JP2014042093A - Radio communication terminal, its control method and its control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid isolation of a radio communication terminal in a radio communication network if the configuration of the radio communication network has been changed due to a change in a communication environment.SOLUTION: A radio communication terminal constitutes a part of a network. The radio communication terminal comprises a communication unit for communicating with another node in the network and a control unit for controlling the communication unit. The control unit includes: first determination means which makes the communication unit temporarily function as a router if a prescribed condition has been established, and further makes the communication unit function as an end device if the prescribed condition has not been established; and second determination means which performs detection related to another node in the network when the communication unit has been temporarily functioning as the router due to the first determination means, and determines whether the communication unit should be restored to the end device or maintained as the router on the basis of the detection result.

Description

  The present invention relates to a radio communication terminal, a control method thereof, and a control program thereof, and more particularly to a radio communication terminal capable of operating as both an end device and a router, a control method thereof, and a control program thereof.

  2. Description of the Related Art Conventionally, a communication system including a plurality of power consumption measuring devices (hereinafter also referred to as “taps”) and a control device for controlling the plurality of power consumption measuring devices for power saving in a home is known. Such a communication system generally employs a short-range wireless communication system. An example of the communication method is ZigBee (registered trademark).

  Nodes existing in the ZigBee (registered trademark) network are classified into a coordinator, a router, and an end device. One coordinator always exists in the network, and is a node that flows and receives data outside the network and has a network management function. Management functions include network startup, device joining / leaving / rejoining, logical network address allocation, routing, routing maintenance, security level setting, and the like. A router is a node that controls communication so that data can be efficiently and stably delivered to a target node in multi-hopping in which data is transferred over a plurality of stages. An end device is a node located at the end of the network. The end device does not transfer data.

  ZigBee (registered trademark) constructs a tree-type network having a coordinator as a vertex. In ZigBee (registered trademark), an end device with a low received signal strength that is located away from the coordinator and the router cannot participate in the network.

  If all the nodes that have been operating as end devices are operated as routers, the probability that even a node with low received signal strength due to being away from the coordinator can join the network via the router increases. Therefore, by operating all nodes other than the coordinator as routers, the number of end devices that cannot participate in the network as described above can be reduced. However, the router cannot go to sleep to relay communication. For this reason, if all the end devices are operated as routers, there is a problem that power consumption increases.

  In the network proposed in Patent Document 1 (Japanese Patent Application Laid-Open No. 2008-85583), a wireless communication terminal registers a route with another wireless communication terminal having a received signal strength higher than a threshold as a routing table in advance. Then, the radio communication terminal maintains the route information stored in the routing table when there is a radio wave bias in the radio communication space between other radio devices.

JP 2008-85583 A

  However, the conventional technology cannot cope with a change in communication environment such as movement of a wireless communication terminal. From this, when a change in the communication environment occurs, an isolated wireless communication terminal can be generated by being excluded from the network. The technology described in Patent Document 1 is a technology that uses previous path information when a radio wave bias occurs in a wireless communication space. Therefore, this technology cannot dynamically set route information according to the current state of the network.

  The present invention has been conceived in view of such circumstances, and the object of the present invention is to provide a wireless communication terminal even when a change occurs in the configuration of the wireless communication network due to changes in the communication environment in the wireless communication network. Is to avoid isolation.

  According to an aspect, a wireless communication terminal configuring a network is provided. The wireless communication terminal includes a communication unit that communicates with other nodes in the network, and a control unit for controlling the communication unit. A control unit configured to cause the communication unit to function temporarily as a router when a predetermined condition is satisfied, and to cause the communication unit to function as an end device when the predetermined condition is not satisfied; When the communication unit is temporarily functioning as a router by the first determination unit, the detection on other nodes in the network is performed, and the communication unit is returned to the end device based on the detection result. Second determination means for determining whether to maintain as a router.

  Preferably, in the detection, when the communication unit is functioning as a router, the second determination means determines that the distance between the wireless communication terminal and the node that is the communication partner in the network and the wireless communication terminal is greater than or equal to a specific distance It is to determine whether or not. The second determination means, when the detection result indicates that the distance is equal to or greater than a specific distance, causes the communication unit to function as a router, and the detection result indicates that the distance is less than the specific distance In addition, the communication unit is configured to function as an end device.

  Preferably, the predetermined condition is that a distance between a node that is a communication partner in the network and the wireless communication terminal is a specific distance or more.

  Preferably, whether or not the distance is equal to or greater than a specific distance is determined based on the radio field intensity of the signal received by the communication unit.

  Preferably, the detection is to determine whether or not there is a node connected to the network via the wireless communication terminal when the communication unit functions as a router. . The second determination means causes the communication unit to function as a router when the detection result is that a node connected to the network via the wireless communication terminal exists, and the determination result is When there is no node connected to the network via the communication terminal, the communication unit is configured to function as an end device.

Preferably, a 2nd judgment means performs a detection for every specific time.
Preferably, the predetermined condition is that a predetermined time has elapsed since the communication unit started functioning as an end device.

  Preferably, the control unit causes the communication unit to function as an end device in the initial state of the wireless communication terminal.

  According to another aspect, a method for controlling a wireless communication terminal constituting a network is provided. In the control method, the wireless communication terminal includes a communication unit that communicates with other nodes in the network, and a processor. In the control method, the processor causes the communication unit to function temporarily as a router when a predetermined condition is satisfied, and further causes the communication unit to function as an end device when the predetermined condition is not satisfied. The processor performs detection on other nodes in the network when the communication unit temporarily functions as a router, and the processor sends the communication unit to the end device based on the detection result. Determining whether to return or maintain as a router.

  According to yet another aspect, a control program is provided. The control program is a program for causing a computer to execute the above-described control method, and is a computer-readable control program for a wireless communication terminal.

  According to an aspect, in a wireless communication terminal, whether to cause the communication unit to function as an end device or a router is determined based on a reception mode of information in a communication unit that transmits and receives information to and from other nodes in the network.

  Thereby, even if a change occurs due to the configuration of the wireless communication network, isolation of the wireless communication terminal can be avoided.

It is the figure which showed schematic structure of the network which concerns on embodiment of this invention. It is a figure showing the external appearance of a monitor. It is a block diagram of a monitor. It is a perspective view of a tap. It is a figure showing the hardware constitutions of the tap. It is a figure showing the hardware constitutions of the tablet terminal. It is a figure for demonstrating the mounting method in a tap and a monitor. It is a figure for demonstrating the mounting method in a tablet terminal. It is a figure which shows the structure of the network Z using a tablet terminal instead of a monitor, a personal computer, and a tablet terminal. It is a block diagram of a tablet terminal. It is a figure showing the function structure of the low-speed radio | wireless communication module. It is a figure for demonstrating the outline | summary of the function switching in a tap. It is a flowchart of the function switching process performed in the node which could participate in the network. FIG. 14 is a sequence diagram of signal transmission / reception between a tap and a monitor in the function switching process of FIG. 13. It is a figure for demonstrating the outline | summary of the function switching in a tap. It is a flowchart of the function switching process performed in the node which could participate in the network. FIG. 17 is a sequence diagram of signal transmission / reception between a tap and a monitor in the function switching process of FIG. 16. It is a figure for demonstrating the outline | summary of the function switching in the node of embodiment of a comparative example. It is a flowchart of the function switching process performed in the tap of a comparative example. FIG. 6 is a diagram illustrating a modification example of the hardware configuration illustrated in FIG. 5. FIG. 6 is a diagram illustrating another modification of the hardware configuration illustrated in FIG. 5.

  Hereinafter, a network including an embodiment of a wireless communication terminal will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[First Embodiment]
<A. Network Overview>
FIG. 1 is a diagram showing a schematic configuration of a network according to an embodiment of the present invention. Referring to FIG. 1, a network Z represents a low-speed wireless communication network (mainly assuming ZigBee (registered trademark)). The network E indicates a high-speed communication network (mainly assuming Ethernet (registered trademark) or WiFi (registered trademark)).

  The network Z includes a monitor 1001 having a HyperText Transfer Protocol (HTTP) server function, a broadband router 1002, a personal computer 1003, a plurality of taps 1004a, 1004b, and 1004c, and a plurality of home appliances (air conditioner 1005, refrigerator 1006). , Television 1007 and the like) and a tablet terminal 1008.

  The power plug 1051 of the air conditioner 1005 is inserted into the socket of the tap 1004a. Similarly, the power plug 1061 of the refrigerator 1006 is inserted into the socket of the tap 1004b. Further, the power plug 1071 of the television 1007 is inserted into the socket of the tap 1004c.

