KR101601181B1 - Ad hoc network node operating method of the same and data transfer method of ad hoc network - Google Patents

Abstract

The present invention relates to a method of operating an ad hoc network node. A method of operating an ad hoc network node according to the present invention includes the steps of determining whether transmission data exists, determining a remaining life time of relay data transmission and direct transmission, And a step of determining whether the data is directly transmitted or not.

Description

TECHNICAL FIELD [0001] The present invention relates to an ad hoc network node, an operation method thereof, and a data transmission method of an ad hoc network.

The present invention relates to a network, and more particularly, to an ad hoc network node, an operation method thereof, and a data transmission method of an ad hoc network.

The wireless network starts from the ALOHA network. The Aloha Network is a network of Hawaii universities to communicate with the islands surrounding Hawaii. Wireless networks include infrastructured networks and infrastructureless networks.

A backbone network refers to a network that is configured based on a fixed and wired infrastructure, such as a base station or an access point (AP).

A backbone network refers to a network that is configured not based on infrastructure such as base stations and access points (APs) but based on wireless mobile terminals. Ad hoc networks are one of backbone networks. An ad hoc network is an autonomous network in which nodes capable of wireless communication construct a network through mutual communication. In an ad hoc network, network nodes construct a topology based on mutual communication.

It is an object of the present invention to provide an ad hoc network node that optimizes the life time of an ad hoc network, an operation method thereof, and a data transmission method of an ad hoc network.

An operation method of an ad hoc network node according to an embodiment of the present invention includes: determining whether transmission data exists; Determining a remaining life time for relay transmission and direct transmission of the transmission data; And determining whether the relay transmission and the direct transmission are based on the determined remaining service life.

In an embodiment, the step of discriminating whether the relay transmission or the direct transmission includes discriminating the relay transmission time of the transmission data based on the determined remaining service life.

In an embodiment, the step of determining the relay transmission time includes the step of setting the relay transmission time so that the remaining lifetime of the network node and the relay node is leveled.

As an embodiment, the step of determining the remaining lifetime in the relay transmission and the direct transmission includes: detecting residual energy; Detecting a first energy consumption rate when directly transmitting the transmission data; Detecting a second energy consumption rate when relaying the transmission data through a neighboring node; Transmitting the detected residual energy and the detected first and second energy consumption rates to a neighboring node; Receiving a remaining lifetime from the neighboring node when the transmission data is relayed through the neighboring node; And determining the remaining lifetime as the remaining lifetime in the relay transmission and the direct transmission.

In an embodiment, the first and second energy consumption rates are transmitted to at least two neighboring nodes, and based on the remaining lifetimes received from the at least two neighboring nodes, one of the at least two neighboring nodes And is selected as a relay node.

If the transmission data does not exist, it is determined whether a transmission ready message is received. If the transmission ready message is not present, the remaining life of the network node when the network node operates as a relay node is determined based on the transmission ready message, And transmitting the lifetime.

Determining whether a relay node selection message according to the transmitted remaining lifetime is received; And operating as a relay node based on the received relay node selection message.

An ad hoc network node according to an embodiment of the present invention includes: a transmission data management unit configured to determine whether transmission data exists; An energy management unit configured to detect residual energy; And a control unit configured to detect a first energy consumption rate when the transmission data is directly transmitted and a second energy consumption rate when relay transmission, and the control unit is configured to detect the remaining energy and the detected first and second energy And determining a remaining life time and a relay transmission time when the relay transmission and the direct transmission are performed based on the consumption rates and determining a relay transmission time and a relay transmission time of the transmission data based on the determined remaining life span and the relay transmission time, And determines whether or not the transmission is performed.

As an embodiment, under the control of the control unit, based on the determined remaining service life and the relay transmission time, some of the transmission data is relayed and the rest is directly transmitted.

A method for transmitting data in an ad hoc network according to an embodiment of the present invention includes: determining a source node and a target node; Determining a candidate node of the relay node; Determining a relay transmission time and a remaining lifetime at which the remaining life time of the source node and the candidate node are equalized; And performing relay transmission during the determined relay transmission time and performing direct transmission for the remaining time.

According to the present invention, when the transmission data is transmitted, the remaining life time of the network node and the relay node is leveled. Thus, the lifetime of the ad hoc network is optimized.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily carry out the technical idea of the present invention. . The same elements will be referred to using the same reference numerals. Similar components will be referred to using similar reference numerals.

1 is a block diagram illustrating an ad hoc network 100 in accordance with an embodiment of the present invention. 2 is a block diagram showing distance information between the first and third to fifth network nodes n1, n3 to n5 of the ad hoc network 100 of FIG. Referring to FIGS. 1 and 2, the first to sixth network nodes n1 to n6 constitute an ad hoc network 100.

The ad-hoc network 100 is an autonomous network in which nodes capable of wireless communication construct a network through mutual communication. That is, the first to sixth network nodes n1 to n6 are devices capable of wireless communication. For example, each of the first to sixth network nodes n1 to n6 may be a computer, a portable computer, an Ultra Mobile PC (UMPC), a netbook, a PDA (Personal Digital Assistants), a portable computer , A mobile phone, a smart phone, and the like, which are capable of transmitting and receiving information in a wireless environment.

