JP6347039B2 - WIRELESS DEVICE, WIRELESS COMMUNICATION SYSTEM EQUIPPED WITH THE SAME, AND PROGRAM RUNNED IN WIRELESS DEVICE - Google Patents

Description

  The present invention relates to a radio apparatus, a radio communication system including the radio apparatus, and a program executed in the radio apparatus.

  2. Description of the Related Art Conventionally, a technique is known in which identification information of a wireless device that is shifted from a sleep state to an activated state is represented by a frame length to activate the wireless device (Patent Document 1).

  In the technique described in Patent Document 1, a transmission-source wireless device generates a wireless frame having a frame length indicating identification information of a wireless device to be activated, and the generated wireless frame is transmitted to a wireless communication partner. Send to a wireless device. Then, the counterpart radio apparatus receives the radio frame and detects the frame length by detecting the received signal of the received radio frame at the sampling interval with an envelope. Thereafter, the counterpart wireless device decodes the detected frame length into the identification information, and shifts from the sleep state to the activated state when the decoded identification information matches its own identification information.

  Then, the transmission source wireless device performs wireless communication with the counterpart wireless device.

  A wireless sensor network including a plurality of sensor terminals and a management terminal is known (Patent Document 2).

  The plurality of sensor terminals includes a sensor. The management terminal constructs a communication path for communicating with the plurality of sensor terminals, and performs wireless communication with each sensor terminal based on the constructed communication path. Then, the management terminal collects sensor values detected by each sensor terminal.

Patent No. 5190569 JP 2013-055551 A

  However, by applying the technology described in Patent Document 1 to the wireless sensor network described in Patent Document 2, at least one sensor terminal existing on the route from the sensor terminal that is the transmission source of sensor values to the management terminal is provided. When it is assumed that sensor values are transmitted from the transmission source sensor terminal to the management terminal while being sequentially activated, there are the following problems.

  If the sampling interval when receiving a wireless frame having a frame length indicating the identification information of the sensor terminal to be activated is increased, the power consumption of the sensor terminal that receives the wireless frame can be reduced, but if the sampling interval is increased, Since the frame length indicating the identification information becomes long, the power consumption of the sensor terminal that transmits the radio frame increases.

  On the other hand, if the sampling interval is shortened, the frame length indicating the identification information can be shortened, so that the power consumption of the sensor terminal that transmits the radio frame can be reduced, but the power consumption of the sensor terminal that receives the radio frame increases.

  Thus, the power consumption when transmitting a radio frame and the power consumption when receiving a radio frame are in a trade-off relationship.

  As a result, there is a problem that it is difficult to reduce the overall power consumption, which is the sum of the power consumption when transmitting a radio frame and the power consumption when receiving a radio frame.

  Therefore, the present invention has been made to solve such a problem, and an object thereof is to provide a wireless device capable of reducing the overall power consumption.

  Another object of the present invention is to provide a wireless communication system including a wireless device capable of reducing the overall power consumption.

  Furthermore, another object of the present invention is to provide a program executed in a wireless device capable of reducing the overall power consumption.

  According to the embodiment of the present invention, the radio apparatus adds or subtracts a desired frame length interval to an average frame length that becomes longer as the sampling interval when detecting the frame length becomes longer and becomes shorter as the sampling interval becomes shorter. The wireless device transmits and receives the first wireless frame having the frame length representing the identification information by representing the identification information of the wireless device by at least one frame length selected from a plurality of frame lengths including the frame length obtained in this way. And a determination means and a receiver. The determining means has a total power amount that is a sum of a reception power amount that is a power consumption amount when receiving the first radio frame and a transmission power amount that is a power consumption amount when transmitting the first radio frame. A suitable sampling interval when it becomes the minimum is determined corresponding to the number of frame transmissions that is the number of transmissions of the first radio frame in a desired time length. The receiver receives the first radio frame and operates at a suitable sampling interval.

  In the wireless device according to the embodiment of the present invention, the total power amount that is the sum of the received power amount when receiving the first wireless frame and the transmitted power amount when transmitting the first wireless frame is minimized. Thus, the sampling interval is determined, and the operation is performed at the determined sampling interval.

  Therefore, the overall power consumption of the wireless device can be reduced.

  Preferably, the wireless device further includes a calculation unit. The calculation means includes a predetermined data collection period, a transmission period of control packets for constructing and / or maintaining the topology of the wireless apparatus in the wireless network, and a lower rank than the wireless apparatus when the topology has a hierarchical structure. The total number of radio frames is calculated using the total number of radio devices existing in the layer and located at a position of 1 hop or more from the radio device, and the communication quality of the link is calculated with respect to the calculated total number of radio frames. Considering this, the number of frame transmissions is calculated by increasing the total number of radio frames. The determining means determines a suitable sampling interval corresponding to the number of frame transmissions calculated by the calculating means.

  The number of frame transmissions is calculated using the data collection period, the control packet transmission period, the total number of wireless devices, and the communication quality of the link. Then, a suitable sampling interval is determined corresponding to the calculated number of frame transmissions.

  Therefore, a suitable sampling interval can be easily determined.

  Preferably, the wireless device further includes detection means. The detection means measures the number of transmissions of the first radio frame in a desired time length and detects the number of frame transmissions. The determining means determines a suitable sampling interval corresponding to the number of frame transmissions detected by the detecting means.

  Since the number of frame transmissions is actually measured, a sampling interval suitable for the wireless network being used can be determined.

  Preferably, the determining means periodically determines a suitable sampling interval.

  Even if the number of frame transmissions changes, the sampling interval can be determined corresponding to the changed number of frame transmissions.

  Preferably, the determining unit holds a first correspondence table indicating a correspondence relationship between the number of frame transmissions and the sampling interval, and determines a suitable sampling interval with reference to the first correspondence table.

  If the number of frame transmissions is acquired, the sampling interval can be easily determined.

  Preferably, the wireless device further includes adjustment means. The adjustment means adjusts a suitable sampling interval or the number of frame transmissions using topology information indicating the topology of the wireless device in the wireless network.

  Even if the number of frame transmissions changes due to a change in topology, it is possible to determine a suitable sampling interval corresponding to the number of frame transmissions while suppressing the time lag until the change in the number of frame transmissions is reflected.

  Preferably, when the topology has a hierarchical structure, the topology information includes a cost value indicating the proximity to the wireless device located at the highest level, the number of hops indicating the proximity to the wireless device located at the highest level, and It consists of at least one of the total number of wireless devices that exist in a lower layer than the wireless device and exist at a position of one hop or more from the wireless device.

  It is possible to adjust to a suitable sampling interval or frame transmission number suitable for the position where the wireless device is present or the number of wireless frames transmitted via the wireless device.

  Preferably, the wireless device further includes an acquisition unit. The acquisition means holds a second correspondence table indicating the correspondence between the frame length and the bit value corresponding to each sampling interval, and stores the second correspondence table in the MAC address of the wireless device for shifting from the sleep state to the activation state. Based on this, the frame length indicating the identification information is obtained from the second correspondence table.

  Identification information can be easily converted into a frame length.

  The wireless device further includes a determination unit. The determination means determines whether to use the receiver based on either the number of frame transmissions or topology information indicating the topology of the wireless device in the wireless network.

  When the determination unit determines not to use the receiver based on the number of frame transmissions or topology information, the power consumption of the receiver is reduced.

  Therefore, the total amount of power in the wireless device can be reduced.

  According to an embodiment of the present invention, a wireless communication system includes the wireless device according to any one of claims 1 to 9.

  The overall power consumption of the wireless communication system can be reduced.

  Furthermore, according to the embodiment of the present invention, a program to be executed by a computer is desired to have an average frame length that becomes longer as the sampling interval when detecting the frame length becomes longer and becomes shorter as the sampling interval becomes shorter. The first radio frame having the frame length representing the identification information and representing the identification information of the wireless device by at least one frame length selected from a plurality of frame lengths including the frame length obtained by adding and subtracting the frame length interval of Is a program for causing a computer to execute in a wireless device for transmitting and receiving the received power amount when the first wireless frame is received and the consumed power amount when transmitting the first wireless frame. A suitable sampling interval when the total amount of power that is the sum of a certain amount of transmission power is minimized, A first step of determining corresponding to the number of transmissions of the first radio frame in a desired time length; a first step in which the receiver receives the first radio frame and operates at a suitable sampling interval; This is a program for causing a computer to execute the two steps.

  By executing a program to be executed by the computer according to the embodiment of the present invention, the sum of the reception power amount when receiving the first radio frame and the transmission power amount when transmitting the first radio frame The sampling interval is determined so that the total power amount is minimum, and the wireless device operates at the determined sampling interval.

  Therefore, the overall power consumption of the wireless device can be reduced.

  Preferably, a predetermined data collection cycle, a transmission cycle of a control packet for constructing and / or maintaining a topology of a wireless device in a wireless network, and a radio in which the program is executed when the topology has a hierarchical structure The total number of radio frames is calculated using the total number of radio devices existing in a lower layer than the device and existing at a position of 1 hop or more from the radio device on which the program is executed. The computer further executes a third step of calculating the number of frame transmissions by increasing the total number of radio frames in consideration of the communication quality of the link with respect to the total number. In the first step, a suitable sampling interval is: It is determined corresponding to the number of frame transmissions calculated in the third step.

  By executing a program to be executed by a computer according to an embodiment of the present invention, the number of frame transmissions is calculated using the data collection period, the transmission period of control packets, the total number of wireless devices, and the communication quality of the link. . Then, a suitable sampling interval is determined corresponding to the calculated number of frame transmissions.

  Therefore, a suitable sampling interval can be easily determined.

  Preferably, the computer further executes a fourth step of measuring the number of transmissions of the first radio frame in a desired time length and detecting the number of frame transmissions. In the first step, a suitable sampling interval is This is determined in accordance with the number of frame transmissions detected in step 4.

  By executing the program to be executed by the computer according to the embodiment of the present invention, the number of frame transmissions is actually measured, so that a sampling interval suitable for the wireless network being used can be determined.

  Preferably, in the first step, a suitable sampling interval is determined periodically.

  By executing the program to be executed by the computer according to the embodiment of the present invention, even if the number of frame transmissions changes, the sampling interval can be determined corresponding to the changed number of frame transmissions.

  Preferably, in the first step, a suitable sampling interval is determined with reference to a first correspondence table showing a correspondence relationship between the number of frame transmissions and the sampling interval.

  If the number of frame transmissions is acquired by executing a program to be executed by a computer according to an embodiment of the present invention, the sampling interval can be easily determined.

  Preferably, the computer further executes a fifth step of adjusting a suitable sampling interval or the number of frame transmissions using topology information indicating a topology of the wireless device in the wireless network.

  By executing a program to be executed by a computer according to an embodiment of the present invention, even if the number of frame transmissions changes due to a change in topology, the time lag until the change in the number of frame transmissions is reflected is suppressed and the frame A suitable sampling interval corresponding to the number of transmissions can be determined.

  Preferably, when the topology has a hierarchical structure, the topology information includes a cost value indicating the proximity to the wireless device located at the highest level, the number of hops indicating the proximity to the wireless device located at the highest level, and It consists of at least one of the total number of wireless devices that exist in a lower layer than the wireless device on which the program is executed and are located at a position of 1 hop or more from the wireless device on which the program is executed.

  By executing a program to be executed by a computer according to an embodiment of the present invention, a radio frame transmitted via a position where a wireless device on which the program is executed is present or a wireless device on which the program is executed The sampling interval or the number of frame transmissions suitable for the number of frames can be adjusted.

  Preferably, on the basis of the MAC address of the wireless device, a sixth step of acquiring a frame length indicating identification information from a second correspondence table indicating a correspondence relationship between the frame length and the bit value corresponding to each sampling interval. Further, it is executed by a computer.

  By executing a program to be executed by a computer according to an embodiment of the present invention, identification information can be easily converted into a frame length.

  Preferably, the computer further executes a seventh step of determining whether to use the receiver based on either the number of frame transmissions or topology information indicating the topology of the wireless device in the wireless network.

  By executing the program to be executed by the computer according to the embodiment of the present invention, when it is determined not to use the receiver based on the number of frame transmissions or topology information, the power consumption of the receiver is reduced.

  Therefore, it is possible to reduce the total amount of power in the wireless device that executes the program.

  According to the embodiment of the present invention, the overall power consumption of a radio apparatus or a radio communication system can be reduced.

1 is a schematic diagram of a wireless sensor network according to an embodiment of the present invention. FIG. It is the schematic which shows the structure of the radio | wireless node shown in FIG. It is a block diagram of the control packet DIO. It is a block diagram of control packet DAO. It is a conceptual diagram of a sampling interval. It is a figure which shows the relationship between total electric energy and a sampling interval. It is a figure which shows the relationship between sampling interval T _{interval_min} and the number of frame transmissions. It is a figure which shows the conversion table which shows the relationship between the number of frame transmissions, and sampling interval T _{interval_min} . It is a figure which shows the relationship between sampling interval T _{interval_min} and average frame length. It is a figure which shows the relationship between the frame length matched with sampling interval T _{interval_min} , and data. It is a conceptual diagram of sampling of a radio | wireless frame. It is a figure for demonstrating the method of transmitting a wakeup signal. It is a block diagram of the routing table which the route control part shown in FIG. 2 holds. It is a figure which shows the arrangement | positioning state of the radio | wireless node in the radio | wireless sensor network shown in FIG. It is a flowchart for demonstrating operation | movement when constructing | assembling a path | route. It is a figure which shows the example of the topology constructed | assembled according to the flowchart shown in FIG. It is a figure which shows the specific example of the routing table shown in FIG. 3 is a flowchart for explaining a sensor value transfer operation in the wireless sensor network shown in FIG. 1. It is a figure which shows the relationship between topology information and sampling interval T _{interval_min} . It is a flowchart for _{demonstrating} the operation _| movement which adjusts sampling interval T _{interval_min} . It is a flowchart for _{demonstrating} the operation _| movement which adjusts sampling interval T _{interval_min} using all of a cost value, the number of hops, and a tree size. It is a figure which shows another relationship between the frame length matched with sampling interval T _{interval_min} , and data. It is a figure which shows the detail of the frame length matched with sampling interval T _{interval_min} of 160 [microseconds] and 320 [microseconds] shown in FIG. It is a figure which shows the detail of the frame length matched with sampling interval T _{interval_min} of 640 [microseconds], 1280 [microseconds], and 2560 [microseconds] shown in FIG. It is a figure for demonstrating 2 steps | paragraphs of intermittent operation | movement. It is a flowchart for demonstrating the operation | movement which switches an operation mode with the frame transmission number N. FIG. It is a figure which shows the relationship between topology information and an operation mode. It is a flowchart for demonstrating the operation | movement which switches the operation mode of a radio node using all of a cost value, the number of hops, and a tree size. It is a figure which shows the simulation result of the relationship between the average power consumption per node, and a sensor data collection period. It is a flowchart which shows the program for making a computer (CPU) perform operation | movement of each wireless node.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a schematic diagram of a wireless sensor network according to an embodiment of the present invention. Referring to FIG. 1, a wireless sensor network 10 according to an embodiment of the present invention includes wireless nodes 1 to 7.

  The wireless nodes 1 to 7 are arranged in the wireless communication space. For example, the wireless nodes 1 to 7 perform wireless communication in a 920 MHz band corresponding to IEEE802.15.4g.

  Each of the wireless nodes 2 to 7 has a sensor.

  The wireless nodes 1 to 7 construct paths from the wireless nodes 2 to 7 to the wireless node 1 using RPL: IPv6 Routing Protocol for Low-Power and Lossy Networks (RFC 6550). Further, the wireless nodes 1 to 7 maintain a route from each of the wireless nodes 2 to 7 to the wireless node 1 using RPL by a method described later.

  When a path from each of the wireless nodes 2 to 7 to the wireless node 1 is established, the wireless sensor network 10 has a topology in which the wireless nodes 1 to 7 are arranged in a hierarchical structure. In this case, the wireless node 1 is arranged in the highest layer, and the wireless nodes 2 to 7 are arranged in a tree shape below the second layer.

  In the embodiment of the present invention, the wireless node 1 is also referred to as “sink”.

  Each of the wireless nodes 1 to 7 determines a sampling interval so that power consumption is minimized by a method described later. Each of the wireless nodes 1 to 7 operates at the determined sampling interval.

  In addition, each of the wireless nodes 1 to 7 generates a wakeup signal using the frame length determined corresponding to the determined sampling interval, and transmits and receives the generated wakeup signal.

  Further, each of the wireless nodes 2 to 7 detects a sensor value by a sensor (not shown), and wirelessly activates the detected wireless sensor node on the route from the wireless node 1 to the wireless node 1. Transmit to node 1.

  In this case, the wireless node existing on the path from each of the wireless nodes 2 to 7 to the wireless node 1 transfers the sensor value received from the other wireless node by a method described later.

  FIG. 2 is a schematic diagram showing the configuration of the wireless node 1 shown in FIG. Referring to FIG. 2, the wireless node 1 includes antennas 11 and 12, a wireless communication unit 13, a control unit 14, a path control unit 15, a sampling interval determination unit 16, a wake-up signal reception unit 17, A wakeup signal determination unit 18 and a frame length correspondence table 19 are included.

  The wireless node 1 has a sleep state and an activated state. In the sleep state, the wakeup signal reception unit 17 and the wakeup signal determination unit 18 operate, and the wireless communication unit 13, the control unit 14, the path control unit 15, the sampling interval determination unit 16, and the frame length correspondence table 19 operate. It is in a stopped state.

  The activated state means that the wakeup signal receiving unit 17 and the wakeup signal determining unit 18 stop operating, the wireless communication unit 13, the control unit 14, the path control unit 15, the sampling interval determination unit 16, and the frame length correspondence table. 19 is operating.

  The antenna 11 is connected to the wireless communication unit 13. The antenna 12 is connected to the wake-up signal receiving unit 17.

  When receiving the activation signal from the wake-up signal determination unit 18, the wireless communication unit 13 shifts from the sleep state to the activation state. The wireless communication unit 13 has a built-in timer, and performs an intermittent operation at regular intervals T when the wakeup signal reception unit 17 and the wakeup signal determination unit 18 are stopped. In other words, the wireless communication unit 13 shifts to the activation state during the time T_1 of the fixed interval T, and shifts to the sleep state during the time T_2 of the fixed interval T. T_1 and T_2 satisfy T_1 + T_2 = T.

  When establishing a route in the wireless sensor network 10 or maintaining the established route, the wireless communication unit 13 receives a control packet from the control unit 14, modulates the received control packet, and transmits the modulated control packet via the antenna 11. To do. The wireless communication unit 13 receives a control packet via the antenna 11, demodulates the received control packet, and outputs the demodulated control packet to the control unit 14. The control packet is composed of DIO and DAO.

  Further, the wireless communication unit 13 measures the number N of frame transmissions, which is the number of wireless frames transmitted per hour. Then, the wireless communication unit 13 outputs the measured frame transmission number N to the sampling interval determination unit 16.

  Further, the wireless communication unit 13 receives a packet including data via the antenna 11, demodulates the received packet, and outputs the demodulated packet to the control unit 14. The wireless communication unit 13 receives a packet including data from the control unit 14, modulates the received packet, and transmits the modulated packet via the antenna 11.

  When the control unit 14 receives the activation signal from the wakeup signal determination unit 18, the control unit 14 shifts from the sleep state to the activation state. The control unit 14 has a built-in timer. When the wakeup signal receiving unit 17 and the wakeup signal determining unit 18 are stopped, the control unit 14 performs intermittent operation at a constant interval T in the same manner as the wireless communication unit 13. Do.

