KR20090044249A - Sensing Data Routing Apparatus and Method for Sensor Nodes Providing Energy Efficiency and Reliability over Wireless Sensor Networks - Google Patents

Abstract

Disclosed are an apparatus and method for sensing data routing of a sensor node that provides energy efficiency and reliability on a wireless sensor network. The apparatus and method receive routing configuration messages including energy remaining information of each of the neighbor sensor nodes from at least one neighboring sensor node within the wireless reception range of the sensor node for a predetermined reception waiting time, The parent node to be routed is selected among the neighbor sensor nodes according to the energy remaining information, and the sensing data is transmitted to the selected parent node. According to the present invention, by selecting the data transfer path in consideration of the remaining energy of the node to distribute the energy consumption of the node to improve the life of the network and to improve the reliability of data transfer using the bypass path.

Sensor networks, modified tree routing, braided multi-path routing, energy efficiency

Description

Reliable and energy efficient routing apparatus and method for sensor node on the wireless sensor networks

The present invention relates to an apparatus and method for sensing data routing of a sensor node that provides energy efficiency and reliability on a wireless sensor network. More particularly, the present invention relates to selecting a data transmission path in consideration of energy remaining of each node in a wireless sensor network. The present invention relates to a sensing data routing apparatus and method of a sensor node on a wireless sensor network that distributes energy consumption of a node and improves reliability of data transmission through a bypass path.

The present invention is derived from the research conducted as part of the IT new growth engine core technology development project of the Ministry of Information and Communication [Task management number: 2005-S-038-03, task name: UHF RF-ID and Ubiquitous networking technology development].

A sensor network is defined as a wireless network consisting of sensor nodes and sink nodes (also known as data centers, gateways or base stations) that have sensing, processing, and wireless communication capabilities. These sensor networks can be used throughout the industry, and typical applications include:

First, it can be used for military reconnaissance, surveillance and command delivery. Second, it can be used for environmental diagnosis related to pollution, forest fire and flood monitoring, and farming in rural areas. Third, in the field of digital home, intelligent sensors can be installed in lighting, windows as well as home appliances, and can provide various convenient functions such as remote control and crime prevention. Fourth, the intelligent building field can be used to improve automation and control and energy efficiency through building monitoring. Fifth, the medical field can be applied to hospital patient management, healthcare, drug management, and systems for the disabled. Lastly, logistics management and telematics fields include logistics management and quality control of production products.

These sensor network applications have common characteristics in their operation, which means that data is transferred from the source corresponding to the actual data sensed by the sensor node to the sink node that collects this data. In the process, the sensor nodes form their own ad hoc network and transmit data to the sink node without using an existing network.

This data transfer process should be developed to meet the following requirements in common. First, the low power design requires maximum sensor node life. Since the place where sensor node is installed is often inconvenient or not easy to access physically, it is not practical to replace or charge the battery by hand. Therefore, it is necessary to maximize the life of the sensor node by designing low power consumption. do. Second, the ability to accept and resolve network topology changes is required. Sensor nodes deployed in the sensor field do not connect directly to a fixed infrastructure network, such as the Internet, but form internal, self-configuring ad hoc networks that communicate internally. It goes through the sink node. The network topology can always change due to sensor nodes moving, failing, or new nodes being deployed. The ability to accept and resolve these changes appropriately is required.

Directed Diffusion (DD) is one of the sensor network routing techniques for data transfer from the source node to the sink node. DD transfers data by forming an optimal transmission path (routing) considering the energy of each node from the sink node to the source node. However, by continuously transmitting data through the established path, the energy of the nodes in the path is exhausted.

EAR (Energy Aware Routing) is a way to improve the limitation of this DD. EAR is a routing technique that ensures that energy consumption is uniform throughout the network. Assuming all nodes know their own and all other nodes in advance, the topology information from the sink node to the source node is stored in a table of each node, and each forwarding node from the source node to the sink node is responsible for By randomly selecting from the table, a route is made through different nodes for every data transfer, which prevents energy consumption from being concentrated on specific nodes. However, there is a burden that all nodes need to know the location information in advance, and both DD and EAR have a disadvantage in that there is no countermeasure when data transfer fails.

