KR20100053360A - Sensor network, communication method for the same and sensor node included in the same - Google Patents

Abstract

PURPOSE: A sensor network, the communication method and a sensor node included in the same are provided to extend lifetime of a sensor node by reducing electric power consumption of the corresponding sensor node with cooperative routing of relay nodes. CONSTITUTION: The first relay node(15) receives an event message from a source node(17). The first relay node transmits the first data message corresponding to the event message to a destination node(S) in the first electricity of a power table. The second relay node(16) receives the event message from the source node. The second relay node transmits the second data message corresponding to the event message to the destination node in the second electricity of the power table.

Description

Sensor network, communication method for the same and sensor node included in the sensor {SENSOR NETWORK, COMMUNICATION METHOD FOR THE SAME AND SENSOR NODE INCLUDED IN THE SAME}

The present invention relates to a sensor network, a communication method for the same, and a sensor node included therein, and more particularly, relay nodes cooperate to have data transmissions reconfigured to transmit data messages to a destination node (eg, a sink node). The present invention relates to a sensor network for transmitting the data messages in synchronization, and a communication method therefor and a sensor node included therein.

A ubiquitous sensor network (USN) is a system for processing and managing the information through a method of transmitting information input through various sensor nodes to an external network through a sink node, and is generally illustrated in FIG. 1 below. Has a structure.

1 is a diagram illustrating a general sensor network.

Referring to FIG. 1, the sensor network includes a sensor field 100 consisting of sensor nodes 102, a sink node 104, and an external network 106.

The sensor nodes 102 collect data requested by a user using a sensor or the like, and transmit the collected data to the external network 106 through the sink node 104. In detail, the sensor nodes 102 are set as child nodes and parent nodes, respectively, and the child nodes transmit the collected data to the parent nodes. As a result, the data collected by the particular sensor node 102 is transmitted to the sink node 104 via this transmission method, generally via multi-hop, as shown in FIG. Here, this transmission path is established by considering the least cost routing path.

In such a sensor network, the sensor node 102 is not powered from the outside, so once all of its power is consumed the sensor node 102 is no longer used. As a result, it is important to reduce power consumption for the efficiency of the sensor network, which has been studied a lot recently. However, since a conventional sensor network establishes a corresponding transmission path considering only the least cost routing path, a specific sensor node can be used considerably more than other sensor nodes. As a result, the power of the specific sensor node is quickly consumed to shorten the life of the sensor node, and thus there is a problem that the efficiency and connectivity of the sensor network may be degraded.

In addition, the random arrangement of sensor nodes could not guarantee that all nodes participate in the network, and the specific sensor node could be separated from other sensor nodes, thereby disconnecting the network. That is, there is a problem in that the connectivity of the sensor network is not excellent.

SUMMARY OF THE INVENTION An object of the present invention is to provide a sensor network, a communication method therefor, and a sensor node included therein, which improve connectivity between nodes while reducing power consumption.

In order to achieve the above object, the sensor network communication method according to an embodiment of the present invention comprises the steps of broadcasting an event message having a power table at the source node; A first relay node receiving the broadcast event message, transmitting a first data message corresponding to the event message to a destination node with a first power included in the power table; And receiving, by the second relay node receiving the broadcast event message, a second data message corresponding to the event message with the second power included in the power table to the destination node. Here, the first power and the second power are set in consideration of weights according to link costs.

The sensor network communication method according to another embodiment of the present invention includes the steps of: determining, by a source node, relay nodes to cooperatively route; Sending an event message having a power table by the source node to a first relay node of the relay nodes; The source node sending the event message to a second relay node of the relay nodes; Transmitting, by the first relay node, a first data message corresponding to the event message to a destination node with a first power included in the power table; And transmitting, by the second relay node, a second data message corresponding to the event message to the destination node with the second power included in the power table. Here, the first power and the second power are set in consideration of weights according to link costs.