  Taps 1004a, 1004b, and 1004c are respectively attached to outlets 1015, 1016, and 1017 installed in the house. Thereby, the taps 1004a, 1004b, and 1004c are supplied with power.

  The taps 1004a, 1004b, and 1004c are power consumption measuring devices that measure the power consumption of each home appliance connected to each of the taps 1004a, 1004b, and 1004c. For example, the tap 1004a measures the power consumption of the air conditioner 1005. Each of the taps 1004a, 1004b, and 1004c transmits the measured power consumption to the monitor 1001. In the following description, for convenience of description, when the taps 1004a, 1004b, and 1004c are expressed without distinction, they are expressed as “tap 1004”.

  Each of the monitor 1001 and the plurality of taps 1004 includes a low-speed wireless communication module. The monitor 1001 and the plurality of taps 1004 constitute a low-speed wireless communication network Z (hereinafter also simply referred to as “network Z”). The monitor 1001 is connected to the broadband router 1002 by Ethernet (registered trademark). The monitor 1001 functions as a gateway for the network Z. The monitor 1001 wirelessly communicates with a plurality of taps 1004 at a low speed.

  The broadband router 1002 may be connected to the Internet. The personal computer 1003 is connected to the broadband router 1002 by Ethernet (registered trademark). The personal computer 1003 may be connected to the broadband router 1002 by WiFi (registered trademark).

  The personal computer 1003 is a general personal computer on which a browser (HTTP client) operates. The personal computer 1003 communicates with the HTTP server of the monitor 1001 via the browser of the personal computer 1003. In this way, the personal computer 1003 can make various settings for the monitor 1001. With the functions of the HTTP server and the HTTP client, even a monitor 1001 having only a poor input device can perform complicated settings.

  The tablet terminal 1008 communicates with the monitor 1001 via the broadband router 1002. The tablet terminal 1008 is connected to the broadband router 1002 by WiFi (registered trademark). Note that the tablet terminal 1008 may be connected to the broadband router 1002 by Ethernet (registered trademark).

  The tablet terminal 1008 can perform various displays regarding power consumption. The tablet terminal 1008 can display power consumption in the network Z, for example. Moreover, the tablet terminal 1008 can display the power consumption of the household appliance selected by the user, for example.

  Below, the example using ZigBee (trademark) which is one of the short-range wireless communication standards for household appliances as the network Z is demonstrated. ZigBee (registered trademark) has lower speed and shorter transmission distance than Bluetooth (registered trademark), but has an advantage of power saving and low cost.

<B. Configuration of Monitor 1001>
FIG. 2 is a diagram illustrating the appearance of the monitor 1001. FIG. 2A is a perspective view of the monitor 1001. FIG. 2B is a side view of the monitor 1001. FIG. 2C is an enlarged view of a main part of another side surface of the monitor 1001.

  Referring to FIG. 2A, the monitor 1001 includes a light emitting unit 1103 and an antenna 1107. The light emitting unit 1103 includes three LEDs (Light Emitting Diodes) 1103a, 1103b, and 1103c for displaying the operating state of the monitor 1001 and the like.

  The LED 1103a is a light emitting element (power LED) for indicating whether the monitor 1001 is on or off. The LED 1103b is a light emitting element (tap LED) for displaying a communication state with the tap 1004. The LED 1103 c is a light emitting element (router LED) for displaying a communication state with the broadband router 1002.

  The antenna 1107 is used for the monitor 1001 to communicate with the taps 1004a, 1004b, and 1004c.

  Referring to FIG. 2B, the monitor 1001 further includes a pairing button 1108 on the surface opposite to the surface on which the light emitting unit 1103 is provided. The pairing button 1108 is a button for changing the monitor 1001 to the pairing permission state.

  Referring to FIG. 2C, the monitor 1001 further includes a slide switch 1109 on a surface different from the surface where the light emitting unit 1103 is provided and the surface where the pairing button 1108 is provided. The slide switch 1109 slides by a user operation. The slide switch 1109 can take any one of a pairing position, a normal position, and a leave position. The slide switch 1109 is used when performing pairing (participation in the network) and leaving (leaving from the network). The slide switch 1109 is set to the normal position during normal use.

  FIG. 3 is a block diagram of the monitor 1001. Referring to FIG. 3, a monitor 1001 includes a control unit 1101, a light emitting unit 1103, a high-speed communication interface unit 1104, a power supply unit 1105, a wireless RF (Radio Freaquency) built-in communication controller unit 1106, an antenna 1107, A pairing button 1108, a slide switch 1109, and a reset switch (not shown) are provided.

  A wireless RF built-in communication controller unit 1106 includes a CPU (Central Processing Unit) 1161, a ROM (Read Only Memory) 1162, a RAM (Random Access Memory) 1163, a GPIO (General Purpose Input / Output) 1164, and a wireless RF unit. 1165 and a UART (Universal Asynchronous Receiver Transmitter) 1166 for communicating with the control unit 1101. Note that the wireless RF built-in communication controller unit 1106 corresponds to a ZigBee (registered trademark) coordinator unit. The ROM 1162, the RAM 1163, the UART 1166, the GPIO 1164, and the wireless RF unit 1165 are connected to the CPU 1161, respectively.

  The wireless RF built-in communication controller unit 1106 is connected to the antenna 1107. The wireless RF built-in communication controller unit 1106 controls communication with communication devices existing on the network Z.

  As the OS (Operating System) of the control unit 1101, for example, Linux (registered trademark) can be used. The control unit 1101 includes a high-performance CPU compared to the CPU 1161, and has abundant memory. With this configuration, the monitor 1001 can realize advanced information processing.

  The high-speed communication interface unit 1104 is an interface for communicating with the broadband router 1002 using Ethernet (registered trademark) or WiFi (registered trademark). The power supply unit 1105 supplies power to the control unit 1101 and the wireless RF built-in communication controller unit 1106.

  The control unit 1101 is connected to a light emitting unit 1103, a high-speed communication interface unit 1104, a power supply unit 1105, a wireless RF built-in communication controller unit 1106, a pairing button 1108, and a slide switch 1109. The control unit 1101 controls the overall operation of the monitor 1001. The control unit 1101 accepts inputs from the pairing button 1108 and the slide switch 1109. In addition, the control unit 1101 issues an output instruction to the light emitting unit 1103.

  Next, an outline of operations when the user performs pairing will be described. First, the user slides the slide switch 1109 from the normal position to the pairing position. Thereafter, the user presses the pairing button 1108. Thereby, the monitor 1001 enters the pairing permission state for a predetermined time (for example, 60 seconds). During this time, the control unit 1101 causes the light emitting unit 1103 to emit light in a predetermined state. Then, when the monitor 1001 is in a pairing permission state, the user plugs the tap 1004 into an outlet so that the monitor 1001 and the tap 1004 are paired.

<C. Configuration of Tap 1004>
FIG. 4 is a perspective view of the tap 1004. Referring to FIG. 4, the tap 1004 includes a plug insertion socket 2101, a plug 2102, an LED 2105, and a setting button 2106. When using the tap, the user inserts the power plug of the home appliance into the socket 2101 and inserts the plug 2102 into an outlet installed in the house (see FIG. 1). Note that the shape of the socket 2101 is determined in accordance with the shape of a power plug of a connected home appliance.

  FIG. 5 is a diagram illustrating a hardware configuration of the tap 1004. Referring to FIG. 5, a tap 1004 includes a socket 2101, a plug 2102, a shunt resistor 2103, a power supply unit 2104, an LED 2105, a setting button 2106, an antenna 2107, a power sensor unit 2110, and low-speed wireless communication. A module 2120, a wiring 2131, a wiring 2132, and a wiring 2133 are provided.

  The power sensor unit 2110 includes a voltage input ADC unit 2111, a current input ADC unit 2112, a multiplier 2113, and a digital / frequency conversion unit 2114. The low-speed wireless communication module 2120 includes a CPU 2121, a ROM 2122, a RAM 2123, a GPIO 2124, and a wireless RF unit 2125.

  The wiring 2132 and the wiring 2133 are connected by a shunt resistor 2103. The shunt resistor 2103 is a very small (several hundred micro ohms) resistor used for measuring current.

  The socket 2101 and the plug 2102 are connected by wirings 2131 to 2133 and a shunt resistor 2103. The wiring 2131 is connected to one terminal of the plug 2102 and one terminal of the socket 2101. The wiring 2132 is connected to the other terminal of the plug 2102 and one end of the shunt resistor 2103. The wiring 2133 is connected to the other terminal of the socket 2101 and the other end of the shunt resistor 2103.

  The power supply unit 2104 is connected to the wiring 2132. The power supply unit 2104 converts alternating current into direct current. The power supply unit 2104 gives the DC power obtained by the conversion to the power sensor unit 2110 and the low-speed wireless communication module 2120.