By way of example, it is assumed that each of the first to sixth network nodes n1 to n6 is located within a mutual communication range. At this time, the specific network node (for example, the fifth network node n5) in the ad-hoc network 100 is connected to the remaining network nodes (for example, first to fourth network nodes n1 to n4 and sixth Network node n6). Illustratively, it is assumed that the fifth network node n5 is a source node that transmits data, and the first network node n1 is a target node to which data is transmitted.

The fifth network node n5 can communicate with the first network node n1 using one of two methods. First, the fifth network node n5 can communicate with the first network node n1 via the other network nodes n2 through n4, n6. That is, the fifth network node n5 may perform relay communication with the first network node n1. Secondly, the fifth network node n5 can communicate directly with the first network node n1.

As the communication distance increases, the power consumption for performing data transmission increases. Therefore, the relay node will be selected based on the distance between the fifth network node n5 as the source node and the second to fourth and sixth network nodes n2 to n4, n6 as the neighbor nodes.

For example, the distance between the fifth network node n5 as the source node and the first network node n1 as the target node is assumed as a reference distance. The amount of energy consumed when data is directly transmitted from the fifth network node n5 as the source node to the first network node n1 as the target node is assumed as the reference consumption amount. When the distance between the relay node and the fifth network node n5 as the source node is longer than the reference distance, the energy consumption when data is transmitted from the fifth network node n5 as the source node to the relay node is larger than the reference consumption amount. When the distance between the relay node and the fifth network node n5 as the source node is shorter than the reference distance, the energy consumption when data is transmitted from the fifth network node n5 as the source node to the relay node is smaller than the reference consumption amount. Therefore, when the relay transmission is performed, a node whose distance from the fifth network node n5, which is the source node among the neighbor nodes, is shorter than the reference distance will be selected as the relay node.

When the distance between the relay node and the first network node n1 as the target node is longer than the reference distance, the energy consumption when data is transmitted from the relay node to the first network node n1 as the target node is larger than the reference consumption amount. When the distance between the relay node and the first network node n1 as the target node is shorter than the reference distance, the energy consumption when data is transmitted from the relay node to the first network node n1 as the target node is smaller than the reference consumption amount. Therefore, when the relay transmission is performed, a node having a distance to the first network node n1, which is the target node among the neighbor nodes, is shorter than the reference distance will be selected as the relay node.

The distance between the fifth network node n5 as the source node and the first network node n1 as the target node is the third distance d3.

The distance between the third network node n3 and the fifth network node n5 as the source node is the first distance d1 and is shorter than the third distance d3. In addition, the distance between the third network node n3 and the first network node n1 as the target node is the second distance d2, which is shorter than the third distance d3. Thus, the third network node n3 may be selected as the relay node.

The distance between the fourth network node n4 and the fifth network node n5 as the source node is the fourth distance d4 and is shorter than the third distance d3. The distance between the fourth network node n4 and the first network node n1 as the target node is the fifth distance d5 and is shorter than the third distance d3. Thus, the fourth network node n4 can be selected as a relay node.

That is, when data is transmitted from the fifth network node n5 as the source node to the first network node n1 as the target node, one of the third and fourth network nodes n3 and n4 is selected as the relay node . When the relay node is selected, the data transmitted from the fifth network node n5, which is the source node, will be transferred via the relay node to the first network node n1 which is the target node.

The fifth network node n5 as the source node can select one of three communication paths and transmit data to the first network node n1 which is the target node. For example, the fifth network node n5, which is the source node, has a first communication path P1 for selecting the third network node n3 as a relay node, a second communication path P2 for direct communication, It is possible to select one of the third communication paths P3 for selecting the network node n4 as the relay node and transmit the data to the first network node n1.

When the fifth network node n5 relays data to the first network node n1 through the third network node n3, the energy of the third and fifth network nodes n3 and n5 is consumed. When the fifth network node n5 transmits data to the third network node n3, the energy of the fifth network node n5 is consumed. The energy consumption according to the data transmission of the fifth network node n5 corresponds to the first distance d1.

When the third network node n3 receives data from the fifth network node n5, the energy of the third network node n3 is consumed. And, when the third network node n3 transmits data to the first network node n1, the energy of the third network node n3 is consumed. The energy consumption according to the data transmission of the third network node n3 corresponds to the second distance d2.

The energy consumption due to data relay of the third network node n3 includes energy consumption due to data reception and energy consumption due to data transmission. Illustratively, the energy consumption due to data reception will be determined according to the operating power of the receiver of the third network node n3 and will have a constant value. Therefore, the energy consumption according to the data relay of the third network node n3, that is, the relay node, will be determined according to the second distance d2, i.e., the data transmission distance. That is, it can be understood that the energy consumption according to the data relay of the third network node n3, that is, the relay node corresponds to the second distance d2, i.e., the data transmission distance.

When the fifth network node n5 directly transmits data to the first network node n1, the energy of the fifth network node n5 is consumed. At this time, the energy consumption due to the data transmission of the fifth network node n5 corresponds to the third distance d3.