An object of the present invention is to select a data transfer path in a wireless sensor network in consideration of the remaining energy of each node, thereby distributing energy consumption of the node and improving reliability of data transfer through a bypass path. An object of the present invention is to provide an apparatus and method for sensing data routing of a sensor node.

In order to achieve the above technical problem, a sensing data routing device of a sensor node in a wireless sensor network according to the present invention includes energy remaining information of each of the neighbor sensor nodes from at least one or more neighboring sensor nodes within a wireless reception range of the sensor node. A routing setting message receiving unit which receives the routing setting messages for a predetermined reception waiting time; A parent node selection unit for selecting a parent node to be routed among neighbor sensor nodes according to energy remaining information of each neighbor sensor node; And a sensing data transmitter for transmitting sensing data to the selected parent node.

In order to achieve the above technical problem, a sensing data routing method of a sensor node in a wireless sensor network according to the present invention includes energy remaining information of each neighboring sensor node from at least one or more neighboring sensor nodes within a wireless receiving range of the sensor node. A routing setup message receiving step for receiving routing setup messages for a predetermined reception waiting time; Selecting a parent node to be routed among neighbor sensor nodes according to energy remaining information of each of the neighbor sensor nodes; And a sensing data transmission step of transmitting sensing data to the selected parent node.

According to the present invention, the data transmission path is selected in consideration of the remaining energy of the node, thereby dispersing the energy consumption of the node, thereby improving the life of the network.

In addition, the path management is performed by using the message overheard in the data routing process, thereby reducing the additional processing cost and improving energy efficiency.

In addition, when sensing data transfer to a parent node fails, a new parent node is selected from among neighboring sensor nodes that can be bypassed to transfer sensing data to provide reliability of data transfer.

The following merely illustrates the principles of the invention. Therefore, those skilled in the art, although not explicitly described or illustrated herein, can embody the principles of the present invention and invent various devices that fall within the spirit and scope of the present invention. Furthermore, all conditional terms and embodiments listed herein are in principle clearly intended for the purpose of understanding the concept of the invention and are not to be limited to the specifically listed embodiments and states. Should be. In addition, it is to be understood that all detailed descriptions, including the principles, aspects, and embodiments of the present invention, as well as listing specific embodiments, are intended to include structural and functional equivalents of these matters. In addition, these equivalents should be understood to include not only equivalents now known, but also equivalents to be developed in the future, that is, all devices invented to perform the same function regardless of structure.

Thus, the functionality of the various elements shown in the figures, including functional blocks represented by a processor or similar concept, can be provided by the use of dedicated hardware as well as hardware capable of executing software in conjunction with appropriate software. When provided by a processor, the functionality may be provided by a single dedicated processor, by a single shared processor or by a plurality of individual processors, some of which may be shared. In addition, the use of terms presented in terms of processor, control, or similar concept should not be interpreted exclusively as a citation of hardware capable of executing software, and without limitation, ROM for storing digital signal processor (DSP) hardware, software. (ROM), RAM, and non-volatile memory are to be understood to implicitly include. Other well known hardware may also be included.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. In describing the present invention, when it is determined that the detailed description of the related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating a configuration of a sensing data routing device of a sensor node on a wireless sensor network according to an embodiment of the present invention, and FIG. 2 is a sensing data routing device of a sensor node on a wireless sensor network shown in FIG. 1. FIG. Is a flowchart illustrating a sensing data routing method performed in FIG.

Referring to FIG. 1, a sensing data routing apparatus of a sensor node according to the present embodiment includes a routing setup message receiver 110, a parent node selecting unit 120, and a sensing data transmitter 130.

The routing setup message receiver 110 receives routing setup messages including energy remaining information of each of the neighbor sensor nodes from at least one neighboring sensor node within the wireless reception range of the sensor node for a predetermined reception waiting time (S210). . The routing configuration message of the neighboring sensor nodes further includes a level in a tree topology connecting the respective sensor nodes constituting the wireless sensor network with the address of the neighboring sensor node and the sink node of the wireless sensor network as a route.

The parent node selecting unit 120 selects a parent node to be routed among the neighboring sensor nodes according to the energy remaining information of each of the neighboring sensor nodes read from the routing setting message received by the routing setting message receiver 110 (S220). The parent node selecting unit 120 selects a node having the highest energy remaining among the neighboring sensor nodes as the parent node, and the energy remaining information storage unit (not shown) stores energy remaining information of each of the neighboring sensor nodes.

