JP2011101281A - Radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To recognize the construction state of a tree structure from the outside. <P>SOLUTION: From a router 2 or an end device 3, a set of own identifier and network address is cyclically reported as device information to a coordinator 1. In the coordinator 1, when predetermined time elapses without change in the set of the identifier and the network address, whose notification is performed as the device information, the connection state of a device of the notification origin of the device information is determined as "stable connection" and the determined connection state is written in a memory. Thus, depending on whether all the devices configuring the tree structure are turned to the "stable connection", whether the optimization of the tree structure has been completed can be recognized from the outside. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a radio communication system having a tree structure.

  In recent years, systems that perform environmental measurement, monitoring, control, and the like using wireless communication are increasing. In a wireless communication system that performs environmental measurement, monitoring, control, and the like, there are many cases where the target area is relatively wide or there are many obstacles for wireless communication in the target area. In such a case, in order to cover the target area, even if it is not possible to communicate directly depending on the environment such as the installation position of the receiver and the transmitter and the radio wave condition, it is possible to perform communication by relaying other devices. It is advantageous to use a communication network.

  As this type of wireless communication network, a wireless communication network using a Zigbee (registered trademark) protocol is considered (for example, see Patent Document 1 and Patent Document 2). Hereinafter, a wireless communication network using the ZigBee protocol is referred to as a ZigBee network.

The ZigBee network is a tree-structured wireless communication network, and is composed of the following three types of devices.
[Device A (Node A)]
It is called the coordinator and exists only in the base layer (top layer) of the network, can communicate with the lower level devices, commands all devices in the network, and sends information specific to each device and sent from each device. Supervises the collection of information coming. In addition to acting as an overall master station for the entire network, an address (network address) is assigned to a device that connects the connection relationship between itself and the parent and child (hereinafter simply referred to as parent-child relationship).

[Device B (Node B)]
It is called a router, exists below the coordinator, can connect and communicate with higher-level devices and lower-level devices, receives commands from the coordinator, and can connect lower-level devices (routers or end devices) It acts as a local master station for these devices. Also, an address (network address) is assigned to a device that has a parent-child relationship with itself.

[Device C (Node C)]
It is called an end device, exists at the end (lowest level) of each branch of the network, can connect and communicate with an upper device, and does not become a master station of another device. For example, in an air conditioning control system, a sensor such as a temperature sensor or a humidity sensor is an end device.

  For each device of the ZigBee network, the maximum number Cm of lower-level devices that can be connected and the deepest depth of the tree structure hierarchy (maximum hierarchy of the tree structure) Lm are determined as network parameters.

  FIG. 17 shows a simple example of a ZigBee network. In the figure, 1 is a coordinator located at the highest level (0th layer), 2-1 and 2-2 are routers located below the coordinator 1 (first layer), and 2-3 to 2-6 are routers 2. Routers located in the lower layer (second layer) of 2-1 to 2-2, 3-1 to 3-8 are end devices located in the lower layer (third layer (lowest layer)) of the routers 2-3 to 2-6 It is.

  In this example, the maximum number Cm of lower-level devices connectable to the coordinator 1 and the router 2 is Cm = 2, the maximum hierarchy Lm of the tree structure is Lm = 3, and the identifier of the coordinator 1 is # 0. The identifiers of the routers 2-1 to 2-6 are set as # 1 to # 6, and the identifiers of the end devices 3-1 to 3-8 are set as # 7 to # 14. These identifiers # 0 to # 14 are uniquely determined for each device and do not change. In this ZigBee network, the coordinator 1 is defined with address blocks AD0 to AD14 as addresses that can be assigned to the entire network, and among these address blocks, “AD0” is assigned as its own address. .

  When connecting the router 2-1 to the coordinator 1, the router 2-1 is brought close to the coordinator 1 and the power is turned on. Then, a connection request called “association (participation application)” (hereinafter referred to as “associate connection request”) is sent from the router 2-1 to the coordinator 1. In response to the associate connection request from the router 2-1, the coordinator 1 assigns the address AD1 to the router 2-1, and assigns the identifier # 1 of the router 2-1 and the address AD1 assigned to the router 2-1. Correspondingly, it is written in the connection information table T0 as having a parent-child relationship (“◯”). In addition, address blocks “AD1 to AD7” including the address AD1 are sent to the router 2-1 as addresses that can be assigned to lower devices.

  Next, when the router 2-2 is brought close to the coordinator 1 and the power is turned on, an associate connection request is sent from the router 2-2 to the coordinator 1. Upon receiving the associate connection request from the router 2-2, the coordinator 1 assigns the address AD8 to the router 2-2, and assigns the identifier # 2 of the router 2-2 and the address AD8 assigned to the router 2-2. Corresponding data is written in the connection information table T0 as having a parent-child relationship. Further, the address block “AD8 to AD14” including the address AD8 is sent to the router 2-2 as an address that can be assigned to the lower device.