When the fifth network node n5 relays data to the first network node n1 through the fourth network node n4, the energy of the fourth and fifth network nodes n4 and n5 is consumed. As described with reference to the third and fifth network nodes n3 and n5, the energy consumption according to the data transmission of the fifth network node n5 corresponds to the fourth distance d4, the energy consumption due to the data relay of the node n4 will correspond to the fifth distance d5.

That is, when the relay transmission is performed, the energy consumption is distributed to the fifth network node n5 as the source node and the third network node n3 or the fourth network node n4 as the relay node. When direct transmission is performed, the energy consumption is concentrated to the fifth network node n5, which is the source node. Considering the energy consumption of the fifth network node n5 as the source node and the third network node n3 or the fourth network node n4 as the relay node, the relay transmission will be selectively performed.

By way of example, relay transmission and direct transmission are performed such that the remaining life of the fifth network node n5 as the source node and the third network node n3 or the fourth network node n4 as the relay node are leveled. For example, part of the transmission data is relay-transmitted so that the remaining lifetime of the fifth network node n5 as the source node and the third network node n3 or the fourth network node n4 as the relay node are leveled, Directly transmitted.

When the remaining lifetime of the fifth network node n5 as the source node and the third network node n3 or the fourth network node n4 as the relay node are leveled, (n5) as a source node and a third network node (n3) as a relay node based on the residual energy amount of the first network node (n5) and the third network node (n3) or the fourth network node (n4) Or to the fourth network node n4. Alternatively, when the remaining lifetime of the fifth network node n5 as the source node and the third network node n3 or the fourth network node n4 as the relay node are leveled, the fifth network node n5 and the total energy of the third network node n3 or the fourth network node n4, which are relay nodes, are all used. That is, when the remaining life of the fifth network node n5 as the source node and the third network node n3 or the fourth network node n4 as the relay node are leveled at the time of data transmission, n5 and the third network node n3 or the fourth network node n4 as the relay node are maximized.

Illustratively, it is assumed that the fifth network node n5 is the source node and one of the third and fourth network nodes n3, n4 is selected as the relay node. However, any of the network nodes n1 to n6 may be selected as a source node or a relay node. That is, at the time of data transmission, if the remaining lifetimes of the source node and the relay node are equalized, the remaining lifetimes of the network nodes n1 to n6 of the ad hoc network 100 will be leveled. Therefore, the channel holding time between the network nodes n1 to n6 of the ad hoc network 100 is maximized, and the lifetime of the ad hoc network 100 is optimized.

Each of the network nodes n1 to n6 includes an information table. The fifth network node (n5) operating as the source node generates the source node information table. The third to fourth network nodes n3 and n4 selected as candidate nodes of the relay node generate the relay node information table. The leveled remaining lifetime and the relay transmission time (or the relay transmission amount) are determined based on the source node information table and the relay node information table. Based on the determined lifetime and the relay transmission time, the relay transmission is performed.

FIG. 3 shows a source node information table. The source node information table includes a source node (SN), a neighbor node (NN), a target node (DN), a direct transmission rate (DTP), a relay transmission rate (RTP), and a residual energy (E).

Referring to Figs. 1 to 3, the fifth network node n5, which is a source node, is connected to the third and fourth network nodes (n1 to n6) as candidate nodes of the relay node based on the distance between the network nodes n1 to n6 n3, and n4. That is, the neighbor node (NN) entry includes the third and fourth network nodes n3 and n4.

The data transmission target node of the fifth network node n5 as the source node is the first network node n1. Thus, the target node (DN) entry includes the first network node n1.

The direct transmission consumption rate (DTP) represents the energy consumption rate of the fifth network node n5 as the source node when the fifth network node n5 as the source node directly transmits data to the target node DN. Illustratively, the direct transmission rate (DTP) is determined based on the distance d3 between the fifth network node n5 as the source node and the first network node n1 as the target node. The direct transmission consumption rate (DTP) increases as the distance between the fifth network node n5 as the source node and the first network node n1 as the target node becomes longer, and the fifth network node n5, which is the source node, (DTP) decreases as the distance between the first network node (n1) and the first network node (n1) decreases. Illustratively, the Direct Transfer Consumption Rate (DTP) is reported to be 10. However, the Direct Transfer Consumption Rate (DTP) described in FIG. 3 is an exemplary value for the sake of brevity and is not limiting.

The relay transmission consumption rate (RTP) represents the energy consumption rate when the fifth network node n5 as the source node performs the relay transmission. The relay transmission consumption rate RTP is determined based on the distances d1 and d4 between the fifth network node n5 as a source node and the third and fourth network nodes n3 and n4 as neighboring nodes. As the distance between the fifth network node n5 as the source node and the third and fourth network nodes n3 and n4 as the neighboring nodes becomes longer, the relay transmission consumption rate RTP increases as the distance between the fifth network node n5, (RTP) decreases as the distance between the first and second network nodes (n5) and (n3) and (n4) is shortened.

Illustratively, the relay transmission rate (RTP) when the fifth node n5, which is the source node, performs the relay transmission through the third network node n3 is described as 5. It is described that the relay transmission consumption rate (RTP) when the fifth network n5, which is the source node, performs the relay transmission through the fourth network node n4 is 2. The values corresponding to the relay transmission consumption rate (RTP) are exemplary values for the sake of brevity and are not limiting.