The level setting unit (not shown) sets the level of the sensor node according to the level of the selected parent node among the levels of each of the neighbor sensor nodes read from the routing setting message received by the routing setting message receiving unit 110.

The routing setup message receiver 110 does not receive routing setup messages from neighboring sensor nodes after the level of the sensor node is set in the level setup unit (not shown). This is to prevent selecting a lower node as a parent node in the tree topology.

The sensing data transmission unit 130 transmits the sensing data to the parent node selected by the parent node selecting unit 120 (S230). In this case, upon successful reception of the transmitted sensing data, the parent node transmits a reception success message including energy remaining information of the parent node.

The sensing data transmission unit 130 retransmits the sensing data within a predetermined retransmission frequency when the reception success response message indicating that the sensing data has been successfully transmitted from the parent nodes is not received within the predetermined reception waiting time.

In case of failing to transmit the sensing data to the parent node, that is, when the sensing data is not transmitted even though the sensing data is retransmitted within the preset number of retransmissions from the parent node, the parent node is selected among the remaining sensor nodes except the parent node. The sensing data is transmitted to the newly selected parent node by reselection. If it fails to deliver the sensing data to the parent node, it provides reliability of data delivery by selecting a new parent node from the neighboring sensor nodes that can be bypassed and transferring the sensing data.

The routing setting message broadcasting unit (not shown) broadcasts a routing setting message including energy remaining information of the sensor node itself. Through this, the remaining nodes, which have not yet been set on the tree topology, receive the routing configuration message, select their parent nodes, and set their own levels to set the data paths to transmit their sensing data.

The energy remaining information updating unit (not shown) overhears a reception success response message including energy remaining information of each of the neighboring sensor nodes from neighboring sensor nodes to store energy of the neighboring sensor nodes stored in the energy remaining information storage unit (not shown). Update remaining amount information. The parent node re-election government re-selects the parent node when the energy remaining information of the neighboring sensor node updated by the energy remaining information updating unit exceeds the threshold set using the energy remaining information of the parent node. By performing path management using this overheard message, it is possible to reduce additional processing costs and improve energy efficiency.

3 is a flowchart illustrating a tree topology based path setting method from a sink node to each sensor node of a wireless sensor network according to an embodiment of the present invention, and FIG. 4 is performed by the path setting method shown in FIG. Is a diagram illustrating a wireless sensor network.

First, the sink node corresponding to the root node sets its level to 0 and broadcasts a route_setup message including its address, level, and energy remaining information (S301).

Each sensor node of the network receives an address and a level of a transmission node included in a routing configuration message received by receiving the routing configuration message broadcast in step S301 for a predefined interval when its level is not set. And energy remaining amount information (S302). The sensor node may receive a routing setup message when the sensor node is within the wireless transmission range of the transmitting node, and conversely, the transmitting node becomes a neighbor sensor node within the wireless receiving range of the sensor node.

The node having the highest energy remaining is selected as its parent node using the information stored in step S302, and the remaining information is stored in the candidate parent node table (S303).

In operation S304, a routing setting message including its own address, its own level set to {parent level + 1}, and its own energy remaining information is broadcasted.

If each sensor node of the network repeats the process of S302 to S304 until all of them set their own levels (S305), as a result, all sensor nodes of the wireless sensor network are assigned a level as shown in FIG. And form a parent node based on the remaining energy, and store candidate parent node information separately.

FIG. 5 is a diagram illustrating a flow of a data transfer method from each sensor node to a sink node of a wireless sensor network according to an embodiment of the present invention, and FIG. 6 is a diagram illustrating the data transfer method illustrated in FIG. 5. A diagram illustrating a wireless sensor network.

The sensor node generating the sensing data or receiving the sensing data from another sensor node transmits a data message including its own address, a destination address set as its parent address, and data to be transmitted to the parent node (S501).

Upon receiving the data message, the parent node transmits an acknowledgment response message (ACK) including a destination address set as its address and a child's address, and its energy remaining to the sensor node which has transmitted the data message (S502).

