JP7025479B2 - Reception status display method, node, slave node and program - Google Patents

Description

The present invention relates to a reception status display method, a node , a slave node, and a program.

In a wireless communication network characterized by wireless multi-hop relay such as a wireless backhaul system and a sensor and actuator network, minimum propagation loss routing is known as a route control algorithm (see, for example, Non-Patent Document 1). This makes the metric a radio wave propagation loss.

H. Furukawa, 2 outsiders, “Wireless Base Node Repeater Network for 4G mobile communications,” in Proc, IST mobile communications summit 2001, pp.607-614, Sep. 2001, Barcelona.

Minimal propagation loss routing has been used so far when only wireless communication is performed between nodes. Conventionally, it has been considered that wireless communication has a degree of freedom in the installation location and the like as compared with wired communication. Therefore, the necessity of adding wired communication to wireless communication has not been substantially discussed.

However, in reality, wireless communication may not be possible. For example, if there is a shield such as indoors and attic, wireless communication may not be possible between the nodes. In such a case, it is suitable to realize not only wireless communication but also wire communication in part. Little has been discussed about routing when some of this is achieved by wired communication.

Therefore, an object of the present invention is to propose a route control method or the like capable of realizing routing in a so-called hybrid network in which wireless communication and wired communication coexist.

The first aspect of the present invention is a route control method for determining a route between the first node and the second node from a plurality of route candidates between the first node and the second node in a network. , Wireless communication and / or wired communication is performed between the nodes of the network, and when the calculation means performs wireless communication between the nodes included in the respective route candidates, it is regarded as a radio wave propagation loss and the wired communication is performed. Assuming that the loss is smaller than that in the case of performing wireless communication, the calculation step for calculating the metric of each route candidate and the determination means use the metric of each route candidate from the plurality of route candidates. It includes a determination step for determining a route between the first node and the second node.

The second aspect of the present invention is the route control method of the first aspect, wherein each node includes one or a plurality of communication interfaces, and in the calculation step, the first node is a route control frame. When the individual calculation means receives the route control frame on the communication interface of wireless communication in the node that has received the route control frame, the metric of the route candidate from the first node to the immediately preceding node is used. When the radio wave propagation loss from the immediately preceding node to the node is added as a terminal metric to be a new metric for the route candidate from the first node to the node, and the route control frame is received by the communication interface of the wired communication. , To the metric of the route candidate from the first node to the immediately preceding node, a value that the loss is smaller than when the immediately preceding node and the node perform wireless communication is added as a terminal metric, and the node from the first node to the preceding node. When the new metric of the route candidate newly calculated for each communication interface is smaller than the current metric calculated before, the new metric is used as the new metric of the route candidates up to. The metric is updated to the current metric, the communication interface is used as an uplink relay destination interface, and the route control frame including the new metric is transmitted from all communicable communication interfaces.

A third aspect of the present invention is the route control method according to the first or second aspect, wherein each node includes one or more communication interfaces, and each communication interface has one or more. The child communication interface of the above is included, and the calculation means calculates the metric of each route candidate for each communication interface, and when a plurality of communication interfaces of the same type are mounted, each child communication. The terminal metric calculated from the route control frame received by the interface is compared, and the metric of each of the route candidates is calculated using the larger terminal metric.

A fourth aspect of the present invention is a node having one or more wireless communication interfaces and one or more wired communication interfaces, and the communication interface is received when the route control frame transmitted by the first node is received. Each time, an individual calculation means for calculating a metric of a route candidate from the first node to the node is provided, and the individual calculation means receives the route control frame at the wireless communication interface, the first node. The radio propagation loss from the immediately preceding node to the node is added to the route candidate metric from the immediately preceding node to the immediately preceding node to obtain the route candidate metric from the first node to the node, and the route control frame is used in the wired communication interface. Is received, the metric of the route candidate from the first node to the immediately preceding node is added with a value that the loss is smaller than that when the immediately preceding node and the node perform wireless communication, and the loss is small from the first node. It is a metric of route candidates to the node.

The fifth aspect of the present invention is the node of the fourth aspect, and the route control frame when the newly calculated route candidate metric is smaller than the previously calculated route candidate metric. Further, it is provided with a communication control means for transmitting the route control frame including the metric of the route candidate from the first node to the node from all the communication interfaces capable of communicating.

