and the number of remaining messages;
If the activity is higher than the preset reference value, the active period is set longer than the dormant period in one period of transmission, and if the activity is lower than the reference value, the dormant period is active within the transmission period of one cycle. A section setting unit that sets a length longer than that; And
And a message transmitter for transmitting a message to another node in the set active period. The method of claim 1,
The information verifying unit,
An energy measuring unit measuring an amount of remaining energy consumed in the total amount of energy; And
And a message number checking unit for checking the remaining number of messages to be transmitted to another node. The method of claim 1,
The calculation unit may calculate,
An energy ratio calculator configured to calculate the energy ratio by dividing the residual energy by the total energy initially held;
A message ratio calculator configured to calculate the message ratio by dividing the remaining number of messages by a total number of messages to be transmitted; And
And an activity calculator for calculating the activity according to Equation A based on the energy ratio and the message ratio.
[Mathematical formula A]

Where A is the activity of the node, a is the weight (0 ≦ a ≦ 1), P _E is the energy ratio, and P _L is the message ratio. The method of claim 1,
Wherein the interval setting unit calculates and sets the active interval and the dormant interval by Equations B and C, respectively:
[Mathematical expression B]

[Mathematical expression C]

Here, R _a is an active period, R _n is a dormant period, T is a period of the node consisting of an active period and a dormant period, and A is the activity of the node. In the message transmission method performed by the node device for adaptively adjusting the message transmission time in a delay-tolerant network composed of a plurality of nodes,
(a) measuring the remaining energy held by the node device and the number of remaining messages to be transmitted;
(b) obtaining an activity defined by a weighted sum of the energy ratio P _E and the message ratio P _L calculated based on the measured residual energy and the number of residual messages;
(c) If the activity is higher than a preset reference value, the active section is set longer than the dormant section in one period of transmission, and if the activity is lower than the reference value, the dormant section in the transmission section of one cycle Setting a length greater than an active period; And
(d) transmitting a message to another node in the set active period. 6. The method of claim 5,
The energy ratio is a value obtained by dividing the residual energy by the total energy initially possessed.
The message ratio is a value obtained by dividing the remaining number of messages by the total number of messages to be transmitted. 6. The method of claim 5,
The activity of step (b) is a message transmission method, characterized in that calculated by the following equation D:
[Mathematical expression D]

Where A is the activity of the node, a is the weight (0 ≦ a ≦ 1), P _E is the energy ratio, and P _L is the message ratio. 6. The method of claim 5,
The method of claim 1, wherein the active and dormant sections of step (c) are calculated and set according to Equations (E) and (F), respectively:
(E)

Equation F

Here, R _a is an active period, R _n is a dormant period, T is a period of the node consisting of an active period and a dormant period, and A is the activity of the node. 6. The method of claim 5,
And the active period is set in proportion to the energy ratio and the message ratio, and the dormant period is set in inverse proportion to the energy ratio and the message ratio. 6. The method of claim 5,
And the remaining energy is the amount of battery held by the node device. 6. The method of claim 5,
(e) if the period (1T) of the node device has elapsed, the process proceeds to the next cycle and repeats again from the step (a). 6. The method of claim 5,
and (f) terminating all operations when the remaining energy of the node device becomes '0' or transmits all remaining messages to be transmitted. A computer-readable recording medium having recorded thereon a program for executing a message transmission method on a computer in a delay-tolerant network according to any one of claims 5 to 12.

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