  When establishing a route in the wireless sensor network 10 or maintaining the established route, the control unit 14 receives a control packet from the route control unit 15 and outputs the received control packet to the wireless communication unit 13. In addition, the control unit 14 receives a control packet from the wireless communication unit 13 and outputs the received control packet to the route control unit 15.

  The control unit 14 receives the sampling interval from the sampling interval determination unit 16. The control unit 14 receives the MAC address of the destination wireless node from the path control unit 15. Then, the control unit 14 calculates a hash value of the MAC address. Thereafter, the control unit 14 receives a correspondence table corresponding to the sampling interval and indicating the relationship between the frame length and the data from the frame length correspondence table 19, and based on the received correspondence table, the data indicating the hash value is received. Convert to frame length. Then, the control unit 14 generates a radio frame having the converted frame length, and outputs the generated radio frame to the radio communication unit 13 as a wakeup signal.

  The control unit 14 receives a sensor value (= data) from a sensor (not shown) and generates a packet including the received sensor value. Then, the control unit 14 outputs the generated packet to the wireless communication unit 13.

  The control unit 14 receives a packet including data from the wireless communication unit 13 and determines whether or not the transmission destination of the received packet is the wireless node 1. Then, when the control unit 14 determines that the transmission destination of the packet is the wireless node 1, the control unit 14 extracts data from the packet and accepts the extracted data. On the other hand, when the control unit 14 determines that the transmission destination of the packet is a wireless node other than the wireless node 1, the control unit 14 outputs a packet including data to the wireless communication unit 13.

  The control unit 14 determines the operation mode of the wireless node 1 and outputs the determined operation mode to the sampling interval determination unit 16.

  When the path control unit 15 receives the activation signal from the wakeup signal determination unit 18, the path control unit 15 shifts from the sleep state to the activation state. Further, the path control unit 15 performs an intermittent operation at a constant interval T in the same manner as the wireless communication unit 13 when the wakeup signal reception unit 17 and the wakeup signal determination unit 18 are stopped.

  When establishing a route in the wireless sensor network 10 or maintaining the established route, the route control unit 15 generates a control packet and outputs the generated control packet to the control unit 14. The route control unit 15 receives a control packet from the control unit 14 and establishes or maintains a route in the wireless sensor network 10 based on the received control packet. Then, the route control unit 15 holds route information indicating the established or maintained route. In addition, the path control unit 15 holds topology information indicating the topology indicating the arrangement state of the wireless nodes 1 to 7 in the wireless sensor network 10.

  The route control unit 15 detects the MAC address of the wireless node with reference to the route information in response to the request for the MAC address of the wireless node, and outputs the detected MAC address to the control unit 14.

  The path control unit 15 outputs path information and / or topology information to the sampling interval determination unit 16 in response to a request from the sampling interval determination unit 16.

  When the sampling interval determination unit 16 receives the activation signal from the wakeup signal determination unit 18, the sampling interval determination unit 16 shifts from the sleep state to the activation state. The sampling interval determination unit 16 performs an intermittent operation at a constant interval T in the same manner as the wireless communication unit 13 when the wakeup signal reception unit 17 and the wakeup signal determination unit 18 are stopped.

The sampling interval determination unit 16 receives the frame transmission number N from the wireless communication unit 13. The sampling interval determination unit 16 receives the operation mode from the control unit 14. The sampling interval determination unit 16 receives route information and / or topology information from the route control unit 15. Then, the sampling interval determination unit 16 determines a sampling interval T _{interval_min} corresponding to the number N of frame transmissions when the total power is minimized by a method described later. Then, the sampling interval determination unit 16 outputs the determined sampling interval T _{interval_min} to the wakeup signal reception unit 17 and the frame length correspondence table 19.

The sampling interval determination unit 16 adjusts the sampling interval T _{interval_min} by a method described later based on the path information. Then, the sampling interval determining unit 16 outputs the adjusted sampling interval T _{interval_min} to the wake-up signal receiving unit 17 and the frame length correspondence table 19.

  The wake-up signal receiving unit 17 and the wake-up signal determining unit 18 have a built-in timer, and shift to an activated state at regular intervals.

The wakeup signal receiving unit 17 receives the sampling interval T _{interval_min} from the sampling interval determining unit 16. Then, when detecting the reception power in the activated state, the wake-up signal receiving unit 17 receives the wake-up signal via the antenna 12, and detects the received signal of the received wake-up signal at the sampling interval T _{interval_min.} The frame length is detected based on the detected detection value. More specifically, the wake-up signal receiving unit 17 detects the frame length by counting the number of “1” in the detection value and multiplying the counted number by the sampling interval T _{interval — min} . Then, the wakeup signal reception unit 17 outputs the detected frame length to the wakeup signal determination unit 18.

The wake-up signal determination unit 18 holds the MAC address of the wireless node 1 in advance. The wakeup signal determination unit 18 receives a correspondence table corresponding to the sampling interval T _{interval_min} and indicating the relationship between the frame length and the data from the frame length correspondence table 19. Further, the wakeup signal determination unit 18 receives the frame length from the wakeup signal reception unit 17. Then, the wakeup signal determination unit 18 refers to the correspondence table and converts the frame length into data. Thereafter, the wakeup signal determination unit 18 determines whether or not the converted data matches the MAC address of the wireless node 1.

  When it is determined that the converted data matches the MAC address of the wireless node 1, the wakeup signal determination unit 18 generates an activation signal to generate the wireless communication unit 13, the control unit 14, the path control unit 15, and the sampling interval determination unit. 16 is output.

  On the other hand, when it is determined that the converted data does not match the MAC address of the wireless node 1, the wakeup signal determination unit 18 discards the converted data and outputs nothing.

  When a broadcast ID or multicast ID, which will be described later, is used, the wakeup signal determination unit 18 generates an activation signal and determines the wireless communication unit 13 when the converted data matches the broadcast ID or multicast ID. The data is output to the control unit 14, the path control unit 15, and the sampling interval determination unit 16.

  On the other hand, when it is determined that the converted data does not match the broadcast ID or the multicast ID, the wakeup signal determination unit 18 discards the converted data and outputs nothing.

  The wake-up signal receiving unit 17 and the wake-up signal determining unit 18 shift to the activated state at regular intervals and perform the above-described operation, and when the above-described operation ends, shift to the sleep state. That is, the wakeup signal reception unit 17 and the wakeup signal determination unit 18 perform an intermittent operation.

The frame length correspondence table 19 shifts to the activated state at regular intervals. The frame length correspondence table 19 holds a correspondence table indicating the relationship between the frame length and data in association with the sampling interval T _{interval_min} . When the frame length correspondence table 19 receives the sampling interval T _{interval_min} from the sampling interval determination unit 16, the frame length correspondence table 19 outputs a correspondence table corresponding to the received sampling interval T _{interval_min} to the control unit 14 and the wakeup signal determination unit 18.

  Note that each of the wireless nodes 2 to 7 illustrated in FIG. 1 has the same configuration as the wireless node 1 illustrated in FIG. 2.

  FIG. 3 is a configuration diagram of the control packet DIO. Referring to FIG. 3, control packet DIO includes a root address, a transmission destination, a transmission source, an ID storage unit, a Rank, and a DTSN.

  The address of the root is composed of the address of the wireless node 1 that is a sink. The transmission destination includes the address of the wireless node that is the transmission destination of the control packet DIO. The transmission source consists of the address of the wireless node that generated the control packet DIO. The ID storage unit consists of ESSID or PANID. Rank is 256 × n (n is a positive integer), and increases by “256” every time the number of hops from the wireless node 1 (= sink) increases by one. Rank represents that the smaller the numerical value, the closer to the sink (= wireless node 1). The DTSN is a positive integer, and increases by “1” every time one wireless node (= any one of the wireless nodes 1 to 7) generates a new control packet DIO. The DTSN is a criterion for determining whether or not to transmit the control packet DAO when each of the wireless nodes 1 to 7 receives the control packet DIO from the same wireless node. More specifically, when each of the wireless nodes 1 to 7 receives the control packet DIO from the same wireless node, the DTSN of the received control packet DIO increases from the DTSN of the previously received control packet DIO. If it is determined that the DTSN of the received control packet DIO is not greater than the DTSN of the previously received control packet DIO, the control packet DAO is not transmitted. An increase in DTSN corresponds to a change in the parent node.

  FIG. 4 is a configuration diagram of the control packet DAO. Referring to FIG. 4, control packet DAO includes a parent node address, a transmission source, and a DAOSsequence.

  The address of the parent node is present on the sink side by one hop from the wireless node that generates the control packet DAO, and includes the addresses of all the wireless nodes that can wirelessly communicate with the wireless node that generates the control packet DAO.

  The transmission source consists of the address of the wireless node that generates the control packet DAO. DAOSsequence is the sequence number of the control packet DAO. The initial value of DAOSsequence is “240”. DAOSsequence consists of an integer in the range of “0” to “255”. DAOSsequence is incremented each time a new control packet DAO is transmitted. When DAOSsequence is smaller than “128”, the maximum value is “127”, and when DAOSsequence is “128” or more, the maximum value is “255”. DAOSsequence becomes “0” after “255”, and then incremented by “1”.

  Whether or not the control packet DAO is new is determined by the following method. Here, the two DAOS sequences to be compared are A and B, respectively.

(I) When A is “128” to “255” and B is “0” to “127”. When (256 + B−A) is less than or equal to SEQUENCE_WINDOW (= 16), A is more than B small.

  If (256 + B−A) is greater than SEQUENCE_WINDOW (= 16), B is smaller than A.

  Then, it is determined that the control packet DAO having the larger one (A or B) is new.

(Ii) When both values are “127” or less, or “128” or more • When the absolute value of the difference between the two values is SEQUENCE_WINDOW (= 16) or less, the comparison result becomes the result as it is.

  When the absolute value of the difference between the two values is larger than SEQUENCE_WINDOW (= 16), it is determined that the two values A and B cannot be compared.

  In this case, it may be determined that the received control packet DAO is not the latest or the control packet DAO having the last received DAOS sequence is determined to be the latest.

  In the embodiment of the present invention, the following three wakeup IDs are defined.

(1) Unicast ID
(2) Multicast ID
(3) Broadcast ID

  The unicast ID is a wakeup ID indicating an arbitrary wireless node, and is an ID that can uniquely identify a wireless node such as a MAC address of each wireless node.

  The multicast ID is a wake-up ID for shifting a specific group of wireless nodes in the radio wave range to an activated state.

  The multicast ID includes a local multicast ID, a parent multicast ID, and a child multicast ID.

  The local multicast ID is a wake-up ID for shifting a wireless node of the same system represented by ESSID or PANID to an activated state.

  The Parent multicast ID is a wake-up ID indicating a wireless node group that can become a parent node when viewed from the wireless nodes 2 to 7 in the wireless sensor network 10.

  The child multicast ID is a wake-up ID indicating a wireless node group accommodated as a child node when viewed from the wireless nodes 1 to 7 in the wireless sensor network 10.

  The broadcast ID is a wake-up ID that can shift all wireless nodes in the radio wave range to the activated state, and is determined in advance in the wireless sensor network 10. The broadcast ID is set in advance in the route control unit 15 of the wireless nodes 1 to 7.

  In the embodiment of the present invention, the above-described unicast ID, multicast ID, and broadcast ID are used as the wake-up ID.

  A method by which the sampling interval determination unit 16 acquires the frame transmission number N will be described.

  The sampling interval determination unit 16 is configured to collect the sensor value (= data) collection period in the wireless sensor network 10, the transmission interval of the control frame (DIO, DAO), the tree size (total number of child nodes) obtained from the topology, and the communication quality of the link. The number N of frame transmissions is calculated based on

  Here, the total number of child nodes is located in a lower hierarchy than the wireless node that calculates the frame transmission number N, and is sent to the sink (= wireless node 1) via the wireless node that calculates the frame transmission number N. This is the total number of wireless nodes that can transmit the value. Also, it is assumed that the sensor values transmitted from all the child nodes reach the wireless node that calculates the frame transmission number N within the sensor value collection cycle. Further, it is assumed that only the control packet DIO is transmitted among the control packets DIO and DAO. This is because when the sensor value is collected in the sink (= wireless node 1), the topology of the wireless sensor network 10 is stable and the control packet DAO is not transmitted. Further, the communication quality of the link consists of the arrival rate of the radio frame to the radio node for calculating the number N of frame transmissions, or a magnification using the received signal strength RSSI. The arrival rate of the radio frame is calculated from the past communication status, and the number of radio frames actually reached the radio node for calculating the number N of frame transmissions is the number of radio frames transmitted from the source radio node. Calculated by dividing.

  When calculating the number N of frame transmissions using this method, the sampling interval determination unit 16, for example, collects the sensor values for 1 minute, transmits the control frames for 5 minutes, and the total number of 100 child nodes. Based on the 20% arrival rate, the frame transmission count N of (60 × 100 + 12) /0.2=30060 [pieces / h] is calculated.

  The reason why the total number of child nodes is used in this method is that the sensor values are collected in the sink (= wireless node 1) existing at the highest level.

  Also, when the received signal strength RSSI is used as the communication quality of the link, if RSSI ≧ −20 dBm, the magnification is 1 ×, and if −50 dBm ≦ RSSI <−20 dBm, the magnification is 2 ×, −80 dBm If RSSI <−50 dBm, the magnification is 5 times, and if RSSI <−80 dBm, the magnification is 10 times. Accordingly, the sampling interval determination unit 16 is based on, for example, a 1-minute sensor value collection period, a 5-minute control frame transmission interval, a total number of 100 child nodes, and −50 dBm ≦ RSSI <−20 dBm. Then, the frame transmission number N of (60 × 100 + 12) × 2 = 1,024 [pieces / h] is calculated.

  Thus, by calculating the number of frame transmissions using the communication quality of the link, the number N of frame transmissions is always the number of radio frames reached, and the accuracy of the number N of frame transmissions can be improved.

  When calculating the number N of frame transmissions using the above-described method, the sampling interval determination unit 16 receives the sensor value collection period from the control unit 14, receives the control frame transmission interval from the path control unit 15, and the path control unit. Based on the topology information received from 15, the tree size (total number of child nodes) is obtained.

  By calculating the frame transmission number N by the method described above, the frame transmission number N can be easily obtained.

  Further, the sampling interval determination unit 16 may receive the number N of frame transmissions actually measured by the wireless communication unit 13 from the wireless communication unit 13.

  By actually measuring the frame transmission number N, the frame transmission number N in accordance with the wireless sensor network 10 can be obtained.

Next, the sampling interval T when the total power amount that is the sum of the power consumption amount when transmitting the radio frame FR having the desired frame length and the power consumption amount when receiving the radio frame FR is minimized. A method for obtaining _{interval_min} will be described.

  FIG. 5 is a conceptual diagram of the sampling interval. Referring to FIG. 5, the wakeup signal receiving unit 17 of each of the wireless nodes 1 to 7 repeatedly performs detection during the detection time and then stops during the stop time. The sampling interval consists of the sum of the detection time and the stop time.

  Further, the power consumed during the stop time of the wakeup signal receiving unit 17 is the power consumption during the stop, and the power consumed during the detection time of the wakeup signal receiving unit 17 is the power consumption during the detection. is there. The power consumption during detection is larger than the power consumption during stoppage.

When the radio frame FR is received, the power consumption per hour in the wake-up signal receiving unit 17 is E _wr [Wh], the power during detection of the wake-up signal receiving unit 17 is P _active , and the wake-up signal is received. The total detection time per hour in the unit 17 is T _active , the resting power of the wake-up signal receiving unit 17 is P _sleep, and the total rest time per hour of the wake-up signal receiving unit 17 is T _sleep . .

Then, the power consumption amount E _wr is determined by the following equation.

E _wr (T _interval ) = P _active × T _active + P _sleep × T _sleep (1)

When calculating the power consumption E _wr using the equation (1), 1 hour is divided by the sampling interval T _interval to determine the number of detections and the number of stops. Then, the detection time is multiplied by the number of detections to obtain a total detection time T _active per hour, and the stop time is multiplied by the number of stops to obtain a total pause time T _sleep per hour. Then, by integrating the total detection time _{T active} obtains the power consumption _{P active} × _{T active} in the power _{P active,} obtaining the power consumption _{P sleep} × _{T sleep} by integrating the total downtime _{T sleep} power _{P sleep.} Finally, the power consumption amount P _active × T _active and the power consumption amount P _sleep × T _sleep are added to obtain the power consumption amount E _wr .

Further, a power consumption amount required to transmit one radio frame FR in the radio communication unit 13 when transmitting the radio frame FR is E _ws [W / frame], and a frame that can be detected at the sampling interval T _interval. The frame transmission time obtained from the length is T _frame , the transmission power of the wireless communication unit 13 is P _transmit , the reception power of the wireless communication unit 13 is _{Pre receive} , and the carrier sense time is T _cs .

Then, the power consumption amount E _ws is determined by the following equation.

E _ws (T _interval ) = _{Pre receive} × T _cs + P _transmit × T _frame (2)

When calculating the power consumption E _ws using equation (2), the frame length is divided by the sampling interval T _interval to obtain the number of sampling times, and the obtained sampling number is multiplied by the sampling interval T _interval to obtain the frame transmission time T _frame. Ask for. Then, a power consumption _{P transmit} × _{T frame} by multiplying the frame transmission time _{T frame} power _{P transmit,} determining the power consumption _{P receive} × _{T cs} by multiplying the carrier sense time _{T cs} in power _{P receive.} Finally, determine the power consumption _{P transmit} × _{T frame} and the power consumption _{P receive} × _{T cs} and power consumption _{E ws} by adding. Here, the amount of power consumption _Preceive × T _cs is added because carrier sense is performed when a radio frame is transmitted, and the radio frame is transmitted when the radio communication space is open.

Note that the power consumption amount E _ws (T _interval ) may be obtained by adding the power consumption amount waiting for ACK (P _active × T _wait ).

The total electric energy E (T _interval ) is determined by the following equation.

E (T _interval ) = E _wr (T _interval ) + E _ws (T _interval ) × N (3)

  FIG. 6 is a diagram illustrating the relationship between the total electric energy and the sampling interval. In FIG. 6, the vertical axis represents the total power amount, and the horizontal axis represents the sampling interval. The total electric energy is obtained using the above-described formulas (1) to (3).

  The curves k1 to k8 indicate that the number of frame transmissions per hour N [pieces / h] is 0.01 [pieces / h], 0.1 [pieces / h], 1 [pieces / h], 10 respectively. The relationship between the total electric energy and the sampling interval when [piece / h], 100 [piece / h], 1000 [piece / h], 10000 [piece / h], and 100,000 [piece / h] are shown.

  Note that the relationship between the total power amount and the sampling interval shown in FIG. 6 is that the longer the sampling interval when detecting the frame length, the longer the frame length and the sampling interval between the frame length and the sampling interval. This is a relationship between the total electric energy and the sampling interval when it is assumed that there is a relationship in which the frame length becomes shorter as the length becomes shorter.

Also, the relationship between the total power amount and the sampling interval shown in FIG. 6 is that the power P _active when the wireless communication unit 13 is operating is 30 [mWh], and the power P _sleep when the wireless communication unit 13 is stopped is 0. 5 is a [mWh], power _{P transmit} required for transmission in a wireless communication unit 13 is 25 [mWh], power _{P receive} necessary for reception in the wireless communication unit 13 is the 20 [mWh], the wakeup signal receiver The relationship between the total power amount and the sampling interval when the power P _active during operation 17 is 50 [mWh] and the power P _sleep when the wake-up signal receiving unit 17 is stopped is 0.002 [mWh]. is there.

Referring to FIG. 6, there is a sampling interval T _{interval_min} that minimizes the total power amount in each frame transmission number N. Further, the sampling interval T _{interval_min} at which the total power is minimized becomes shorter as the number N of frame transmissions increases (see curves k1 to k8).