The sensor node used in the cooperative routing sensor network according to an embodiment of the present invention includes a sensing unit for collecting specific data; A signal processing unit for transmitting the notification message and the event message to the first relay node and the second relay node for cooperative routing; And calculating a weight using a first link cost between the first relay node and a destination node and a second link cost between the second relay node and the destination node, and using the weight to determine the first relay node. And a power calculator configured to set power for the second relay node and power for the second relay node. Here, the event message includes a power table having information on the power set by the power calculator.

In the sensor network according to the present invention, since a plurality of relay nodes cooperate to transmit a data message to a destination node, for example, a sink node, a wireless transmission range of the network can be extended, thereby improving network connectivity. In addition, since the power consumption of the sensor node can be reduced by the cooperative routing, the lifespan of the sensor node can be extended. However, the relay nodes transmit the data message in synchronization with the destination node.

In addition, the sensor network uses weights calculated through link costs to add more overhead to the best connected nodes and reduce the overhead of the remaining nodes, thus reducing the overall power consumption of the sensor network. There is an advantage.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. Like reference numerals are used for like elements in describing each drawing.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and are not construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

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

2 is a diagram illustrating a concept of cooperative routing in a sensor network according to an embodiment of the present invention.

In the sensor network of the present embodiment, in particular the wireless sensor network, a plurality of sensor nodes, for example two sensor nodes 200 and 202, are configured to collect data collected by the source node as shown in FIG. For example, it transmits in cooperation with a sink node. In this case, the wireless transmission range 210 or 212 of each sensor node 200 and 202 is limited to a specific range, but since the sensor nodes 200 and 202 cooperate to route, the wireless transmission range 214 ) Is expanded as shown in FIG. 2.

That is, the sensor network of the present invention extends the data transmission range by overlapping the transmission powers of the plurality of sensor nodes. However, the sensor nodes transmit the data messages synchronously when transmitting the data messages having the collected data to the destination node. For example, the time when the first sensor node transmits the data message to the destination node and the time when the second sensor node transmits the data message to the destination node are the same, that is, the sensor nodes transmit the data messages. At the same time to the destination node. Detailed description thereof will be described later.

As mentioned above, when the sensor nodes transmit the data messages in synchronization, the data transmission range is extended due to the overlap of the transmission power, thereby improving connectivity of the network (between the sensor nodes).

In addition, since the transmit power is increased by cooperative routing of the sensor nodes, even though each sensor node transmits a data message with a low transmit power, the total transmit power may be the same as in a conventional sensor network. It can be reduced so that the life of the sensor nodes can be extended. As a result, unlike in the conventional sensor network in which the lifetime of a specific sensor node is shortened, thereby reducing the connectivity and efficiency of the entire network, in the sensor network of the present embodiment, the lifetime of the sensor nodes is extended by reducing the power consumption. Network connectivity and efficiency can be improved. In particular, in the present situation where it is impossible to charge the sensor node externally, the method of reducing such power consumption has great significance.

In addition, the sensor network of the present embodiment calculates the link costs between the sensor nodes and the destination node to determine the connection state between the nodes, and then increases the transmission power of the nodes with good connection state and increases the connection state. Improve the efficiency of transmit power by reducing transmit power of bad nodes. This transmission power control is performed at the source node, which will be described in detail later.

Hereinafter, the configuration of such a sensor network will be described in more detail with reference to the accompanying drawings.

3 is a diagram illustrating a sensor network according to an embodiment of the present invention.

Referring to FIG. 3, the sensor network of the present embodiment includes a plurality of sensor nodes 1 to 17 and a sink node S. FIG.

Assume the sensor node 17 of the sensor nodes 1 to 17 is a source node. In this case, the remaining nodes 1 to 16 that do not operate as source nodes will be referred to as relay nodes hereinafter.

In a conventional sensor network, the data collected by the source node 17 was transmitted to the sink node S via a mininum cost routing path, for example via the relay node 16. However, the sensor network of the present embodiment not only transmits the data collected by the sword node 17 to the sink node S through the relay node 16 but also to the sink node S through the relay node 15. do. That is, relay nodes 15 and 16 cooperatively transmit the data message. Here, the data transmission time point from the relay node 16 to the sink node S is set to be the same as the data transmission time point from the relay node 15 to the sink node S. FIG. A specific operation method for this will be described later.