  The voltage input ADC unit 2111 is connected to the wiring 2131 and the wiring 2132. The voltage input ADC unit 2111 outputs the voltage (potential difference) between the wiring 2131 and the wiring 2132 to the multiplier 2113 as a digital signal.

  The current input ADC unit 2112 is connected to the wiring 2132 and the wiring 2133. The current input ADC unit 2112 outputs the current value of the current flowing through the shunt resistor 2103 to the multiplier 2113 as a digital signal.

  The multiplier 2113 multiplies the output from the voltage input ADC unit 2111 and the output from the current input ADC unit 2112, and outputs a digital signal obtained by the multiplication to the digital / frequency conversion unit 2114.

  The digital / frequency converter 2114 converts the input digital signal into a frequency signal. The digital / frequency converter 2114 outputs the frequency signal obtained by the conversion to the GPIO 2124 of the low-speed wireless communication module 2120.

  The CPU 2121 performs data conversion on the frequency signal acquired from the GPIO 2124. The wireless RF unit 2125 transmits a signal obtained by data conversion to the monitor 1001 using the antenna 2107.

  The ROM 2122 stores programs executed by the CPU 2121. The RAM 2123 temporarily stores data processed by the CPU 2121 and processed data.

  The LED 2105 indicates the data processing state of the tap 1004 by a color that blinks and / or turns on. A setting button 2106 is used for initial setting of the tap 1004 by the user.

  The CPU 2121 also converts a signal received via the antenna 2107 as appropriate and uses it for the processing described in this specification.

<D. Configuration of Tablet Terminal 1008>
FIG. 6 is a diagram illustrating a hardware configuration of the tablet terminal 1008. Referring to FIG. 6, tablet terminal 1008 includes a CPU 4010, a touch screen 4020, a clock 4030, a memory 4040, a button 4050, a communication interface 4060, and a speaker 4070. The touch screen 4020 includes a display 4021 and a touch panel (tablet) 4022, and the touch panel 4022 is laid on the surface of the display 4021. However, the tablet terminal 1008 may not include the touch panel 4022.

  The memory 4040 is realized by various types of RAM, ROM, flash memory, hard disk, and the like. The memory 4040 stores an OS, various control programs executed by the CPU 4010, and various data tables such as a table read by the CPU 4010.

  The CPU 4010 executes various kinds of information processing and the like by executing various programs stored in the memory 4040. The program here includes not only a program directly executable by the CPU but also a program in a source program format, a compressed program, an encrypted program, and the like.

  The display 4021 displays the power consumption of each of the home appliances 1005 to 1007 by being controlled by the CPU 4010, for example. The touch panel 4022 detects a touch operation with a user's finger and inputs touch coordinates or the like to the CPU 4010. The CPU 4010 receives a command from the user via the touch panel 4022.

  The button 4050 is disposed on the surface of the tablet terminal 1008. A plurality of buttons such as a determination key, a direction key, and a numeric keypad may be arranged on the tablet terminal 1008. The button 4050 receives a command from the user. A button 4050 inputs a command from the user to the CPU 4010.

  The communication interface 4060 communicates with the monitor 1001 via the broadband router 1002 under the control of the CPU 4010. As described above, the communication interface 4060 communicates with the broadband router 1002 using, for example, WiFi (registered trademark).

  The speaker 4070 outputs sound based on a command from the CPU 4010. For example, the CPU 4010 causes the speaker 4070 to output sound based on the sound data. The clock 4030 inputs the current date and time to the CPU 4010 based on a command from the CPU 4010.

<E. Implementation example>
FIG. 7 is a diagram for explaining a mounting method in the tap 1004 and the monitor 1001. That is, FIG. 7 is a diagram for explaining a software structure in the tap 1004 and the monitor 1001.

  Referring to FIG. 7, the tap 1004 includes a ZigBee (registered trademark) application 3401 and a Z-STACK ZigBee (registered trademark) protocol stack 3402. The ZigBee (registered trademark) application 3401 acquires information on power consumption from a power measurement microcomputer (not shown), and converts the information into a predetermined format. The ZigBee (registered trademark) application 3401 sends information regarding power consumption to the monitor 1001 in the predetermined format. The Z-STACK ZigBee (registered trademark) protocol stack 3402 is a ZigBee (registered trademark) compliant protocol stack for a communication device portfolio and platform using IEEE802.15.4.

  The wireless RF built-in communication controller unit 1106 (ZigBee coordinator unit) of the monitor 1001 includes a ZigBee (registered trademark) application 3111, a Z-STACK ZigBee (registered trademark) protocol stack 3112, and a UART 1166. The ZigBee (registered trademark) application 3111 receives the information regarding the power consumption described above from the tap 1004. The Z-STACK ZigBee (registered trademark) protocol stack 3112 is similar to the Z-STACK ZigBee (registered trademark) protocol stack 3402 in the tap 1004. The ZigBee (registered trademark) for a portfolio of communication devices and platforms using IEEE802.15.4. ) A compliant protocol stack. As described above, the UART 1166 is a transmitter for communicating with the control unit 1101.

  A control unit 1101 (see FIG. 3) of the monitor 1001 includes a ZigBee (registered trademark) manager 3121, a Z-STACK monitor library 3122, a UART 3123, an LED & switch control 3124, and a UDP / IP (User Datagram Protocol / Internet Protocol). A port 12131 and an Ethernet (registered trademark) 3125 are included. The ZigBee (registered trademark) manager 3121 is one of applications stored in the control unit 1101. Note that another application stored in the control unit 1101 is a tap information collection application for collecting information on the tap 1004.

  The ZigBee (registered trademark) manager 3121 manages the nodes of ZigBee (registered trademark). The ZigBee (registered trademark) manager 3121 determines what kind of node exists in the network Z of ZigBee (registered trademark). Furthermore, when there is a change in the ZigBee (registered trademark) node, the ZigBee (registered trademark) manager 3121 detects the change, and notifies the other application of the change.

  The ZigBee (registered trademark) manager 3121 monitors the LED & switch control 3124. Specifically, the ZigBee (registered trademark) manager 3121 is a program for controlling the light emission of the LEDs 1103 a, 1103 b, and 1103 c and processing input from the pairing button 1108 and the slide switch 1109. The ZigBee (registered trademark) manager 3121 takes the form of a server, and when there is an access from another device, it replies to the other device (communication based on the ZigBee upper protocol). Further, the ZigBee (registered trademark) manager 3121 has a function as a monitor discovery server and a function (pairing application) for performing pairing.

  The Z-STACK monitor library 3122 communicates with the wireless RF built-in communication controller unit 1106 by directly exchanging data with the UART 3123. When the UART 3123 transmits data to the wireless RF built-in communication controller unit 1106, the Z-STACK monitor library 3122 receives some response from the wireless RF built-in communication controller unit 1106 via the UART 3123. More specifically, a ZigBee (registered trademark) manager 3121, a tap information collection application, and a device control library 3802 (see FIG. 8) to be described later communicate with ZigBee via the Z-STACK monitor library 3122. Note that some commands transmitted by the Z-STACK monitor library 3122 are for the wireless RF built-in communication controller unit 1106 and others are for the tap 1004.

  The UDP / IP port 12131 is one of UDP / IP ports. The UDP / IP port 12131 converts data into a UDP packet. The UDP / IP port 12131 communicates with the broadband router 1002 using the Ethernet (registered trademark) 3125. For example, the UDP / IP port 12131 uses the Ethernet (registered trademark) 3125 and can perform communication based on the above ZigBee upper layer protocol and the monitor discovery protocol. In this specification, the number “12131” in “UDP / IP port 12131” means a port number.

  FIG. 8 is a diagram for explaining a mounting method in the tablet terminal 1008. That is, FIG. 8 is a diagram for explaining a software structure in the tablet terminal 1008.

  Referring to FIG. 8, a tablet terminal 1008 includes a UI (User Interface) application 3801, a device control library 3802, a UDP / IP port (port is arbitrary) 3803, a WiFi (registered trademark) 3804, and a monitor discovery application. 3805, UDP / IP port (port is arbitrary) 3806, and WiFi (registered trademark) 3807. The numbers “3803” and “3806” in “UDP / IP port 3803” and “UDP / IP port 3806” are reference numerals and do not represent port numbers.

  The UI application 3801 is an application for displaying a UI on the display 4021 of the tablet terminal 1008. The device control library 3802 is a library used for controlling other communication devices such as the monitor 1001. The monitor discovery application 3805 is an application for the tablet terminal 1008 to discover the monitor 1001.