  When the router 2-3 is brought close to the router 2-1 and the power is turned on, an associate connection request is sent from the router 2-3 to the router 2-1. Upon receiving the associate connection request from the router 2-3, the router 2-1 assigns the address AD2 to the router 2-3, and also assigns the identifier # 3 of the router 2-3 and the address AD2 assigned to the router 2-3. Are written in the connection information table T1 as having a parent-child relationship. In addition, address blocks “AD2 to AD4” including the address AD2 are sent to the router 2-3 as addresses that can be assigned to lower devices.

  When the end device 3-1 is brought close to the router 2-3 and the power is turned on, an associate connection request is sent from the end device 3-1 to the router 2-3. The router 2-3 receives the associate connection request from the end device 3-1, assigns the address AD3 to the end device 3-1, and assigns the identifier # 7 of the end device 3-1 to the end device 3-1. The assigned address AD3 is associated and written in the connection information table T1 as having a parent-child relationship. Hereinafter, similarly, an address is assigned to each device.

  In the above description, for example, the operation of bringing the end device 3-1 close to the router 2-3 and turning on the power is the router 2-within the radio wave reachable range (self communication range) of the end device 3-1 (child device). 3 (parent device candidate) is positioned and the power is turned on, and the end device 3-1 is considered as the closest parent device candidate in its communication range as the router 2-3. And parent-child relationship. Similarly, other child devices establish a parent-child relationship with the parent device candidate closest to the communication range of the other child device.

  In this ZigBee network, for example, when a radio wave failure occurs in the transmission path between the router 2-1 (parent device) and the router 2-3 (child device), the information from the router 2-3 is transferred to the router 2- 1 will not be received. For example, as shown in FIG. 18A, the router 2-2 is in the closest position within the radio wave coverage area of the router 2-3, and the router 2-2 has not yet formed a parent-child relationship with a lower device. Shall. Here, when a radio wave failure or the like occurs in the transmission path between the router 2-1 and the router 2-3, the router 2-3 performs disconnection (power off) and reconnection (power on). When the power of the router 2-3 is turned off (disconnected), the contents of the address AD2 and the connection information table T1 assigned to the router 2-3 are lost. Subsequently, when the power source of the router 2-3 is turned on (reconnected), a parent-child relationship is established between the router 2-3 and the router 2-2.

  As a result, as shown in FIG. 18B, the connection information indicating the parent-child relationship with the router 2-3 is written in the connection information table T1 of the router 2-2, and new information from the router 2-2 is written into the router 2-3. Address AD9 is assigned, and the router 2-2 becomes a new parent device of the router 2-3. Further, since the end devices 3-1 and 3-2 cannot communicate with the router 2-3, the end devices 3-1 and 3-2 are disconnected and reconnected, and the parent-child relationship is established again with the router 2-3. As a result, the connection information indicating the parent-child relationship with the end devices 3-1 and 3-2 is written in the connection information table T1 of the router 2-3, and is newly transmitted from the router 2-3 to the end devices 3-1 and 3-2. Addresses AD10 and AD11 are assigned. In this way, when a radio wave interference or the like occurs in the transmission path between the parent device and the child device, the tree structure is automatically rearranged.

  Although a simple example is shown in FIG. 17, in reality, there are many layers of routers 2 between the highest level coordinator 1 and the lowest level end device 3. The number of devices 3 also increases, and the network is large.

JP 2006-5928 A JP 2006-42370 A

  As described above, in the ZigBee network, the parent device assigns a range of addresses to the child device connected to the own device, and the child device further assigns the assigned address to the child device connected to the own device. Assign an address range from the range. In this case, since the address range is finite, the hierarchical depth of the tree structure can only take a finite value obtained by a function using the total number of addresses and the number of lower devices that can be connected to the device as parameters. . For this reason, for each device of the ZigBee network, the maximum number Cm of subordinate devices that can be connected and the maximum depth of the tree structure hierarchy (maximum tree structure hierarchy) Lm are determined as network parameters.

  However, in a conventional ZigBee network, for example, a device newly connected to the tree structure is “the number of connections of the lower device of the upper device does not exceed the maximum number Cm”, “the device of its own is of the tree structure Since the parent-child relationship is established with the uppermost device in the closest communication range on the condition that the restriction of “the maximum depth Lm of the hierarchy is not exceeded”, it is positioned at each end in the network tree structure. The bias of the device (end device) hierarchy and the number of lower devices connected to each higher device occur.

  For example, it is assumed that the end device 3-1 is newly connected to a tree structure of a ZigBee network as shown in FIG. In this ZigBee network, the network parameters are Cm = 3 and Lm = 4.

  In this example, the router 2-3-2-8 is located in the communication area of the end device 3-1. In this case, the end device 3-1 is connected to the router 2-7 located closest to the communication range of the end device 3-1 (FIG. 19B) and is located at the fourth layer (maximum hierarchy) in the tree structure. In the tree structure, there is a bias in the hierarchy of end devices and a bias in the number of lower devices connected to each higher device.

  That is, in the tree structure in FIG. 19B, the end devices are the routers 2-4, 2-6, 2-8, and the end device 3-1, but the router 2-4 is the second layer, the router 2-6. , 2-8 are located in the third layer, and the end device 3-1 is located in the fourth layer. Further, in the example of FIG. 19B, although not remarkably, for example, three lower devices may be connected to the router 2-3, for example, and the lower devices connected to each upper device may be connected. There is a bias in the number of devices.