If the reception success response message is not received from the parent node within a predetermined time (S503), the sensor node retransmits the data message to the parent node within the set number of retransmissions (S504). If the set number of retransmissions is exceeded, it is determined that data transfer has failed to the parent node, and the node having the highest energy level is reselected as the parent node in the candidate parent node (S505) and the data message is transmitted to the reselected parent node. (S506).

When each sensor node performs the processes of S501 to S507 up to the sink node, the sensing data is transferred from the sensor node (node 9) that generated the sensing data to the sink node (node 0) as shown in FIG. 6. Will be.

In this process, the path management step considering the remaining energy of the node is as follows. In a wireless environment, messages transmitted and received are received by all nodes within the transmission range of the transmitting node. Route management is performed using these characteristics and response messages. The receiving node receiving the data message sends an acknowledgment message containing its energy level to the transmitting node that sent the data message, in which case nodes within the radio transmission range of the transmitting node may overhear the acknowledgment message. do. Each node that receives the response message checks whether the sending node that sent the response message corresponds to one of its parent and candidate parent nodes, and if so, sends the remaining energy information of the node to the acknowledgment message. Update the energy remaining information of the included transmission node. If the updated energy remaining amount is greater than the threshold value δ set according to the current remaining energy amount of the parent node, the parent node is updated with the transmitting node of the overhearded success response message, and the information of the previous parent is added to the candidate parent information. Save it.

As shown in FIG. 6, data transfer from the source node 9 to the sink node 0 may occur through path_1 first, and then through path_2 based on the updated information. As a result, the routing method according to the present invention achieves braided multi-path routing, thereby preventing energy consumption from being concentrated on a specific node.

7 illustrates a structure of a routing setup message according to an embodiment of the present invention.

Referring to FIG. 7, the routing setup message includes a header 701, a source address field 702, a destination address field 703, a level field 704, and an energy remaining amount information field 705.

The header 701 includes information on the message type, the source address field 702 includes address information of the node transmitting the message, and the destination address to be included in the destination address field 703 is set to a broadcast address. . The level field 704 and the energy remaining amount information field 705 include the level and energy remaining amount information of the node transmitting the message, respectively.

8 is a diagram showing the structure of a reception success message according to an embodiment of the present invention.

Referring to FIG. 8, the reception success response message includes a header 801, a source address field 802, a destination address field 803, and an energy remaining amount information field 804.

The header 801 includes information regarding the message type, the source address field 802 includes address information of a node that has received a data message, and the destination address field 803 is address information of a node which has transmitted a data message. It includes.

The energy remaining information field 804 includes energy remaining information of the node that received the data message, so that the node overhearing the reception success response message does not need to receive a separate message regarding the energy remaining information. The routing path can be managed based on the remaining energy information included in the response message.

9 is a diagram illustrating a structure of a data message according to an embodiment of the present invention.

Referring to FIG. 9, a data message includes a header 901, a source address field 902, a destination address field 903, and a sensing data field 904.

 The header 901 includes information regarding the message type, the source address field 902 includes address information of the node that has received the data message, and the destination address included in the destination address field 903 is the address of the parent node. Becomes

10A to 10D are diagrams illustrating a flow of a method of receiving a message by a sensor node according to an embodiment of the present invention. The process of receiving and processing the routing setting message shown in FIG. 7 (S1011 to S1015), and FIG. 8. Receiving and processing the received acknowledgment message (S1021 to 1025) and receiving and processing the data message shown in FIG. 9 (S1031 to S1032).

Referring to FIG. 10A, the sensor node receives a message (S1001) and determines a type of a message through a header of the message.

Referring to FIG. 10B, when the message type is a routing setting message (S1010), it is checked whether the destination address is set to broadcast (S1011), and the address, level, and energy of the transmitted node included in the routing setting message. The remaining amount information is stored (S1012). When the predefined reception waiting time expires (S1013), reception of the routing setup message is stopped, a parent node is selected, and a candidate parent node table is generated (S1014). And it broadcasts a routing setup message including its address, level and energy remaining information (S1015).

Referring to FIG. 10C, when the type of message is an acknowledgment of success (S1020), the destination address checks its own address (S1021), and when it is its own address, the transmission of the data message transmitted by itself is successful. It checks (S1022). If the destination address is the address of the parent node or the address of the candidate parent node (S1023), the energy remaining information of the parent node or the candidate parent node is corrected (S1024), and the parent node and the candidate parent node are modified according to the modified energy remaining information. Update is made (S1025).