  The UDP / IP ports 3803 and 3806 are one of UDP / IP ports. The UDP / IP ports 3803 and 3806 convert data into UDP packets. UDP / IP ports 3803 and 3806 communicate with the broadband router 1002 using WiFi (registered trademark) 3804 and 3807, respectively. Specifically, the UDP / IP port 3803 uses WiFi (registered trademark) 3804 to perform communication based on the above ZigBee upper protocol. The UDP / IP port 3806 performs communication based on the monitor discovery protocol using WiFi (registered trademark) 3807.

  Here, a method for discovering the monitor 1001 using the monitor discovery application 3805 will be described as follows. First, the tablet terminal 1008 broadcasts a predetermined signal using a monitor discovery protocol. Based on the broadcast, the tablet terminal 1008 receives a response from a monitor in the same LAN (Local Area Network) segment. The tablet terminal 1008 acquires the IP address included in the response (that is, the IP address of the monitor that made the response). Thereby, the tablet terminal 1008 can find the monitor 1001. The tablet terminal 1008 sets the device control library 3802 for the IP address.

<F. Modification of network configuration>
(F1. First modification)
Next, an alternative configuration of the monitor 1001 will be described. FIG. 9 is a diagram illustrating a schematic configuration of a network when a tablet terminal is used as a control device of the network Z. Specifically, FIG. 9 is a diagram illustrating a configuration of a network Z using the tablet terminal 1009 instead of the monitor 1001, the personal computer 1003, and the tablet terminal 1008.

  Referring to FIG. 9, network Z includes tablet terminal 1009, broadband router 1002, a plurality of taps 1004a, 1004b, 1004c, and a plurality of home appliances (air conditioner 1005, refrigerator 1006, television 1007, etc.). Prepare. The tablet terminal 1009, the plurality of taps 1004, and the plurality of home appliances 1005 to 1007 constitute a low-speed wireless communication network Z. The tablet terminal 1009 is connected to the broadband router 1002 by high-speed wireless communication such as WiFi (registered trademark).

  FIG. 10 is a block diagram of the tablet terminal 1009. The tablet terminal 1009 includes a control unit 1901, an operation unit 1902, a display unit 1903, a high-speed communication interface unit 1904, a power supply unit 1905, a low-speed wireless communication module 1906, and an antenna 1907.

  The operation unit 1902 is an input device such as an operation key or a touch sensor. The display unit 1903 is an output device such as a liquid crystal display. The high-speed communication interface unit 1904 is an interface for performing wireless communication with the broadband router 1002. The power supply unit 1905 supplies power to the control unit 1901 and the low-speed wireless communication module 1906.

  The control unit 1901 is connected to the operation unit 1902, the display unit 1903, the high-speed communication interface unit 1904, the power supply unit 1905, and the low-speed wireless communication module 1906. A control unit 1901 controls the overall operation of the tablet terminal 1009. The control unit 1901 receives an input from the operation unit 1902. In addition, the control unit 1901 issues an output instruction to the display unit 1903.

More specifically, the control unit 1901 includes a CPU, a RAM, a ROM, a UART, and a GPIO. RAM, ROM, UART, and GPIO are each CP
Connected to U.

The low speed wireless communication module 1906 is connected to the antenna 1107. The low-speed wireless communication module 1906 controls communication with the power consumption measuring device in the low-speed wireless communication network Z. The low-speed wireless communication module 1906 includes a CPU, RAM, ROM, UART, GPIO, and a wireless RF (Radio Frequency) unit. RAM and R
The OM, UART, and GPIO are each connected to the CPU.

  Since the tablet terminal 1009 has the above-described configuration, the same effect as that of the configuration using the monitor 1001, the personal computer 1003, and the tablet terminal 1008 can be obtained.

(F2. Second modification)
In the above description, ZigBee (registered trademark) has been described as an example of the personal area network, but the personal area network is not limited to this. As a personal area network, the present invention can also be applied to other communication systems that support multi-hop.

<G. Functional configuration of low-speed wireless communication module 2120>
FIG. 11 is a diagram illustrating a functional configuration of the low-speed wireless communication module 2120. Referring to FIG. 11, the low-speed wireless communication module 2120 includes a communication unit 21201, a participation request unit 21202, a first determination unit 21203, a second determination unit 21204, a function switching unit 21205, and a notification unit 21206. Including.

  The communication unit 21201 communicates with other nodes in the network Z (see FIG. 1). The participation request unit 21202 transmits a request for participation in the network Z to the coordinator of the network Z via the communication unit 21201.

  In the present embodiment, as described above, the communication unit 21201 can function as either an end device or a router in the network Z. For this reason, when ZigBee (registered trademark) is adopted as a communication method in the network Z, a physical device that implements the communication unit 21201 has an FFD (Full-Function) having full functions in accordance with the IEEE 802.15.4 standard. Device).

  The second determination unit 21204 determines whether the communication unit 21201 functions as an end device or a router in the network Z based on the content of information received by the communication unit 21201. The second determination unit 21204 outputs the determination result to the function switching unit 21205. Based on the determination result received from the second determination unit 21204, the function switching unit 21205 sets the function of the communication unit 21201 to either an end device or a router.

  In the present embodiment, in the initial state of the tap 1004, the function of the communication unit 21201 is an end device. Then, the first determination unit 21203 causes the communication unit 21201 to temporarily function as a router when a predetermined condition is satisfied, and further changes the function of the communication unit 21201 when the predetermined condition is not satisfied. Return to end device. In the present embodiment, the predetermined condition is, for example, that a distance between a node that is a communication partner of the tap 1004 in the network Z and the tap 1004 is a specific distance or more.

  The first determination unit 21203 determines whether the predetermined condition is satisfied. In accordance with the determination result, the function switching unit 21205 switches the function of the communication unit 21201 between the router and the end device. In this specification, the function (router or end device) of the communication unit 21201 in the low-speed wireless communication module 2120 may be referred to as the function of the tap 1004 in the network Z.

  That is, in this embodiment, the first determination unit 21203 determines whether or not to temporarily switch the function of the tap 1004 from the end device to the router. When the function of tap 1004 is switched to the router, second determination unit 21204 determines whether to maintain the function of tap 1004 at the router or to switch to the end device.

  The notification unit 21206 notifies the coordinator of the network Z of the result of switching the function of the communication unit 21201 by the communication unit 21201 via the communication unit 21201.

  The communication unit 21201 is realized by the wireless RF unit 2125, for example. The participation request unit 21202, the first determination unit 21203, the second determination unit 21204, the function switching unit 21205, and the notification unit 21206 are realized, for example, by the CPU 2121 executing a predetermined program.

The function of each element in the low-speed wireless communication module 2120 will be described more specifically.
At the start of the communication operation of the low-speed wireless communication module 2120, the participation request unit 21202 requests participation in the network Z by transmitting a Hello packet via the communication unit 21201. The start of the communication operation of the low-speed wireless communication module 2120 is, for example, when the supply of power to the tap 1004 is started or when an operation on a predetermined operation unit such as a reset button is performed on the tap 1004. In this state, the function of the communication unit 21201 is an end device.

  When the participation of the tap 1004 in the network Z is completed, the first determination unit 21203 determines whether or not the predetermined condition described above is satisfied. When the first determination unit 21203 determines that the predetermined condition is satisfied, the first determination unit 21203 outputs to the function switching unit 21205 an instruction to switch the function of the communication unit 21201 from the end device to the router. In response to this, the notification unit 21206 notifies the coordinator of the network Z via the communication unit 21201 that the function of the communication unit 21201 has been switched from the end device to the router.

  When the communication unit 21201 functions as a router, the second determination unit 21204 determines whether the distance between the node that is the communication partner of the tap 1004 in the network Z and the tap 1004 is equal to or greater than a specific distance. to decide. In the present embodiment, second determination unit 21204 determines whether the distance to the communication partner is equal to or greater than the specific distance, depending on whether the radio field intensity of the signal received by communication unit 21201 is less than the specific strength. Determine whether. More specifically, the second determination unit 21204 determines that the distance to the communication partner is equal to or greater than the specific distance when the radio field intensity is equal to or less than a specific intensity. On the other hand, the second determination unit 21204 determines that the distance to the communication partner is less than the specific distance when the radio field intensity exceeds the specific intensity.

  If the second determination unit 21204 determines that the distance between the communication partner and the tap 1004 is equal to or greater than the specific distance, the second determination unit 21204 maintains the function of the communication unit 21201 at the router. On the other hand, if the second determination unit 21204 determines that the distance between the communication partner and the tap 1004 is less than the specific distance, the second determination unit 21204 instructs the function switching unit 21205 to return the function of the communication unit 21201 to the end device. . In response to this, the notification unit 21206 notifies the coordinator of the network Z via the communication unit 21201 that the function of the communication unit 21201 has been switched from the router to the end device.