The residual energy E represents the residual energy of the fifth network node n5 which is the source node. Illustratively, the residual energy E of the fifth network node n5, which is the source node, is shown to be 60. The numerical values corresponding to the residual energy E are exemplary values for the sake of brevity and are not limited.

As described above, the third and fourth network nodes n3 and n4 corresponding to the neighbor nodes, which are candidates for the relay node, the fifth network node n5, which is the source node, and the first network node n1 , And the distance between the fifth network node n5 as the source node and the third and fourth network nodes n3 and n4 as the neighbor nodes, the information table of Fig. 3 can be generated . That is, the fifth network node n5 as the source node calculates the information table based on the distance between the first network node n1 as the target node and the third and fourth network nodes n3 and n4 as the neighbor nodes Can be generated. Illustratively, the distance information will be detected based on parameters such as communication delay, communication quality, communication energy consumption, and the like. For example, when data is exchanged between the network nodes n1 to n6, the distance between the network nodes n1 to n6 will be determined. For example, when a network node is registered in the ad hoc network 100, a control message will be exchanged. Based on the exchanged control message, the distance between the newly registered network node and the existing network nodes will be determined.

Based on the information table of Fig. 3, the remaining lifetime of the fifth network node n5, which is the source node, can be calculated. For example, the remaining lifetime of the fifth network node n5, which is the source node when performing the direct transmission, corresponds to a value obtained by dividing the residual energy E by the direct transmission consumption rate (DTP). The remaining lifetime of the fifth network node n5, which is the source node when performing the relay transmission, corresponds to a value obtained by dividing the residual energy E by the relay transmission consumption rate (RTP).

4 shows relay node information tables. The relay node information tables include the source node SN, the target node DN, the RP rate at the relay, the consumption rate at the densimeter (nRP), and the remaining energy En items.

The source node SN and the target node (DN) items are the same as those described with reference to Fig. Therefore, detailed description is omitted.

The consumption rate RP at the relay is calculated by multiplying the data from the third network node n3 which is the candidate node of the relay node or the fifth network node n5 whose source node is the fourth network node n4, represents the energy consumption rate of the third network node n3 or the fourth network node n4, which is the candidate node, when relaying to the first network node n1. Illustratively, the relay rate RP is the distance between the third network node n3 or the fourth network node n4, which is the candidate node, and the first network node n1, which is the target node, The energy consumption rate of the receiver of the relay node, that is, the energy consumption rate of the receiver of the relay node. When the distance between the third network node n3 or the fourth network node n4 as the candidate node and the first network candidate n1 as the target node becomes longer, the relaying consumption rate RP increases, When the distance between the network node n3 or the fourth network node n4 and the first network node n1 as the target node is shortened, the relaying consumption rate RP is reduced.

Illustratively, the third network node n3 has a dissipation rate RP of 4 and the fourth network node N4 has a dissipation factor RP of three. However, the numerical values corresponding to the dissipation rate (RP) at the time of relaying are exemplary values for the sake of brevity and are not limited.

(NRP) is a value obtained by multiplying the data from the third network node n3 as the candidate node or the fifth network node n5 as the source node by the fourth network node n4 as the first network node n1, The third network node n3 or the fourth network node n4, which is the candidate node, when the relay node B does not relay the traffic to the fourth network node n4. For example, the consumption ratio (nRP) at the hydrometer can be calculated by multiplying the energy consumption rate by the operating power of the third network node n3 or the fourth network node n4 which is the candidate node, the energy consumption rate of the third network node n3, An energy consumption rate by data transmission using the network node n4 as a source node, and the like.

Illustratively, the consumption ratio nRP of the third network node n3 is 1 and the consumption ratio nRP of the fourth network node n4 is 2. However, the numerical values corresponding to the consumption ratio (nRP) at the hydrometer are exemplary values for a brief description, and are not limited.

The remaining energy En represents the remaining energy of each of the third network node n3 and the fourth network node n4, which are candidate nodes.

As described above, based on the distance between the fifth network node n5 as the source node, the third network node n3 as the candidate node or the fourth network node n4 and the target node, Can be determined. That is, the third network node n3 or the fourth network node n4, which is a candidate node of the relay node, can form an information table based on the distance to the first network node n1 which is the target node. Based on the formed information table, the remaining lifetime of each of the candidate nodes, third network node n3 and fourth network node n4, can be calculated.

When performing the relay transmission, the remaining lifetime of the third network node n3 or the fourth network node n4, which is the candidate node, corresponds to the value obtained by dividing the residual energy En by the consumption rate RP in relaying. The remaining lifetime of the third network node n3 or the fourth network node n4 corresponding to the candidate node does not correspond to the value obtained by dividing the residual energy En by the consumption ratio nRP at the hydrometer.

5 is a graph for explaining a method for determining the remaining service life and the relay transmission time. In Fig. 5, the horizontal axis represents time, and the vertical axis represents the energy of the fifth network node n5, which is the source node, and the third network node n3 or the fourth network node n4, which are candidate nodes. That is, FIG. 5 shows a change with time of the energy of the network node.