The sixth aspect of the present invention is the node of the fourth or fifth aspect, and the path in the wireless communication interface which is at least the metric of the smallest route candidate among the wireless communication interfaces with respect to the display unit. It is provided with display control means for displaying the reception status of the control frame.

A seventh aspect of the present invention is a node according to any one of the fourth to sixth aspects, wherein at least one of the wired communication interfaces has a power feeding function to and / or connects to another node to be connected. It has a power receiving function for the node of.

An eighth aspect of the present invention is a program for making a computer having one or more wireless communication interfaces and one or more wireless communication interfaces function as a node of any of the fourth to seventh aspects. be.

The invention of the present application may be regarded as a computer-readable recording medium in which the program of the eighth aspect is (steadily) recorded.

According to each viewpoint of the present invention, in a hybrid network system in which wireless communication and wired communication are mixed, the wired communication path is evaluated to have less loss than wireless communication, and is made similar to the minimum propagation loss routing of wireless communication. By determining the route, it becomes possible to realize the routing.

Further, as in the second aspect of the present invention, the path of the node provided with a plurality of communication interfaces may be evaluated for each communication interface. For example, even if the same wireless communication is used, the case of using Wi-Fi and the case of using another communication method are evaluated as different routes. This makes it possible to realize communication using the most efficient communication interface.

Further, as in the third aspect of the present invention, when the communication interface includes a plurality of child communication interfaces, the communication interface is used by evaluating the one having the worst communication environment among them. Communication quality can be guaranteed. That is, for example, when a plurality of Wi-Fi child communication interfaces are included, the communication quality is the worst, and the entire Wi-Fi communication interface is evaluated and compared with that of another wireless communication interface. As a result, for example, in a Wi-Fi communication interface, an uplink (for example, a line for realizing transmission from a slave node to a core node) is realized by some child communication interfaces, and another child communication interface is used. Even if a downlink (for example, a line for realizing transmission from a core node to a slave node) is realized, it is possible to select the communication interface having the best communication quality. The inventor has so far proposed a periodic intermittent transmission method (IPT). The IPT enhances the efficiency of the entire network by periodically transmitting intermittently on the downlink and transmitting on the uplink as soon as possible. IPT has improved the communication quality of the entire network by distinguishing between the upper and lower lines. Evaluating communication quality by distinguishing between upper and lower lines is a matter that is not generally done. As described above, according to the third aspect of the present invention, not only different types of communication interfaces (for example, wired communication IF and wireless communication IF) but also the same type of communication interface (for example, wireless communication IF). , It becomes possible to evaluate the entire child communication interface included in the communication interface and determine the route with the least propagation loss.

Further, according to the sixth aspect of the present invention, by displaying the reception status of the route control frame in the wireless communication interface, it becomes possible to easily determine whether or not the use of wired communication is suitable. .. Each node is equipped with a reroute button for transmitting a route control frame and an LED for displaying the reception status. The node installation worker presses the reroute button of the node every time a new node is installed, and grasps the reception status by the lighting state of the LED. If the route control frame is received correctly, the LED is turned on, and if it cannot be received, the LED is turned off. Further, when the route control frame can be correctly received, the LED is blinked according to the number of blinks of the LED in proportion to the reception intensity of the route control frame, and then turned on. As a result, the installation worker can determine on the spot whether or not the installation location of the installed node is appropriate. Since the transmission of the route control frame is performed by pressing the reroute button provided on the node, the installation worker presses the reroute button of the node after installing the node, and if the LED of the node does not light after that, the LED of the node does not light up. You can immediately know that the installation location is inappropriate. If the LED does not light up, it is impossible to establish a relay route wirelessly, and it is possible to take measures such as moving the node or connecting to an adjacent node by wire.

Further, according to the seventh aspect of the present invention, since the wired communication interface is provided with the power feeding function and / or the power receiving function, it is not necessary to newly provide a power supply or the like.

It is a block diagram which shows the outline of the structure of the node which concerns on embodiment of this invention. It is a flow diagram which shows an example of the operation of the 1st node. It is a flow diagram which shows an example of the operation of the node other than the 1st node. It is a figure which shows an example of the path formation starting from a node A in the case of four nodes A, B, C and D.

Hereinafter, examples of the present invention will be described with reference to the drawings. The invention of the present application is not limited to this embodiment.

The network system in this embodiment includes a plurality of nodes and communicates between the nodes. This embodiment is for determining a route between one node and another. After the route is determined between the nodes, data is transmitted and received using the route.