  When the function of the communication unit 21201 is returned to the end device, the first determination unit 21203 again determines whether or not the predetermined condition is satisfied.

  As described above, in the present embodiment, in the initial state of the tap 1004 (low-speed wireless communication module 2120), the communication unit 21201 functions as an end device.

  During a period in which the communication unit 21201 functions as an end device, the first determination unit 21203 determines whether or not the predetermined condition is satisfied. If the first determination unit 21203 determines that the predetermined condition is satisfied, the first determination unit 21203 switches the function of the communication unit 21201 from the end device to the router.

  When the function of the communication unit 21201 is switched to the router, the second determination unit 21204 determines whether the distance between the tap 1004 and the communication partner is equal to or greater than the specific distance. When determining that the distance is less than the specific distance, the second determination unit 21204 switches the function of the communication unit 21201 from the router to the end device.

<H. Overview of function switching process in tap>
Next, with reference to FIG. 12, an outline of processing (function switching processing) for the tap 1004 to determine whether the function of the own device is an end device or a router will be described.

  FIG. 12 shows three states of the network Z. FIG. 12A shows an initial state of network construction, FIG. 12B shows a state where reconstruction is performed in the network Z, and FIG. 12C shows the state after the reconfiguration. The state of the network Z is shown.

  In each of FIGS. 12A to 12C, a monitor 1001 and taps 1004a, 1004b, and 1004c are shown as nodes constituting a ZigBee (registered trademark) network. Among these, the monitor 1001 functions as a coordinator in a ZigBee (registered trademark) network. The taps 1004a, 1004b, and 1004c function as end devices or routers.

  First, referring to FIG. 12A, in the initial state of network construction, taps 1004a, 1004b, and 1004c all operate (function) as end devices. That is, the taps 1004a, 1004b, and 1004c all output a network participation request to the monitor 1001 that is a coordinator.

  In FIG. 12A, among the taps 1004a, 1004b, and 1004c, the tap 1004c is too far away from the monitor 1001 that is the coordinator, and therefore cannot communicate with the monitor 1001 and cannot participate in the network.

  Next, referring to FIG. 12B, among the taps 1004a, 1004b, and 1004c, each tap (tap 1004a and tap 1004b) that can join the network determines the distance between the monitor 1001 that is the coordinator and the own device. calculate. The calculation of the distance may be realized by an optical method such as a non-contact method using infrared rays, or the radio wave intensity of a signal received from the monitor 1001 is acquired, and the radio wave intensity is determined in a predetermined relationship. In some cases, the conversion may be realized based on the conversion.

  In this embodiment, a node that is more than a specific distance away from the coordinator switches its function from the end device to the router. The specific distance is, for example, the maximum distance at which communication with other devices in the ZigBee (registered trademark) network is possible, or a distance slightly shorter than the maximum distance. That is, a node existing at a specific distance is located at or near the boundary between an area where a ZigBee (registered trademark) network is possible and an area where the network is impossible.

  In the example of FIG. 12B, the distance between the tap 1004a and the monitor 1001 is less than the specific distance, but the distance between the tap 1004b and the monitor 1001 is not less than the specific distance. Thereby, the tap 1004b switches the function of the own device to the router.

  The tap 1004b is within a range of a distance that allows wireless communication with the tap 1004c. Therefore, the tap 1004b receives the request to join the network from the tap 1004c and transfers it to the monitor 1001.

  The transfer allows the tap 1004c to participate in the network Z through the tap 1004b as shown in FIG.

  As described with reference to FIGS. 12A to 12C, in this embodiment, not all nodes other than the coordinator in the network Z function as routers, but the distance from the coordinator is different. Only nodes that are capable of wireless communication and that are longer than the specific distance function as routers. Thereby, only the node located at the boundary (or the vicinity thereof) of the communication range of the network can selectively function as a router. As a result, a node at a position where network communication is not possible can participate in the network. Also, only some of the existing nodes have their functions switched to routers. Thereby, the power consumption as the whole network can be suppressed as much as possible. In particular, the network reconstruction described with reference to FIG. 12B is periodically executed by periodically calculating the reference radio wave intensity at the tap 1004 functioning as an end device. Thereby, the function of the tap 1004 can be switched dynamically.

<I. Function switching process flow>
FIG. 13 is a flowchart of the function switching process executed in each of the nodes (tap 1004a and tap 1004b) that can join the network, as shown in FIG.

  Referring to FIG. 13, when the process for participation in the network is completed, in step S100, CPU 2121 (see FIG. 5) acquires the radio field intensity of the signal by communication in the network, and the acquired radio field intensity The reference radio wave intensity is calculated based on At this time, the CPU 2121 sets the function of the tap 1004 to the end device.

  The reference radio wave intensity is an average value of several times (for example, 5 times or 10 times) of the radio wave intensity acquired in step S100.

  Next, in step S110, the CPU 2121 determines whether or not the reference radio wave intensity acquired in step S110 exceeds a predetermined threshold value. If the CPU 2121 determines that the reference radio wave intensity exceeds the threshold, the process proceeds to step S120. On the other hand, if CPU 2121 determines that the reference radio wave intensity is equal to or less than the threshold value, the process proceeds to step S130.

  In step S120, CPU 2121 waits for a fixed time (for example, about 500 msec), and then returns the process to step S100. In step S120, the CPU 2121 sets the function of the tap 1004 as an end device.

  On the other hand, in step S130, the CPU 2121 changes the function of the tap 1004 to a router and advances the process to step S140.

  Next, in step S140, the CPU 2121 shifts to a state where other nodes are allowed to participate in the network (hereinafter referred to as “participation permitted state”). In the participation permission state, when the CPU 2121 receives a Hello packet request from another router, the request is transferred to the monitor 1001 as a coordinator.

  Next, in step S150, the CPU 2121 determines whether or not a predetermined participation permission time has elapsed since the tap 1004 shifted to the participation permission state in step S140. When CPU 2121 determines that the participation permission time has elapsed, the process proceeds to step S160. In addition, participation permission time shall be about 60 sec, for example.

  In step S160, the CPU 2121 sets the tap 1004 to a state in which other nodes are prohibited from participating in the network (hereinafter referred to as “participation prohibited state”), and proceeds to step S170. In the participation prohibited state, the CPU 2121 does not transfer the request to the monitor 1001 even if it receives a request to join the network from another node.

  In step S170, CPU 2121 acquires the radio field intensity of the signal received by tap 1004 from another node in the network, as in step S100, and advances the process to step S180.

  In step S180, the CPU 2121 calculates the reference radio wave intensity based on the radio wave intensity acquired in step S170 in the same manner as in step S100, and returns the process to step S110.

  The CPU 2121 according to the first embodiment continuously executes the processing illustrated in FIG. 13 until the supply of power is stopped by being removed from the outlet 1015 (see FIG. 1), for example.

  As described above, according to the function switching process described with reference to FIG. 13, the tap 1004 functions as an end device when the reference radio wave intensity exceeds a predetermined threshold. On the other hand, the tap 1004 functions as a router when the reference radio wave intensity is equal to or less than the threshold value. The tap 1004 functioning as a router permits other nodes to join the network for the participation permission time. Allowing another node to join the network means transferring a request for joining the network from another node to the monitor 1001.

  That the reference radio wave intensity of the tap 1004 exceeds the threshold value corresponds to the distance between the tap 1004 and the communication partner in the network of the tap 1004 being less than a specific distance. This is because in radio communication, as the distance between communicating terminals becomes shorter, the radio wave intensity at each terminal of signals transmitted and received tends to increase. That the reference radio wave intensity of the tap 1004 is equal to or smaller than the threshold value means that the distance between the tap 1004 and the node of the communication partner of the tap 1004 is equal to or greater than a specific distance.

  In the process of FIG. 13, if the reference radio wave intensity exceeds the threshold value, the tap 1004 functions as a router (steps S110 and S130). On the other hand, if the reference radio wave intensity exceeds the threshold, the tap 1004 functions as an end device (steps S110 and S120).

  As described in steps S110 and S130 to S180, the CPU 2121 causes the tap 1004 to temporarily function as a router on condition that the reference radio wave intensity is equal to or less than a threshold value.

  If the state where the reference radio wave intensity is less than the threshold is maintained, the function of the tap 1004 is maintained by the router. This corresponds to the process proceeding from step S110 to step S130 after the process returns from step S180 to step S110. On the other hand, after the processing is returned to step S110, if the reference radio wave intensity exceeds the threshold value, the function of the tap 1004 is returned from the router to the end device.