As described with reference to FIGS. 1 to 4, the energy consumption rate (DTP) when the fifth network node n5, which is the source node, performs direct transmission is greater than the energy consumption rate (RTP) high. The energy consumption rate RP at the time of relay of the third network node n3 or the fourth network node n4 as the relay node is higher than the energy consumption rate nRP at the time of the hydrometer. Therefore, if the relay transmission and the direct transmission are performed in combination, the remaining lifetimes of the fifth network node n5 as the source node and the third network node n3 or the fourth network node n4 as the relay node can be leveled .

In Fig. 5, the relay transmission is performed until the first time T1 is reached. In the relay transmission period, the energy consumption rate of the fifth network node n5 as the source node is the relay transmission consumption rate (RTP), and the energy consumption rate of the third network node n3 or the fourth network node n4, which is the relay node, Consumption rate (RP). After the first time T1, direct transmission is performed. In the direct transmission period, the energy consumption rate of the fifth network node n5 as the source node is the direct transmission consumption rate (DTP), and the energy consumption rate of the third network node n3 or the fourth network node n4, which is the relay node, Consumption rate (nRP).

The energy of the fifth network node n5 as the source node and the energy of the third network node n3 or the fourth network node n4 as the relay node are exhausted at the same time point T2 as shown in Fig. A first time T1 may be set. When the relay transmission is performed during the first time T1 and then the direct transmission is performed, the fifth network node n5 as the source node and the third network node n3 or the fourth network node n4, which are relay nodes, Are exhausted together at the second time T2. That is, the remaining life of the fifth network node n5 as the source node and the third network node n3 or the fourth network node n4 as the relay node are leveled.

In order to determine the first time, the fifth network node n5 as the source node transmits the source node information table (see Fig. 3) to the third and fourth network nodes n3 and n4 as candidate nodes. Based on the source node information table received from the fifth network node n5 as the source node and the relay node information table (see Fig. 4) of each of the third and fourth network nodes n3 and n4, which are candidate nodes, 1 hour (T1) can be determined. The first time T1 is calculated by Equation (1).

The first time T1 calculated by the equation (1) represents the relay transmission time, the second time T2 is the fifth network node n5 which is the source node, the third network node n3 which is the neighbor node, 4 represents the time at which the remaining lifetime of the network node n4 is leveled.

That is, when the fifth network node n5 as the source node transmits the source node information table to the third network node n3 or the fourth network node n4 as the candidate node, the third network node n3, which is the candidate node, Or the fourth network node n4 may calculate the first time T1 and the second time T2. That is, the relay transmission time T1 and the leveled remaining lifetime can be calculated. If the third network node n3 or the fourth network node n4, which is a candidate node, is selected as the relay node, the relay transmission will be performed until the first time T1, and then the direct transmission will be performed. That is, based on the source node information table and the relay node information table, the remaining lifetime of the fifth network node n5 as the source node and the third network node n3 or the fourth network node n4 as the relay node are leveled .

When there are two or more candidate nodes of the relay node, the fifth network node n5, which is the source node, transmits the source node information table to the third to fourth network nodes n3 and n4, which are two or more candidate nodes. The third to fourth network nodes n3 and n4, which are candidate nodes, respectively calculate the first time T1 and the second time T2 and transmit them to the fifth network node n5 as the source node. The fifth network node n5 as the source node will select the candidate node that transmitted the second longest time T2 of the third to fourth network nodes n3 and n4 as candidate nodes as the relay node. Then, it will perform the relay transmission for the first time T1 received from the selected relay node, for example the third network node n3 or the fourth network node n4, and then perform the direct transmission.

Based on FIGS. 2, 3 and 1, when a relay transmission is performed through the third one of the third to fourth network nodes n3 and n4 as the candidate nodes, (T1) is calculated as 88/7 and the second time (T2) is calculated as 86/7. When the relay transmission is performed through the fourth network node n4 among the third to fourth network nodes n3 and n4 as the candidate nodes, the first time T1 is calculated as 40/13, The time T2 is calculated as 110/13.

The second time T2 corresponding to the third network node n3, i.e., the leveled remaining lifetime is longer than the second time T2 corresponding to the fourth network node n4, i.e., the leveled remaining lifetime. Therefore, when the third network node n3 is selected as the relay node, the channel holding time between the fifth network node n5 as the source node and the third network node n3 as the relay node increases. Thus, the lifetime of the ad hoc network 100 is optimized.

Illustratively, the fifth network node n5, which is the source node, is connected to the third and fourth network nodes n3 and n4, which are candidate nodes, according to a second time T2, i.e. a probabilistic method based on the leveled remaining lifetime , And selects a relay node. With a probabilistic method based on a leveled residual lifetime, problems due to uncertainties such as mobility can be avoided.

Illustratively, the second times T2 of the third and fourth network nodes n3 and n4, which are candidate nodes, will be sorted in descending order. The weights W1 and W2 are weighted at the aligned second times T2. For example, the aligned second times T2 will be multiplied by weights W1 and W2, respectively. Illustratively, the weights W1 and W2 are selected such that the weights W1 and W2 are positive and the sum of the weights W1 + W2 is one.

The probability P1 that the third one of the third to fourth network nodes n3 and n4, which are candidate nodes, is selected as the relay node may be defined by the following equation (2).

T2 = (n3) * W1 / (T2 (n3) * W1 + T2 (n4) * W2)

Here T2 (n3) is the second time T2 of the third network node n3 and T2 (n4) is the second time T2 of the fourth network node n4.