  Further, when the frame transmission number N is any one of 10 [pieces / h], 100 [pieces / h], 1000 [pieces / h], 10000 [pieces / h], and 100,000 [pieces / h], the total power As the sampling interval increases, the amount decreases to a minimum value and then increases (see curves k4 to k8). The relationship in which the total power amount increases as the sampling interval increases after the total power amount reaches the minimum value has been found for the first time in the embodiment of the present invention.

After drawing the curves k1 to k8, at each frame transmission number N, the sampling interval T _interval — min (= points A1, A2, A3, A4, A5, A6 where the total power amount is minimum) when the total power amount is minimum. (Sampling interval).

FIG. 7 is a diagram illustrating the relationship between the sampling interval T _{interval — min} and the number N of frame transmissions.

In FIG. 7, the vertical axis represents the sampling interval T _{interval — min} , and the horizontal axis represents the frame transmission number N.

When the sampling interval T _{interval_min} when the total power amount is minimized in each frame transmission number N, the relationship between the frame transmission number N and the sampling interval T _{interval_min} is plotted to obtain an approximate expression. This approximate expression is represented by the following expression, for example.

T _{interval_min} = αN ^β (4)
In Expression (4), α and β are constants determined by the power consumption of the wireless communication unit 13, the power consumption of the wakeup signal receiving unit 17, and the number of frames constituting the wakeup signal.

  The approximate expression represented by Expression (4) is a curve k9 or a straight line k10 in the logarithmic graph.

When the constant α is 14482 and the constant β is −0.482, the approximate expression is represented by T _{interval_min} = 14482N ^−0.482 .

Therefore, if this approximate expression is set in the sampling interval determination unit 16 in advance, the sampling interval determination unit 16 determines the frame transmission number N calculated by itself or based on the frame transmission number N received from the wireless communication unit 13. Based on the above, the sampling interval T _{interval —} min when the total power E (T _interval ) is minimized can be obtained.

In the embodiment of the present invention, the sampling interval determination unit 16 may hold a correspondence table indicating the relationship between the number N of frame transmissions and the sampling interval T _{interval_min} instead of the above-described approximate expression.

FIG. 8 is a diagram showing a correspondence table showing the relationship between the number of frame transmissions and the sampling interval T _{interval_min} .

Referring to FIG. 8, correspondence table TBL1 includes the number of frame transmissions and a sampling interval T _{interval_min} . The number of frame transmissions and the sampling interval T _{interval — min} are associated with each other.

When the number N of frame transmissions is ≧ 2723 [pieces / h], the sampling interval T _{interval — min} is 160 [μsec]. When the frame transmission number N is 646 [pieces / h] ≦ N <2723 [pieces / h], the sampling interval T _{interval_min} is 320 [μsec]. When the number N of frame transmissions is 153 [pieces / h] ≦ N <646 [pieces / h], the sampling interval T _{interval_min} is 640 [μsec]. When the frame transmission number N is 36 [pieces / h] ≦ N <153 [pieces / h], the sampling interval T _{interval — min} is 1280 [μsec]. When the frame transmission number N is 9 [pieces / h] ≦ N <36 [pieces / h], the sampling interval T _{interval — min} is 2560 [μsec]. When the frame transmission number N is 2 [pieces / h] ≦ N <9 [pieces / h], the sampling interval T _{interval — min} is 5120 [μsec]. When the frame transmission number N is N <2 [pieces / h], the sampling interval T _{interval — min} is 10240 [μsec].

Thus, the sampling interval T _{interval — min} is doubled every time the range of the frame transmission number N decreases by one range. This is due to the following reason. One reason is to simplify the circuit configuration of the wakeup signal receiving unit 17, and another reason is to suppress the type of the sampling interval T _{interval_min} . Although it is necessary to hold a correspondence table between the sampling interval T _{interval_min} of each wireless node and the corresponding frame length and data, if it is increased linearly in units of 160 [μs], 64 in the range up to 10240 [μs]. Sampling intervals T _{interval — min} are required. As a result, if a correspondence table is also stored, a large amount of memory is required. However, as described above, every time the range of the frame transmission number N decreases by one range, the sampling interval T _{interval_min} is doubled, so that the number of memories can be reduced to seven and the memory can be saved.

Upon receiving the frame transmission number N from the wireless communication unit 13, the sampling interval determination unit 16 refers to the correspondence table TBL1, detects the sampling interval T _{interval_min} corresponding to the received frame transmission number N, and detects the detected sampling The interval T _{interval —} min is determined as a sampling interval when the total power is minimized.

In the correspondence table TBL1, the sampling interval T _{interval_min} becomes longer every integral multiple of 160 [μsec] as the number N of frame transmissions decreases, but the integral multiple of 160 [μsec] is just an example. Therefore, in the correspondence table TBL1, the sampling interval T _{interval_min} may be increased for each unit other than an integral multiple of 160 [μsec] as the frame transmission number N decreases.

The sampling interval determination unit 16 may determine the sampling interval T _{interval_min} based on the number N of frame transmissions every time a wakeup signal is transmitted. For example, the frame transmission may be performed periodically such as one month. The sampling interval T _{interval_min} may be determined based on the number N.

By determining the sampling interval T _{interval_min} based on the number N of frame transmissions every time a wakeup signal is transmitted or periodically, even if the number N of frame transmissions changes, the number N of frame transmissions corresponding to the changed number Thus, the sampling interval T _{interval — min} can be determined.

As shown in the correspondence table TBL1, the following effect can be obtained by determining the sampling interval T _{interval —} min when the total power amount is minimized to be increased every integral multiple of 160 [μsec] as the number N of frame transmissions decreases. Is obtained.

When the sampling interval is calculated using an approximate expression, the sampling interval is calculated in the order of μsec. However, as shown in the correspondence table TBL1, it is more preferable to determine the sampling interval T _{interval_min in} units of 160 [μsec]. The circuit of the unit 17 can be simplified. That is, when the sampling interval T _{interval_min} is calculated in the order of μsec, the wakeup signal receiving unit 17 needs to determine the sampling timing with the accuracy of the order of μsec and perform sampling, so the circuit configuration of the wakeup signal receiving unit 17 Becomes complicated. However, when the sampling interval T _{interval_min} is determined in units of 160 [μsec], the memory can be reduced as described above, so that the circuit configuration of the wake-up signal receiving unit 17 can be simplified.

  As a result, the frame length can be easily shared among a plurality of wireless nodes while suppressing the memory usage.

Also, by determining the sampling interval T _{interval_min} using the correspondence table TBL1, the sampling interval T _{interval_min} can be easily determined.

The range of the frame transmission number N in the correspondence table TBL1 is an example. Therefore, in the embodiment of the present invention, a range of the frame transmission number N different from the range of the frame transmission number N shown in FIG. 8 may be associated with the sampling interval T _{interval_min} .

FIG. 9 is a diagram illustrating the relationship between the sampling interval T _{interval_min} and the average frame length.

Referring to FIG. 9, correspondence table TBL2 includes a sampling interval T _{interval_min} and an average frame length. The sampling interval T _{interval_min} and the average frame length are associated with each other.

The average frame length 2620 [.mu.sec] is associated with the sampling interval _{T Interval_min} of 10 [.mu.sec], the average frame length of 3000 [.mu.sec] is associated with the sampling interval _{T Interval_min} of 20 [μsec], 3760 [ the average frame length .mu.sec] is associated with the sampling interval _{T Interval_min} of 40 [.mu.sec], the average frame length of 5280 [.mu.sec] is associated with a sampling interval _{T Interval_min} of 80 [μsec].

The average frame length 8320 [.mu.sec] is associated with the sampling interval _{T Interval_min} of 160 [.mu.sec], the average frame length of 14400 [.mu.sec] is associated with the sampling interval _{T Interval_min} of 320 [.mu.sec], the average frame length 26560 [.mu.sec] is associated with the sampling interval _{T Interval_min} of 640 [.mu.sec], the average frame length of 50880 [μsec] is associated with a sampling interval _{T Interval_min} of 1280 [μsec].

Furthermore, the average frame length 99520 [.mu.sec] is associated with the sampling interval _{T Interval_min} of 2560 [.mu.sec], the average frame length of 196800 [μsec] is associated with the sampling interval _{T Interval_min} of 5120 [.mu.sec], the average frame length 391360 [μsec] is associated with the sampling interval _{T Interval_min} of 10240 [.mu.sec], the average frame length of 780.48 thousand [.mu.sec] is associated with a sampling interval _{T Interval_min} of 20480 [μsec].

Thus, the average frame length becomes longer as the sampling interval T _{interval_min} becomes longer, and becomes shorter as the sampling interval T _{interval_min} becomes shorter. The difference between two adjacent average frame lengths is 380 [μsec], 760 [μsec], 1520 [μsec], 3040 [μsec], 6080 [μsec], and 12160 [12160 [12] in the direction in which the sampling interval T _{interval — min} becomes longer. μsec], 24320 [μsec], 48640 [μsec], 97280 [μsec], 194560 [μsec], and 389120 [μsec]. That is, the difference between two adjacent average frame lengths increases in accordance with 380 × 2 ^m−1 (m is a positive integer) in the direction in which the sampling interval T _{interval — min} increases.

This is to prevent a plurality of frame lengths assigned to a plurality of wake-up IDs of a plurality of wireless nodes based on the average frame length from overlapping between a plurality of sampling intervals T _{interval — min} .

Note that the difference between two adjacent average frame lengths may be increased according to an expression other than 380 × 2 ^m−1 in the direction in which the sampling interval T _{interval — min} is increased. In general, the difference between two adjacent average frame lengths is that a plurality of frame lengths assigned to a plurality of wake-up IDs of a plurality of wireless nodes based on the average frame length are equal to a plurality of sampling intervals T _{interval_min} . If they do not overlap, the sampling interval T _{interval_min} may be increased in the direction in which the _interval increases.

The specific values of the sampling interval T _{interval_min} and the average frame length in the correspondence table TBL2 are examples. Therefore, in the embodiment of the present invention, the specific value different from the specific value of the sampling interval T _{interval_min} shown in FIG. 9 and the specific value different from the specific value of the average frame length shown in FIG. The correspondence table TBL2 may be created.

FIG. 10 is a diagram illustrating the relationship between the frame length associated with the sampling interval T _{interval_min} and the data.

Referring to FIG. 10, correspondence table TBL3 includes a sampling interval T _{interval_min} , a frame length, and data. The frame length and data are associated with each other. The correspondence between the frame length and the data is associated with the sampling interval T _{interval_min} .

When the sampling interval T _{interval_min} is 160 [μsec], the data of 0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xA, 0xB, 0xC, 0xD, 0xE, 0xF are respectively 7.04, 7.20, 7.36, 7.52, 7.68, 7.84, 8.00, 8.16, 8.32, 8.48, 8.64, 8.80, 8. Corresponding to frame lengths of 96, 9.12, 9.28, and 9.44 [msec]. Each of 0x0 to 0xF consists of 4 bits.

The frame length of 7.04, 7.20,..., 9.44 [μsec] has an average frame length of 8.32 [msec] associated with a sampling interval T _{interval_min} of 160 [μsec], 8 Frame length obtained by adding or subtracting an average frame length of .32 [msec] in units of 0.16 [msec] (= sampling interval T _{interval —} min of 160 [μsec]).

Note that a plurality of frame lengths are generated by adding or subtracting an average frame length of 8.32 [msec] in units of 0.16 [msec] (= sampling interval T _{interval —} min of 160 [μsec]). This is because the interval T _{interval_min} is 160 [μsec], so that two different frame lengths can be identified.

When the sampling interval T _{interval_min} is 320 [μsec], the data of 0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xA, 0xB, 0xC, 0xD, 0xE, 0xF are respectively 11.84, 12.16, 12.48, 12.80, 13.12, 13.44, 13.76, 14.08, 14.40, 14.72, 15.04, 15.36, 15. 68, 16.00, 16.32, and 16.64 [msec] frame lengths.

The frame length of 11.84, 12.16,..., 16.64 [μsec] has an average frame length of 14.40 [msec] associated with a sampling interval T _{interval_min} of 320 [μsec], 14 Frame length obtained by adding or subtracting an average frame length of .40 [msec] in units of 0.32 [msec] (= sampling interval T _{interval —} min of 320 [μsec]).

Note that the average frame length of 14.40 [msec] is added or subtracted in units of 0.32 [msec] (= sampling interval T _{interval —} min of 320 [μsec]) to generate a plurality of frame lengths. This is because the interval T _{interval_min} is 320 [μsec], so that two different frame lengths can be identified.

When the sampling interval T _{interval_min} is 640 [μsec], the data of 0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xA, 0xB, 0xC, 0xD, 0xE, 0xF are respectively 21.44, 22.08, 22.72, 23.36, 24.00, 24.64, 25.28, 25.92, 26.56, 27.20, 27.84, 28.48, 29. It is associated with a frame length of 12, 29.76, 30.40, 31.04 [msec].

The frame length of 21.44, 22.08,..., 31.04 [μsec] is an average frame length of 26.56 [msec] associated with a sampling interval T _{interval_min} of 640 [μsec]; Frame length obtained by adding or subtracting an average frame length of .56 [msec] in units of 0.64 [msec] (= sampling interval T _{interval —} min of 640 [μsec]).

Note that the average frame length of 26.56 [msec] is added or subtracted in units of 0.64 [msec] (= 640 [μsec] sampling interval T _{interval —} min) to generate a plurality of frame lengths by sampling. This is because the interval T _{interval_min} is 640 [μsec], so that two different frame lengths can be identified.

When the sampling interval T _{interval_min} is 1280 [μsec], the data of 0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xA, 0xB, 0xC, 0xD, 0xE, 0xF are respectively 40.64, 41.92, 43.20, 44.48, 45.76, 47.04, 48.32, 49.60, 50.88, 52.16, 53.44, 54.72, 56. It is associated with a frame length of 00, 57.28, 58.56, 59.84 [msec].

40.64, 41.92,..., 59.84 [μsec] has an average frame length of 50.88 [msec] associated with a sampling interval T _{interval —} min of 1280 [μsec], and 50 The frame length obtained by adding or subtracting the average frame length of .88 [msec] in units of 1.28 [msec] (= sampling interval T _{interval —} min of 1280 [μsec]).

Note that a plurality of frame lengths are generated by adding or subtracting an average frame length of 50.88 [msec] in units of 1.28 [msec] (= 1280 [μsec] sampling interval T _{interval —} min). This is because the interval T _{interval — min} is 1280 [μsec], so that two different frame lengths can be identified.

When the sampling interval T _{interval_min} is 2560 [μsec], the data of 0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xA, 0xB, 0xC, 0xD, 0xE, 0xF are respectively 79.04, 81.60, 84.16, 86.72, 89.28, 91.84, 94.40, 96.96, 99.52, 102.08, 104.64, 107.20, 109. 76, 112.32, 114.88, and 117.44 [msec].

The frame length of 79.04, 81.60,..., 117.44 [μsec] has an average frame length of 99.52 [msec] associated with the sampling interval T _{interval_min} of 2560 [μsec], and 99 The frame length obtained by adding or subtracting the average frame length of 0.52 [msec] in units of 2.56 [msec] (= 2560 [μsec] sampling interval T _{interval — min} ).

Note that a plurality of frame lengths are generated by adding or subtracting an average frame length of 99.52 [msec] in units of 2.56 [msec] (= 2560 [μsec] sampling interval T _{interval — min} ). This is because the interval T _{interval_min} is 2560 [μsec], so that two different frame lengths can be identified.

In this way, 7.04, 7.20..., 9.8 corresponding to the sampling intervals T _{interval_min} of 160 [μsec], 320 [μsec], 640 [μsec], 1280 [μsec], and 2560 [μsec], respectively. 44 [msec], 11.84, 12.16, ..., 16.64 [msec], 21.44, 22.08, ..., 31.04 [msec], 40.64, 41.92 ,..., 59.84 [msec], 79.04, 81.60,..., 117.44 [msec] have frame lengths of 160 [μsec], 320 [μsec], 640 [μsec], 1280 [μsec], 2560 [μsec ] corresponding respectively to the sampling interval _{T Interval_min} of 8.32 [μsec], 14.40 [μsec ] 26.56 [μsec], 50.88 [μsec ], obtained by adding or subtracting the average frame length 99.52 [.mu.sec] in units of the sampling interval _{T interval_min.}

  The frame length correspondence table 19 of each of the wireless nodes 1 to 7 holds a correspondence table TBL3.

FIG. 11 is a conceptual diagram of radio frame sampling. Referring to FIG. 11, the received signal of radio frame FR is envelope-detected at a sampling interval T _{interval_min} of 160 [μsec]. Then, the number of detection values “1” detected by the envelope detection is counted, and the frame length is detected by multiplying the number of “1” s by a sampling interval T _{interval —} min of 160 [μsec].

  The radio frame FR1 has a frame length of L1, and the radio frame FR2 has a frame length of L2. The frame length L1 and the frame length L2 are composed of two adjacent frame lengths among a plurality of frame lengths of 7.04, 7.20,..., 9.44 [msec] in the correspondence table TBL3.

As described above, the frame lengths L1 and L2 are detected by detecting the received signals of the radio frames FR1 and FR2 at the sampling interval T _{interval_min} of 160 [μsec], so that the received signals of the radio frame FR2 are 160 [μsec]. The number of detection values “1” obtained by envelope detection at the sampling interval T _{interval_min} of] is obtained by envelope detection of the received signal of the radio frame FR1 at the sampling interval T _{interval_min} of 160 [μsec]. The number of detection values is “1” larger than the number of “1”.

As a result, the frame length L2 is longer than the frame length L1 by 160 [μsec] (= sampling interval T _{interval — min} ).

  Therefore, the two frame lengths L1 and L2 can be identified.

Similarly, when a sampling interval T _{interval_min} other than 160 [μsec] is used, two adjacent frame lengths can be identified.

  FIG. 12 is a diagram for explaining a method of transmitting a wakeup signal.

  In the embodiment of the present invention, the wake-up ID is represented by a frame length. More specifically, the wakeup ID is represented by WuID1 to WuID4. Therefore, the wake-up signal includes four radio frames having four frame lengths respectively corresponding to the bit values of WuID1 to WuID4.

Referring to FIG. 12, the receiving node determines sampling interval T _{interval_min} by the above-described method, and includes the determined sampling interval T _{interval_min} (for example, 640 μsec) in control packet DIO and transmits the packet to the transmitting node.

The wireless communication unit 13 of the transmission node receives the control packet DIO, demodulates the received control packet DIO, and outputs it to the control unit 14. Then, the control unit 14 of the transmission node receives the control packet DIO from the wireless communication unit 13, extracts the sampling interval T _{interval_min} (= 640 μsec) from the received control packet DIO, and holds it.

  Thereafter, when the receiving node shifts the receiving node from the sleep state to the active state, the transmitting node control unit 14 receives the MAC address of the receiving node from the path control unit 15 and calculates a hash value of the received MAC address. In this case, it is assumed that the hash value is composed of 16 bits [0000000000000001], for example.

Then, the control unit 14 of the transmission node refers to the correspondence table TBL3 stored in the frame length correspondence table 19, and 21.44, 22.08,... Corresponding to the sampling interval T _{interval_min} of 640 [μsec]. , 31.04 [msec], a frame length of 22.08 [msec] corresponding to 0x1 (= 0000), a frame length of 21.44 [msec] corresponding to 0x0 (= 0000), and 0x0 ( The frame length of 21.44 [msec] corresponding to = 0000) and the frame length of 21.44 [msec] corresponding to 0x0 (= 0000) are detected.