  In the process of FIG. 13, the reference radio wave intensity is calculated based on the radio wave intensity of a plurality of times. Thereby, even if the measured value of the radio wave intensity at the tap 1004 varies every time it is measured, the variation can be reduced and the determination at step S120 can be performed.

  In the process of FIG. 13, even if it is determined that the reference radio wave intensity is equal to or smaller than the threshold value in step S120, the process in step S120 is executed again after the process is executed up to step S180. As a result, the communication environment of the tap 1004 continuously changes such as when a person passes through the vicinity of the tap 1004 or when furniture is arranged in the vicinity of the tap 1004. Even in the case, the tap 1004 can dynamically switch its function.

  FIG. 14 is a sequence diagram of signal transmission / reception between the tap 1004 and the monitor 1001 in the function switching process described with reference to FIG.

  When the tap 1004 is activated, for example, when power supply is started, the function of the tap 1004 is set in the end device as described in the process of step S100 in FIG. In response to this, as shown in step S10 in FIG. 14, the tap 1004 notifies the monitor 1001 that the own device has been activated as an end device.

  Subsequently, as shown in step S12 in FIG. 14, the tap 1004 performs initial setting of the own device.

  In response to the notification in step S10, the monitor 1001 transmits setting information to the tap 1004 as shown in step S14 in FIG. The setting information includes a threshold as an end device and a standby time.

  After that, the tap 1004 acquires the radio field intensity of the own device (step S16) and calculates the reference radio field intensity (step S18). In FIG. 13, the acquisition of the radio wave intensity has been described as the process of step S100 or step S170. The calculation of the reference radio wave intensity has been described as the process of step S100 or step S180.

  If the reference radio wave intensity exceeds the threshold, the tap 1004 sets its own state (function) to the end device, and then waits in the sleep state for a certain time. These processes have been described in FIG. 13 as the processes of step S110 and step S120. Further, the predetermined time is determined by the setting information transmitted by the monitor 1001 in step S14, for example. When the tap 1004 is functioning as an end device, it shifts to a sleep state for a certain period of time, then shifts to a wake state, and again acquires radio wave intensity (step S16), calculates reference radio wave intensity (step S18), and Then, it is determined whether or not the reference radio wave intensity exceeds a threshold value.

  On the other hand, if the reference radio wave intensity is less than or equal to the threshold, tap 1004 sets the state (function) of the own device to the router (step S22). This process corresponds to the process in step S130 of FIG. Further, the tap 1004 notifies the monitor 1001 that the function of the own device has been changed to the router (step S24).

  After setting the function of the own device in the router, the tap 1004 permits other nodes to participate in the network during the participation permission time (step S150) (step S26). Thereafter, the tap 1004 shifts to a state in which other nodes are prohibited from joining the network (step S28), and waits for a predetermined time (“standby time” in FIG. 14) (step S30). ). The permission and prohibition of participation of other nodes in the network corresponds to the processing in steps S140 to S160 in FIG.

  Thereafter, the process returns to step S16. Then, the tap 1004 determines the reference radio wave intensity, and determines whether to maintain the state (function) of the own device by the router or to switch to the end device based on the reference radio wave intensity. The tap 1004 shifts the processing to step S16 when the function of the own device is maintained by the router. The tap 1004 shifts the process to step S20 when switching the function of the own device to the end device.

[Second Embodiment]
<Overview of Tap 1004 Function>
In the description of the first embodiment, the function of the tap 1004 has been described with reference to FIG. The second embodiment differs from the first embodiment in the implementation mode of the function in the function element of the tap 1004.

  More specifically, also in the second embodiment, the first determination unit 21203 determines whether or not to temporarily switch the function of the tap 1004 from the end device to the router. When the function of tap 1004 is switched to the router, second determination unit 21204 determines whether to maintain the function of tap 1004 at the router or to switch to the end device.

  In the tap 1004 of the first embodiment, the second determination unit 21204 determines whether the tap 1004 functions as a router or an end device based on the distance between the tap 1004 and a communication partner in the network Z. It was judged. In the tap 1004 according to the second embodiment, the second determination unit 21204 causes the tap 1004 to function as a router based on whether there is another node connected to the network Z via the tap 1004. Or function as an end device.

  More specifically, when there is a node connected to the network Z via its own device, the tap 1004 continues to set the function of the own device in the router. On the other hand, when the tap 1004 determines that there is no router connected to the network Z via the own device, the tap 1004 switches the function of the own device to the end device.

  Also in the present embodiment, the tap 1004 functions as an end device in the initial state. Then, the first determination unit 21203 causes the tap 1004 to temporarily function as a router when a predetermined condition is satisfied, and further changes the function of the tap 1004 when the predetermined condition is not satisfied. Return to. In the second embodiment, the predetermined condition is, for example, that a certain time has elapsed since the tap 1004 started functioning as an end device. That is, in the tap 1004 of the second embodiment, the first determination unit 21203 determines whether or not a certain time has elapsed since the function of the tap 1004 is set or switched to the end device. Judge that it has passed. When the first determination unit 21203 determines that the predetermined time has elapsed, the function switching unit 21205 switches the function of the tap 1004 to a router.

<Overview of function switching process at tap>
Next, an overview of the function switching process executed by the tap 1004 of the second embodiment will be described with reference to FIG.

  FIG. 15 shows three states of the network Z. FIG. 15 (A) shows the initial state of network construction, FIG. 15 (B) shows the state where reconstruction is performed in the network Z, and FIG. 15 (C) shows the state after the reconstruction. The state of the network Z is shown.

  In each of FIGS. 15A to 15C, a monitor 1001 and taps 1004a, 1004b, and 1004c are shown as nodes constituting a ZigBee (registered trademark) network. Among these, the monitor 1001 functions as a coordinator in a ZigBee (registered trademark) network. The taps 1004a, 1004b, and 1004c function as end devices or routers.

  First, referring to FIG. 15A, in the initial state of network construction, taps 1004a, 1004b, and 1004c all operate (function) as end devices. That is, the taps 1004a, 1004b, and 1004c all output a network participation request to the monitor 1001 that is a coordinator.

  In FIG. 15A, among the taps 1004a, 1004b, and 1004c, the tap 1004c is too far from the monitor 1001 that is the coordinator, and therefore cannot communicate with the monitor 1001 and cannot participate in the network.

  Next, referring to FIG. 15B, among the taps 1004a, 1004b, and 1004c, each tap (tap 1004a and tap 1004b) that can join the network switches its function to a router at predetermined time intervals. , A request to join the network Z from another node is received. Thereby, the tap 1004b can receive the participation request to the network Z from the tap 1004c. When the tap 1004b receives the participation request from the tap 1004c, the tap 1004b transfers the participation request to the monitor 1001.

  The transfer allows the tap 1004c to participate in the network Z through the tap 1004b as shown in FIG.

  When the tap 1004b receives the request to join the network Z from the tap 1004c, the tap 1004b maintains the function as a router. On the other hand, if the tap 1004a does not receive the participation request, the function is returned to the end device.

  If the connection of the tap (tap 1004c) that has received the participation request to the network is maintained after the tap 1004b receives the participation request, the function of the tap 1004b is also maintained in the router. On the other hand, if the connection of the tap 1004c to the network is stopped, the function of the tap 1004b is returned to the end device. The determination as to whether or not the connection of the tap 1004c to the network is maintained is performed, for example, at specific times.

  In the second embodiment, the predetermined time and the specific time are the same length (the time from the start of incrementing the count value of a “state switching timer” described later until reaching a “threshold” described later) Is done. However, they need not be the same length.

  In the second embodiment described with reference to FIGS. 15A to 15C, a node other than the coordinator in the network Z does not always function as a router, but a router at regular intervals. To function as. A node that receives a request to join the network Z from another node during the period of functioning as a router continues to function as a router. On the other hand, a node that has not received the participation request from another node returns its function to the end device. Furthermore, the network reconstruction described with reference to FIG. 15B is executed at specific times. As a result, the minimum necessary number of nodes in the network can be selectively and continuously functioned as a router. Therefore, a node in a position where network communication is impossible can participate in the network. In addition, since only some of the nodes continue to function as routers, the power consumption of the entire network can be suppressed as much as possible compared to the case where all of the nodes always function as routers.

<Function switching process flow>
FIG. 16 is a flowchart of the function switching process executed in each of the nodes (tap 1004a and tap 1004b) that can join the network as shown in FIG. 15 (A).

  Referring to FIG. 16, when the process for joining the network is completed, in step S200, CPU 2121 (see FIG. 5) sets a threshold value for the state switching timer, and the process proceeds to step S210. The state switching timer is realized, for example, when the CPU 2121 executes a time measuring operation. In step S200, the CPU 2121 sets the function of the tap 1004 to the end device.