  When such a tree structure bias occurs, a device that can be connected to the network if the tree structure is not biased is “the number of connections of the lower device of the upper device does not exceed the maximum number Cm”, “ Depending on the restriction that “the device does not exceed the minimum depth Lm of the tree structure hierarchy”, there is a possibility that the device cannot be connected to the network, or the number of devices that can be connected to the network is the number of devices that can be connected by design. The problem that the number becomes smaller than that occurs.

  In order to solve such a problem, the applicant assigns a parent node function located within his communication range as an optimization operation at the time of connection with a higher-level device in the tree structure or at the time of reconnection during connection. The current hierarchy in which the device is located and the number of lower devices directly connected to the device are read from the device having the number, and the number of lower devices directly connected is less than the maximum number Cm. Consider a connection method that determines the device with the shallowest current hierarchy as the optimal connection destination device in the tree structure, and connects to the determined connection destination device (reconnects if connected) Yes. By adopting such a connection method, a network having an optimal tree structure can be automatically constructed.

  However, the above-described optimization operation (operation for determining an optimum connection destination device in the tree structure and connecting to the device) is performed at a fixed period after connection with the device, and the connection destination is determined by the optimization operation. Since the device may be automatically switched, it is impossible to grasp the current construction state of the tree structure from the outside. In particular, when starting up a network or adding devices, it is necessary to start control after confirming that all devices are connected or that the network is stable. I need to know when it's done.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a radio communication system capable of grasping the construction state of the tree structure from the outside. is there.

  In order to achieve such an object, the present invention includes a first device that is always located at the top, a second device that is always located at the bottom of each branch, and a lower level than the first device. In a tree-structured wireless communication system comprising a third device positioned higher than the second device, the first and second devices located within the communication range of the second and third devices as optimization operations Based on the current hierarchy in which the third device is located and the number of lower-level devices directly connected to the device, the optimum connection destination device in the tree structure is determined, and the determined connection destination device A device that stores, as device information, a set of a tree structure optimizing means for connection and a network address dynamically assigned by the connection position in the tree structure. Device information storage means and device information notification means for periodically notifying device information stored in the device information storage means to the first device, the first device from the second and third devices Device connection status determination means for determining the connection status of each device in the tree structure based on periodically notified device information, and device connection status for storing the connection status of each device determined by the device connection status determination means And storage means.

  In the present invention, the second and third devices periodically notify the first device of the pair of the identifier and the network address as device information, and the first device is the second and third devices. The connection state of the device is determined based on the device information periodically notified from, and the determined connection state of each device is stored. For example, when device information is notified, the identifier in the device information is checked. When the identifier is not stored in the device connection state storage unit, the connection state of the device that is the notification source of the device information is changed to “ “Normal connection” is determined, and the determined connection state is associated with the device information and stored in the device connection state storage unit. Also, when device information is notified, the identifier in the device information is checked. When the identifier is stored in the device connection state storage means, the combination of the identifier in the device information and the network address is checked. If the combination is not stored in the device connection state storage unit, the connection state of the device that is the source of the device information is determined as “normal connection”, and the determined connection state is associated with the device information. And stored in the device connection state storage means. In addition, when the device information stored in the device connection state storage means includes device information that has passed a predetermined time since the identifier in the device information was last notified, the device information and the device information are stored. Delete the connection status associated with the information. If the device information stored in the device connection state storage means includes device information in which the combination of the identifier and the network address in the device information does not change for a predetermined time or more, the device information notification source device The connection state is determined as “stable connection”, and the connection state stored in association with the device information is updated.

  In the present invention, identifier storage means for storing identifiers of devices registered as second and third devices constituting the tree structure in the first device, and each device stored in the device connection state storage means You may make it provide the tree structure construction state judgment means which judges the construction state of the present tree structure based on a connection state. In this case, in the tree structure construction state determination means, for all of the identifiers stored in the identifier storage means, a pair of the identifier and the network address is stored in the device connection state storage means, and the identifier and the network address When all the connection states stored in association with the pair are “stable connection”, the construction state of the tree structure is determined as the state in which the optimization is completed, and the identifier stored in the identifier storage unit For all of the above, the pair of the identifier and the network address is stored in the device connection state storage means. However, at least one “normal connection” is stored in the connection state stored in association with the pair of the identifier and the network address. ”, It is determined that the construction state of the tree structure has not been optimized, and is stored in the identifier storage means. Even one identifier, set with its identifier and network address may not be stored in the device connection state storage means, so as to determine the state devices that are not connected to the build state of the tree structure is present.

  In the present invention, a notification request from the outside may be received to notify the connection status of each device stored in the device connection status storage means to the outside. The determination result of the construction state means may be notified to the outside.