  Thereafter, the control unit 14 of the transmission node transmits a radio frame FR1 having a frame length of 22.08 [msec], a radio frame FR2 having a frame length of 21.44 [msec], and a frame of 21.44 [msec]. A radio frame FR3 having a length and a radio frame FR4 having a frame length of 21.44 [msec] are generated. Then, the control unit 14 of the transmission node outputs a wakeup signal composed of the radio frames FR1 to FR4 to the radio communication unit 13.

  The wireless communication unit 13 of the transmission node receives the wakeup signal composed of the radio frames FR1 to FR4 from the control unit 14, and modulates the received wakeup signal (= radio frames FR1 to FR4). Then, the wireless communication unit 13 of the transmission node transmits the modulated wakeup signal via the antenna 11. In this case, the radio communication unit 13 of the transmission node sequentially transmits the modulated radio frames FR1 to FR4.

The wake-up signal receiving unit 17 of the receiving node receives the wake-up signal via the antenna 12 and obtains a bit string by detecting the received signal of the received wake-up signal at the sampling interval T _{interval_min} (= 640 μsec). .

  Thereafter, the wakeup signal receiving unit 17 of the receiving node counts the number of “1” from the beginning of the bit string, stops the counting when the bit value of the bit string becomes “0”, and counts when the counting is stopped. The value is set to the number N1 of “1” and the count value is reset. Thereafter, when the bit value of the bit string becomes “1”, the wake-up signal receiving unit 17 of the receiving node counts the number of “1” until the bit value of the bit string becomes “0”, and the bit value of the bit string becomes “ When it reaches 0, the count is stopped, the count value when the count is stopped is set to the number N2 of “1”, and the count value is reset.

  The wake-up signal receiving unit 17 of the receiving node repeats this operation until the end of the bit string to obtain four “1” numbers N1 to N4.

The wakeup signal receiver 17 of the receiving node multiplies the number N1 by the sampling interval T _{interval_min} (= 640 μsec) to obtain a frame length of 22.08 msec, and obtains the sampling interval T _{interval_min} (= 640 μsec) for the number N2. Multiplying to obtain a frame length of 21.44 msec, multiplying the number N3 by the sampling interval T _{interval_min} (= 640 μsec) to obtain a frame length of 21.44 msec, and obtaining the number N4 of the sampling interval T _{interval_min} (= 640 μsec) Multiply to obtain a frame length of 21.44 msec.

  Then, the wakeup signal reception unit 17 of the receiving node outputs the frame length of 22.08 msec, the frame length of 21.44 msec, the frame length of 21.44 msec, and the frame length of 21.44 msec to the wakeup signal determination unit 18 To do.

  The wakeup signal determination unit 18 of the receiving node receives the frame length of 22.08 msec, the frame length of 21.44 msec, the frame length of 21.44 msec, and the frame length of 21.44 msec from the wakeup signal reception unit 17. Also, the wakeup signal determination unit 18 of the receiving node receives the correspondence table TBL3 from the frame length correspondence table 19.

Then, the wakeup signal determination unit 18 of the receiving node refers to the correspondence table TBL3 to detect 0x1 corresponding to the sampling interval T _{interval_min} (= 640 μsec) and the frame length of 22.08 msec, and the sampling interval T _{interval_min} (= 640 μsec) and 21.44 msec corresponding to a frame length of 0x0 are detected, and sampling interval T _{interval_min} (= 640 μsec) and 0x0 corresponding to a frame length of 21.44 msec are detected, and sampling interval T _{interval_min} (= 640 μsec) and 21 are detected. Detect 0x0 corresponding to a frame length of .44 msec. After that, the wakeup signal determination unit 18 of the receiving node obtains a wakeup ID composed of 0x00x00x00x1 (= [0000000000000001]) by arranging 0x1, 0x0, 0x0, 0x0 in a line.

  Then, the wakeup signal determination unit 18 of the receiving node determines whether or not the wakeup ID of [0000000000000001] matches the MAC address of the receiving node.

  When the wakeup signal determination unit 18 of the receiving node determines that the wakeup ID of [0000000000000001] matches the MAC address of the receiving node, the wakeup signal determination unit 18 generates an activation signal to generate the wireless communication unit 13, the control unit 14, and the path control unit 15. And output to the sampling interval determination unit 16. As a result, the receiving node shifts from the sleep state to the activated state.

  On the other hand, when the wakeup signal determination unit 18 of the receiving node determines that the wakeup ID of [0000000000000001] does not match the MAC address of the receiving node, the wakeup ID of [0000000000000001] is discarded and nothing is output.

In this way, the transmitting node generates and transmits a wakeup signal from a plurality of radio frames having a frame length determined corresponding to the sampling interval T _{interval_min} determined so that the total power amount is minimized, The receiving node performs reception processing of the wake-up signal at the sampling interval T _{interval_min} and shifts to the activated state.

  Therefore, power consumption due to transmission / reception of the wakeup signal can be reduced.

  In the embodiment of the present invention, when a unicast ID is used, in the unicast ID, WuID1 is fixed to 0x1, and WuID2 to WuID4 are obtained from the MAC address of the wireless node to be activated. Consists of a bit hash value.

  When a broadcast ID is used, WuID1 is fixed to 0xF in the broadcast ID, and WuID2 to WuID4 are each composed of a 12-bit hash value obtained from the MAC address of the activation source wireless node.

  Further, when the local multicast ID of the multicast ID is used, in the local multicast ID of the multicast ID, WuID1 is fixed to 0x2, and WuID2 to WuID4 are made up of identifiers indicating the same system such as PANID or RPL instance ID. If the PANID or RPL instance ID is not 12 bits, the hash value of the PANID or RPL instance ID is calculated to be 12 bits.

  Further, when the Parent multicast ID of the multicast ID is used, in the Parent multicast ID of the multicast ID, WuID1 is fixed to 0x3, and WuID2 to WuID4 are 12-bits obtained from the MAC address of the activation source wireless node. Consists of a hash value.

  Furthermore, when the child multicast ID of the multicast ID is used, in the child multicast ID of the multicast ID, WuID1 is fixed to 0x4, and WuID2 to WuID4 are 12-bits obtained from the MAC address of the activation source wireless node. Consists of a hash value.

  FIG. 13 is a configuration diagram of the routing table RT held by the route control unit 15 shown in FIG. Referring to FIG. 13, routing table RT includes a transmission destination, the next radio node, the number of hops, and Rank. The transmission destination, the next wireless node, the number of hops, and Rank are associated with each other.

  The transmission destination includes a wake-up signal, control packets DIO and DAO, and a MAC address MACadd of a wireless node that receives the packet. The next wireless node includes the MAC address MACadd_NB of the wireless node adjacent on the transmission side to the wireless node holding the routing table RT on the route to the transmission destination.

  The number of hops consists of the number of hops h from the wireless node holding the routing table RT to the destination wireless node. Rank indicates the degree of proximity of the transmission destination (wireless node) to the sink (= wireless node), and consists of r = 256 × j (= 256, 512, 768,...).

  FIG. 14 is a diagram illustrating an arrangement state of the wireless nodes 1 to 3 in the wireless sensor network 10 illustrated in FIG.

  Referring to FIG. 14, radio nodes 1 to 3 have radio wave ranges REG1 to REG3, respectively. The wireless node 1 exists in a region where the two radio wave ranges REG1 and REG2 overlap. The wireless node 2 exists in an area where the three radio wave ranges REG1 to REG3 overlap. The wireless node 3 exists in a region where the two radio wave ranges REG2 and REG3 overlap.

  In this manner, in the state where there is a wireless node whose own radio wave range does not reach the sink (= wireless node 1), a path from each wireless node 2 to 7 to the sink (= wireless node 1) is constructed.

A route construction method will be described. FIG. 15 is a flowchart for explaining an operation when a route is constructed. Referring to FIG. 15, when the operation of constructing a route is started, control unit 14 of wireless node 1 (= sink) receives a broadcast ID from route control unit 15 as a wakeup ID of the wakeup signal. Further, the control unit 14 receives the correspondence table TBL3 from the frame length correspondence table 19, and receives the sampling interval T _{interval_min} (= 1280 μsec) from the sampling interval determination unit 16.

Then, the control unit 14 of the wireless node 1 calculates the hash value of the MAC address of the wireless node 2, 12-bit hash value _{a 1 a 2 a 3 a 4} a 5 a 6 a 7 a 8 a 9 a 10 a ₁₁ a ₁₂ is acquired. Table Consequently, the broadcast ID _{as a 9 a 10 a 11 a 12} = 0x2, a 5 a 6 a 7 a 8 = 0x0, a 1 a 2 a 3 a 4 = 0x3, 0xF, by 0x2,0x0,0x3 Is done.

Thereafter, the control unit 14 of the wireless node 1 refers to the correspondence table TBL3, and a plurality of 40.64, 41.92,..., 59.84 [msec] corresponding to the sampling interval T _interval — min (= 1280 μsec). Among them, a frame length FL1 of 59.84 [msec] corresponding to 0xF, a frame length FL2 of 43.20 [msec] corresponding to 0x2, and a frame length FL3 of 40.64 [msec] corresponding to 0x0, , A frame length FL4 of 44.48 [msec] corresponding to 0x3 is detected.

  Then, the control unit 14 of the wireless node 1 generates four wireless frames FR1 to FR4 having four frame lengths FL1 to FL4, respectively, and outputs them to the wireless communication unit 13.

  The radio communication unit 13 of the radio node 1 receives the four radio frames FR1 to FR4 from the control unit 14, modulates the received wakeup signal WuS including the four radio frames FR1 to FR4, and modulates the wake-up signal. The up signal WuS is broadcast via the antenna 11 (step S1).

  The wake-up signal receiving unit 17 of the wireless node 2 shifts to an activated state at regular intervals and confirms the presence or absence of received power via the antenna 12. Then, when detecting the received power, the wakeup signal receiving unit 17 of the wireless node 2 receives the wakeup signal WuS via the antenna 12, and based on the received radio wave of the received wakeup signal by the method described above. Four frame lengths FL1 to FL4 are detected. Then, the wakeup signal reception unit 17 of the wireless node 1 outputs the four frame lengths FL1 to FL4 to the wakeup signal determination unit 18.

  The wakeup signal determination unit 18 of the wireless node 2 receives the correspondence table TBL3 from the frame length correspondence table 19. When the wakeup signal determination unit 18 of the wireless node 2 receives the four frame lengths FL1 to FL4 from the wakeup signal reception unit 17, the four frame lengths are referred to by the method described above with reference to the correspondence table TBL3. FL1 to FL4 are converted into bit values 0xF, 0x2, 0x0, and 0x3, respectively, and a broadcast ID is acquired. Then, the wakeup signal determination unit 18 of the wireless node 2 determines that the broadcast ID matches the previously held wakeup ID (= broadcast ID), generates an activation signal, generates the wireless communication unit 13, the control unit 14, The data is output to the path control unit 15 and the sampling interval determination unit 16. Thereby, the wireless node 2 shifts from the sleep state to the activated state (step S2).

  Thereafter, the control unit 14 of the wireless node 2 generates an activation notification including the MAC address of the wireless node 2 and outputs the generated activation notification to the wireless communication unit 13. The wireless communication unit 13 of the wireless node 2 receives the activation notification from the control unit 14, modulates the received activation notification, and broadcasts the modulated activation notification via the antenna 11.

  The wireless communication unit 13 of the wireless node 1 receives the activation notification via the antenna 11. Then, the control unit 14 of the wireless node 1 receives an activation notification from the wireless communication unit 13.

  When receiving the activation notification, the control unit 14 of the wireless node 1 detects that the wireless node 2 has shifted to the activated state.

  The path controller 15 of the wireless node 1 then sends the root address consisting of the MAC address MACadd1 of the wireless node 1 (= sink), the transmission destination consisting of the MAC address MACadd2 of the wireless node 2, and the wireless node 1 (= sink). A DIO1 = [MACadd1 / MACadd2 / MACadd1 / ESSID / 256/1] including a transmission source consisting of the MAC address MACadd1, an ID storage unit consisting of ESSID or PANID, a Rank consisting of 256, and a DTSN consisting of 1 is generated. Then, the generated DIO1 = [MACadd1 / MACadd2 / MACadd1 / ESSID / 256/1] is output to the control unit 14.

  The control unit 14 of the wireless node 1 receives DIO1 = [MACadd1 / MACadd2 / MACadd1 / ESSID / 256/1] from the path control unit 15 and receives the received DIO1 = [MACadd1 / MACadd2 / MACadd1 / ESSID / 256/1]. Is output to the wireless communication unit 13.

  The wireless communication unit 13 of the wireless node 1 receives DIO1 = [MACadd1 / MACadd2 / MACadd1 / ESSID / 256/1] from the control unit 14 and receives the received DIO1 = [MACadd1 / MACadd2 / MACadd1 / ESSID / 256/1]. Modulate. Then, the wireless communication unit 13 of the wireless node 1 transmits the modulated DIO1 = [MACadd1 / MACadd2 / MACadd1 / ESSID / 256/1] via the antenna 11 (step S3). Thereafter, the wireless node 1 shifts from the activated state to the sleep state.

  On the other hand, the wireless communication unit 13 of the wireless node 2 receives DIO1 = [MACadd1 / MACadd2 / MACadd1 / ESSID / 256/1] via the antenna 11 (step S4), and the received DIO1 = [MACadd1 / MACadd2 // MACadd1 / ESSID / 256/1] is output to the control unit 14.

  The control unit 14 of the wireless node 2 receives DIO1 = [MACadd1 / MACadd2 / MACadd1 / ESSID / 256/1] from the wireless communication unit 13 and receives the received DIO1 = [MACadd1 / MACadd2 / MACadd1 / 256 / ESSID / 256 / 1] is output to the route control unit 15.

  The path control unit 15 of the wireless node 2 receives DIO1 = [MACadd1 / MACadd2 / MACadd1 / ESSID / 256/1] from the control unit 14. Then, the path control unit 15 of the wireless node 2 detects that the root is the wireless node 1 with reference to the head address MACadd1 of the DIO1. Further, the path control unit 15 of the wireless node 2 refers to the second address MACadd2 of DIO1, and detects that the transmission destination of DIO1 is the wireless node 2. Further, the path control unit 15 of the wireless node 2 refers to the third address MACadd1 of DIO1, and detects that the transmission source of DIO1 is the wireless node 1 (= sink). Further, the path control unit 15 of the wireless node 2 takes out the Rank consisting of “256” and the DTSN consisting of “1” from the DIO 1 and holds them. Then, the path control unit 15 of the wireless node 2 detects that the number of hops from the wireless node 1 (= sink) to the wireless node 2 is “1” based on the Rank including “256”. This is because the “256” Rank is the minimum value of the Rank, and the wireless node 2 directly receives the Rank consisting of the minimum value “256” from the wireless node 1 (= sink). The path controller 15 of the wireless node 2 detects that the wireless node 1 (= sink) is the parent node of the wireless node 2 because the wireless node 1 (= sink) has the smallest Rank.

  Then, the route control unit 15 of the wireless node 2 stores MACadd1 in the transmission destination of the routing table RT, stores MACadd1 in the next wireless node, stores “1” in the hop count, and stores “256” in the Rank. Store. Then, the path control unit 15 of the wireless node 2 detects that the Rank of the wireless node 2 is “512” based on the Rank of “256”, and holds the Rank of “512”.

  Thereafter, since the path control unit 15 of the wireless node 2 receives DIO first, it detects that the DTSN has increased based on the DTSN consisting of “1” and determines to transmit DAO.

Then, the control unit 14 of the wireless node 2 generates a unicast ID as a wakeup ID of the wakeup signal in response to a request from the route control unit 15. Since DAO is transmitted to the wireless node 1, the control unit 14 of the wireless node 2 receives the MAC address MACadd 1 of the wireless node 1 from the path control unit 15. Then, the control unit 14 of the wireless node 2 calculates the hash value of the MAC address MACadd1, and the 12-bit hash value b ₁ b ₂ b ₃ b ₄ b ₅ b ₆ b ₇ b ₈ b ₉ b ₁₀ b ₁₁ b ₁₂ To get. As a result, unicast ID _{as b 9 b 10 b 11 b 12} = 0x5, b 5 b 6 b 7 b 8 = 0x2, b 1 b 2 b 3 b 4 = 0x8, the 0x1,0x5,0x2,0x8 expressed.

Thereafter, the control unit 14 of the wireless node 2 refers to the correspondence table TBL3, and a plurality of 40.64, 41.92, ..., 59.84 [msec] corresponding to the sampling interval T _{interval_min} (= 1280 μsec). Among them, a frame length FL5 of 40.64 [msec] corresponding to 0x1, a frame length FL6 of 47.04 [msec] corresponding to 0x5, and a frame length FL7 of 43.20 [msec] corresponding to 0x2 , A frame length FL8 of 50.88 [msec] corresponding to 0x8 is detected.

  Then, the control unit 14 of the wireless node 2 generates four wireless frames FR5 to FR8 having four frame lengths FL5 to FL8, respectively, and outputs them to the wireless communication unit 13.

  The wireless communication unit 13 of the wireless node 2 receives the four wireless frames FR5 to FR8 from the control unit 14, modulates the received wakeup signal WuS including the four wireless frames FR5 to FR8, and modulates the wake-up signal. The up signal WuS is broadcast via the antenna 11 (step S5).

  The wake-up signal receiving unit 17 of the wireless node 1 shifts to an activated state at regular intervals and confirms whether there is received power. Then, when detecting the received power, the wakeup signal receiving unit 17 of the wireless node 1 receives the wakeup signal WuS via the antenna 12, and based on the received radio wave of the received wakeup signal WuS, the method described above Detects four frame lengths FL5 to FL8. Then, the wakeup signal reception unit 17 of the wireless node 1 outputs the four frame lengths FL5 to FL8 to the wakeup signal determination unit 18.

  When receiving the four frame lengths FL5 to FL8 from the wakeup signal receiving unit 17, the wakeup signal determination unit 18 of the wireless node 1 refers to the correspondence table TBL3 and performs the four frame lengths FL5 to FL5 according to the method described above. FL8 is converted into bit values 0x1, 0x5, 0x2, and 0x8, respectively, and a unicast ID is acquired.

  Then, the wakeup signal determination unit 18 of the wireless node 1 determines that the unicast ID matches the previously held wakeup ID, generates an activation signal, and generates the wireless communication unit 13, the control unit 14, and the path control unit 15. And output to the sampling interval determination unit 16. Thereby, the wireless node 1 shifts from the sleep state to the activated state (step S6).

  Thereafter, the wireless node 1 generates and broadcasts an activation notification by the same method as the wireless node 2.

  Then, in response to the activation notification transmitted from the wireless node 1, the path control unit 15 of the wireless node 2 includes “1”, the address of the parent node including the MAC address MACadd1, the transmission source including the MAC address MACadd2. DAO1 including “DAOSsequence” is generated and output to the control unit 14.

  The control unit 14 of the wireless node 2 receives DAO1 = [MACadd1 / MACadd2 / 1] from the path control unit 15 and outputs the received DAO1 = [MACadd1 / MACadd2 / 1] to the wireless communication unit 13.

  The wireless communication unit 13 of the wireless node 2 receives DAO1 = [MACadd1 / MACadd2 / 1] from the control unit 14 and modulates the received DAO1 = [MACadd1 / MACadd2 / 1]. Then, the wireless communication unit 13 of the wireless node 2 transmits the modulated DAO1 = [MACadd1 / MACadd2 / 1] via the antenna 11 (step S7).

  Thereafter, the wireless node 2 shifts from the activated state to the sleep state.

  The wireless communication unit 13 of the wireless node 1 receives DAO1 = [MACadd1 / MACadd2 / 1] via the antenna 11 (step S8), demodulates the received DAO1 = [MACadd1 / MACadd2 / 1], and controls the control unit 14 to output.