The node includes a wireless communication IF and a wired communication IF. Between the nodes, there are cases where packets are sent and received by wireless communication IF, and there are cases where packets are sent and received by wired communication IF. When the nodes are connected by wire, transmission / reception may be possible using either the wireless communication IF or the wired communication IF. Therefore, in the process of determining the route, it is not enough to determine whether a node on the route sends a packet to the next node, as in the case of only a general wireless communication IF. In this embodiment, when a node on the route sends a packet to the next node, it is necessary to decide whether to use the wireless communication IF or even the wired communication IF.

The conventional route control algorithm is based on the premise that wireless communication is performed between all the nodes. Therefore, it has not been possible to determine whether to use the wireless communication IF or the wired communication IF by the conventional route control algorithm.

Further, in this embodiment, even if it is a wireless communication interface, it is provided with a plurality of wireless communication interfaces such as those by Wi-Fi and those by other communication methods. Further, the Wi-Fi wireless communication interface includes a plurality of child communication interfaces. This is because, for example, some Wi-Fi child communication interfaces realize an uplink on the route, and another Wi-Fi child communication interface realizes a downlink on the route. The realization of the upper and lower lines separately by using a plurality of child communication interfaces is a matter that the inventor has demonstrated its effectiveness as the periodic intermittent transmission method is developed. Therefore, little research and development has been done on such matters so far.

In this embodiment, the metric is determined for each communication IF, and further, the metric is appropriately determined not only in the case of the wireless communication IF but also in the case of the wired communication IF, thereby hybridizing the wireless communication IF and the wired communication IF. It is possible to realize route control even in a simple system.

The route determined in this embodiment shall be a tree structure. In this tree structure, communication is made between the parent node and the child node. Therefore, in the parent node and the child node, information on which communication IF is used and which node is transmitted is stored. The route needs to be determined prior to operation (ie, when communication packets are being sent and received).

FIG. 1 is a block diagram showing an outline of the configuration of a node (an example of the “first node” and the “second node” in the claims of the present application) according to an embodiment of the present invention. Identification information (hereinafter, referred to as "identification information") for identifying the node is set in each node.

The node 1 includes a wireless communication interface (IF) unit 3, a wired communication IF unit 5, a communication control unit 7 (an example of the “communication control means” of the present claim), and an individual calculation unit 7 (the “application claim” of the present application. It is an example of "individual calculation means", and the individual calculation unit 7 on the route candidate between the first node and the second node is an example of the "calculation means" in the claims of the present application) and the determination unit 11 (the present application). An example of the "decision means" of the claim), a route storage unit 13, a display unit 15 (an example of the "display means" of the claim of the present application), and a display control unit 17 (the "display control means" of the claim of the present application). An example) is provided.

The wireless communication IF unit 3 includes m (m is a natural number) wireless communication IFs 21 ₁ , ..., 21 _m . For example, Wi-Fi. Although not shown, each wireless communication IF 21 includes a plurality of child communication IFs. The wired communication IF unit 5 includes n (n is a natural number) wired communication IFs 23 ₁ , ..., 23 _n . For example, Ethernet (registered trademark), PLC, and the like. Although not shown, each wired communication IF 23 includes a plurality of child communication IFs. The wireless communication IF21 and the wired communication IF23 are for communicating with other nodes. Here, the wired communication IF 23 may have a function of supplying power to another node to be connected (power supply function) and a function of receiving power supply from another node to be connected (power receiving function). Even if the hardware is equipped with a communication IF, for example, a communication IF that is set so that communication is not possible or a wired communication IF that is not connected to another node is not subject to transmission / reception of the route control frame. You may remove it. Further, when connected to a global network such as a core node, the communication IF connected to the global network may be excluded from the targets of transmission / reception of the route control frame.

The communication control unit 7 controls transmission / reception of packets and the like with other nodes. The individual calculation unit 9 calculates the metric from the node that transmitted the route control frame to the node. The determination unit 11 selects one from the route candidates from the node that transmitted the route control frame to the node based on the metric. The route storage unit 13 stores the selected route. For example, the root node in the tree structure stores the identification information of the child node and the information of the communication IF to be used. An internal node other than the root node (an internal node is a node having a child node. In the following, an internal node other than the root node is referred to as an "internal slave node") uses the identification information of its own parent node. Stores communication IF information, identification information of its own child node, and communication IF information to be used. The leaf node stores the identification information of its own parent node and the information of the communication IF to be used.