According to one embodiment of the invention, the source node 17 knows in advance the information about the relay nodes 15 and 16 to cooperatively route. In detail, the source node 17 may store a routing table having information about the entire sensor nodes 1 to 17 or information about relay nodes associated with the source node 17. Thereafter, the source node 17 can identify the relay nodes 15 and 16 to cooperatively route using the routing table in the data transmission, and control the relay nodes 15 and 16 to cooperatively route. . However, the data message transmission direction is preferably set from the child node to the parent node.

Referring back to FIG. 3, the majority of cooperative routing, but depending on the environment, the corresponding data message passes through only the least cost routing path (e.g. 14-13-S) without cooperative routing. ) May be sent. That is, the sensor network may implement data message transmission only through the cooperative routing transmission method, or may use the cooperative routing transmission method and the least cost routing path transmission method together.

Hereinafter, the synchronization process in the cooperative routing process will be described first, and then the power redistribution process will be described in detail.

First, the synchronization process will be described in detail with reference to the accompanying drawings.

4 and 5 are diagrams illustrating a synchronization process in a sensor network according to an embodiment of the present invention.

4 and 5, the source node 400 broadcasts a notification message N indicating that an event message E is to be transmitted (S500). In this case, the source node 400 measures the broadcasting time point t1 of the notification message N by executing a timing unit existing inside or outside thereof.

According to another embodiment of the present invention, since the source node 400 knows in advance through the routing table the relay nodes 402 and 404 to cooperatively route, the notification message N is relayed only to the relay nodes 402 and 404. You can also send. Of course, even in this case, the source node 400 measures the transmission time t1 of the notification message N by executing a timing unit existing inside or outside thereof.

Subsequently, relay nodes 402 and 404 receive the notification message N, and then relay nodes 402 and 404 respond in response to the received notification message N, respectively. After generating the ACK and the second ACK, and transmits to the source node 400 (S502 and S504). Here, the response message (the first ACK or the second ACK) may include information on the authentication number (ID) of the corresponding relay node 402 or 404 and the link cost between itself and the destination node. have.

Subsequently, source node 400 receives response messages (first ACK and second ACK). In this case, the source node 400 measures the time point t2 at which the first response message (first ACK) is received and the time point t3 at which the second response message (second ACK) is received using the timing unit. Then, the information on the received time points t2 and t3 is mapped to the corresponding relay node and stored. Here, it is preferable that the source node 400 stores the information about the measured time points t1 to t3 in its own memory, but may also store it in an external memory according to circumstances.

The source node 400 then calculates the message exchange time with the first relay node 402, i.e. (t2-t1 = T1), and the message exchange time with the second relay node 404, i.e. (t3-t1 = Calculate T2). This is to calculate the time taken when a message is sent from the source node 400 to the relay node 402 or 404. According to another embodiment of the present invention, when the source node 400 broadcasts the event message E, the broadcast node includes information on the broadcast time point in the event message E, and the relay node 402 or 404 sends the event. When the message E arrives, the time at which the message is transmitted is calculated, and the information about the calculated time may be included in the response message and transmitted to the source node 400. That is, the method for calculating the message transmission time is not limited to a specific method and may be variously modified.

Subsequently, the source node 400 calculates the transmission time difference through the difference between T1 and T2.

Subsequently, the source node 400 sets wait times for the relay nodes 402 and 404 respectively according to the calculated transmission time difference, and then sinks having information on the set wait times. Create a sync table.

Apart from generating the sink table, the source node 400 calculates weights using the link costs included in the response messages (the first ACK and the second ACK), and uses the weights to relay nodes 402 and 404. Set the transmit power for Thereafter, the source node 400 generates a power table having information on the set transmission powers, and includes the generated power table in the event message E. A detailed description of the power setting process will be described later.