Referring to FIG. 10D, when the type of message is a data message (S1030), the destination address is identified as its own address (S1031), and when it is its own address, a data message is transmitted to the parent node (S1032).

FIG. 11 is a flowchart illustrating a method of transmitting a data message of a sensor node according to an embodiment of the present invention. When a data message transmission process shown in FIG. 9 and data transmission to a parent node fail, a parent node in a candidate parent node is illustrated. Re-selecting and transmitting the data message to the reselected new parent node.

FIG. 11 illustrates the data transfer method shown in FIG. 5 in more detail. Therefore, even if omitted below, the above description of the data delivery method illustrated in FIG. 5 is also applied to the data message transmission method according to the present embodiment.

The sensor node generates sensing data or receives it from another sensor node in the form of a data message (S1101) and transmits it to its parent node in the form of a data message (S1102). If there is no response by waiting for an acknowledgment message from the parent node during the predetermined reception waiting time (S1103 to S1104), the transmission is retransmitted by a predetermined number of retransmissions (S1105). Nevertheless, if the reception success response message is not received, it is checked whether the candidate parent node table is empty (S1106), and when it is not empty, the parent node is reselected among candidate parent nodes, and the information of the parent node is updated according to the new parent node. S1107).

The invention may also be embodied as computer readable code on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, hard disk, floppy disk, flash memory, optical data storage device, and also carrier waves (for example, transmission over the Internet). It is also included to be implemented in the form of. The computer readable recording medium can also be distributed over computer systems connected over a computer network so that the computer readable code is stored and executed in a distributed fashion. Also, the font ROM data structure according to the present invention can be read by a computer on a recording medium such as a computer readable ROM, RAM, CD-ROM, magnetic tape, hard disk, floppy disk, flash memory, optical data storage device, and the like. It can be implemented as code.

As described above, the present invention has been described based on the preferred embodiments, but these embodiments are intended to illustrate the present invention, not to limit the present invention, and those skilled in the art to which the present invention pertains should be practiced without departing from the spirit of the present invention. It will be apparent that various changes, modifications, or adjustments to the examples are possible. Therefore, the protection scope of the present invention will be limited only by the appended claims, and should be construed as including all such changes, modifications or adjustments.

1 is a diagram illustrating a configuration of an apparatus for sensing data routing of a sensor node on a wireless sensor network according to an embodiment of the present invention.

2 is a flowchart illustrating a sensing data routing method of a sensor node on a wireless sensor network according to an embodiment of the present invention.

3 is a flowchart illustrating a tree topology based path setting method from a sink node to each sensor node of a wireless sensor network according to an embodiment of the present invention.

4 is a diagram illustrating a wireless sensor network in which a tree topology based path establishment method is performed according to an embodiment of the present invention.

5 is a diagram illustrating a flow of a data transfer method from each sensor node to a sink node in a wireless sensor network according to an embodiment of the present invention.

6 is a diagram illustrating a wireless sensor network in which a data transfer method from each sensor node to a sink node is performed according to an embodiment of the present invention.

7 illustrates a structure of a routing setup message according to an embodiment of the present invention.

8 is a diagram showing the structure of a reception success message according to an embodiment of the present invention.

9 is a diagram illustrating a structure of a data message according to an embodiment of the present invention.

10A to 10D are diagrams illustrating a flow of a method of receiving a message by a sensor node according to an embodiment of the present invention.

11 is a flowchart illustrating a method of transmitting a data message by a sensor node according to an embodiment of the present invention.