The probability P2 that the fourth network node n4 among the third to fourth network nodes n3 and n4, which are candidate nodes, is selected as the relay node may be defined by Equation (3).

P2 = T2 (n4) * W1 / (T2 (n3) * W1 + T2 (n4) * W2)

Here T2 (n3) is the second time T2 of the third network node n3 and T2 (n4) is the second time T2 of the fourth network node n4.

The weights may vary depending on the uncertainty of the ad hoc network 100. For example, when the network nodes n1 through n6 of the ad hoc network 100 are fixed network nodes, the uncertainty is minimized. At this time, the value of the first weight W1 is set to one. At this time, the candidate node that transmitted the second longest time T2 of the third to fourth network nodes n3 and n4, which are the candidate nodes, will be selected as the relay node.

There are uncertainties when the network nodes n1 through n6 of the ad hoc network 100 are the moving network nodes. At this time, the weights W1 and W2 weighted on the third and fourth network nodes n3 and n4, which are candidate nodes, are set to uniform values. Therefore, depending on the ratio of the second times T2 of the third and fourth network nodes n3 and n4, which are candidate nodes, the relay node will be selected.

In FIG. 5, it is shown that the direct transmission is performed after the relay transmission is performed. However, the technical idea of the present invention can be applied such that relay transmission is performed after direct transmission is performed.

The first time T1 received from the neighbor node is the time at which the relay transmission is performed. It can be understood that the first time T1 represents the ratio of the residual energy amount of the source node and the neighboring node. Illustratively, when the first time T1 is less than the reference value, that is, when the ratio of the remaining energy amount of the source node and the residual energy amount of the neighboring node is lower than the reference value, the source node does not select the neighboring node as the relay node will be.

As described above, the relay transmission amount and the direct transmission amount are set such that the remaining lifetime of the source node and the relay node is leveled at the time of data transmission. Also, among the candidate nodes of the relay node, a candidate node having a long remaining lifetime is selected as the relay node. Thus, the lifetime of the ad hoc network 100 is optimized.

FIG. 6 is a block diagram illustrating the network node described with reference to FIGS. 1-5. 6, a network node (e.g., n5) includes an energy management unit 10, a transmission data management unit 20, a transmission / reception unit 30, and a control unit 40. [

The energy management unit 10 operates in response to the control of the control unit 40. [ The energy management unit 10 is configured to monitor the residual energy E of the network node n5. The energy management unit 10 provides the control unit 40 with the amount of the residual energy E.

The transmission data management unit 20 operates in response to the control of the control unit 40. [ The transmission data management unit 20 includes a communication queue. For example, the transmission data to be transmitted by the network node n5 will be stored in the communication queue of the transmission data management unit 20. [ Data relayed and transmitted by the network node n5 will also be stored in the communication queue. In response to the control of the control unit 40, the data stored in the communication queue is transmitted through the transmission / reception unit 30.

The transmission / reception unit 30 operates in response to the control of the control unit 40. The transmission / reception unit 30 provides transmission means and reception means.

The control unit 40 is configured to control all operations of the network node n5. The control unit 40 is connected to the energy management unit 10, the transmission data management unit 20, and the transmission / reception unit 30.

7 is a flowchart for explaining a first embodiment of the communication operation of the network node n5 in Fig. Referring to FIGS. 6 and 7, in step S110, it is determined whether there is data in the queue. When transmission data is generated, transmission data is stored in a communication queue of the transmission data management unit 20. [ That is, if data exists in the queue, it indicates that transmission data has occurred. If there is data in the queue, step S115 is performed.

For example, when data is detected in the communication queue of the transmission data management unit 20, the control unit 40 will perform the operation of step S115. If there is no data in the queue, step S145 is performed. For example, when no data is detected in the communication queue of the transmission data management unit 20, the control unit 40 will perform the operation of step S145.

In step S115, a ready-to-send (RTS) message is transmitted to neighboring nodes. The RTS message is a message indicating the ready state of transmission. That is, the RTS message indicates that the network node n5 has transmission data.

The RTS message includes the direct transmission rate (DTP), the relay transmission rate (RTP), and the residual energy (E) of the network node n5. For example, the control unit 40 receives the residual energy E from the energy management unit 10. Based on the distance to the target node and the distance to the candidate nodes, the control unit 40 calculates the direct transmission consumption rate (DTP) and the relay transmission consumption rate (RTP). The control unit 40 controls the transceiver 30 such that the residual energy E and the calculated direct transmission consumption rate DTP and the relay transmission consumption rate RTP are transmitted to the candidate nodes. Thereafter, step S120 is performed.

In step 120, an ACK message is received. The ACK message is received from the candidate nodes, respectively, in response to the RTS message. The ACK message includes a first time (T1, i.e., relay transmission time) and a second time (T2, i.e., a normalized remaining lifetime). As described with reference to Figs. 1 to 5, the control unit 40 will select a candidate node corresponding to the longest time among the received second times T2 as a relay node. For example, the control unit 40 will select the relay node in a probabilistic manner based on the received second times T2 and the weights.