Subsequently, the source node 400 broadcasts an event message E having the generated sink table, the generated power table, and the collected data to relay nodes 402 and 404 (S506).

Subsequently, the first relay node 402 analyzes the event message E to detect a waiting time allocated to the first relay node 402 and waits for the waiting time from the time at which the event message E is received, and then has the data. The data message D is transmitted to the destination node 406, for example, the sink node (S508). In this case, the first relay node 402 transmits the data message D to the destination node 406 with the first power set in the power table.

Also, the second relay node 404 analyzes the event message E to detect a waiting time allocated to the second relay node 404 and waits for the waiting time from the time point at which the event message E is received, and then has the data. The data message D is transmitted to the destination node 406 (S510). As a result, the relay nodes 402 and 404 can output the data messages D simultaneously. Of course, the second relay node 402 sends the data message D to the destination node 406 with the second power set in the power table. Here, it is preferable that the second power has a different size from the first power.

Hereinafter, in order to more easily understand the synchronization process and the power setting process will be described through a practical example.

First, let's look at the synchronization process. However, assuming that the message exchange time T1 between the source node 400 and the first relay node 402 is 4 seconds, the message exchange time T2 between the source node 400 and the second relay node 404 is assumed. Assume 2 sec.

In this case, the time taken to transmit the event message E from the source node 400 to the first relay node 402 is approximately 2 seconds, and the event message from the source node 400 to the second relay node 404. The time taken to transmit (E) is approximately 1 second. Therefore, the transmission time difference is (2-1 = 1) seconds, which is calculated as (T1-T2) / 2.

Therefore, if the first waiting time for the first relay node 402 is set to zero, the second waiting time for the second relay node 404 is set to one second corresponding to the transmission time difference. This setting information is stored in the sink table.

When the source node 400 transmits an event message E having the sink table and the power table to the first relay node 402, the first relay node 402 receives data because the first waiting time is 0 seconds. The message D is sent to the destination node 406 as soon as the event message E is received (2 seconds until reception). As a result, the time taken from when the source node 400 sent the event message E to the first relay node 402 sending the data message is 2 seconds.

In addition, when the source node 400 transmits the event message E to the second relay node 404, the second relay node 404 receives the event message E because the second waiting time is 1 second. One second after the time (1 second elapsed), the data message (D) is sent to the destination node (406). As a result, the time taken from when the source node 400 sends the event message E to the second relay node 404 sending the data message is 2 seconds. That is, the relay nodes 402 and 404 simultaneously send data messages D to the destination node 406 two seconds after the source node 400 sends the event message E. FIG. That is, the data messages D are synchronously transmitted, and thus, as the transmission power is increased, the wireless transmission range can be extended and power consumption of individual nodes can be reduced.

Next, we will look at the power setting process.

6 and 7 illustrate a power setting process according to an embodiment of the present invention.

Referring to FIG. 6, each relay node R1 and R2 calculates each link cost LC through Equation 1 below.

, 여기서 LC(a,b)는 a 노드와 b 노드 사이의 링크 비용을 의미하고, SNRmin은 요구되는 최소 SNR의 문턱값(threshold value)을 나타내며, P_η는 신호의 잡음(noise) 파워를 의미하고, α는 전력 감쇄 상수를 나타낸다.

Where LC (a, b) denotes the link cost between node a and node b, SNRmin denotes the threshold value of the minimum SNR required, and P _η denotes the noise power of the signal. And α represents a power decay constant.

Referring to Equation 1 above, it can be seen that the connectivity between the nodes is excellent the smaller the link cost.

Hereinafter, it is assumed that the link cost between the first relay node R1 and the destination node D is 5 and the link cost between the second relay node R2 and the destination node D is 7.

The source node determines these link costs through the response messages and then calculates the power according to the cooperative routing through Equation 2 below.