  According to the present invention, the first device determines the connection state of the device based on the device information periodically notified from the second and third devices, and determines the connection state of each determined device. For example, when there is no change in the combination of the identifier notified as device information and the network address and a predetermined time has passed, the connection state of the device that is the notification source of the device information is changed to “ For example, it is possible to determine the current tree structure construction state from the outside by determining “stable connection”.

It is the schematic which shows an example of the tree structure of the ZigBee network under construction as one embodiment of the radio communications system concerning the present invention. It is a figure which shows the state by which the end device was connected to the tree structure of this ZigBee network. It is a schematic block diagram of the coordinator used for this ZigBee network. It is a schematic block diagram of the router used for this ZigBee network. It is a schematic block diagram of the end device used for this ZigBee network. It is a flowchart for demonstrating the process at the time of the notification of the device information from the low-order device in a coordinator. It is a figure which shows the writing condition of the connection status based on the device information (identifier + address) to each node connection status list table immediately after the device of identifier # 1 is connected, and the device information. It is a figure which shows the writing condition of the connection status based on the device information to each node connection status list table immediately after the device of identifier # 1- # 8 was connected, and the device information. It is a flowchart for demonstrating the process at the time of deletion of the device information from each node connection state list table. It is a flowchart for demonstrating the determination process of the connection destination device at the time of power activation in an end device (the optimization operation at the time of power activation). It is a figure which shows the writing condition of the connection status based on the device information to each node connection status list table immediately after the device of identifier # 1- # 9 was connected, and the device information. It is a flowchart for demonstrating the process in a coordinator at the time of shifting the connection state in each node connection state list table from "normal connection" to "stable connection". It is a figure which shows the state (The state where optimization of the tree structure was completed) in which all the connection states shifted from "normal connection" to "stable connection" in each node connection state list table. It is a flowchart for demonstrating the notification process of the connection state of each node in a coordinator. FIG. 3 is a schematic block diagram of a coordinator when a coordinator is provided with a function for determining a construction state of a tree structure and a notification function. It is a flowchart for demonstrating the determination process of the construction state of the tree structure in a coordinator. It is a figure which shows the simple example of the conventional ZigBee network. It is a figure explaining operation | movement when a radio wave disturbance etc. generate | occur | produce in the transmission path between routers in the conventional ZigBee network. It is a figure explaining operation | movement when an end device is connected as a new device to the tree structure of the conventional ZigBee network.

Hereinafter, the present invention will be described in detail based on embodiments.
[Embodiment 1]
FIG. 1 is a schematic diagram showing an example of a tree structure of a ZigBee network that is under construction as an embodiment of a wireless communication system according to the present invention.
In FIG. 19, the same reference numerals as those in FIG. 19A denote the same or equivalent components as those described with reference to FIG.

  In this ZigBee network, the network parameters are Cm = 3 and Lm = 4, the routers 2-1 and 2-2 are connected to the coordinator 1, and the router 2-3 is connected to the router 2-1. The router 2-2 is connected to the routers 2-4 and 2-5, the router 2-3 is connected to the routers 2-6 and 2-7, and the router 2-5 is connected to the router 2-8. ing. The end device 3-1 is about to be connected to this tree structure.

  In FIG. 1, for example, (0, 2) added to the coordinator 1 indicates the connection state (a, b) of the coordinator 1 in this tree structure. That is, the coordinator 1 is located in the 0th layer of the tree structure, and since the routers 2-1 and 2-2 are connected as lower devices, the current hierarchy in which the coordinator 1 is located is directly connected to a = 0. The number of subordinate devices is b = 2, and its connection state in the tree structure is represented as (0, 2).

  Similarly, the router 2-1 located in the first layer is (1,1), the router 2-2 is (1,2), the router 2-3 located in the second layer is (2,2), the router 2-4 is (2,0), router 2-5 is (2,1), router 2-6 located at the third layer is (3,0), router 2-7 is (3,0), router 2-8 represents (3, 0) as its own connection state in the tree structure.

  In this tree structure, the identifier of the coordinator 1 is # 0, the identifiers of the routers 2-1 to 2-8 are # 1 to # 8, the identifier of the end device 3-1 is # 9, and the coordinator 1 has the address AD0. Router 2-1 has an address AD1, Router 2-2 has an address AD8, Router 2-3 has an address AD2, Router 2-4 has an address AD9, and Router 2-5 has an address AD12. The router 2-6 is assigned an address AD3, the router 2-7 is assigned an address AD4, and the router 2-8 is assigned an address AD13. An address is not yet assigned to the end device 3-1.

  FIG. 3 shows a schematic block diagram of the coordinator 1. The coordinator 1 includes a processing unit 1A, a storage unit 1B, and an RF circuit (wireless transmission / reception circuit) 1C. In addition to basic functions such as the network declaration function 1A1, the parent node function 1A2, and the communication function (inter-node communication function, communication relay function) 1A3, the processing unit 1A has its own connection state as a function unique to this embodiment. A determination function 1A4, its own connection state notification function 1A5, a connection state determination function 1A6 of each node, and a connection state notification function 1A7 of each node are provided. These functions are obtained as processing operations according to a program executed by the processing unit 1A.