Illustratively, if there is no candidate node of the relay node, that is, if the network node closest to the target node is the source node, the control unit 40 will not select the relay node. Illustratively, if the relay transmission time is less than the reference time, the control unit 40 will not select the relay node. If the relay node is selected, step S130 is performed. If the relay node is not selected, step S140 is performed.

In step S130, relay transmission is performed. The control unit 40 controls the transmission / reception unit 30 so that data stored in the communication queue of the transmission data management unit 20 is transmitted to the selected relay node. The controller 40 controls the transceiver 30 such that the relay transmission is performed during the first time T1 corresponding to the selected relay node.

In step S135, it is determined whether there is data in the queue. Illustratively, when the first time T1 and the second time T2 corresponding to the selected relay node are the same, the transmission data will be delivered to the target node only via relay transmission. In this case, if the relay transmission is performed during the first time T1, the transmission data of the transmission data management unit 20 are all transmitted. That is, there will be no data in the communication queue. If there is no data in the queue, the communication operation is terminated.

When the first time T1 corresponding to the selected relay node is shorter than the second time T2, the transmission data is transmitted to the target node through relay transmission and direct transmission. In this case, even if the relay transmission is performed during the first time T1, data exists in the communication queue of the transmission data management unit 20. [ If there is data in the queue, step S140 is performed.

In step S140, direct transmission is performed. The control unit 40 controls the transmitting / receiving unit 30 so that the transmission data stored in the communication queue of the transmission data management unit 20 is transmitted to the target node. When the direct transfer is completed, the communication operation is ended.

In step S110, if there is no data in the queue, that is, if no transmission data is generated, step S145 is performed. In step S145, the control unit 40 determines whether an RTS message is received. If the RTS message is not received, the communication operation is terminated. If the RTS message is received, step S150 is performed.

The RTS message is received when one of the neighboring nodes is preparing to transmit data. Therefore, based on the received RTS message, the control unit 40 calculates the relay node operating environment. The RTS message includes the direct transmission rate (DTP), the relay transmission rate (RTP), and the residual energy (E) of the source node. The control unit 40 receives the residual energy En from the energy management unit 10. [ The control unit 40 calculates the RP rate at the time of relay and the nRP at the time of the hydrometer based on the distance to the target node. Based on the direct transmission consumption rate (DTP), the relay transmission consumption rate (RTP), the residual energy of the source node (E), the consumption rate at relay (RP), the consumption rate at nonspring (nRP), and the residual energy (En) , The control unit 40 calculates the first time T1 and the second time T2. That is, the control unit 40 calculates the relay transmission time T1 and the levelized remaining service life T2.

In step S155, an ACK message is transmitted. The controller 40 controls the transceiver 30 such that an ACK message including the first time T1 and the second time T2 is transmitted to the source node of the RTS message.

In step S160, it is determined whether it is selected as a relay node. Illustratively, when a relay node selection message is received from the source node of the RTS message, it will be determined to be selected as the relay node. If the relay node selection message is not received from the source node of the RTS message, it will be determined that it is not selected as the relay node. As another example, if a relay node unselect message is received from the source node of the RTS message, it will be determined that it is not selected as the relay node. If it is not selected as the relay node, the communication operation is ended. If it is selected as a relay node, data relay is performed in step S165. The control unit 40 will control the transmission / reception unit 30 to perform the relay transmission. Thereafter, when the data relay is completed, the communication operation is ended.

The communication operation described with reference to Fig. 7 will be repeatedly performed while network node n5 joins ad hoc network 100. Fig. That is, if transmission data is generated while the network node n5 participates in the ad-hoc network 100, relay transmission and direct transmission will be performed (steps S115 to S140). When the network node n5 is participating in the ad hoc network 100 and the RTS message is received when no transmission data is generated, the network node n5 will operate as a candidate node of the relay node in steps S150 and S155. If the network node n5 is selected as the relay node, the network node n5 will operate as a relay node (step S165).

As described above, in the ad-hoc network 100, the channel holding time between the network nodes n1 to n6 is maximized. Thus, the lifetime of the ad hoc network 100 is optimized. Also, the network nodes n1 to n6 determine the relay transmission time T1 and the levelized remaining service life T2 through minimized communication (RTS message and ACK message). Thus, the overhead for performing the lifetime optimization of the ad hoc network 100 is reduced.

8 is a flowchart for explaining a second embodiment of the communication operation of the network node n5 in Fig. Referring to FIGS. 6 and 8, in step S210, the network node n5 selects a relay node. The selection of the relay node has been described with reference to Figs. Therefore, detailed description is omitted.

In step S220, the network node n5 transmits data. Data transmission includes relay transmission and direct transmission.

In step S230, it is determined whether data of the reference amount has been transmitted. If the data of the reference amount has not been transmitted, step S250 is performed. If the data of the reference amount has been transmitted, step S240 is performed.

In step S240, the network node n5 reselects the relay node. Thereafter, step S250 is performed.

In step S250, it is determined whether or not the data transfer is completed. When the data transfer is completed, the communication operation is ended. If the data transfer has not been completed, the data transfer continues in step S220.