When the cooperative routing power P _C is calculated through Equation 1 above, P _C = 1 / (1/5 + 1/7) = 2.9. That is, the relay node R1 may transmit a data message to the destination node D with a power of 2.9, and the relay node R2 may also transmit a corresponding data message to the destination node D with a power of 2.9. As a result, power consumption can be distributed to the relay nodes R1 and R2 without being overhead to a particular node. However, even in this case, inefficient power consumption may occur at relay nodes around a specific node. Therefore, the power setting method of the present invention resets the power using the weight value W for efficient power consumption.

Specifically, the sensor network of the present embodiment increases the power burden between the nodes R1 and D with low link cost, that is, with high connectivity, and the nodes R2 and D with high link cost, i.e., with low connectivity. Reduces power burden between As a result, the overall network power consumption can be reduced.

Hereinafter, the power setting process will be described in detail using the following equations.

, 여기서 P1은 가장 링크 비용이 우수한 노드들 사이의 전력을 의미한다.

Where P1 is the power between the nodes with the best link cost.

, 여기서 Pi는 i번째로 링크 비용이 우수한 노드들 사이의 전력을 의미한다.

Where P i is the power between the nodes with the highest link cost.

When the weight W is obtained through the above Equation 3, W = 5/12. Therefore, the power between nodes R1 and D having the best link cost is calculated as 4.13 through Equation 4, and the power between other nodes R2 and D is calculated as 1.2 through Equation 5. .

That is, the power between well-connected nodes R1 and D is increased by 1.23 from 2.9 to 4.13, while the power between nodes that are not connected is decreased by 1.7 from 2.9 to 1.2. do. As a result, the power required for full cooperative routing is reduced from 5.8 to 5.33.

In short, the overall power consumption of the sensor network can be reduced by adding more overhead to well-connected nodes and reducing the overhead of nodes that are disconnected.

Although two cooperative routing nodes are exemplified above, three or more relay nodes may cooperatively route. However, if the number of cooperative routing relay nodes increases considerably, the total calculation amount and the like increase, so it is desirable to appropriately set the number of relay nodes for cooperative routing.

Hereinafter, a power setting process when three relay nodes are used will be described with reference to FIG. 7. Here, as shown in FIG. 7, the link cost between nodes R1 and D is assumed to be 2, the link cost between nodes R2 and D is assumed to be 4, and nodes R3 and D are represented. Assume that the link cost between six.

In this case, the power between the best connected nodes R1 and D is set to increase from 0.92 to 1.07, and then the power between the best connected nodes R1 and D decreases from 0.92 to 0.5. Power between nodes R3 and D having the lowest connection state is set to decrease from 0.92 to 0.36. Here, the process of calculating the power can be easily inferred from the description of FIG. 6 and thus will be omitted.

As a result, the power required for full cooperative routing is reduced from 2.76 to 1.93.

In short, the sensor network of the present invention can reduce the total power by using the weight (W).

Experimental results according to these results will be described in detail with reference to the accompanying drawings.

FIG. 8 is a diagram illustrating power consumption between nodes having the best connection state, and FIG. 9 is a diagram illustrating power consumption between nodes having a poor connection state. 10 is a diagram illustrating power consumption of the entire network. Here, it is assumed that two relay nodes, and the link cost between nodes having excellent link cost is assumed to be 10.

Referring to FIG. 8, the power consumption 802 between nodes having the best link cost in the sensor network of the present invention is the best link in a sensor network (hereinafter, referred to as an existing sensor network) with no power reset. It is found that the power consumption between nodes having a cost is large compared to 800. This is because more overhead is added to nodes having excellent link costs.

However, the power consumption 902 between nodes having low link cost in the sensor network of the present invention is considerably compared to the power consumption 900 between nodes having low link cost in the existing sensor network as shown in FIG. Smallness is confirmed.

Looking at the total power, it is confirmed that the total power consumption 1002 in the sensor network of the present invention is smaller than the total power consumption 1000 in the existing sensor network as shown in FIG. 10.

That is, the sensor network of the present invention can improve power efficiency by using weights.

In short, the sensor network of the present invention can perform cooperative routing in synchronization, and reset power using weights to improve power efficiency.