  In the processing unit 1A, its own connection state determination function 1A4 determines the connection state (a, b) in the tree structure of the coordinator 1, and stores the determined connection state (a, b) in the storage unit 1B. The own connection state notification function 1A5 notifies the connection state (a, b) in the tree structure of the coordinator 1 stored in the storage unit 1B in response to an inquiry from another device. The connection state determination function 1A6 of each node determines the connection state of each node in the tree structure based on device information from each node, which will be described later, and associates the determined connection state of each node with the device information in the storage unit. Write to each node connection state list table TB1 in 1B. The connection status notification function 1A7 of each node notifies the connection status of each node in each node connection status list table TB1 in response to a request from the user.

  In addition to the connection state (a, b) in the tree structure of the coordinator 1 and each node connection state list table TB1, the storage unit 1B stores the identifier of the coordinator 1, network parameters in the tree structure, and the entire network. Addressable address blocks, addresses assigned to the coordinator 1, and the like are stored. Further, the connection state of each node determined by the connection state determination function 1A6 of each node is different from the connection state (a, b) determined by its own connection state determination function 1A4, and is “normal connection” and “stable”. Connection ". This will be described later.

  FIG. 4 shows a schematic block diagram of the router 2. The router 2 includes a processing unit 2A, a storage unit 2B, and an RF circuit 2C. In addition to basic functions such as a parent node function 2A1 and a communication function (inter-node communication function, communication relay function) 2A2, the processing unit 2A includes its own connection state determination function 2A3 as a function unique to the present embodiment, It has its own connection status notification function 2A4, connection destination determination function (tree structure optimization function) 2A5, and device information notification function 2A6. These functions are obtained as processing operations according to a program executed by the processing unit 2A.

  In the processing unit 2A, its own connection state determination function 2A3 determines the connection state (a, b) in the tree structure of the router 2, and stores the determined connection state (a, b) in the storage unit 2B. The own connection state notification function 2A4 notifies the connection state (a, b) in the tree structure of the coordinator 1 stored in the storage unit 1B in response to an inquiry from another device. The connection destination determination function 2A5 determines an optimum connection destination device in the tree structure as an optimization operation, and performs connection with the determined connection destination device. The device information notifying function 2A6 notifies the coordinator 1 of the set of its own identifier and its assigned address as device information.

  In addition to the connection state (a, b) in the tree structure of the router 2 described above, the storage unit 2B includes an identifier of the router 2, a network parameter in the tree structure, an address assigned to the router 2, and an upper device. An address block that can be assigned to a lower-level device to be sent is stored.

  In the processing unit 2A, the connection destination determination function 2A5 performs the above-described optimization operation at the same time as the power is turned on, and performs the optimization operation after connection to the device by the optimization operation at the time of power-on. It repeats with the predetermined period T1. Further, the device information notification function 2A6 executes the above-described notification of the device information to the coordinator 1 at a predetermined cycle T2. In the present embodiment, the execution cycle T1 of the optimization operation is much longer than the device information notification cycle T2.

  FIG. 5 shows a schematic block diagram of the end device 3. The end device 3 includes a processing unit 3A, a storage unit 3B, and an RF circuit 3C. In addition to basic functions such as the child node function 3A1 and communication function (inter-node communication function) 3A2, the processing unit 3A includes a connection destination determination function (tree structure optimization function) 3A3 as a function unique to the present embodiment. And a device information notification function 3A4. These functions are obtained as processing operations according to a program executed by the processing unit 3A.

  In the processing unit 3A, the connection destination determination function 3A3 determines an optimum connection destination device in the tree structure as an optimization operation, and performs connection with the determined connection destination device. The device information notification function 3A4 notifies the coordinator 1 of the set of its own identifier and its assigned address as device information. The connection destination determination function 3A3 and the device information notification function 3A4 in the end device 3 are the same as the connection destination determination function 2A5 and the device information notification function 2A6 in the router 2.

  The storage unit 3B stores an identifier of the end device 3, a network parameter in the tree structure, an address assigned to the end device 3, and the like.

[Create each node connection status table]
In the tree structure shown in FIG. 1, the router 2-1 uses the pair of the identifier # 1 and the address AD1 as device information, the router 2-2 uses the pair of the identifier # 2 and the address AD8 as device information, and the router 2- 3 is a set of identifier # 3 and address AD2 as device information, router 2-4 is a set of identifier # 4 and address AD9 as device information, and router 2-5 is a set of identifier # 5 and address AD12. As device information, the router 2-6 uses a set of identifier # 6 and address AD3 as device information, the router 2-7 uses a set of identifier # 7 and address AD4 as device information, and the router 2-8 uses identifier # 8. And the address AD13 are notified to the coordinator 1 at a cycle T1 as device information.

  For example, when the coordinator 1 is notified of the set of the identifier # 1 and the address AD1 from the router 2-1 as device information (FIG. 6: YES in step S101), the identifier # 1 in the notified device information is It is checked whether or not it is written in each node connection state list table TB1 (hereinafter simply referred to as table TB1) in the storage unit 1B (step S102).