The display unit 15 displays at least the communication status of the wireless communication IF unit 3. For example, LED lighting and the like. The display control unit 17 performs display control such as turning on / off of the display unit 15 according to the communication state of the wireless communication IF unit 3. The display control unit 17 displays the communication status of the wireless communication IF 21 that gives the minimum metric when the route control frame is transmitted / received. Of the wired communication IF23, the communication status of the wired communication IF23 that gives the minimum metric may be displayed.

The following describes the operation of each node when determining the route between the first node (an example of the "first node" of the present claim) and the second node (an example of the "second node" of the present claim). explain. In this embodiment, the first node is, for example, a core node and plays a leading role in determining a route.

FIG. 2 is a flow chart showing an example of the operation of the first node.

The communication control unit 7 of the first node broadcasts a route control frame to another node by the wireless communication IF unit 3 and the wired communication IF unit 5 (step STC1). Then, the wireless communication IF unit 3 and the wired communication IF unit 5 stand by for receiving a route control frame from another node (step STC2).

When the route control frame is received, the communication control unit 7 manages the communication IF and the child node (step SATC3). For example, when a new route control frame is received from a node that is a child node of the first node, the identification information of the child node and the communication IF to be used are stored. If a route control frame is received from a node registered as a child node and the communication IF is different, the communication IF used for communication with that child node is changed. In addition, when a route control frame that uses a route via another internal slave node is received from a child node registered as a child node in the previous route control frame, the information of that child node is deleted. Further, the display control unit 17 controls the display unit 15 to display the reception status of the route control frame in the wireless communication IF unit 3.

If not received in step STC2, the process proceeds to step STC4.

In step STC4, the communication control unit 7 determines whether or not a certain time (transmission interval of the route control frame) has elapsed. If a certain time (transmission interval of the route control frame) has not elapsed, the process returns to step STC2 and waits for reception of the route control frame. When a certain time (transmission interval of the route control frame) has elapsed, the process proceeds to step STC5.

In step STC5, the communication control unit 7 determines whether or not a certain time (route control time) has elapsed. If the time for the route control process has not elapsed, the process returns to step STC1 and the route control frame is transmitted. When the time for the route control processing elapses, the route control processing is terminated.

FIG. 3 is a flow chart showing an example of the operation of a node other than the first node. The communication control unit 7 initializes the metric (step STS1). The route storage unit 13 stores the initialized metric. Hereinafter, the metric stored in the route storage unit 13 is referred to as a “retention metric”. Then, the reception of the route control frame is waited for (step STS2). If received, the process proceeds to step STS3. If not received, the process proceeds to step STS12.

The communication control unit 7 determines whether or not the communication IF that has received the route control frame is a wireless communication IF (step STS3). If it is received by the wireless communication IF unit 3, the process proceeds to step STS4. If it is received by the wired communication IF unit 5, the process proceeds to step STS5.

In step STS4, the individual calculation unit 9 obtains the radio wave propagation loss between the node that transmitted the route control frame (hereinafter referred to as “most recent node”). Here, in this embodiment, the route control frame between the nodes is transmitted and received by all communicable child communication interfaces. Therefore, for example, when a route control frame is obtained from a certain node, the worst value among the radio wave propagation losses in the child communication interface included in the received communication interface is used. For example, if the route control frame is obtained only from some child communication interfaces, it may not be possible to send / receive the frame or the like, so the metric update process may not be performed. Then, the radio wave propagation loss is added to the metric from the first node to the nearest node stored in the route control frame to obtain the metric from the first node to the node. Then, the process proceeds to step STS6.

In step ST5, the individual calculation unit 9 adds a specified value to the metric from the first node to the nearest node stored in the route control frame to obtain the metric from the first node to the node. The specified value is a value very close to 0 dB (for example, 0.05 dB). The normal radio wave propagation loss is about -30 dB to -80 dB. Therefore, by setting the value extremely close to 0, it is judged that the quality is better than the communication by the wireless communication IF. Here, as the specified value, the largest value is used in the communication interface included in the child communication interface that has received the route control frame. As the specified value, the value having a high priority of the wired communication IF may be set to a small value. For example, in the case of Ethernet (registered trademark), the value may be smaller than that in the case of PLC. These specified values may be adjusted by the values after the decimal point. Further, for example, it may be determined by a random number. Then, the process proceeds to step STS6.