Claims (24)

In the sensing data routing device of a sensor node on a wireless sensor network consisting of a sink node and at least one sensor node, A routing configuration message receiver configured to receive routing configuration messages including energy remaining information of each of the neighbor sensor nodes from at least one neighboring sensor node within a wireless reception range of the sensor node for a predetermined reception waiting time; A parent node selecting unit for selecting a parent node to be routed among the neighbor sensor nodes according to energy remaining information of each of the neighbor sensor nodes; And And a sensing data transmission unit for transmitting sensing data to the selected parent node. The method of claim 1, The sensing data transmission unit If the sensing data transmission to the parent node fails, the sensing data routing device of the sensor node, characterized in that for transmitting the sensing data by reselecting the parent node among the remaining neighboring sensor nodes except the selected parent node. The method of claim 1, The parent node selecting unit selects a node having the highest energy remaining among the neighboring sensor nodes as a parent node. The method of claim 1, And a routing setting message broadcaster configured to broadcast a routing setting message including energy remaining information of the sensor node. The method of claim 1, And the parent node transmits a reception success response message including energy remaining information of the parent node when receiving the transmitted sensing data. The method of claim 1, The sensing data transmission unit The sensor node retransmits the sensing data within a predetermined number of retransmissions when the acknowledgment response message indicating that the sensing data has been successfully transmitted from the parent nodes is not received within a predetermined reception waiting time. Sensing data routing device. The method of claim 1, And an energy remaining information storage unit for storing energy remaining information of the neighboring sensor nodes according to the received routing setting messages. The method of claim 7, wherein And an energy remaining information update unit configured to update an energy remaining information of the stored neighbor sensor nodes by overhearing a reception success response message including energy remaining information of each of the neighbor sensor nodes from the neighbor sensor nodes. Sensing data routing device of sensor node. The method of claim 8, If the updated energy remaining information of the neighboring sensor node exceeds the threshold set using the energy remaining information of the parent node, the sensing data of the sensor node further comprises a parent node re-decision to reselect the parent node. Routing device. The method of claim 1, The routing setup message further includes the level of each of the neighbor sensor nodes in a tree topology connecting at least one sensor node on the wireless sensor network with the sink node as a route. Routing device. The method of claim 10, And a level setting unit configured to set a level of the sensor node according to the level of the selected parent node among the levels of each of the neighbor sensor nodes. The method of claim 11, And the routing setting message receiving unit does not receive the routing setting messages from the neighboring sensor nodes after the level of the sensor node is set in the level setting unit. In the sensing data routing method of a sensor node on a wireless sensor network consisting of a sink node and at least one sensor node, A routing configuration message receiving step of receiving routing configuration messages including energy remaining information of each of the neighbor sensor nodes from a wireless reception range of the sensor node during a predetermined reception waiting time; Selecting a parent node to be routed among the neighbor sensor nodes according to energy remaining information of each of the neighbor sensor nodes; And And a sensing data transmission step of transmitting sensing data to the selected parent node. The method of claim 13, The sensing data transmission step If it fails to transmit the sensing data to the parent node, the sensing data of the sensor node further comprises the step of re-selecting the parent node among the remaining neighboring sensor nodes except the selected parent node to transmit the sensing data. Routing method. The method of claim 13, The selecting of the parent node includes selecting a node having the highest energy remaining among the neighboring sensor nodes as a parent node. The method of claim 13, And transmitting a routing setting message including energy remaining information of the sensor node. The method of claim 13, And if the parent node succeeds in receiving the transmitted sensing data, transmitting a successful response message including energy remaining information of the parent node. The method of claim 13, The sensing data transmission step Retransmitting the sensing data within a predetermined retransmission frequency when the acknowledgment response message indicating that the sensing data has been successfully transmitted from the parent nodes is not received within a predetermined reception waiting time. Sensing data routing method of the sensor node. The method of claim 13, And storing energy remaining information of the neighboring sensor nodes according to the received routing configuration messages. The method of claim 19, Updating the energy remaining information of the stored neighbor sensor nodes by overhearing a reception success response message including energy remaining information of each of the neighbor sensor nodes from the neighbor sensor nodes; Sensing data routing method. The method of claim 20, And reselecting a parent node if the energy remaining information of the updated neighbor sensor node exceeds a threshold set using the energy remaining information of the parent node. The method of claim 13, The routing configuration message further includes the level of each of the neighboring sensor nodes in a tree topology connecting at least one sensor node on the wireless sensor network with the sink node as a route. Way. The method of claim 22, And setting a level of the sensor node according to the level of the selected parent node among the levels of each of the neighbor sensor nodes. The method of claim 23, wherein And after the level of the sensor node is set in the level setting step, not receiving the routing setting messages from the neighbor sensor nodes.

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