  The control unit 14 of the wireless node 1 receives DAO1 = [MACadd1 / MACadd2 / 1] from the wireless communication unit 13 and outputs the received DAO1 = [MACadd1 / MACadd2 / 1] to the path control unit 15.

  The path control unit 163 of the wireless node 1 receives DAO1 = [MACadd1 / MACadd2 / 1] from the control unit 14. Then, the path control unit 15 of the wireless node 1 detects that the wireless node 2 is a child node of the wireless node 1 with reference to the head address MACadd1 and the second address MACadd2 of the DAO1. This is because the wireless node 1 directly receives DAO 1 from the wireless node 2. Then, the route control unit 15 of the wireless node 2 stores the address MACadd2 in the destination of the routing table RT and the next wireless node, stores “1” in the number of hops, and stores “512” in the Rank. In this case, since the route control unit 15 of the wireless node 1 directly receives DAO 1 from the wireless node 2, it is understood that the number of hops from the wireless node 1 to the wireless node 2 is “1”. Further, since the number of hops from the wireless node 1 to the wireless node 2 is “1”, the route controller 15 of the wireless node 1 understands that the Rank of the wireless node 2 is “512”.

  Thereafter, the wireless node 2 performs the same operation as the operation of the wireless node 1 in step S1, and broadcasts the wakeup signal WuS (step S9).

  Then, the wireless node 3 shifts from the sleep state to the activated state by the same operation as the operation of the wireless node 2 in step S2 (step S10), and broadcasts an activation notification including the address MACadd3.

  Thereafter, when receiving the activation notification, the wireless node 2 transmits DIO by the same operation as the operation of the wireless node 1 in step S3 (step S11), and shifts from the activated state to the sleep state.

  The wireless node 3 receives the DIO (step S12), and stores the route information of the new route in the routing table RT by the same method as the wireless node 2 described above based on the received DIO. Further, the wireless node 3 detects that its own Rank is “768” based on the Rank (= 512) included in the received DIO, and holds the Rank including “768”. Further, the wireless node 3 detects that the numerical value of DTSN included in the received DIO is increasing, and determines to transmit DAO.

  Then, the wireless node 3 unicasts a wakeup signal WuS composed of a wireless frame having a frame length representing a unicast ID by the same operation as the operation of the wireless node 2 in step S5 (step S13).

  The wireless node 2 shifts from the sleep state to the activated state by the same operation as that in step S2 (step S14), and broadcasts an activation notification including the address MACadd2 of the wireless node 2.

  When receiving the activation notification, the wireless node 3 transmits DAO by the same operation as that in step S7 (step S15). Thereafter, the wireless node 3 shifts from the activated state to the sleep state.

  The wireless node 2 receives the DAO (step S16), determines that the received DAO is the latest by the method described above based on the DAOS sequence included in the DAO, and determines that the DAO should be transferred.

  Then, the wireless node 2 transmits a wakeup signal WuS composed of a wireless frame having a frame length representing a unicast ID by the same operation as the operation of step S5 (step S17).

  Then, the wireless node 1 shifts from the sleep state to the activated state by the same operation as that in step S6 (step S18), and broadcasts an activation notification including the address MACadd1 of the wireless node 1.

  After that, when receiving the activation notification, the wireless node 2 transmits DAO by the same operation as that in step S6 (step S19).

  The wireless node 1 receives the DAO (step S20), and since the address of the parent node of the DAO is MACadd2, and the transmission source is the MAC address MACadd3, the MAC address MACadd3 is stored in the transmission destination of the routing table RT. The MAC address MACadd2 is stored in the wireless node, “2” is stored in the hop count, “768” is stored in the Rank, and the routing table RT is updated. Note that the wireless node 1 has already stored in the routing table RT that the number of hops from itself to the wireless node 2 is “1” corresponding to the route having the wireless node 2 as a transmission destination. Therefore, it can be detected that the number of hops from itself to the wireless node 3 is “2”. The wireless node 1 has already been stored in the routing table RT corresponding to the route having the wireless node 2 as the transmission destination, so that the rank of the wireless node 2 is “512”. Since it is the wireless node 2, it can be detected that the Rank of the wireless node 3 is “768”.

  Thereafter, the wireless nodes 1 to 7 repeatedly execute the above-described operation, establish a route from the wireless node 1 to each of the wireless nodes 2 to 7, and create a routing table RT including route information of the established route. Then, the wireless node 1 creates and holds topology information indicating the topology state of the wireless nodes 1 to 7 based on the created routing table RT.

  In the flowchart shown in FIG. 15, when transmitting DIO, the wireless node 1 broadcasts a wake-up signal to shift the wireless node 2 to the activated state, and then transmits DIO (see steps S1 to S3). And the wireless node 1 will transfer to a sleep state, if transmission of DIO is completed.

  In addition, when the wireless node 2 shifts to the activated state according to the wake-up signal, when receiving the DIO and transmitting DAO, the wireless node 1 unicasts the wake-up signal to shift the wireless node 1 to the activated state, and then DAO is transmitted (see steps S4, S5 and S7). When the wireless node 2 completes the DAO transmission, the wireless node 2 shifts to the sleep state.

  Further, when transmitting the DIO, the wireless node 2 broadcasts a wakeup signal to shift the wireless node 3 to the activated state, and then transmits the DIO (see steps S9 to S11). And the wireless node 2 will transfer to a sleep state, if transmission of DIO is completed.

  Further, when the wireless node 3 shifts to the activated state according to the wake-up signal, when receiving the DIO and transmitting DAO, the wireless node 3 unicasts the wake-up signal to shift the wireless node 2 to the activated state, and then DAO is transmitted (see steps S12, S13, S15). And the wireless node 3 will transfer to a sleep state, if transmission of DAO is completed.

  Further, when the wireless node 2 enters the activated state in response to the wake-up signal, when receiving the DAO and transferring the DAO, the wireless node 1 causes the wireless node 1 to enter the activated state by unicasting the wake-up signal, and then DAO is transmitted (see steps S16, S17, S19). When the wireless node 2 completes the DAO transmission, the wireless node 2 shifts to the sleep state.

  As described above, when each of the wireless nodes 1 to 3 shifts to the activated state, the wireless nodes 1 to 3 perform necessary operations and then shift to the sleep state. In the activated state, when the wireless node 2 needs to transfer the DAO received from the wireless node 3, the wireless node 2 shifts to the sleep state after completing the DAO transfer. As a result, the DAO transmitted from the wireless node 3 is quickly delivered to the wireless node 1. In other words, the wireless nodes 1 to 3 shift to the activated state only when necessary, perform necessary operations, and then shift to the sleep state.

In addition, when each of the wireless nodes 1 to 3 shifts the transmission destination from the sleep state to the activated state, the power consumption required for transmitting the wakeup signal WuS and the power consumption required for receiving the wakeup signal WuS The sampling interval T _{interval_min} is determined so that the total power amount, which is the sum of the two, is minimized, and the wakeup signal WuS is transmitted and received using the determined sampling interval T _{interval_min} .

  Therefore, when establishing a route in the wireless sensor network 10, power consumption can be reduced.

  FIG. 16 is a diagram showing an example of a topology constructed according to the flowchart shown in FIG.

  Referring to FIG. 16, steps S1 to S8 shown in FIG. 15 are executed, whereby wireless node 2 is connected to wireless node 1 (see (a) of FIG. 16).

  Thereafter, steps S9 to S20 shown in FIG. 15 are executed, whereby the wireless node 3 is connected to the wireless node 2 (see FIG. 16B).

  Then, by repeatedly executing Steps S1 to S20 shown in FIG. 15, the wireless node 4 is connected to the wireless node 1 (see (c) of FIG. 16), the wireless node 5 is connected to the wireless node 4, The wireless node 6 is connected to the wireless node 4, and the wireless node 7 is connected to the wireless node 5 (see (d) of FIG. 16).

  When the wireless node 1 that is the sink creates the routing table RT, the wireless node 1 receives the control packet DAO created by each of the wireless nodes 2 to 7, and creates the control packet DAO in the control packet DAO. The address of the parent node of the wireless node (= any of wireless nodes 2 to 7) is stored. Therefore, the wireless node 1 can grasp the topology shown in FIG. 16D by sequentially receiving the control packet DAO created by each of the wireless nodes 2 to 7.

  As described above, in the wireless sensor network 10, there is no loop-like path, and a tree-structure topology is constructed according to the RPL.

  The wireless node 1 is a sink, and the parent node of the wireless nodes 2 and 4 is the wireless node 1. The wireless node 2 is a parent node of the wireless node 3, and the wireless node 4 is a parent node of the wireless nodes 5 and 6. Further, the wireless node 5 is a parent node of the wireless node 7.

  On the other hand, the wireless nodes 2 and 4 are child nodes of the wireless node 1, the wireless nodes 5 and 6 are child nodes of the wireless node 4, and the wireless node 7 is a child node of the wireless node 5.

  As a result, the wireless node 1 has two wireless nodes 2 and 4 as child nodes, the wireless node 2 has one wireless node 3 as a child node, and the wireless node 4 has two wireless nodes 5 and 6. As a child node, the wireless node 5 has one wireless node 7 as a child node.

  Therefore, the wireless node 1 (= sink) is arranged in the highest layer, the wireless nodes 2 and 4 are arranged in the second layer, the wireless nodes 3, 5, and 6 are arranged in the third layer, and the wireless node 7 is arranged in the first layer. Arranged in four layers.

  In this way, the wireless nodes 1 to 7 construct a topology having a hierarchical structure according to the RPL. In this topology, there is one parent node for each wireless node. Accordingly, the wireless nodes 1 to 7 are arranged in a tree shape from the highest layer to the lower layer.

  Further, when receiving a plurality of DIOs including Ranks having the same value, each wireless node calculates a transmission / reception probability that is the number of DIOs transmitted / received per unit time, and the calculated transmission / reception probability is maximum. The wireless node that transmitted the DIO is selected as the parent node.

  The flowchart shown in FIG. 15 is executed periodically (for example, every 30 minutes), or when a new wireless node enters the wireless sensor network 10, or the parent node of each wireless node 2-7 is changed. Or run when deleted. Further, the flowchart shown in FIG. 15 is executed when the topology changes.

  When a new wireless node enters the wireless sensor network 10, the newly entered wireless node broadcasts DIS, which is a DIO transmission request. Then, when the wireless node that has received DIS transmits DIO, the flowchart shown in FIG. 15 is executed, and a new topology is constructed.

  FIG. 17 is a diagram showing a specific example of the routing table RT shown in FIG. Note that the routing table RT-1 illustrated in FIG. 17 is the routing table RT in the wireless node 5 illustrated in FIG.

  Referring to FIG. 17, routing table RT-1 of wireless node 5 has wireless nodes 1, 4, and 7 as transmission destinations. When the transmission destination is the wireless node 4 (MACadd4), the MAC address MACadd4 of the wireless node 4 is stored in the “next wireless node” corresponding to the transmission destination. Then, “1” is stored in the “hop count” corresponding to the transmission destination. In addition, “512” is stored in “Rank” corresponding to the transmission destination.

  The wireless node 5 receives the control packet DIO generated by the wireless node 4 from the wireless node 4, and detects that the transmission source included in the received control packet DIO is the wireless node 4 (= MACadd4). It is detected that the wireless node 4 is a wireless node adjacent to itself and that the number of hops to the wireless node 4 is “1”. Further, the wireless node 5 detects that “512” is stored in “Rank” included in the control packet DIO received from the wireless node 4, and the “Rank” of the wireless node 4 is “512”. Is detected. Therefore, the wireless node 5 can create route information on the first row of the routing table RT-1.

  When the wireless node 5 detects that “Rank” included in the control packet DIO received from the wireless node 4 is “512” and the “root address” included in the control packet DIO is MACadd1, It is detected that “Rank” of “768” is “768” (= 512 + 256). The wireless node 5 has its own “Rank” of “768”, and “Rank” increases by “256” for each hop. Therefore, “768” is divided by “256”, and the division result is obtained. The number of hops to the wireless node 1 (= 2) is obtained by subtracting “1” from “3”. Note that “1” is subtracted from the division result “3” because “Rank” of the wireless node 1 is “256”, and in order to obtain the number of hops, how many times “Rank” has increased is obtained. It is necessary. Further, since the “root address” is MACadd1, the wireless node 5 understands that “Rank” corresponding to the wireless node 1 as the transmission destination is “256”. Furthermore, since the wireless node 5 receives the control packet DIO from the wireless node 4 and the number of hops to the wireless node 1 is “2”, the “next wireless node” corresponding to the wireless node 1 as the transmission destination is It is detected that the wireless node 4 (= MACadd4). Therefore, the wireless node 5 can create route information on the second row of the routing table RT-1.

  Further, the wireless node 5 receives the control packet DAO from the wireless node 7, and based on the transmission source (= MACadd7) included in the received control packet DAO, the wireless node 7 is a child node adjacent to itself. Is detected. The “parent node address” included in the control packet DAO is MACadd5 (= wireless node 5), and the control packet DAO is a response to the control packet DIO, and is in the upstream direction (from each wireless node 2 to 7 to the wireless node). 1 (direction to 1). Accordingly, the wireless node 5 detects that the wireless node 7 is its own child node. Further, since the wireless node 5 directly receives the control packet DAO from the wireless node 7, it detects that the number of hops to the wireless node 7 is “1”. Further, the wireless node 5 detects that “Rank” of the wireless node 7 is “1024” because its “Rank” is “768” and the number of hops to the wireless node 7 is “1”. To do. Accordingly, the wireless node 5 can create route information on the third row of the routing table RT-1.

  When the wireless node 1 transmits a data packet including data to the wireless node 7, the wireless node 1 transmits route information from the wireless node 1 to the wireless node 7 (= wireless node 1 → wireless node 4 → wireless node 5 → A data packet including the wireless node 7) and data is generated and transmitted. Therefore, each of the wireless nodes 4 and 5 on the route indicated by the route information (= wireless node 1 → wireless node 4 → wireless node 5 → wireless node 7) is route information (= wireless node 1 → wireless node 4 → wireless). By referring to the node 5 → the wireless node 7), it is possible to store route information whose destination is a wireless node 2 hops away from itself in the routing table RT.

  As a result, each of the wireless nodes 2 to 7 can store, in the routing table RT, route information having all the wireless nodes constituting the wireless sensor network 10 as transmission destinations.

  FIG. 18 is a flowchart for explaining the sensor value transfer operation in the wireless sensor network 10 shown in FIG.

  Referring to FIG. 18, when the control unit 14 of the wireless node 3 receives the activation time from the built-in timer, it shifts to the activation state and activates the wireless communication unit 13, the path control unit 15, and the sampling interval determination unit 16. Transition to the state. As a result, the wireless node 3 shifts to the activated state.

  And the control part 14 of the radio | wireless node 3 controls a sensor (not shown) so that a sensor value may be detected.

  After that, when receiving a sensor value from a sensor (not shown), the control unit 14 of the wireless node 3 routes the parent node of the wireless node 3 to transmit the received sensor value to the wireless node 1 (= sink). The control unit 15 is inquired.

  Then, the control unit 14 of the wireless node 3 receives the address MACadd2 of the wireless node 2 that is the parent node of the wireless node 3 from the route control unit 15.

  Then, the control unit 14 of the wireless node 3 generates the wakeup signal WuS by the method described above based on the MAC address MACadd2 and the correspondence table TBL3, and outputs the generated wakeup signal WuS to the wireless communication unit 13.

  The wireless communication unit 13 receives the wakeup signal WuS from the control unit 14, modulates the received wakeup signal WuS, and transmits the modulated wakeup signal WuS via the antenna 11 (step S21).

  Then, the wireless node 2 shifts from the sleep state to the activated state according to the wake-up signal WuS from the wireless node 3 by the same operation as that in step S2 shown in FIG. 15 (step S22), and the address of the wireless node 2 An activation notification including MACadd2 is broadcast.

  Upon receiving the activation notification, the wireless node 3 detects that the wireless node 2 has been activated. Then, the control unit 14 of the wireless node 3 transmits a packet including the address MACadd1 of the wireless node 1 (= sink), the address MACadd2 of the wireless node 2 that transmitted the activation notification, the address MACadd3 of the wireless node 3, and the sensor value. PKT1 = [MACadd1 / MACadd2 / MACadd3 / sensor value] is generated, and the generated packet PKT1 = [MACadd1 / MACadd2 / MACadd3 / sensor value] is output to the wireless communication unit 13. The wireless communication unit 13 of the wireless node 3 receives the packet PKT1 = [MACadd1 / MACadd2 / MACadd3 / sensor value] from the control unit 14, modulates the received packet PKT1, and transmits the modulated packet PKT1 via the antenna 11. Transmit (step S23). Thereafter, the wireless node 3 shifts from the activated state to the sleep state.

  The wireless node 2 receives the packet PKT1 = [MACadd1 / MACadd2 / MACadd3 / sensor value] from the wireless node 3 (step S24). Then, the wireless node 2 detects that the leading address of the packet PKT1 is the address MACadd1 of the wireless node 1, and detects that the packet PKT1 should be transferred to the wireless node 1.

  Then, the wireless node 2 transmits the wake-up signal WuS by the same operation as that of the wireless node 3 in step S21 (step S25). In response to the wake-up signal WuS from the wireless node 2, the wireless node 1 shifts from the sleep state to the activated state by the same operation as the operation of the wireless node 2 in step S22 (step S26), and the address MACadd1 of the wireless node 1 Broadcast a startup notification containing.

  Upon receiving the activation notification, the wireless node 2 generates a packet PKT2 = [MACadd1 / MACadd1 / MACadd3 / sensor value] in which the address MACadd2 of the packet PKT1 = [MACadd1 / MACadd2 / MACadd3 / sensor value] is changed to the address MACadd1. The generated packet PKT2 = [MACadd1 / MACadd1 / MACadd3 / sensor value] is transmitted (step S27). Then, the wireless node 2 shifts from the activated state to the sleep state.

  The wireless node 1 receives the packet PKT2 = [MACadd1 / MACadd1 / MACadd3 / sensor value] from the wireless node 2 (step S28). Then, the control unit 14 of the wireless node 1 extracts the transmission source address MACadd3 and sensor value from the received packet PKT2, and holds the extracted address MACadd3 and sensor value in association with each other.

  Thereafter, the wireless node 2 shifts from the sleep state to the activated state by a timer interrupt, and receives a sensor value from a sensor (not shown). Then, the wireless node 2 transmits the wakeup signal WuS by the same operation as the operation of the wireless node 3 in step S21 (step S29).

  The wireless node 1 shifts from the sleep state to the activated state in response to the wake-up signal WuS from the wireless node 2 (step S30), and broadcasts an activation notification including the address MACadd1 of the wireless node 1.

  When receiving the activation notification, the wireless node 2 transmits a packet PKT3 = [MACadd1 / MACadd1 / MACadd2 / sensor value] including the sensor value by the same operation as the operation of the wireless node 3 in step S23 (step S31).

  The wireless node 1 receives the packet PKT3 = [MACadd1 / MACadd1 / MACadd2 / sensor value] (step S32). Then, the control unit 14 of the wireless node 1 extracts the transmission source address MACadd2 and the sensor value from the packet PKT3, and holds the extracted transmission source address MACadd2 and the sensor value in association with each other.

  In this way, according to the flowchart shown in FIG. 18, the sensor values detected by the wireless nodes 2 to 7 are transmitted to the wireless node 1 (= sink) and held in the wireless node 1 (= sink).