In step ST6, the determination unit 11 compares the metric calculated by the individual calculation unit 9 with the retention metric stored in the route storage unit 13. If the calculated metric is smaller than the retention metric, the process proceeds to step STS7 for updating. If the retention metric is not updated, the process proceeds to step STS10.

In step STS7, the determination unit 11 updates the retention metric stored in the route storage unit 13. Also, the communication IF used for communication with the parent node is updated. Then, in step STS8, the parent node is updated to the nearest node. Then, the updated metric is stored in the route control frame and transmitted to another node (step STS9).

In step STS10, if necessary, the communication IF and the child node are managed. This is the same as in the case of the first node. Further, the display control unit 17 controls the display unit 15 to display the reception status of the route control frame in the wireless communication IF unit 3. The installer of the node can easily determine whether or not it is better to make a wired connection from the display of the display unit 15. That is, if the reception status of the route control frame is good, wireless communication may be used. However, if the reception condition is poor, it is desirable to make a wired connection. Further, for example, by displaying the communication status of the wired communication on the display unit 15, it is possible to obtain which wired communication should be used. Then, the process proceeds to step STS11.

In step STS11, the communication control unit 7 determines whether or not a certain time (route control time) has elapsed. If the time for the route control process has not elapsed, the process returns to step STC2 and waits for reception of the route control frame. When the time for the route control processing elapses, the route control processing is terminated.

By performing the process of FIG. 3 in the second node and the internal slave node from the first node to the second node, it is possible to form a path between the first node and the second node. It becomes. That is, when the second node receives the route control frame, the nearest node presents a route candidate between the first node and the second node. The determination unit of the second node compares the metric of the route candidate presented so far with the metric of the newly presented route candidate, and finally determines the best one as the route. At this time, not only the wireless communication IF but also the wired communication IF is taken into consideration as the metric. Therefore, even in a network system in which these are mixed, it is possible to form a route from the first node to the second node.

FIG. 4 is a diagram showing an example of path formation starting from node A in the case of four nodes A, B, C and D. (A) indicates between communicable nodes. The four nodes can communicate with each other by the wireless communication IF. Nodes C and D are connected by wire. Therefore, wireless communication and wired communication are possible between the nodes C and D.

(B) shows a state in which node A has transmitted a route control frame. Nodes B, C and D receive the routing frame transmitted by node A. Nodes B, C, and D update the route storage unit 13 so that node A becomes a parent node.

(C) shows a state in which node B has transmitted a route control frame. Nodes A, C and D receive the routing frame. Here, the node A recognizes that the node B has become a child node, and updates the route storage unit 13. It is assumed that the nodes C and D have not been updated.

(D) shows the state in which the node D has transmitted the route control frame. The nodes A and B are transmitted by the wireless communication IF. The node C is transmitted by the wireless communication IF and the wired communication IF. Nodes A, B and C receive the routing frame. The node A recognizes that the node D has become a child node, and updates the route storage unit 13. It is assumed that the nodes B and C have not been updated.

(E) indicates a state in which the node C has transmitted a route control frame. The node C transmits to the nodes A and B by the wireless communication IF, and transmits to the node D by the wireless communication IF and the wired communication IF. Node A recognizes that node C has become a child node. It is assumed that the node B has not been updated. It is assumed that the node D is updated to receive by the wired communication IF via the node C.

(F) shows a state in which the route control frame is transmitted when the node D receives the wire communication IF via the node C. The nodes A and B are transmitted by the wireless communication IF. The node C is transmitted by the wireless communication IF and the wired communication IF. The node A recognizes that the node D is out of the child node, and updates the route storage unit 13. The node C recognizes that the node D becomes a child node and communicates by the wired communication IF.

(G) shows the route formed by the above procedure. Node A is a root node.
Node B is a child node of node A and is a leaf node. Node C is a child node of node A and is an internal slave node. Node D is a child node of node C and is a leaf node. Communication is realized by the wireless communication IF between the nodes A and B and between the nodes A and C. Communication is realized between the nodes C and D by the wired communication IF.