  If the identifier # 1 is not written in the table TB1 (NO in step S102), the connection state of the router 2-1 that is the device information notification source is determined as “normal connection” (step S103). The determined connection state is associated with the notified device information (a pair of identifier # 1 and address AD1) and written in the table TB1 (see step S104, FIG. 7).

  If the identifier # 1 is written in the table TB1 (YES in step S102), it is checked whether or not the set of the identifier # 1 and the address AD1 in the notified device information is written in the table TB1 (step S102). S105). Here, if the set of identifier # 1 and address AD1 has been written in table TB1 (YES in step S105), the reception processing of the device information notified without changing the contents of table TB1 is terminated.

  Even if the identifier # 1 is written in the table TB1 (YES in step S102), if the pair of the identifier # 1 and the address AD1 in the notified device information is not written in the table TB1 (step S105) NO), assuming that the address has changed, the connection state of the router 2-1 that is the device information notification source is determined as “normal connection” (step S103), and the determined connection state is notified. It is written in the table TB1 in association with the received device information (step S104).

  Similarly to the router 2-1, the coordinator 1 connects each node based on device information (a pair of an identifier and an address) notified to the other routers 2-2 to 2-8 in the tree structure. And the connection state of each determined node is written in the table TB1.

  FIG. 8 exemplifies the state of writing the connection state of each node in the tree structure to the table TB1. In this example, immediately after the routers 2-1 to 2-8 are connected, the connection states of the routers 2-1 to 2-8 are all determined to be “normal connection”.

  The coordinator 1 periodically checks the time TM1 from the last notification for all the identifiers in the table TB1 (FIG. 9: step S201), and this time TM1 is determined in advance. For identifiers that have passed the time N1 (N1> T2, T2: device information transmission cycle) (YES in step S202), a table of the identifier and address pair together with the connection state associated with the pair. Delete from TB1 (step S203).

[End device connection]
In FIG. 1, when the end device 3-1 is turned on (FIG. 10: YES in step S301), all the devices having the parent node function located in the communication range of the end device 3-1 are in the tree structure. The connection status (a, b) is inquired (step S302).

  In the example of FIG. 1, routers 2-3 to 2-8 are located within the communication area of the end device 3-1, and these routers 2-3 to 2-8 have a parent node function. Therefore, the end device 3-1 inquires of the routers 2-3 to 2-8 about the connection state (a, b) in the tree structure. In response to the inquiry from the end device 3-1, the routers 2-3 to 2-8 return the connection state (a, b) stored in the storage unit 2B to the end device 3-1.

  In this case, the router 2-3 is connected (2, 2), the router 2-4 is connected (2, 0), the router 2-5 is connected (2, 1), and the router 2-6 is connected. The router 2-7 returns the connection state (3, 0), the router 2-7 returns the connection state (3, 0), and the router 2-8 returns the connection state (3, 0) to the end device 3-1. In the connection state (a, b) returned to the end device 3-1, a indicates the current hierarchy in which the router is located, and b indicates the number of lower-level devices directly connected to the router. Is shown.

  Next, the end device 3-1 determines a connection destination device based on the connection state (a, b) sent from the routers 2-3 to 2-8 (step S303). The connection destination device is determined as follows.

  First, in the connection state (a, b), the number b of directly connected lower devices is compared with the maximum number Cm of connectable lower devices defined as network parameters. A device whose number b of lower devices is less than the maximum number Cm of lower devices that can be connected (b <Cm) is extracted.

  In this example, the maximum number Cm of lower-level devices that can be connected is Cm = 3, and the number of lower-level devices directly connected in the connection state (a, b) read from the routers 2-3 to 2-8. Since all b are less than Cm, routers 2-3 to 2-8 are extracted.

  Next, the end device 3-1 extracts the device having the smallest current hierarchy “a” in the connection state (a, b) of the extracted routers 2-3 to 2-8 as a connection destination device candidate. . That is, among the routers 2-3 to 2-8, the device with the shallowest current hierarchy that is located is extracted as a candidate for a connection destination device. In this example, routers 2-3 to 2-5 located in the second layer are extracted as connection destination device candidates.

  The end device 3-1 uses the router having the smallest number of directly connected lower devices among the routers 2-3 to 2-5 extracted as candidates for the connection destination device as the connection destination device. select. In this example, the number b of the lower devices directly connected to the router 2-3 is 2, the number b of the lower devices directly connected to the router 2-4 is 0, and the router 2-5 Since the number b of the lower-level devices directly connected to is 1, the router 2-4 is selected as the device having the smallest number of the lower-level devices directly connected, and the selected router 2-4 is connected. Determine as the destination device.

  The end device 3-1 determines the router 2-4 as the connection destination device in this way, and then attempts to connect to the router 2-4 (step S 304, see FIG. 2). Thereby, the end device 3-1 and the router 2-4 are connected. In this case, in the router 2-4, when the end device 3-1 is connected, the connection state (a, b) is changed from (2, 0) to (2, 1). Further, an address AD10 is assigned to the end device 3-1.