  In the flowchart shown in FIG. 18, when transmitting the sensor value, the wireless node 3 unicasts the wakeup signal to shift the wireless node 2 to the activated state, and then transmits the sensor value (see steps S21 to S23). ). And the wireless node 3 will transfer to a sleep state, if transmission of a sensor value is completed.

  In addition, when the wireless node 2 transitions to the activated state in response to the wake-up signal, the wireless node 1 receives the sensor value and transfers the sensor value, unicasts the wake-up signal to cause the wireless node 1 to transition to the activated state, Thereafter, the sensor value is transmitted (see steps S25, S26, and S27). And the wireless node 2 will transfer to a sleep state, if the transfer of a sensor value is completed.

  Further, when transmitting the sensor value detected by itself, the wireless node 2 unicasts the wakeup signal to shift the wireless node 1 to the activated state, and then transmits the sensor value (see steps S29 to S31). . And the wireless node 2 will transfer to a sleep state, if transmission of a sensor value is completed.

  As described above, when the wireless nodes 1 to 3 perform the necessary operations in the transmission and transfer operations of the sensor values to the wireless node 1 and then perform necessary operations, the wireless nodes 1 to 3 shift to the sleep state. In the activated state, when transferring the sensor value received from the wireless node 3, the wireless node 2 shifts to the sleep state after completing the transfer of the sensor value. As a result, the sensor value transmitted from the wireless node 3 is quickly delivered to the wireless node 1. In other words, the wireless nodes 1 to 3 shift to the activated state only when necessary, perform necessary operations, and then shift to the sleep state.

In addition, when each of the wireless nodes 1 to 3 shifts the transmission destination from the sleep state to the activated state, the power consumption required for transmitting the wakeup signal WuS and the power consumption required for receiving the wakeup signal WuS The sampling interval T _{interval_min} is determined so that the total power amount, which is the sum of the two, is minimized, and the wakeup signal WuS is transmitted and received using the determined sampling interval T _{interval_min} .

  Therefore, the power consumption can be reduced in the operation of transmitting and transferring the sensor value to the wireless node 1.

[Adjustment of frame transmission number N or sampling interval T _{interval_min} ]
When counting the number N of frame transmissions, statistical information is used, so that there is a time lag in setting the number N of frame transmissions. The increase / decrease in the number N of frame transmissions is mainly caused by a change in the topology of the wireless nodes 1 to 7 in the wireless sensor network 10.

Therefore, the number N of frame transmissions or the sampling interval T _{interval_min} is adjusted using topology information so that no time lag occurs.

Since there is a relationship indicated by the correspondence table TBL1 between the frame transmission number N and the sampling interval, adjusting the frame transmission number N adjusts the sampling interval T _{interval — min} .

FIG. 19 is a diagram illustrating the relationship between the topology information and the sampling interval T _{interval_min} .

Referring to FIG. 19, correspondence table TBL4 includes topology information and sampling interval T _{interval_min} . The topology information and the sampling interval T _{interval — min} are associated with each other.

  The topology information includes a cost value, the number of hops, and a tree size. The cost value represents the proximity from each of the wireless nodes 2 to 7 to the sink (= wireless node 1). And when a topology is constructed | assembled by RPL mentioned above, a cost value consists of Rank mentioned above, for example. In this case, the smaller the Rank, the closer to the sink (= wireless node 1).

  The number of hops is the number of hops from each wireless node 2 to 7 to the sink (= wireless node 1), and represents the proximity from each wireless node 2 to 7 to the sink (= wireless node 1). In this case, the smaller the number of hops, the closer to the sink (= wireless node 1). In the embodiment of the present invention, the number of hops consists of 0, 1, 2, 3,.

The tree size is the total number of radio nodes arranged in a lower layer than the radio node AD that adjusts the number N of frame transmissions or the sampling interval T _{interval_min} and arranged at a position of one hop or more from the radio node AD. For example, in the topology shown in FIG. 16D, when the wireless node AD is the wireless node 4, the tree size is “3”.

When the cost value satisfies the cost value <512, the sampling interval T _{interval_min} is adjusted to 160 μsec, and when the cost value satisfies 512 ≦ cost value <1024, the sampling interval T _{interval_min} is adjusted to 320 μsec and the cost value is 1024. When satisfying ≦ cost value <1536, the sampling interval T _{interval_min} is adjusted to 640 μsec. When the cost value satisfies 1536 ≦ cost value, the sampling interval T _{interval_min} is adjusted to 1280 μsec.

As described above, the sampling interval T _{interval_min} is adjusted to increase as the cost value increases (that is, as the wireless nodes 2 to 7 move away from the sink (= wireless node 1)), and the cost value decreases. (Ie, as each wireless node 2-7 becomes closer to the sink (= wireless node 1)), it is adjusted to become smaller.

This is due to the following reason. When the cost value is increased, that is, when the wireless node AD is far from the sink (= wireless node 1), the wireless node AD has a smaller number of child nodes, so the number of times the sensor value is transmitted and transferred is reduced. Less. As a result, the wireless node AD decreases the number of times of transmitting / receiving the wakeup signal WuS. Therefore, the sampling interval T _{interval_min} is lengthened to reduce the power consumption in receiving the wakeup signal WuS. When the sampling interval T _{interval_min} is increased, the frame length of the radio frame constituting the wakeup signal WuS is increased (see the correspondence table TBL3), and the power consumption in transmission of the wakeup signal WuS is increased. Since the number of times of transmitting / receiving the wakeup signal WuS is reduced, the overall power consumption is reduced.

On the other hand, when the cost value becomes small, that is, when the wireless node AD becomes close to the sink (= wireless node 1), the wireless node AD transmits and forwards the sensor value because the number of child nodes increases. The number of times increases. As a result, the radio node AD increases the number of times of transmitting / receiving the wakeup signal WuS. Therefore, the sampling interval T _{interval_min} is shortened to shorten the frame length of the radio frame constituting the wakeup signal WuS (see correspondence table TBL3), thereby reducing the power consumption in the transmission of the wakeup signal WuS. . Note that, when the sampling interval T _{interval_min} is shortened, the power consumption during reception of the wakeup signal WuS increases, but the frame length of the radio frame constituting the wakeup signal WuS is shortened. The time required for transmission / reception is shortened, the collision of the wake-up signal WuS can be avoided, and the sensor value can be collected in the sink (= wireless node 1) while suppressing the delay.

When the hop count satisfies the hop count <2, the sampling interval T _{interval_min} is adjusted to 160 μsec. When the hop count satisfies 2 ≦ the hop count <4, the sampling interval T _{interval_min} is adjusted to 320 μsec. Sampling interval T _{interval_min} is adjusted to 640 μsec, and when the number of hops satisfies 6 ≦ hop number, sampling interval T _{interval —} min is adjusted to 1280 μsec.

As described above, the sampling interval T _{interval_min} is adjusted to increase as the number of hops increases (that is, as each of the wireless nodes 2 to 7 moves away from the sink (= wireless node 1)), and the number of hops decreases. (Ie, as each wireless node 2-7 becomes closer to the sink (= wireless node 1)), it is adjusted to become smaller. The reason is the same as the reason described in relation to the cost value and the sampling interval T _{interval — min} .

Further, when the tree size satisfies 100 <tree size, the sampling interval T _{interval_min} is adjusted to 160 μsec, and when the tree size satisfies 50 <tree size ≦ 100, the sampling interval T _{interval_min} is adjusted to 320 μsec. Sampling interval T _{interval —} min is adjusted to 640 μsec, and when the tree size satisfies tree size ≦ 20, sampling interval T _{interval —} min is adjusted to 1280 μsec.

As described above, the sampling interval T _{interval — min} is adjusted to increase as the tree size decreases, and is adjusted to decrease as the tree size increases.

The _reason why the sampling interval T _{interval_min} is adjusted to increase as the tree size decreases is that the number of radio nodes (= number of child nodes) existing in lower layers than the radio node AD decreases as the tree size decreases. Thus, the number of times of transmitting and transferring the sensor value is reduced, and the number of times of transmitting / receiving the wakeup signal WuS is reduced. Therefore, as described above, the total power consumption is reduced by reducing the power consumption in receiving the wakeup signal WuS. This is because it can be reduced.

On the other hand, the sampling interval T _{interval_min} is adjusted so as to decrease as the tree size increases. The number of radio nodes existing in lower layers than the radio node AD (= number of child nodes) increases as the tree size increases. Increases the number of times the sensor value is transmitted and transferred, and the number of times the wakeup signal WuS is transmitted / received increases. As described above, the sensor avoids the collision of the wakeup signal WuS and suppresses the delay. This is because it is necessary to collect values to the sink (= wireless node 1).

In the correspondence table TBL4, the sampling interval T _{interval_min} is doubled in units of 160 μsec. This is for simplifying the circuit of the wake-up signal receiving unit 17.

FIG. 20 is a flowchart for explaining an operation of adjusting the sampling interval T _{interval — min} .

Referring to FIG. 20, when the operation for adjusting the sampling interval T _{interval_min} is started, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 receives the topology information from the path control unit 15. And the sampling interval determination part 16 of each radio | wireless node 1-7 acquires Rank of the radio | wireless node (one of radio | wireless nodes 1-7) with which self is mounted with reference to topology information.

  Then, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 determines whether or not the acquired cost value including the Rank satisfies the cost value <512 (Step S41).

When it is determined in step S41 that the cost value satisfies the cost value <512, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 adjusts the sampling interval T _{interval_min} to 160 [μsec] (step S42).

  On the other hand, when it is determined in step S41 that the cost value does not satisfy the cost value <512, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 determines whether the cost value satisfies 512 ≦ cost value <1024. Is further determined (step S43).

When it is determined in step S43 that the cost value satisfies 512 ≦ cost value <1024, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 adjusts the sampling interval T _{interval_min} to 320 [μsec] (step S44). ).

  On the other hand, when it is determined in step S43 that the cost value does not satisfy 512 ≦ cost value <1024, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 satisfies whether the cost value satisfies 1024 ≦ cost value <1536. It is further determined whether or not (step S45).

When it is determined in step S45 that the cost value satisfies 1024 ≦ cost value <1536, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 adjusts the sampling interval T _{interval_min} to 640 [μsec] (step S46). ).

On the other hand, when it is determined in step S45 that the cost value does not satisfy 1024 ≦ cost value <1536, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 adjusts the sampling interval T _{interval_min} to 1280 [μsec]. (Step S47).

  And after any of step S42, S44, S46, S47, a series of operation | movement is complete | finished.

When it is determined in step S45 that the cost value does not satisfy 1024 ≦ cost value <1536, the sampling interval T _{interval_min} is adjusted to 1280 [μsec] because the cost value is 1024 ≦ cost value in step S45. This is because, when it is determined that <1536 is not satisfied, it is determined that the cost value is 1536 or more.

As described above, Rank is composed of 256, 512, 768,. Therefore, when it is determined that the cost consisting of Rank satisfies the cost value <512, Rank consists of 256. As described above, the wireless node 1 (= sink) has a rank of 256, and the sensor values transmitted from the wireless nodes 2 to 7 are concentrated on the wireless node 1 (= sink). That is, the number of radio frames received by the radio node 1 (= sink) increases. Therefore, when it is determined that the cost satisfies the cost value <512, the sampling interval T _{interval_min} is adjusted to the smallest 160 [μsec].

Then, as the cost value (= Rank) increases, that is, as the arrangement position becomes farther from the sync, the sampling interval T _{interval_min} is adjusted to a larger value (see steps S44, S46, and S47). This is because the number of times the wireless node transmits and transfers the sensor value decreases as the distance from the sink increases, so that the power consumption when receiving the wake-up signal is reduced.

After the operation of adjusting the sampling interval T _{interval_min} illustrated in FIG. 20 is completed, each of the wireless nodes 1 to 7 operates at the adjusted sampling interval T _{interval_min} and executes the flowchart illustrated in FIG. 15 or FIG.

When the sampling interval T _{interval_min} is adjusted using the number of hops instead of the cost value, it is determined in step S41 whether or not the hop number satisfies the hop number <2. In step S43, the hop number is 2 ≦ It is determined whether or not the number of hops <4 is satisfied. In step S45, it is determined whether or not the number of hops satisfies 4 ≦ the number of hops <6.

When the sampling interval T _{interval_min} is adjusted using the tree size instead of the cost value, it is determined in step S41 whether or not the tree size satisfies 100 <tree size. In step S43, the tree size is 50 <. It is determined whether or not tree size ≦ 100 is satisfied. In step S45, it is determined whether or not the tree size satisfies 20 <tree size ≦ 50.

When the sampling interval T _{interval_min} is adjusted using all of the cost value, the number of hops, and the tree size, it is determined whether or not the condition is satisfied in the order of the tree size, the cost value, and the number of hops.

  In this case, “cost value <512, hop count <2, 100 <tree size” is the first condition, and “512 ≦ cost value <1024, 2 ≦ hop count <4, 50 <tree size ≦ 100”. The second condition is “1024 ≦ cost value <1536, 4 ≦ hop count <6, 20 <tree size ≦ 50”, and the third condition is “1536 ≦ cost value, 6 ≦ hop count, tree size ≦ 20 "is the fourth condition.

FIG. 21 is a flowchart for explaining the operation of adjusting the sampling interval T _{interval_min} using all of the cost value, the number of hops, and the tree size.

  Referring to FIG. 21, when a series of operations is started, sampling interval determination unit 16 of each of wireless nodes 1 to 7 sets k = 1 (step S51). k is one of 1, 2, 3, and 4.

  Then, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 detects the kth condition of the tree size, the cost value, and the number of hops from the correspondence table TBL4 (step S52).

  Thereafter, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 receives the topology information from the route control unit 15. Then, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 refers to the topology information, and acquires the Rank, the number of hops, and the tree size of the wireless node (one of the wireless nodes 1 to 7) on which it is mounted. To do.

  Then, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 determines whether or not the conditions are satisfied in the order of tree size, cost value, and number of hops (step S53).

  When it is determined in step S53 that the conditions are not satisfied in the order of tree size, cost value, and number of hops, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 sets k = k + 1 (step S54). And a series of operation | movement transfers to step S52, and step S52-S54 mentioned above is repeatedly performed until it determines with satisfy | filling conditions in order of a tree size, a cost value, and the number of hops in step S53.

  If it is determined in step S53 that the conditions are satisfied in the order of tree size, cost value, and number of hops, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 determines whether or not k = 1 ( Step S55).

When it is determined in step S55 that k = 1, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 sets the sampling interval T _{interval_min} to 160 [μsec] (step S56).

  On the other hand, when it is determined in step S55 that k = 1 is not satisfied, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 determines whether k = 2 is satisfied (step S57).

When it is determined in step S57 that k = 2, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 sets the sampling interval T _{interval_min} to 320 [μsec] (step S58).

  On the other hand, when it is determined in step S57 that k = 2 is not satisfied, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 determines whether or not k = 3 (step S59).

When it is determined in step S59 that k = 3, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 sets the sampling interval T _{interval_min} to 640 [μsec] (step S60).

On the other hand, when it is determined in step S59 that k = 3 is not satisfied, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 sets the sampling interval T _{interval_min} to 1280 [μsec] (step S61).

  And after any of step S56, S58, S60, S61, a series of operation | movement is complete | finished.

  When step S53 is executed for the first time, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 uses the first condition “cost value <512, hop count <2, 100 <tree size” to If it is determined whether the size satisfies 100 <tree size and it is determined that the tree size satisfies 100 <tree size, then it is determined whether the cost value satisfies cost value <512. If it is determined that the cost value <512 is satisfied, finally, it is determined whether or not the hop count satisfies the hop count <2.

  The sampling interval determination unit 16 of each of the wireless nodes 1 to 7 determines that the conditions are satisfied in the order of the tree size, the cost value, and the number of hops when all of the tree size, the cost value, and the number of hops satisfy the conditions.

  On the other hand, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 does not satisfy the conditions in the order of the tree size, the cost value, and the number of hops when any one of the tree size, the cost value, and the number of hops does not satisfy the condition. Is determined.

  When step S53 is executed for the second time, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 sets the second condition “512 ≦ cost value <1024, 2 ≦ hop count <4, 50 <tree size. ≦ 100 ”, it is determined whether or not the condition is satisfied in the order of the tree size, the cost value, and the number of hops in the same manner as when step S53 is executed for the first time.

  When step S53 is executed for the third time and the fourth time, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 sets the third condition “1024 ≦ cost value <1536, 4 ≦ hop count <6, 20 <Tree size ≦ 50 ”and the fourth condition“ 1536 ≦ cost value, 6 ≦ hop count, tree size ≦ 20 ”are similarly used to satisfy the conditions in the order of tree size, cost value, and hop count. It is determined whether or not.

When adjusting the sampling interval T _{interval_min} using two of the cost value, the number of hops, and the tree size, the sampling interval determining unit 16 of each of the wireless nodes 1 to 7 performs the sampling interval T according to the flowchart shown in FIG. Adjust _{interval_min} .

  In this case, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 sequentially determines whether or not the condition is satisfied according to two priorities selected from the cost value, the number of hops, and the tree size.

  When the tree size and the cost value are selected from the cost value, the number of hops, and the tree size, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 determines whether or not the tree size satisfies the kth condition in step S53. When the tree size satisfies the kth condition, it is determined whether the cost value satisfies the kth condition. Then, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 determines that the conditions are satisfied in the order of the tree size and the cost value when all of the tree size and the cost value satisfy the kth condition.

  On the other hand, when any of the tree size and the cost value does not satisfy the kth condition, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 determines that the conditions are not satisfied in the order of the tree size and the cost value.

  When the cost value and the number of hops are selected from the cost value, the number of hops, and the tree size, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 determines whether or not the cost value satisfies the kth condition in step S53. When the cost value satisfies the kth condition, it is determined whether or not the number of hops satisfies the kth condition. The sampling interval determination unit 16 of each of the wireless nodes 1 to 7 determines that the conditions are satisfied in the order of the cost value and the number of hops when all of the cost value and the number of hops satisfy the kth condition.

  On the other hand, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 determines that the condition is not satisfied in the order of the cost value and the number of hops when either the cost value or the number of hops does not satisfy the kth condition.

  When the tree size and the number of hops are selected from the cost value, the number of hops, and the tree size, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 determines whether or not the tree size satisfies the kth condition in step S53. When the tree size satisfies the kth condition, it is determined whether or not the number of hops satisfies the kth condition. Then, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 determines that the conditions are satisfied in the order of the tree size and the number of hops when all of the tree size and the number of hops satisfy the kth condition.

  On the other hand, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 determines that the conditions are not satisfied in the order of the tree size and the number of hops when either the tree size or the number of hops does not satisfy the kth condition.

As described above, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 adjusts the sampling interval T _{interval_min} using at least two of the tree size, the cost value, and the number of hops according to the flowchart shown in FIG. When the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 adjusts the sampling interval T _{interval_min} using at least two of the tree size, the cost value, and the number of hops, the tree size, the cost value, and the number of hops have priority. A ranking is assigned, and whether or not the tree size or the like satisfies the condition is determined according to the priority. The reason is as follows.

This is because the tree size is the largest, the cost value is the second largest, and the number of hops is the smallest factor that affects the number of times each wireless node 1 to 7 transmits and receives wireless frames. Therefore, by determining whether or not the conditions are satisfied in the order of the tree size, the cost value, and the number of hops, it is _possible to adjust the sampling interval T interval — _min suitable for the number of times each of the wireless nodes 1 to 7 transmits and receives the wireless frame.

In the embodiment of the present invention, the sampling interval T _{interval_min} of the correspondence table TBL4 may be replaced with the frame transmission number N, and the frame transmission number N may be adjusted according to the cost value, the number of hops, and the tree size.