  In step S210, CPU 2121 increments the count value of the state switching timer by a predetermined unit value, and proceeds to step S220.

  In step S220, the CPU 2121 determines whether or not the count value of the state switching timer has reached the threshold set in step S200. If it is determined that the count has reached, the process proceeds to step S240. On the other hand, when CPU 2121 determines that the count value of the switching timer has not reached the threshold value, the process proceeds to step S230. In step S220, the CPU 2121 resets the count value of the state switching timer.

  In step S230, the CPU 2121 waits for a certain time (for example, about 500 msec), and then returns the process to step S210.

  In step S240, the CPU 2121 changes the function of the tap 1004 to a router and advances the process to step S250.

  In step S250, the CPU 2121 shifts to a state in which other nodes are allowed to participate in the network (participation permitted state).

  Next, in step S260, the CPU 2121 determines whether or not a predetermined participation permission time has elapsed since the tap 1004 shifted to the participation permission state in step S250. If CPU 2121 determines that the participation permission time has elapsed, it proceeds to step S270. In addition, participation permission time shall be about 60 sec, for example.

  In step S270, the CPU 2121 determines whether or not a new node is connected to the tap 1004 on which the CPU 2121 is mounted. If it is determined that it is connected, the process proceeds to step S280. If it is determined that it is not connected, the process proceeds to step S300. , Proceed with each process. The new node is a node newly connected to the network Z via the tap 1004 equipped with the CPU 2121 that executes step S270. More specifically, in step S270, the CPU 2121 determines whether or not the connection request received from another node has been transmitted to the monitor 1001 in step S250. If it is determined that the connection request has been transmitted, the CPU 2121 transmits to step S280. If not, the process proceeds to step S300.

  In step S280, CPU 2121 sets tap 1004 to a state in which participation of other nodes in the network is prohibited (participation prohibited state), and proceeds to step S290.

  In step S290, the CPU 2121 waits for a predetermined time while maintaining the function of the tap 1004 in the router, and then returns the process to step S210.

  When the process is returned to step S210 while the function of the tap 1004 is maintained in the router, the CPU 2121 waits again until the time measured by the state switching timer reaches the threshold (steps S210 to S230), and permission to participate is obtained. A connection request to the network Z from another node is accepted for the time (steps S250 and S260), and the determination in step S270 is executed.

  In step S270 after the second time, the CPU 2121 determines whether there is a node connected to the network Z via the tap 1004 including the CPU 2121. The presence of a node connected to the network Z via the tap 1004 means that in any of the steps S250 executed so far, the connection request to the network Z from another node is received, It is determined whether the connection of the node to the network Z is maintained. “In any of the steps S250 executed so far” means that not only the step S250 executed immediately before but also the step S250 executed so far when the second and subsequent steps S270 are executed. In any of the above, it means that.

  The CPU 2121 of the second embodiment continuously executes the process shown in FIG. 16 until the power supply is stopped by being removed from the outlet 1015 (see FIG. 1), for example.

  As described above, in the function switching process described with reference to FIG. 16, when the tap 1004 is functioning as a router, it is determined whether another node is connected to the network Z via the tap 1004. . This determination corresponds to the function of the second determination unit 21204. If such “other node” exists, the function of the tap 1004 is maintained by the router (step S280). On the other hand, if there is no such “other node”, the function of the tap 1004 is switched to the end device (step S300).

  When the function of the tap 1004 is set to the end device in step S200 or step S300, it is determined from that point whether the count value of the state switching timer has reached the threshold value. This determination corresponds to the function of the first determination unit 21203. When the count value of the state switching timer reaches the threshold value, the function of the tap 1004 is switched to the router (step S240).

  In the present embodiment, the times referred to in the determinations of the first determination unit 21203 and the second determination unit 21204 are both from when the count of the state switching timer is started until the count value reaches the threshold value. ing. Note that the times referred to in the determination in each determination unit need not be the same length.

  FIG. 17 is a sequence diagram of signal transmission / reception between the tap 1004 and the monitor 1001 in the function switching processing described with reference to FIG.

  When the tap 1004 is activated, for example, when power supply is started, the function of the tap 1004 is set in the end device as described in the processing of step S100 in FIG. In response to this, as shown in step S50 in FIG. 17, the tap 1004 notifies the monitor 1001 that the own device has been activated as an end device.

  Subsequently, as shown in step S52 in FIG. 17, the tap 1004 performs initial setting of the own device.

  In response to the notification in step S10, the monitor 1001 transmits setting information to the tap 1004 as shown in step S54 in FIG. The setting information includes a threshold as an end device and a standby time.

  Thereafter, the tap 1004 repeats incrementing the count value of the state switching timer (step S56) and waiting for a fixed time (step S58), as described as the process of step S210 in FIG. The certain time is the certain time described in step S230 of FIG.

  When the count value of the state switching timer reaches the above threshold, the tap 1004 changes its own function to a router (step S60). This process corresponds to the process described as the process of steps S220 and S240 in FIG. Further, the tap 1004 notifies the monitor 1001 of the change of the function of the own device (step S62).

  Then, the tap 1004 is in a participation permission state until the participation permission time elapses (step S64). This process corresponds to the process described as the process of steps S250 and S260 in FIG.

  Thereafter, the tap 1004 waits for a certain time (step S66), and if there is no other node connected to the network Z via the own device, the function (state) of the own device is changed to an end device (step S68). ). These processes correspond to the processes described as the processes in steps S270 and S300 in FIG. Further, the tap 1004 notifies the monitor 1001 of the change of the function (state) at this time (step S70). On the other hand, if there is another node connected to the network Z via its own device, the tap 1004 transitions to the participation prohibited state without changing its own function to an end device, and then waits for a certain period (step). S32, step S34).

[Comparative example]
Next, with reference to FIG. 18 and FIG. 19, an embodiment of a comparative example with respect to the first embodiment and the second embodiment will be described.

  In the comparative example, when the count value of the state switching timer first reaches the threshold value from the initial state, the tap 1004 switches the function of the own device to the router as in the second embodiment. When there is another node connected to the network via the own device, the tap 1004 maintains the function of the own device with the router, and when there is no other node, the tap 1004 Switch to the end device. However, in the comparative example, unlike the second embodiment, after that, the tap 1004 does not switch the function of the own device based on the presence or absence of a node connected to the network Z via the own device.

<Overview of function switching>
FIG. 18 is a diagram for describing an overview of function switching in the node according to the embodiment of the comparative example.

  Next, an overview of the function switching process executed by the tap 1004 of the second embodiment will be described with reference to FIG.

  FIG. 18 shows three states of the network Z. 18A shows an initial state of network construction, FIG. 18B shows a state where reconstruction is performed in the network Z, and FIG. 18C shows the state after the reconstruction. The state of the network Z is shown.

  Each of FIGS. 18A to 18C shows a monitor 1001 and taps 1004a, 1004b, and 1004c as nodes constituting a ZigBee (registered trademark) network. Among these, the monitor 1001 functions as a coordinator in a ZigBee (registered trademark) network. The taps 1004a, 1004b, and 1004c function as end devices or routers.

  First, referring to FIG. 18A, in the initial state of network construction, taps 1004a, 1004b, and 1004c all operate (function) as end devices. That is, the taps 1004a, 1004b, and 1004c all output a network participation request to the monitor 1001 that is a coordinator.

  In FIG. 18A, among the taps 1004a, 1004b, and 1004c, the tap 1004c is too far from the monitor 1001 that is the coordinator, and therefore cannot communicate with the monitor 1001 and cannot participate in the network.

  Next, referring to FIG. 18B, among the taps 1004a, 1004b, and 1004c, the taps (tap 1004a and tap 1004b) that have joined the network have a specific time after the start of connection to the network Z. The function is switched to the router, and a request to join the network Z from another node is received. Thereby, the tap 1004b can receive the participation request to the network Z from the tap 1004c. When the tap 1004b receives the participation request from the tap 1004c, the tap 1004b transfers the participation request to the monitor 1001.

  By this transfer, as shown in FIG. 18C, the tap 1004c can join the network Z through the tap 1004b.

  On the other hand, if the tap 1004a does not receive the participation request, the function is returned to the end device.

  As described above, in the comparative example, the tap 1004 does not determine whether to switch the function of the own device thereafter.

  Therefore, for example, even if the tap 1004c stops connecting to the network Z from the state shown in FIG. 18C, the tap 1004b maintains its function in the router. For this reason, the tap 1004b does not need to function as a router, but continues to function as a router. As a result, the tap 1004b wastes power by functioning as a router in vain.