  Here, as can be seen from the comparison with the conventional example shown in FIG. 19, in the conventional example shown in FIG. 19, the third-layer router in which the end device 3-1 is closest to its own communication area. 2-7. In this embodiment, the number of lower-level devices directly connected among the second-layer routers 2-3 to 2-5 in the shallowest hierarchy in its communication range Is connected to the router 2-4 having the smallest number. As a result, it is possible to reduce the bias of the hierarchy of each terminal device and the bias of the number of lower devices connected to each higher device in the network tree structure, and to achieve a balanced tree structure. become.

  In this example, among the routers 2-3 to 2-5 extracted as connection destination device candidates, the router 2-4 having the smallest number of directly connected lower devices is selected as the connection destination device. However, for example, the nearest router may be selected as a connection destination device. There is no communication problem with any of the routers 2-3 to 2-5 extracted as connection destination device candidates, but considering the balance of the network, It is better to connect to the router 2-4 having the smallest number.

[Notification of device information from end device]
When the end device 3-1 is connected to the router 2-4, the end device 3-1 starts to notify the coordinator 1 of the set of its own identifier # 9 and the address AD 10 assigned to itself at the cycle T 2 as device information.

[Update each node connection status table]
When the coordinator 1 is notified of the pair of the identifier # 9 and the address AD10 from the end device 3-1 as device information (FIG. 6: YES in step S101), the identifier # 9 in the notified device information is stored in the table. It is checked whether data has been written to TB1 (step S102).

  In this case, since the identifier # 9 is not written in the table TB1 (NO in step S102), the connection state of the end device 3-1 that is the device information notification source is determined as “normal connection” (step S103). The determined connection state is written in the table TB1 in association with the notified device information (a pair of the identifier # 9 and the address AD10) (see step S104, FIG. 11).

  Then, in the next cycle T2, when the pair of the identifier # 9 and the address AD10 is notified as device information from the end device 3-1 (YES in step S101), the coordinator 1 includes the device information in the notified device information. It is determined that the identifier # 9 has been written in the table TB1 (YES in step S102), and it is checked whether the pair of the identifier # 9 and the address AD10 in the notified device information has been written in the table TB1. (Step S105). In this case, since the set of the identifier # 9 and the address AD10 is written in the table TB1 (YES in step S105), the reception process of the notified device information is terminated while the contents of the table TB1 remain unchanged.

[Transition from "Normal connection" to "Stable connection" in the connection status of each node connection status list]
The coordinator 1 periodically checks the time TM2 when the combination of the identifier and the address remains unchanged and the device information (the pair of the identifier and the address) written in the table TB1 remains unchanged. (FIG. 12: Step S401). In this example, the time TM2 after the device information is written in the table TB1 is checked.

  If there is device information in which this time TM2 has passed a predetermined time N2 (N2> T1, T1: optimization operation execution period) (YES in step S402), the device information includes The associated connection state is shifted to “stable connection” (step S403).

  As a result, in FIG. 2, when the routers 2-1 to 2-8 and the end device 3-1 continue the connection state with the same device for N2 hours or more, that is, if the connection destination device is not switched for N2 hours or more, All the connection states of the nodes in the table TB1 are “stable connection” (see FIG. 13).

  When there is a request from the user (FIG. 14: YES in step S501), the coordinator 1 notifies the user of the connection state of each node in the table TB1 (step S502). Here, if all the connection states of each node to be notified are “stable connection”, it is understood that the optimization of the tree structure is completed, and even one connection state of each node to be notified is “normal connection” ", It can be seen that the optimization of the tree structure has not been completed.

  In this way, the user can grasp whether or not the optimization of the tree structure has been completed by making a request to the coordinator 1 when starting up the network or adding a node.

[Embodiment 2]
In the first embodiment, when there is a request from the user, the connection state of each node in the table TB1 is notified. And the user may be notified of the determined construction state of the tree structure.

  In this case, as shown in FIG. 15, the processing unit 1A of the coordinator 1 is provided with a tree structure construction state determination function 1A8 and a tree structure construction state determination result notification function 1A9, and the identifiers of the nodes constituting the tree structure are stored in the storage unit 1B. Make sure to register with.

  In this example, the tree structure construction state determination function 1A8 checks whether or not the pair of the identifier and the address is written in the table TB1 for all the identifiers registered in the storage unit 1B (FIG. 16: Step S601).

  Here, for all of the identifiers registered in the storage unit 1B, if the pair of the identifier and the address is written in the table TB1 (YES in step S601), it is associated with the pair of the identifier and the address. It is checked whether or not all the connected states are “stable connection” (step S602).

  If all the connection states associated with the pair of the identifier and the address are “stable connection” (YES in step S602), it is determined that the construction state of the tree structure is the state where the optimization has been completed. (Step S603).

  On the other hand, if there is at least one “normal connection” in the connection state associated with the pair of the identifier and the address (NO in step S602), the tree structure construction state has not been optimized. The state is determined (step S604).

  In addition, even if one of the identifiers registered in the storage unit 1B has not been written in the table TB1 (NO in step S601), the device that is not connected to the construction state of the tree structure Is determined to exist (step S605).