1 node 3 wireless communication IF unit 5 wired communication IF unit 7 communication control unit 9 individual calculation unit 11 decision unit 13 route storage unit 15 display unit 17 display control unit

Claims (9)

It is provided in the first node that functions as a slave node in a tree network in which a tree-shaped route with the core node as a base point is sequentially constructed by propagating a route control radio signal transmitted from the core node through a plurality of slave nodes . When the reroute button is pressed when the first node is newly installed in the tree network, the first node forms the tree network and functions as the core node. The lighting state of the LED (light emitting diode) provided in the first node is controlled according to the reception status of the route control radio signal from the to the first node which has not joined the tree network.
Controlling the lighting state indicates by lighting the LED that the first node is in a position where it can join the tree network when the first node receives the route control radio signal. That, and when the first node does not receive the route control radio signal, the fact that the first node is not in a position where it can join the tree network is due to a lighting state different from the lighting of the LED. Including showing,
Reception status display method. The route control radio signal includes a cumulative metric for propagation loss from the core nodes of the tree network.
The first node determines the second node to be the parent node in the tree network based on the cumulative metric.
The reception status display method according to claim 1. The lighting state indicating the reception of the route control radio signal indicates that the tree network from the core node of the tree network to the first node is constructed.
The reception status display method according to claim 1 or 2. The lighting state indicating reception of the route control radio signal includes blinking the LED a number of times proportional to the reception intensity of the route control radio signal and then lighting the LED.
The reception status display method according to any one of claims 1 to 3. A first node that functions as a slave node in a tree network in which a tree-shaped route with the core node as a base point is sequentially constructed by propagating a route control radio signal transmitted from the core node through a plurality of slave nodes .
With the reroute button,
LED (light emitting diode) and
A control unit that controls the lighting state of the LED,
Equipped with
The control unit
When the reroute button is pressed when the first node is newly installed in the tree network, the second node forming the tree network and functioning as the core node is not in the tree network. The lighting state of the LED is controlled according to the reception status of the route control radio signal reaching the first node of the subscription.
Controlling the lighting state indicates by lighting the LED that the first node is in a position where it can join the tree network when the first node receives the route control radio signal. That, and when the first node does not receive the route control radio signal, the fact that the first node is not in a position where it can join the tree network is due to a lighting state different from the lighting of the LED. Including showing,
node. A computer that functions as a slave node in a tree network in which a tree-shaped route with the core node as a base point is sequentially constructed by propagating a route control radio signal transmitted from the core node through a plurality of slave nodes. To,
When the reroute button provided in the first node is pressed when the first node is newly installed in the tree network, the second node forming the tree network and functioning as the core node . The lighting state of the LED (light emitting diode) provided in the first node is controlled according to the reception status of the route control radio signal from the node of the node to the first node which has not joined the tree network. ,
Controlling the lighting state indicates that the first node is in a position where it can join the tree network when the first node receives the route control radio signal, and said . It comprises indicating by turning off the LED that the first node is not in a position where it can join the tree network when the first node does not receive the routing radio signal .
A program that executes processing. A slave node in a tree network in which a tree-shaped route with the core node as a base point is sequentially constructed by propagating a route control frame transmitted from the core node to a plurality of slave nodes.
A radio receiving means for receiving the route control frame transmitted from the core node or another slave node, and
A control means for displaying the reception status of the route control frame in the wireless receiving means to an LED (light emitting diode), and a control means.
With a reroute button,
When the reroute button is operated when the own node is newly installed in the tree network, the control means has the LED according to the reception status of the route control frame in the wireless receiving means thereafter. Controls the lighting state of
To control the lighting state, when the wireless receiving means receives the route control frame , the LED indicates that the own node is in a position where it can join the tree network, and the wireless reception The LED indicates that the local node is not in a position where it can join the tree network when the means does not receive the route control frame .
Slave node. The tree network is
(1) In the slave node that has received the route control frame, the cumulative metric included in the route control frame is updated based on the communication status of the slave node that has received the route control frame.
(2) A process in which a parent node is determined based on the updated cumulative metric in the slave node that has received the route control frame.
(3) A process in which the routing control frame including the updated cumulative metric is further transmitted to another slave node in the slave node that has received the routing control frame.
(4) When the route control frame transmitted in the process of (3) is received by the parent node determined in the process of (2), the slave node serving as a child node in the parent node It is constructed by repeating the recognized process .
The slave node according to claim 7. As the process of (1), when the route control frame is received, the cumulative metric included in the received route control frame is used between the node immediately before transmitting the received route control frame and the own node. Communication status, update means to update according to,
As the process of (2), a determination means for determining the immediately preceding node to be the parent node of the own node based on the updated cumulative metric.
As the process of (3), the radio transmission means for transmitting the route control frame including the updated cumulative metric to another slave node including at least the determined parent node.
8. The slave node according to claim 8 .

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