  In this case, the number N of frame transmissions is adjusted to decrease as the cost value increases and to increase as the cost value decreases. Further, the frame transmission number N is adjusted so as to decrease as the hop number increases and to increase as the hop number decreases. Further, the frame transmission number N is adjusted to increase as the tree size increases and to decrease as the tree size decreases. When the frame transmission count N is adjusted, the frame transmission count N may be adjusted when two or all of the cost value, the hop count, and the tree size satisfy the conditions of the correspondence table TBL4.

  Then, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 adjusts the frame transmission number N according to the flowchart shown in FIG. 20 or FIG.

When the frame transmission number N is adjusted, the sampling interval T _{interval_min} corresponding to the adjusted frame transmission number N is determined based on the correspondence table TBL1.

When adjusting the number N of frame transmissions or the sampling interval T _{interval_min} , the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 holds the correspondence table TBL4, and the topology information and routing table RT held by the route control unit 15 To obtain topology information (= cost value, number of hops and tree size), and based on the obtained topology information (= cost value, number of hops and tree size) and correspondence table TBL4, the number N of frame transmissions _{Alternatively} , the sampling interval T _{interval — min} is adjusted. Then, when adjusting the frame transmission number N, the sampling interval determination unit 16 of each of the wireless nodes 1 to 7 refers to the correspondence table TBL1 and detects the sampling interval T _{interval_min} corresponding to the adjusted frame transmission number N. Determine the sampling interval.

By adjusting the frame transmission number N or the sampling interval T _{interval_min} by the above-described method, the time lag due to the fluctuation of the frame transmission number N can be suppressed, and the sampling interval T _{interval_min} can be set according to the topology of the wireless sensor network 10. As a result, the total amount of power can be reduced in accordance with the topology of the wireless sensor network 10.

Further, by selecting the cost value, the number of hops, and the tree size as the topology information, the position passes through the wireless nodes 1 to 7 other than the wireless node existing at the position where the wireless nodes 1 to 7 exist or at the highest layer. Thus, the sampling interval T _{interval — min} or the frame transmission number N can be adjusted to be suitable for the number of radio frames transmitted.

  Further, the number N of frame transmissions may be adjusted so as to increase as the communication quality of the link decreases in consideration of the communication quality of the link described above. That is, the number N of frame transmissions may be adjusted to increase as the arrival rate of the radio frame decreases, and the number N of frame transmissions may be adjusted to increase as the received signal strength RSSI decreases. .

  In the above description, it has been described that the cost value is composed of 256, 512,..., But in the embodiment of the present invention, the cost value is not limited to this, and the cost value is constructed by a route using RPL. Or when it is maintained, it may consist of Ranks other than 256, 512,.

  Further, the cost value may be composed of something other than Rank, and may be composed of anything as long as it indicates the proximity between the wireless node and the sink.

  Further, the conditions of the cost value, the number of hops, and the tree size in the correspondence table TBL4 are examples, and in the embodiment of the present invention, the correspondence table TBL4 is transmitted or received by a difference in proximity between the wireless node and the sink. Any condition may be used as long as it indicates a difference in the number of radio frames.

[Another example of correspondence table between frame length and data]
FIG. 22 is a diagram illustrating another relationship between the frame length associated with the sampling interval T _{interval_min} and the data.

  Referring to FIG. 22, correspondence table TBL5 has the same configuration as correspondence table TBL3 (see FIG. 10), and only the frame length associated with each sampling interval is different.

When the sampling interval T _{interval_min} is 160 [μsec], the data of 0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xA, 0xB, 0xC, 0xD, 0xE, 0xF are respectively 2.56 [msec], 3.20 [msec], 3.84 [msec], 4.48 [msec], 5.12 [msec], 5.76 [msec], 6.40 [msec], 7 .04 [msec], 7.68 [msec], 8.32 [msec], 8.96 [msec], 9.60 [msec], 10.24 [msec], 10.88 [msec], 11. This is associated with a frame length of 52 [msec] and 12.16 [msec].

Then, in a plurality of frame lengths of 2.56 [msec], 3.20 [msec],..., 12.16 [msec], a difference between two adjacent frame lengths is 0.64 [msec]. = 640 [μsec], which is four times the sampling interval T _{interval —} min of 160 [μsec].

When the sampling interval T _{interval_min} is 320 [μsec], the data of 0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xA, 0xB, 0xC, 0xD, 0xE, 0xF are respectively 12.48 [msec], 13.76 [msec], 15.04 [msec], 16.32 [msec], 17.60 [msec], 18.88 [msec], 20.16 [msec], 21 .44 [msec], 22.72 [msec], 24.00 [msec], 25.28 [msec], 26.56 [msec], 27.84 [msec], 29.12 [msec], 30. Corresponding to frame lengths of 40 [msec] and 31.68 [msec].

Then, in a plurality of frame lengths of 12.48 [msec], 13.76 [msec],..., 31.68 [msec], the difference between two adjacent frame lengths is 1.28 [msec]. = 1280 [μsec], which is four times the sampling interval T _{interval —} min of 320 [μsec].

When the sampling interval T _{interval_min} is 640 [μsec], the data of 0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xA, 0xB, 0xC, 0xD, 0xE, 0xF are respectively 32.32 [msec], 34.88 [msec], 37.44 [msec], 40.00 [msec], 42.56 [msec], 45.12 [msec], 47.68 [msec], 50 .27 [msec], 52.80 [msec], 55.36 [msec], 57.92 [msec], 60.48 [msec], 63.04 [msec], 65.60 [msec], 68. It is associated with a frame length of 16 [msec] and 70.72 [msec].

Then, in a plurality of frame lengths of 32.32 [msec], 34.88 [msec],..., 70.72 [msec], the difference between two adjacent frame lengths is 2.56 [msec]. = 2560 [μsec], which is four times the sampling interval T _{interval —} min of 640 [μsec].

When the sampling interval T _{interval_min} is 1280 [μsec], the data of 0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xA, 0xB, 0xC, 0xD, 0xE, 0xF are respectively 72.00 [msec], 77.12 [msec], 82.24 [msec], 87.36 [msec], 92.48 [msec], 97.60 [msec], 102.72 [msec], 107 .84 [msec], 112.96 [msec], 118.08 [msec], 123.20 [msec], 128.32 [msec], 133.44 [msec], 138.56 [msec], 143. The frame length is 68 [msec] and 148.80 [msec].

Then, in a plurality of frame lengths of 72.00 [msec], 77.12 [msec],... 148.80 [msec], the difference between two adjacent frame lengths is 5.12 [msec]. = 5120 [μsec], which is four times the sampling interval T _{interval —} min of 1280 [μsec].

When the sampling interval T _{interval_min} is 2560 [μsec], the data of 0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xA, 0xB, 0xC, 0xD, 0xE, 0xF are respectively 151.36 [msec], 161.60 [msec], 171.84 [msec], 182.08 [msec], 192.32 [msec], 202.56 [msec], 212.80 [msec], 223 .04 [msec], 233.28 [msec], 243.52 [msec], 253.76 [msec], 264.00 [msec], 272.24 [msec], 284.48 [msec], 294. Corresponding to a frame length of 72 [msec] and 304.96 [msec]

Further, in a plurality of frame lengths of 151.36 [msec], 161.60 [msec],..., 304.96 [msec], the difference between two adjacent frame lengths is 10.24 [msec]. = 10240 [μsec], which is four times the sampling interval T _{interval —} min of 2560 [μsec].

  The frame length of 2.56 [msec] is the minimum frame length in the wireless standard used in the wireless sensor network 10.

FIG. 23 is a diagram illustrating details of the frame length associated with the sampling intervals T _{interval_min} of 160 [μsec] and 320 [μsec] illustrated in FIG.

When the sampling interval T _{interval_min} is 160 [μsec], the average frame length is 8.32 [msec] (see the correspondence table TBL2 in FIG. 9).

Referring to FIG. 23A, since 8.32− (0.16 [msec] × 36) = 2.56 [msec], the frame length of 2.56 [msec] is the average frame length. _-It is represented by (T _{interval_min} × 36).

Further, since 8.32− (0.16 [msec] × 32) = 3.20 [msec], the frame length of 3.20 [msec] is expressed by an average frame length− (T _{interval_min} × 32). Is done.

  Hereinafter, similarly, the frame lengths of 3.84 [msec], 4.48 [msec],..., 12.16 [msec] are expressed by the formula shown in FIG.

As a result, a plurality of frame lengths of 2.56 [msec], 3.20 [msec],..., 12.16 [msec] are 4 (i−1) (i = 1, 1) in the sampling interval T _interval — _min . 2, 3, and so on) is added to or subtracted from the average frame length.

When the sampling interval T _{interval_min} is 320 [μsec], the average frame length is 14.40 [msec] (see the correspondence table TBL2 in FIG. 9).

Referring to FIG. 23B, 14.40 [msec] − (0.32 [msec] × 6) = 12.48 [msec], so the frame length of 12.48 [msec] is Average frame _length- (T _{interval_min} × 6).

Further, since 14.40 [msec] − (0.32 [msec] × 2) = 13.76 [msec], the frame length of 13.76 [msec] is an average frame length− (T _{interval_min} × 2 ).

  Similarly, the frame lengths of 15.04 [msec], 16.32 [msec],..., 31.68 [msec] are expressed by the formula shown in FIG.

As a result, a plurality of frame lengths of 12.48 [msec], 13.76 [msec],..., 31.68 [msec] are multiplied by the sampling interval T _{interval_min} by (2 + 4 (i−1)). It includes the frame length obtained by adding or subtracting the result to or from the average frame length.

FIG. 24 is a diagram illustrating details of the frame length associated with the sampling intervals T _{interval_min} of 640 [μsec], 1280 [μsec], and 2560 [μsec] illustrated in FIG.

When the sampling interval T _{interval_min} is 640 [μsec], the average frame length is 26.56 [msec] (see the correspondence table TBL2 in FIG. 9).

Referring to (a) of FIG. 24, since 26.56 [msec] + (0.64 [msec] × 9) = 32.32. [Msec], the frame length of 32.32 [msec] is It is represented by the average frame length + (T _{interval_min} × 9).

Also, since 26.56 [msec] + (0.64 [msec] × 13) = 34.88 [msec], the frame length of 34.88 [msec] is the average frame length + (T _interval — min × 13). ).

  Similarly, the frame lengths of 37.44 [msec], 40.00 [msec],..., 70.72 [msec] are expressed by the formula shown in FIG.

As a result, a plurality of frame lengths of 32.32 [msec], 34.88 [msec],..., 70.72 [msec] are multiplied by (9 + 4 (i−1)) to the sampling interval T _{interval —} min. It includes the frame length obtained by adding the result to the average frame length.

When the sampling interval T _{interval_min} is 1280 [μsec], the average frame length is 50.88 [msec] (see the correspondence table TBL2 in FIG. 9).

Referring to (b) of FIG. 24, since 50.88 [msec] + (1.28 [msec] × 16.5) = 72.00 [msec], the frame length is 72.00 [msec]. Is represented by the average frame length + (T _{interval_min} × 16.5).

Further, since 50.88 [msec] + (1.28 [msec] × 20.5) = 77.12 [msec], the frame length of 77.12 [msec] is the average frame length + (T _{interval —} min X20.5).

  Hereinafter, similarly, the frame lengths of 82.24 [msec], 87.36 [msec],..., 148.80 [msec] are expressed by the formula shown in FIG.

As a result, the plurality of frame lengths of 72.00 [msec], 77.12 [msec],..., 148.80 [msec] are set to (16.5 + 4 (i−1)) in the sampling interval T _{interval —} min. It includes the frame length obtained by adding the result of multiplication to the average frame length.

When the sampling interval T _{interval — min} is 2560 [μsec], the average frame length is 99.52 [msec] (see the correspondence table TBL2 in FIG. 9).

Referring to (c) of FIG. 24, since 99.52 [msec] + (2.56 [msec] × 20.25) = 151.36 [msec], the frame length of 151.36 [msec] Is represented by the average frame length + (T _{interval_min} × 20.25).

Since 99.52 [msec] + (2.56 [msec] × 24.25) = 161.60 [msec], the frame length of 161.60 [msec] is the average frame length + (T _{interval_min} X24.25).

  In the same manner, the frame lengths of 171.84 [msec], 182.08 [msec],..., 304.96 [msec] are expressed by the equation shown in FIG.

As a result, the plurality of frame lengths of 151.36 [msec], 161.60 [msec],..., 403.96 [msec] have (20.25 + 4 (i−1)) as the sampling interval T _{interval —} min. It includes the frame length obtained by adding the result of multiplication to the average frame length.

Therefore, the plurality of frame lengths associated with each sampling interval T _{interval — min} shown in FIG. 22 is obtained by adding and subtracting the result obtained by multiplying the sampling interval T _{interval — min} by a real number (referred to as “desired frame length interval”) to the average frame length. The obtained frame length is included.

  When the wakeup signal is generated using the frame length shown in FIG. 22, the frame length correspondence table 19 of each of the wireless nodes 1 to 7 holds the correspondence table TBL5. And the control part 14 of each radio | wireless node 1-7 reads the correspondence table TBL5 from the frame length correspondence table 19, and produces | generates the wakeup signal by the method mentioned above.

The frame length shown in FIG. 10 is obtained by adding or subtracting the result obtained by multiplying the sampling interval T _{interval_min} by 4i to the average frame length.

Therefore, in the embodiment of the present invention, the plurality of frame lengths associated with each sampling interval T _{interval_min} is obtained by multiplying the sampling interval T _{interval_min} by a real number (= “desired frame length interval”) as the average frame length. Includes the frame length obtained by addition / subtraction.

A difference between two adjacent frame lengths in a plurality of frame lengths associated with each sampling interval T _{interval — min} illustrated in FIG. 10 is equal to the sampling interval T _{interval — min} .

Further, the difference between two adjacent frame lengths in a plurality of frame lengths associated with each sampling interval T _{interval — min} shown in FIG. 22 is equal to four times the sampling interval T _{interval — min} .

In the embodiment of the present invention, the difference between two adjacent frame lengths in a plurality of frame lengths associated with each sampling interval T _{interval_min} is obtained by multiplying the sampling interval T _{interval_min} and the sampling interval T _{interval_min} by four times. In general, the sampling interval T _{interval_min} may be an integer multiple. This is because the two frame lengths can be identified if the difference between two adjacent frame lengths is an integer multiple of the sampling interval T _{interval — min} .

  By converting the bit value into the frame length using the correspondence tables TBL3 and TBL5, or converting the frame length into the bit value, mutual conversion between the bit value and the frame length can be easily performed. In addition, mutual conversion between a bit value and a frame length can be performed in the same manner among a plurality of wireless nodes. As a result, a correct wakeup signal is transmitted and received, and the wireless node to be activated can be activated accurately.

[action mode]
In the embodiment of the present invention, the duty cycling mode, the on-demand wake-up mode, and the delayed wake-up mode are set in each of the wireless nodes 1 to 7, and these three modes are set according to the number N of frame transmissions or the topology. Switch.

(A) Duty Cycling Mode In this mode, the operations of the wakeup signal receiving unit 17 and the wakeup signal determining unit 18 are stopped, and each of the wireless nodes 1 to 7 performs an intermittent operation periodically. That is, in this mode, the wakeup signal reception unit 17 and the wakeup signal determination unit 18 are completely stopped in operation.

(B) OnDemand Wake-up Mode In this mode, the wakeup signal receiving unit 17 and the wakeup signal determining unit 18 perform an intermittent operation.

(C) Delayed Wake-up Mode In this mode, the wake-up signal receiving unit 17 and the wake-up signal determining unit 18 perform a two-stage intermittent operation described later.

  The control unit 14 of each of the wireless nodes 1 to 7 determines the operation mode based on the frame transmission number N. More specifically, the control unit 14 of each of the wireless nodes 1 to 7 determines the operation mode as the Duty Cycling mode when the frame transmission number N is 20000 [pieces / h] or more. Then, the control unit 14 of each of the wireless nodes 1 to 7 outputs a stop signal STOP to the wakeup signal reception unit 17 and the wakeup signal determination unit 18, and transmits a signal ITM instructing intermittent operation to the wireless communication unit 13 and path control. Output to the unit 15, the sampling interval determination unit 16, and the frame length correspondence table 19. The wake-up signal receiving unit 17 and the wake-up signal determining unit 18 completely stop the operation in response to the stop signal STOP. The wireless communication unit 13, the path control unit 15, the sampling interval determination unit 16, and the frame length correspondence table 19 perform an intermittent operation according to the signal ITM.

  Further, the control unit 14 of each of the wireless nodes 1 to 7 determines the operation mode as the on-demand wake-up mode when the frame transmission number N is 200 [pieces / h] or more and less than 20000 [pieces / h]. Then, the control unit 14 of each of the wireless nodes 1 to 7 outputs the signal ITM to the wakeup signal reception unit 17 and the wakeup signal determination unit 18. The wakeup signal reception unit 17 and the wakeup signal determination unit 18 perform an intermittent operation according to the signal ITM.

  Further, the control unit 14 of each of the wireless nodes 1 to 7 determines the operation mode to the Delayed Wake-up mode when the frame transmission number N is less than 200 [pieces / h]. Then, the control unit 14 of each of the wireless nodes 1 to 7 outputs the signal DLY to the wakeup signal reception unit 17 and the wakeup signal determination unit 18. The wake-up signal receiving unit 17 and the wake-up signal determining unit 18 receiving unit perform a two-stage intermittent operation according to the signal DLY.

  FIG. 25 is a diagram for explaining a two-stage intermittent operation. Referring to FIG. 25, wakeup signal receiving unit 17 and wakeup signal determining unit 18 of each of wireless nodes 1 to 7 periodically shift to an activated state at intervals of 100 msec when packets PKT1 to PKT6 are not detected. The presence or absence of received power is confirmed for 100 μsec. A reference value for determining that there is received power is set in advance, and it is determined whether the received power is greater than or equal to the reference value, and the presence or absence of received power is confirmed.

Then, when the wakeup signal receiving unit 17 and the wakeup signal determining unit 18 of each of the wireless nodes 1 to 7 detect the packet PKT2 at the timing t1, the wakeup signal receiving unit 17 and the wakeup signal determining unit 18 maintain the activated state thereafter, and the reception of the packets PKT2 to PKT6 is completed. It shifts to the sleep state at a later timing t2. Then, the wakeup signal receiver 17 and the wakeup signal determiner 18 of each of the wireless nodes 1 to 7 operate at a sampling interval T _{interval_min} smaller than the interval of 100 [msec] when receiving the packets PKT2 to PKT6.

As described above, the wakeup signal reception unit 17 and the wakeup signal determination unit 18 of each of the wireless nodes 1 to 7 check the reception power with a long cycle of 100 [msec] until the reception of the packet is detected, and the packet Is detected, a two-stage intermittent operation that operates at a sampling interval T _{interval — min} smaller than 100 [msec] is performed.

  When the number N of frame transmissions is less than 200 [pieces / h], power consumption can be reduced by performing the above-described two-stage intermittent operation.

  FIG. 26 is a flowchart for explaining the operation of switching the operation mode according to the frame transmission number N.

  Referring to FIG. 26, when a series of operations is started, the control unit 14 of each of the wireless nodes 1 to 7 receives the frame transmission number N from the wireless communication unit 13, and the received frame transmission number N is 20000 [ It is determined whether or not it is equal to or greater than the number of pieces / h] (step S71).

  When it is determined in step S71 that the number N of frame transmissions is 20000 [number / h] or more, the control unit 14 of each of the wireless nodes 1 to 7 sets the operation mode to the duty cycling mode (step S72). And the control part 14 of each radio | wireless node 1-7 produces | generates the stop signal STOP, outputs it to the wakeup signal receiving part 17 and the wakeup signal determination part 18, and produces | generates the signal ITM, the radio | wireless communication part 13, The result is output to the path control unit 15, the sampling interval determination unit 16, and the frame length correspondence table 19.