  The tree structure construction state judgment result notification function 1A9 accepts a request from the user, operates the tree structure construction state judgment function 1A8, and displays the judgment result of the construction state of the tree structure obtained by the tree structure construction state judgment function 1A8. Notify the user.

  The wireless communication system of the present invention can be used in various fields such as a medium-scale and large-scale monitoring control system having a mesh structure in which a communication trunk line is wireless. Specifically, it can be applied to a room air conditioning system by VAV (variable air volume adjustment).

  DESCRIPTION OF SYMBOLS 1 ... Coordinator, 1A ... Processing part, 1B ... Storage part, 1C ... RF circuit, 2 (2-1 to 2-8) ... Router, 2A ... Processing part, 2B ... Storage part, 2C ... RF circuit, 3 (3 -1) ... end device, 3A ... processing unit, 3B ... storage unit, 3C ... RF circuit, 1A1 ... network declaration function, 1A2 ... parent node function, 1A3 ... communication function (inter-node communication function, communication relay function), 1A4 ... own connection state determination function, 1A5 ... own connection state notification function, 1A6 ... connection state determination function of each node, 1A7 ... connection state notification function of each node, 1A7 ... tree structure construction state determination function, 1A8 ... tree structure Construction state judgment result notification function, 2A1 ... parent node function, 2A2 ... communication function (inter-node communication function, communication relay function), 2A3 ... own connection state judgment function, 2A4 ... own connection state notification machine 2A5: Connection destination decision function (tree structure optimization function), 2A6 ... Device information notification function, 3A1 ... Child node function, 3A2 ... Communication function (inter-node communication function), 3A3 ... Connection destination decision function (tree structure optimization) Function) 3A4... Device information notification function, TB1... Each node connection state list table.

Claims (5)

A first device that is always located at the top, a second device that is always located at the bottom of each branch, and a position lower than the first device and higher than the second device In a tree-structured wireless communication system comprising a third device,
The second and third devices are:
As an optimization operation, in the tree structure based on the current hierarchy in which the first and third devices located in its communication range are located and the number of lower-level devices directly connected to the device A tree structure optimizing unit that determines an optimal connection destination device and connects to the determined connection destination device;
Device information storage means for storing, as device information, a set of a self-identifier and a network address dynamically given by a connection position in the tree structure;
Device information notifying means for periodically notifying device information stored in the device information storing means to the first device;
The first device is:
Device connection state determination means for determining a connection state of each device in the tree structure based on the device information periodically notified from the second and third devices;
A wireless communication system comprising: a device connection state storage unit that stores a connection state of each device determined by the device connection state determination unit. The wireless communication system according to claim 1, wherein
The device connection state determination means includes
When the device information is notified, the identifier in the device information is checked. When the identifier is not stored in the device connection state storage unit, the connection state of the device that is the notification source of the device information is changed to “ It is determined that the connection is normal, and the determined connection state is associated with the device information and stored in the device connection state storage unit.
When the device information is notified, the identifier in the device information is checked. When the identifier is stored in the device connection state storage unit, the combination of the identifier in the device information and the network address is checked. If the combination is not stored in the device connection state storage unit, the connection state of the device that is the notification source of the device information is determined as “normal connection”, and the determined connection state corresponds to the device information. And storing it in the device connection state storage means,
If the device information stored in the device connection state storage means includes device information that has passed a predetermined time since the identifier in the device information was last notified, the device information together with the device information Delete the connection status associated with
If the device information stored in the device connection state storage means includes device information in which the combination of the identifier and the network address in the device information does not change for a predetermined time or longer, the connection of the device that is the notification source of the device information A wireless communication system, characterized in that the state is determined to be “stable connection” and the connection state stored in association with the device information is updated. The wireless communication system according to claim 1 or 2,
The first device is:
A wireless communication system comprising device connection state notification means for receiving a notification request from outside and notifying the connection state of each device stored in the device connection state storage means to the outside. The wireless communication system according to claim 2,
The first device is:
Identifier storage means for storing identifiers of devices registered as the second and third devices constituting the tree structure;
Tree structure construction state judgment means for judging the current construction state of the tree structure based on the connection state of each device stored in the device connection state storage means;
The tree structure construction state determination means includes:
For all the identifiers stored in the identifier storage means, a pair of the identifier and the network address is stored in the device connection state storage means, and is stored in association with the pair of the identifier and the network address. If all the connection states are "stable connection", it is determined that the construction state of the tree structure is the state in which the optimization is completed,
For all the identifiers stored in the identifier storage means, a pair of the identifier and the network address is stored in the device connection state storage means, but is stored in association with the pair of the identifier and the network address. If there is at least one “normal connection” in the connection state, it is determined that the construction state of the tree structure has not been optimized,
Even if one of the identifiers stored in the identifier storage means is not stored in the device connection state storage means, a device that is not connected to the construction state of the tree structure. A wireless communication system, characterized in that it is determined to exist. The wireless communication system according to claim 4, wherein
The first device is:
A wireless communication system comprising: a tree structure construction state determination result notifying means for receiving a notification request from the outside and notifying the determination result of the tree structure construction state means to the outside.

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