  Also, for example, from the state shown in FIG. 18C, a request for a new tap 1004 that cannot communicate directly with the monitor 1001 or the tap 1004b but can communicate with the tap 1004a is output to the network Z. Even so, since the tap 1004a maintains its function in the end device, it cannot receive the connection request. Even if it is received, the tap 1004a cannot transfer the connection request to the monitor 1001. As a result, the network of the comparative example cannot allow the new tap 1004 to participate in the network Z.

On the other hand, in the second embodiment, these two disadvantages do not occur.
Specifically, from the state shown in FIG. 15C, when the tap 1004c stops connecting to the network Z, the tap 1004b performs the function by the processing of step S270 and step S300 (FIG. 16). Switch to the end device. For this reason, when it is not necessary for the tap 1004b to function as a router, the function is switched to the end device. Therefore, the tap 1004b can avoid unnecessary power consumption by functioning as a router in vain.

  Also, from the state shown in FIG. 15C, when a new tap 1004 that cannot communicate directly with the monitor 1001 or the tap 1004b but can communicate with the tap 1004a outputs a request for connecting to the network Z. The tap 1004a can cause the new tap 1004 to participate in the network Z. This is because the tap 1004a temporarily functions as a router in steps S220 and S240, and transfers the connection request for the new tap 1004 to the monitor 1001 in step S250. Therefore, the network Z according to the second embodiment can cause the network Z to include a new tap 1004 that the network of the comparative example cannot participate in the network Z.

<Function switching process flow>
FIG. 19 is a flowchart of the function switching process executed in each of the nodes (tap 1004a and tap 1004b) that can join the network as shown in FIG.

  Referring to FIG. 19, when the process for joining the network is completed, tap 1004 switches its own function from the end device in the initial state to the router, and shifts to the participation permitted state in step S900. To do. At this time, the CPU 2121 notifies the monitor 1001 of the function change of the tap 1004 including the CPU 2121.

  Then, the CPU 2121 executes network construction processing for a predetermined network construction time (for example, about 60 seconds) (steps S910 and S920). The network construction process here is a process of accepting a participation request to the network Z from another node and transferring the participation request to the monitor 1001 when the participation request is received.

  In step S930, the CPU 2121 determines whether a child tap is connected to the tap 1004 including the CPU 2121. The child tap is a tap 1004 connected to the network Z via a tap 1004 including the CPU 2121. When CPU 2121 determines that there is a child tap, CPU 2121 advances the process to step S940. On the other hand, when CPU 2121 determines that there is no child tap, CPU 2121 advances the process to step S960.

  In step S940, the CPU 2121 advances the process to step S950 while maintaining the function (state) of the tap 1004 including the CPU 2121 in the router.

  In step S950, the CPU 2121 shifts to the participation prohibited state, and ends the function switching process.

  On the other hand, in step S960, the CPU 2121 changes the function (state) of the tap 1004 including the CPU 2121 to an end device, and ends the function switching process. At this time, the CPU 2121 notifies the monitor 1001 of the function change of the tap 1004 including the CPU 2121.

[Modification (1)]
In the first and second embodiments, in the initial state, the function of the tap 1004 is set to the end device. In the initial state of the tap 1004, the function may be a router.

[Modification (2)]
In the first embodiment, the tap 1004 determines the distance between the tap 1004 and the communication partner depending on whether the radio field intensity of the signal received from the communication partner in the network Z exceeds a specific threshold. It was judged whether it was less than the distance. The tap 1004 identifies the communication partner based on a signal received from the communication partner, and a device that directly measures the distance between the identified communication partner and the own device. You may get from. In this case, the tap 1004 determines whether or not to switch the function of the own device to the router based on the acquired distance.

  More specifically, the tap 1004 may acquire the distance from the device via a network, or may include the device as shown in FIG. FIG. 20 is a diagram illustrating a modification of the hardware configuration illustrated in FIG. In FIG. 20, the device is shown as a distance measuring sensor 2108. The distance measuring sensor 2108 measures the distance between the communication partner specified as described above and the main body of the tap 1004 in a non-contact manner using, for example, infrared rays or ultrasonic waves.

[Modification (3)]
As described with reference to FIG. 5, the program executed by the CPU 2121 may be stored in the ROM 2122, or may be recorded on a recording medium that is detachable from the tap 1004.

  In this case, the tap 1004 further includes a media drive 2109 as shown in FIG. In this example, the CPU 2121 reads information recorded on the recording medium 9000 via the media drive 2109 and writes information on the recording medium 9000.

  The recording medium 9000 includes a CD-ROM (Compact Disk-Read Only Memory), a DVD-ROM (Digital Versatile Disk-Read Only Memory), a USB (Universal Serial Bus) memory, a memory card, an FD (Flexible Disk), a hard disk, Magnetic tape, cassette tape, MO (Magnetic Optical Disk), MD (Mini Disk), IC (Integrated Circuit) card (excluding memory cards), optical card, mask ROM, EPROM, EEPROM (Electronically Erasable Programmable Read Only Memory), etc. And a medium for storing the program in a nonvolatile manner.

[Modification (4)]
In the first and second embodiments, the tap 1004 is cited as an example of the wireless communication terminal. Note that the wireless communication terminal is not limited to a tap as long as the terminal has a communication function for connecting to a network.

  Examples of the device that realizes the wireless communication terminal include various devices such as a smartphone, a mobile phone, a notebook computer, and a tablet terminal.

[Effect of the embodiment]
In the wireless communication network described above, the function (of the communication unit) of the wireless communication terminal is dynamically changed between the end device and the router in accordance with a change in the configuration of the wireless communication network.

  Thereby, even if a change occurs due to the configuration of the wireless communication network, isolation of the wireless communication terminal can be avoided.

  It should be thought that embodiment disclosed this time and its modification are illustrations in all the points, and are not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims. It is intended that the techniques disclosed in the embodiments and the modifications thereof can be implemented alone or in combination as much as possible.

  1001 monitor, 1004, 1004a, 1004b, 1004c tap, 2120 low-speed wireless communication module, 2121 CPU, 21201 communication unit, 21202 participation request unit, 21203 first determination unit, 21204 second determination unit, 21205 function switching unit, 21206 notification unit .

Claims (10)

A wireless communication terminal constituting a network,
A communication unit that communicates with other nodes in the network;
A control unit for controlling the communication unit,
The controller is
First determination means for temporarily functioning the communication unit as a router when a predetermined condition is satisfied, and further causing the communication unit to function as an end device when the predetermined condition is not satisfied;
When the communication unit is temporarily functioning as a router by the first determination unit, detection on other nodes in the network is performed, and the communication unit is turned into an end device based on the detection result. And a second determination means for determining whether to return or maintain the router as a router. In the detection, when the communication unit is functioning as a router, the second determination means specifies a distance between the wireless communication terminal and a node that is a communication partner with the wireless communication terminal in the network. To determine whether or not the distance is greater than
The second determination means includes
When the detection result indicates that the distance is equal to or greater than a specific distance, the communication unit functions as a router;
2. The wireless communication terminal according to claim 1, wherein when the detection result indicates that the distance is less than the specific distance, the communication unit is configured to function as an end device.   The wireless communication terminal according to claim 2, wherein the predetermined condition is that a distance between a node that is a communication partner in the network and the wireless communication terminal is equal to or greater than the specific distance.   4. The wireless communication terminal according to claim 2, wherein whether or not the distance is equal to or greater than the specific distance is determined based on a radio wave intensity of a signal received by the communication unit. In the detection, when the communication unit functions as a router, the second determination unit determines whether there is a node connected to the network via the wireless communication terminal. And
The second determination means includes
When the result of the detection is that there is a node connected to the network via the wireless communication terminal, the communication unit functions as a router,
The communication unit is configured to function as an end device when the result of the determination is that there is no node connected to the network via the wireless communication terminal. Item 2. A wireless communication terminal according to Item 1.   The wireless communication terminal according to claim 5, wherein the second determination unit executes the detection every specific time.   The wireless communication terminal according to claim 5, wherein the predetermined condition is that a predetermined time has elapsed since the communication unit started functioning as an end device.   The wireless communication terminal according to claim 1, wherein the control unit causes the communication unit to function as an end device in an initial state of the wireless communication terminal. A method of controlling a wireless communication terminal constituting a network, wherein the wireless communication terminal includes a communication unit that communicates with other nodes in the network, and a processor, and the control method includes:
The processor causing the communication unit to temporarily function as a router when a predetermined condition is satisfied, and further causing the communication unit to function as an end device when the predetermined condition is not satisfied; and ,
The processor performing detection for other nodes in the network when the communication unit temporarily functions as a router;
And a step of determining whether to return the communication unit to an end device or to maintain the processor as a router based on the detection result.   A computer-readable control program for a wireless communication terminal for causing a computer to execute the control method according to claim 9.

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