In the above, the relay nodes all seemed to be active, but the relay nodes remain idle to reduce power consumption and then change to active as the notification message N is sent. May be

According to another embodiment of the present invention, relay nodes for cooperative routing for a particular source node are not preset but may be variably configured. In detail, the source node may broadcast the notifies message to the surrounding area and then select relay nodes corresponding to some of the response messages transmitted in response to the notify message as relay nodes to cooperatively route. For example, the source node may select the relay nodes corresponding to the response messages received until 4 seconds have elapsed after broadcasting the notification message as relay nodes to cooperatively route. Then, the source node always generates a sink table and a power table through the measured times and link costs, and sends an event message with the sink table, the power table and the collection data to relay nodes to cooperatively route. Cooperative routing can be controlled.

That is, the source node of the sensor network of the present invention controls the relay nodes such that predetermined or later selected relay nodes simultaneously transmit data messages D to the destination node and finally to the sink node.

11 is a block diagram illustrating a source node according to an embodiment of the present invention.

Referring to FIG. 11, the source node of the present embodiment includes a control unit 1100, a wireless communication unit 1102, a sensing unit 1104, a storage unit 1106, a power supply unit 1108, a signal processing unit 1110, and a timing unit 1112. ), A power calculator 1114 and a table generator 1116.

The wireless communication unit 1102 is a connection path with the outside, and is not limited to a specific method for wireless communication, and various communication methods such as Zigbee may be used. Of course, not only wireless communication but also wired communication method may be used.

The sensing unit 1104 collects data requested by the user or data set to be sensed in advance. For example, the sensing unit 1104 may detect recognition information about a specific object or surrounding environment information in real time.

The storage unit 1106 is a part for storing various data. Preferably, the storage unit 1106 stores a program for driving a source node, the collected data, information on the measured times, weights, information on the reset power, and the like. do.

The power supply 1108 supplies power to various components of the source node. Of course, such a power supply 1108 has a limit having a limited capacity. Therefore, a method using a solar cell may be considered to overcome such limitations of power supply capacity.

The signal processor 1110 generates a notice message N, an event message E, and the like, and broadcasts the generated messages N and E to the corresponding relay node. Of course, when the source node operates as a cooperative routing node of another sensor node, the signal processor 1110 may generate a response message and a data message D.

The timing unit 1112 measures a time point at which the notification message N is broadcast and a time point at which response messages transmitted from the relay nodes are received.

The power calculator 1114 calculates a weight using the link costs, and calculates a power to be reset using the calculated weight.

The table generator 1116 generates a sink table that stores information about wait times and a power table that stores information about the reset power. Here, the calculation of the waiting times may be performed by the timing unit 1112 or by the table generator 1116.

The controller 1100 generally controls the operations of the components of the source node.

The embodiments of the present invention described above are disclosed for purposes of illustration, and those skilled in the art having ordinary knowledge of the present invention may make various modifications, changes, and additions within the spirit and scope of the present invention. Should be considered to be within the scope of the following claims.

1 is a diagram illustrating a general sensor network.

2 is a diagram illustrating a concept of cooperative routing in a sensor network according to an embodiment of the present invention.

3 is a diagram illustrating a sensor network according to an embodiment of the present invention.

4 and 5 are diagrams illustrating a synchronization process in a sensor network according to an embodiment of the present invention.

6 and 7 illustrate a power setting process according to an embodiment of the present invention.

8 is a diagram illustrating power consumption between nodes having the best connection state.

FIG. 9 is a diagram illustrating power consumption between nodes in which a connection state is lost. FIG.

10 is a diagram illustrating power consumption of the entire network.

11 is a block diagram illustrating a source node according to an embodiment of the present invention.