That is, when transmitting the transmission data, the network node n5 selects the relay node and performs the relay transmission and the direct transmission. When the data of the reference amount is successively transmitted, the network node n5 reselects the relay node, and performs relay transmission and direct transmission. Thus, the energy consumption for data transmission can be distributed to the source node and the at least two relay nodes. That is, the channel retention time between the source node and the at least two relay nodes can be optimized.

Fig. 9 is a block diagram showing a third embodiment of the communication method of the network node n6 of Fig. 6; Fig. In Fig. 9, it is assumed that the sixth network node n6 is the source node and the first network node n1 is the target node. When the sixth network node n6 as the source node transmits data to the first network node n1 as the target node, it can perform the relay transmission through the at least two relay nodes. For example, the sixth network node n6 as the source node can transmit data to the first network node n1 as the target node via the fifth network node n5 and the third network node n3. Thus, energy consumption for data transmission can be distributed to the source node and at least two relay nodes. That is, the channel retention time between the source node and the at least two relay nodes can be optimized.

Illustratively, when the RTS message received from the sixth network node n6, which is the source node, includes the multi-relay information, the candidate node of the first relay node (e.g., the fifth network node n5) will detect the candidate node of the second relay node (e.g., the third network node n3). The information tables will be exchanged between the sixth network node n6 as the source node, the fifth network node n5 as the first candidate node, and the third network node n3 as the second candidate node. Based on the information tables, the relay transmission time and the direct transmission time will be determined. For example, the relay transmission time may be determined by a relay node, such as a first network node n5, which is the first and second candidate nodes, a relay transmission time through the third network node n3, a fifth network node n5, And the relay transmission time through the third network node n3 which is the second candidate node.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. Therefore, the scope of the present invention should not be limited to the above-described embodiments, but should be determined by the equivalents of the claims of the present invention as well as the claims of the following.

1 is a block diagram illustrating an ad hoc network according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating distance information between first and third to fifth network nodes of the ad hoc network of FIG. 1; FIG.

FIG. 3 shows a source node information table.

4 shows relay node information tables.

5 is a graph for explaining a method for determining the remaining service life and the relay transmission time.

FIG. 6 is a block diagram illustrating the network node described with reference to FIGS. 1-5.

7 is a flowchart for explaining a first embodiment of the communication operation of the network node of Fig.

8 is a flowchart for explaining a second embodiment of the communication operation of the network node in Fig.

9 is a block diagram showing a third embodiment of the communication method of the network node of FIG.

Claims (10)

A method of operating an ad hoc network node comprising: Determining whether transmission data exists by a transmission data management unit of the network node; Determining, by a control unit of the network node, a remaining life time of each of the network node and the relay node when relaying the transmission data through the relay node and directly transmitting the transmission data to the target node; And Determining whether the network node is relaying and direct transmission based on the remaining lifetime of the network node and the relay node. The method according to claim 1, The step of determining whether the relay transmission or the direct transmission is performed And determining a relay transmission time of the transmission data based on the determined remaining service life. 3. The method of claim 2, The step of determining the relay transmission time And setting the relay transmission time such that the remaining lifetime of the network node and the relay node is leveled. The method according to claim 1, The step of determining the remaining lifetime in the relay transmission and the direct transmission includes Detecting residual energy; Detecting a first energy consumption rate when directly transmitting the transmission data; Detecting a second energy consumption rate when relaying the transmission data through a neighboring node; Transmitting the detected residual energy and the detected first and second energy consumption rates to a neighboring node; Receiving a remaining lifetime from the neighboring node when the transmission data is relayed through the neighboring node; And And determining the remaining lifetime as the remaining lifetime in the relay transmission and the direct transmission. 5. The method of claim 4, Wherein the first and second energy consumption rates are transmitted to at least two neighbor nodes, Wherein one of the at least two neighboring nodes is selected as a relay node based on the remaining lifetimes received from the at least two neighboring nodes. The method according to claim 1, Determining whether a transmission ready message is received if the transmission data does not exist, determining a remaining service life when the network node operates as a relay node based on the transmission ready message, and transmitting the determined remaining service life ≪ / RTI > further comprising the steps of: The method according to claim 6, Determining whether a relay node selection message according to the transmitted remaining lifetime is received; And And operating as a relay node based on the received relay node selection message. A transmission data management unit configured to determine whether transmission data exists; An energy management unit configured to detect residual energy; And And a control unit configured to detect a first energy consumption rate when the transmission data is directly transmitted and a second energy consumption rate when relay transmission is performed, Wherein the controller determines a remaining life time and a relay transmission time when performing the relay transmission and the direct transmission based on the detected residual energy and the detected first and second energy consumption rates, And an ad hoc network node for determining whether the transmission data is directly transmitted or relayed based on the remaining service life and the relay transmission time. 9. The method of claim 8, An ad hoc network node in which a part of the transmission data is relayed and the rest is directly transmitted under the control of the control unit based on the determined remaining service life and the relay transmission time. A method of data transmission in an ad hoc network comprising: The source node determining a candidate node of a relay node to transmit data to the target node based on the distance between the source node and the candidate node; Determining, by the source node and the candidate node, a relay transmission time and a remaining lifetime at which a remaining life time of the source node and the candidate node is leveled; And Performing a relay transmission from the source node to the target node via the relay node during the determined relay transmission time, and performing a direct transmission from the source node to the target node for the remaining time.

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