Claims (12)

Broadcasting an event message having a power table at the source node; A first relay node receiving the broadcast event message, transmitting a first data message corresponding to the event message to a destination node with a first power included in the power table; And And transmitting, by the second relay node receiving the broadcast event message, a second data message corresponding to the event message to the destination node with the second power included in the power table. And the first power and the second power are set in consideration of weights according to link costs. The method of claim 1, wherein the time point at which the first relay node transmits the first data message is the same as the time point at which the second relay tod transmits the second data message. The method of claim 1, wherein the sensor network communication method, The source node broadcasting a notice message; The first relay node sending a first response message to the source node in response to the broadcasted notification message; And Sending, by the second relay node, a second response message to the source node in response to the broadcasted notification message, The first response message includes information about the link cost between the first relay node and the destination node, and the second response message includes information about the link cost between the second relay node and the destination node. Sensor network communication method characterized in that. The method of claim 3, wherein the sensor network communication method, Measuring, by the source node, a first time from the broadcast time point to the time point at which the first response message is received from the first relay node; Measuring a second time from the broadcast time point to the time point when the second response message is received from the second relay node; Calculating a difference between the first time and the second time; Generating the sink table having information on a first waiting time for a first relay node and a second waiting time for the second relay node according to the calculation result value; Calculating a weight using information on link costs included in the response messages; Setting power for each of the relay nodes using the weights; And Generating the power table having information on the set powers; The link cost is expressed as

(LC (a, b) refers to the link cost between a node and b nodes, SNRmin denotes a threshold value (threshold value) of the minimum required SNR, P _η is the mean noise (noise) power of the signal , α represents a power attenuation constant), and the weight W is

Sensor network communication method, characterized in that calculated by. The power of a relay node having a low link cost is varied to a power larger than a reference power calculated according to cooperative routing, and the power of a relay node having a high link cost is varied to a power less than the reference power. Equation for

(Pi means power between nodes having the i-th excellent link cost). The method of claim 4, wherein the first relay node transmits the data message to the destination node after the first waiting time has elapsed from the time point at which the event message is received, and the second relay node is configured to transmit the event message. And transmitting the data message to the destination node after the second waiting time has elapsed from the received time point. Determining, by the source node, relay nodes to cooperatively route; Sending an event message having a power table by the source node to a first relay node of the relay nodes; The source node sending the event message to a second relay node of the relay nodes; Transmitting, by the first relay node, a first data message corresponding to the event message to a destination node with a first power included in the power table; And Transmitting, by the second relay node, a second data message corresponding to the event message to the destination node with a second power included in the power table, And the first power and the second power are set in consideration of weights according to link costs. 8. The method of claim 7, wherein the time point at which the first relay node transmits the first data message is the same as the time point at which the second relay tod transmits the second data message. The method of claim 7, wherein the sensor network communication method, Sending, by the first relay node, information about a link cost between the first relay node and the destination node to the source node; The second relay tod transmitting information about a link cost between the second relay node and the destination node to the source node; Calculating a weight using the information on the link cost; Setting power for each of the relay nodes using the weights; And And generating the power table having information about the set powers. 10. The method of claim 9, wherein the power of the relay node having a low link cost is varied to a power larger than a reference power calculated according to cooperative routing, and the power of the relay node having a high link cost is varied to a power less than the reference power. Sensor network communication method. A sensor node used in a cooperative routing sensor network, A sensing unit collecting specific data; A signal processing unit for transmitting the notification message and the event message to the first relay node and the second relay node for cooperative routing; And A weight is calculated using a first link cost between the first relay node and a destination node and a second link cost between the second relay node and the destination node, and the weight is used for the first relay node. A power calculator configured to set power and power for the second relay node; And the event message comprises a power table having information on power set by the power calculator. The method of claim 11, wherein the sensor node, A first time is measured between when the corresponding message is transmitted from the sensor node to the first relay node and when a first response message is received from the first relay node, and the second relay node is detected from the sensor node. Further comprising a timing unit for measuring a first time between the time of transmitting the notification message to the second relay node and the time when the second response message is received, The timing unit or the signal processor calculates a difference between the first time and the second time, and the signal processor sets wait times for the relay nodes according to the calculated result and stores the set wait times. And generate the event message having a sink table.

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