  The wakeup signal reception unit 17 and the wakeup signal determination unit 18 of each wireless node 1 stop operating in response to the stop signal STOP, and correspond to the wireless communication unit 13, the path control unit 15, the sampling interval determination unit 16, and the frame length. Table 19 performs an intermittent operation according to the signal ITM (step S73).

  On the other hand, when it is determined in step S71 that the number N of frame transmissions is not greater than 20000 [pieces / h], the control unit 14 of each of the wireless nodes 1 to 7 determines that the number N of frame transmissions is 200 ≦ N <20000 [pieces / h. h] is further determined (step S74).

  When it is determined in step S74 that the number N of frame transmissions satisfies 200 ≦ N <20000 [pieces / h], the control unit 14 of each of the wireless nodes 1 to 7 sets the operation mode to the on-demand wake-up mode. (Step S75).

  And the control part 14 of each radio | wireless node 1-7 produces | generates the signal ITM, and outputs it to the wakeup signal receiving part 17 and the wakeup signal determination part 18. The wakeup signal reception unit 17 and the wakeup signal determination unit 18 of each of the wireless nodes 1 to 7 perform an intermittent operation according to the signal ITM (step S76).

  On the other hand, when it is determined in step S74 that the frame transmission number N does not satisfy 200 ≦ N <20000 [pieces / h], the control unit 14 of each of the wireless nodes 1 to 7 sets the operation mode to the Delayed Wake-up mode. (Step S77).

  And the control part 14 of each radio | wireless node 1-7 produces | generates the signal DLY, and outputs it to the wakeup signal receiving part 17 and the wakeup signal determination part 18. The wakeup signal reception unit 17 and the wakeup signal determination unit 18 of each of the wireless nodes 1 to 7 perform a two-stage intermittent operation according to the signal DLY (step S78).

  And after any of step S73, S76, S78, a series of operation | movement is complete | finished.

  In step S73, the wakeup signal reception unit 17 and the wakeup signal determination unit 18 of each of the wireless nodes 1 to 7 stop operating, and the wireless communication unit 13, the control unit 14, the path control unit 15, and the sampling interval determination unit. 16 and the frame length correspondence table 19 perform an intermittent operation.

  More specifically, the wireless communication unit 13, the control unit 14, the path control unit 15, the sampling interval determination unit 16, and the frame length correspondence table 19 of each of the wireless nodes 1 to 7 periodically shift to the activated state. 15 or 18 is performed according to the flowchart shown in FIG. 18, and then the process shifts to the sleep state.

  The control unit 14 of each of the wireless nodes 1 to 7 discards the received wakeup signal when the wireless communication unit 13 receives the wakeup signal and receives the received wakeup signal from the wireless communication unit 13. To do. This is because the wake-up signal is represented by the frame length as described above and does not include a meaningful bit string.

  When the number N of frame transmissions is 20000 [pieces / h] or more, the operation mode is set to the duty cycling mode. Therefore, when the number N of frame transmissions is large, the wakeup signal receiving unit 17 and the wakeup signal receiving unit 17 If the signal determination unit 18 is stopped and the intermittent operation is performed, the communication delay of the control packets DIO, DAO and the like can be suppressed and the wakeup signal reception unit 17 and the wakeup signal determination unit 18 are stopped so that the wireless nodes 1 to 7 Power consumption can be reduced.

  Therefore, when the number N of frame transmissions is 20000 [pieces / h] or more, the operation mode is set to the duty cycling mode.

In step S74, when the frame transmission number N does not satisfy 200 [pieces / h] ≦ N <20000 [pieces / h], that is, when the frame transmission number N is less than 200 [pieces / h], The wakeup signal reception unit 17 and the wakeup signal determination unit 18 perform a two-step intermittent operation when the number of frame transmissions N is small as described above, until the reception power is detected. This is because when the received power is detected, the power consumption of each of the wireless nodes 1 to 7 can be reduced by operating at the sampling interval T _{interval — min} .

  FIG. 27 is a diagram illustrating the relationship between topology information and operation modes. Referring to FIG. 27, correspondence table TBL6 includes topology information and operation modes. The topology information and the operation mode are associated with each other.

  As described above, the topology information includes at least one of a cost value, the number of hops, and a tree size.

  When the cost value satisfies the cost value <512, the operation mode is set to the duty cycling mode. When the cost value satisfies 512 ≦ cost value <1024, the operation mode is set to the on-demand wake-up mode. When the cost value satisfies 1024 ≦ cost value, the operation mode is set to the Delayed Wake-up mode.

  When the hop count satisfies the hop count <2, the operation mode is set to the duty cycling mode. When the number of hops satisfies 2 ≦ the number of hops <4, the operation mode is set to the on-demand wake-up mode. When the hop number satisfies 4 ≦ hop number, the operation mode is set to the Delayed Wake-up mode.

  When the tree size satisfies 100 <tree size, the operation mode is set to the duty cycling mode. When the tree size satisfies 50 <tree size ≦ 100, the operation mode is set to the on-demand wake-up mode. When the tree size satisfies the tree size ≦ 50, the operation mode is set to the Delayed Wake-up mode.

  When the cost value is less than 512, the Rank constituting the cost value is 256, and the wireless node for which the operation mode is set is a sink. Then, the wireless node that is the sink receives many sensor values. That is, the wireless node that is a sink receives many wireless frames. Therefore, the operation mode is set to the duty cycling mode.

  When the number of hops is less than 2, the wireless node for which the operation mode is set exists at the position of one hop from the sink, and the sensor value is transmitted and transferred many times. That is, the radio node for which the operation mode is set transmits and receives many radio frames. Therefore, the operation mode is set to the duty cycling mode.

  When the tree size is larger than 100, since the wireless node for which the operation mode is set has many child nodes, the sensor value is transmitted and transferred many times. That is, the radio node for which the operation mode is set transmits and receives many radio frames. Therefore, the operation mode is set to the duty cycling mode.

  When the cost value is 1024 or more, the wireless node for which the operation mode is set is arranged in the fourth layer or lower. That is, the operation mode setting target wireless node is arranged at a position away from the sink. Therefore, the operation mode setting target wireless node has a small number of times of transmitting and transferring the sensor value. That is, the wireless node for which the operation mode is set transmits / receives a small number of wireless frames. Therefore, the operation mode is set to the Delayed Wake-up mode. When the number of hops is 4 or more, or when the tree size is 50 or less, the operation mode is set to the Delayed Wake-up mode for the same reason.

  When the cost value is 512 or more and less than 1024, or when the number of hops is 2 or more and less than 4, or when the tree size is greater than 50 and 100 or less, the radio transmitted and received by each of the radio nodes 1 to 7 The number of frames is between the number of radio frames in the Duty Cycling mode and the number of radio frames in the Delayed Wake-up mode. Therefore, the operation mode is set to the on-demand wake-up mode.

  The operation when switching the operation mode of each of the wireless nodes 1 to 7 using one of the cost value, the number of hops, and the tree size is executed according to the flowchart shown in FIG.

  When the operation mode is switched using the cost value, the control unit 14 of each of the wireless nodes 1 to 7 determines whether or not the cost value satisfies the cost value <512 in step S71, and the cost is determined in step S74. It is determined whether or not the value satisfies 512 ≦ cost value <1024.

  When switching the operation mode using the number of hops, the control unit 14 of each of the wireless nodes 1 to 7 determines whether or not the number of hops satisfies the number of hops <2 in step S71, and in step S74, the hop number It is determined whether the number satisfies 2 ≦ hop number <4.

  Furthermore, when the operation mode is switched using the tree size, the control unit 14 of each of the wireless nodes 1 to 7 determines whether or not the tree size satisfies 100 <tree size in step S71, and in step S74, the tree It is determined whether or not the size satisfies 50 <tree size ≦ 50.

  When the operation modes of the wireless nodes 1 to 7 are switched using all of the cost value, the number of hops, and the tree size, it is determined whether or not the conditions are satisfied in the order of the tree size, the cost value, and the number of hops.

  In this case, “cost value <512, hop count <2, 100 <tree size” is the first condition, and “512 ≦ cost value <1024, 2 ≦ hop count <4, 50 <tree size ≦ 100”. The second condition, “1024 ≦ cost value <1536, 4 ≦ number of hops <6, 20 <tree size ≦ 50” is the third condition. Further, the control unit 14 of each of the wireless nodes 1 to 7 holds a correspondence table TBL6.

  FIG. 28 is a flowchart for explaining the operation of switching the operation mode of the wireless node using all of the cost value, the number of hops, and the tree size.

  Referring to FIG. 28, when a series of operations is started, control units 14 of wireless nodes 1 to 7 set p = 1 (step S81). p consists of one of 1, 2, and 3.

  Then, the control unit 14 of each of the wireless nodes 1 to 7 detects the p-th condition of the tree size, the cost value, and the number of hops from the correspondence table TBL6 (Step S82).

  Thereafter, the control unit 14 of each of the wireless nodes 1 to 7 receives the topology information from the route control unit 15. And the control part 14 of each radio | wireless node 1-7 acquires Rank, the number of hops, and tree size of the radio | wireless node (one of radio | wireless nodes 1-7) in which self is mounted with reference to topology information.

  Then, the control unit 14 of each of the wireless nodes 1 to 7 determines whether or not the conditions are satisfied in the order of the tree size, the cost value, and the number of hops (step S83).

  When it is determined in step S83 that the conditions are not satisfied in the order of tree size, cost value, and number of hops, the control unit 14 of each of the wireless nodes 1 to 7 sets p = p + 1 (step S84). Then, the series of operations proceeds to step S82, and the above-described steps S82 to S84 are repeatedly executed until it is determined in step S83 that the conditions are satisfied in the order of tree size, cost value, and number of hops.

  If it is determined in step S83 that the conditions are satisfied in the order of tree size, cost value, and number of hops, the control unit 14 of each of the wireless nodes 1 to 7 determines whether or not p = 1 (step S85). ).

  When it is determined in step S85 that p = 1, the control units 14 of the wireless nodes 1 to 7 set the operation mode to the duty cycling mode (step S86). Thereafter, the same operation as that in step S73 described above is performed (step S87).

  On the other hand, when it is determined in step S85 that p = 1 is not satisfied, the control unit 14 of each of the wireless nodes 1 to 7 determines whether p = 2 (step S88).

  When it is determined in step S88 that p = 2, the control units 14 of the wireless nodes 1 to 7 set the operation mode to the on-demand wake-up mode (step S89). Thereafter, the same operation as that in step S76 described above is executed (step S90).

  On the other hand, when it is determined in step S88 that p = 2 is not true, the control unit 14 of each of the wireless nodes 1 to 7 sets the operation mode to the Delayed Wake-up mode (step S91). Thereafter, the same operation as that in step S78 described above is executed (step S92).

  And after any of step S87, S90, S92, a series of operation | movement is complete | finished.

  When step S83 is executed for the first time, the control unit 14 of each of the wireless nodes 1 to 7 detects the first condition “cost value <512, hop count <2, 100 <tree size” from the correspondence table TBL6. . Then, the control unit 14 of each of the wireless nodes 1 to 7 determines whether or not the tree size satisfies 100 <tree size, and determines that the tree size satisfies 100 <tree size. When it is determined whether or not the value <512 is satisfied, and it is determined that the cost value satisfies the cost value <512, it is finally determined whether or not the hop number satisfies the hop number <2.

  When all of the tree size, the cost value, and the number of hops satisfy the conditions, the control unit 14 of each wireless node 1 to 7 determines that the conditions are satisfied in the order of the tree size, the cost value, and the number of hops.

  On the other hand, when any one of the tree size, the cost value, and the number of hops does not satisfy the condition, the control unit 14 of each wireless node 1 to 7 determines that the conditions are not satisfied in the order of the tree size, the cost value, and the number of hops. To do.

  When step S83 is executed for the second time, the control unit 14 of each of the wireless nodes 1 to 7 sets the second condition “512 ≦ cost value <1024, 2 ≦ hop count <4, 50 <tree size ≦ 100. Is detected from the correspondence table TBL6. Then, the control unit 14 of each of the wireless nodes 1 to 7 determines whether or not the conditions are satisfied in the order of the tree size, the cost value, and the number of hops in the same manner as when step S83 is executed for the first time.

  When step S83 is executed for the third time, the control unit 14 of each of the wireless nodes 1 to 7 sets the third condition “1024 ≦ cost value <1536, 4 ≦ hop count <6, 20 <tree size ≦ 50”. It is detected from the correspondence table TBL6, and similarly, it is determined whether or not the conditions are satisfied in the order of tree size, cost value, and hop count.

  When the operation mode of the wireless node is switched using two of the cost value, the number of hops, and the tree size, the control unit 14 of each wireless node 1 to 7 switches the operation mode according to the flowchart shown in FIG.

  In this case, the control unit 14 of each of the wireless nodes 1 to 7 sequentially determines whether or not the condition is satisfied according to two priorities selected from the cost value, the number of hops, and the tree size.

  When the tree size and the cost value are selected from the cost value, the number of hops, and the tree size, the control unit 14 of each of the wireless nodes 1 to 7 determines whether or not the tree size satisfies the pth condition in step S83. When the tree size satisfies the pth condition, it is determined whether or not the cost value satisfies the pth condition. Then, the control unit 14 of each of the wireless nodes 1 to 7 determines that the conditions are satisfied in the order of the tree size and the cost value when all of the tree size and the cost value satisfy the pth condition.

  On the other hand, when any one of the tree size and the cost value does not satisfy the p-th condition, the control unit 14 of each of the wireless nodes 1 to 7 determines that the condition is not satisfied in the order of the tree size and the cost value.

  When the cost value and the number of hops are selected from the cost value, the number of hops, and the tree size, the control unit 14 of each of the wireless nodes 1 to 7 determines whether or not the cost value satisfies the pth condition in step S83. When the cost value satisfies the pth condition, it is determined whether or not the number of hops satisfies the pth condition. Then, the control unit 14 of each of the wireless nodes 1 to 7 determines that the conditions are satisfied in the order of the cost value and the number of hops when all of the cost value and the number of hops satisfy the p-th condition.

  On the other hand, the control unit 14 of each of the wireless nodes 1 to 7 determines that the condition is not satisfied in the order of the cost value and the number of hops when either the cost value or the number of hops does not satisfy the p-th condition.

  When the tree size and the number of hops are selected from the cost value, the number of hops, and the tree size, the control unit 14 of each wireless node 1 to 7 determines whether or not the tree size satisfies the p-th condition in step S83. When the tree size satisfies the pth condition, it is determined whether or not the number of hops satisfies the pth condition. Then, the control unit 14 of each of the wireless nodes 1 to 7 determines that the conditions are satisfied in the order of the tree size and the number of hops when all of the tree size and the number of hops satisfy the pth condition.

  On the other hand, when any one of the tree size and the number of hops does not satisfy the p-th condition, the control unit 14 of each of the wireless nodes 1 to 7 determines that the conditions are not satisfied in the order of the tree size and the number of hops.

  Thus, the control unit 14 of each of the wireless nodes 1 to 7 switches the operation mode using at least two of the tree size, the cost value, and the number of hops according to the flowchart shown in FIG.

  As described above, it is determined whether or not the conditions are satisfied in the order of the tree size, the cost value, and the number of hops. Therefore, by determining whether or not the conditions are satisfied in the order of the tree size, the cost value, and the number of hops, it is possible to adjust the operation mode suitable for the number of times each of the wireless nodes 1 to 7 transmits and receives the wireless frame.

  In the flowchart shown in FIG. 26, when it is determined in step S71 that the frame transmission number N is 20000 [number / h] or more, the operation mode of the wireless node is set to the duty cycling mode (see step S72). The wakeup signal receiving unit 17 and the wakeup signal determining unit 18 are stopped (see step S73).

  On the other hand, when it is determined in step S71 that the number N of frame transmissions is not 20000 [pieces / h] or more, the operation mode of the wireless node is set to a mode other than the duty cycling mode (see steps S75 and S77). The signal receiving unit 17 and the wake-up signal determining unit 18 perform an intermittent operation (see Steps S76 and S78).

  In the flowchart shown in FIG. 28, when it is determined in step S83 that the conditions are satisfied in the order of tree size, cost value, and number of hops, and it is determined in step S85 that p = 1, The operation mode is set to the duty cycling mode (see step S86), and the wakeup signal receiving unit 17 and the wakeup signal determining unit 18 are stopped (see step S87).

  On the other hand, when it is determined in step S83 that the conditions are satisfied in the order of tree size, cost value, and number of hops, and it is determined that p = 1 is not satisfied in step S85, the operation mode of the wireless node is other than Duty Cycling mode. The mode is set (see steps S89 and S91), and the wakeup signal receiving unit 17 and the wakeup signal determining unit 18 perform an intermittent operation (see steps S90 and S92).

  Therefore, the control unit 14 of each of the wireless nodes 1 to 7 determines the wakeup signal reception unit 17 and the wakeup signal determination based on either the frame transmission number N or the topology information (= cost value, hop number, and tree size). Whether to use the unit 18 is determined.

  Thereby, when it is determined that the wakeup signal reception unit 17 and the wakeup signal determination unit 18 are not used, each wireless node 1 to 7 can reduce the power consumption when receiving the wakeup signal. As a result, the total power amount of each wireless node 1 can be reduced.

  Further, by switching the operation mode of the radio node according to the flowchart shown in FIG. 26 or FIG. 28, the radio node can be operated in an operation mode suitable for the position where the radio node exists or the number of radio frames transmitted and received. As a result, wasteful power consumption in the wireless node can be reduced.

  FIG. 29 is a diagram illustrating a simulation result of the relationship between the average power consumption per node and the sensor data collection period.

  In FIG. 29, the vertical axis represents the average power consumption per node, and the horizontal axis represents the sensor data collection period. The number of wireless nodes used for the simulation is 100.

On the paper surface of FIG. 29, in each sensor data collection period, the leftmost bar graph to the sixth bar graph have sampling intervals T _{interval_min} of 320 [μsec], 640 [μsec], 1280 [μsec], and 2560 [μsec], respectively. , 5120 [μsec], 10240 [μsec], the average power consumption per node is shown. 29, the rightmost bar graph in each sensor data collection period indicates the average power consumption per node when the present invention is applied.

Referring to FIG. 29, the average power consumption per node when the present invention is applied in the sensor data collection period of 1 minute, 5 minutes, 10 minutes, 15 minutes, 30 minutes and 60 minutes is the sampling. This is lower than the average power consumption per node when the interval T _{interval_min} is fixed.

  Further, as the sensor data collection cycle becomes shorter, the amount of power consumption reduced by applying the present invention increases. Therefore, the present invention can greatly reduce the power consumption particularly when the sensor data collection period is short.

  In the above, the present invention has been described by taking the wireless sensor network 10 as an example. However, in the embodiment of the present invention, the present invention is not limited to this, and the present invention has a long sampling interval when detecting the frame length. The sleep state by at least one frame length selected from a plurality of frame lengths including a frame length obtained by adding / subtracting a desired frame length interval to / from an average frame length that becomes longer and shorter as the sampling interval becomes shorter It can be applied to any wireless network as long as the wireless device includes a wireless device that transmits and receives a wireless frame having a frame length representing the identification information.

  In the above description, the number N of frame transmissions is described as the number of transmissions of radio frames per hour. However, in the embodiment of the present invention, the number of frame transmissions N is not limited to this. Any number of radio frames may be transmitted in the time length.

  Furthermore, in the embodiment of the present invention, the operations of the wireless nodes 1 to 7 described above may be executed by a program. In this case, each of the wireless nodes 1 to 7 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Randum Access Memory). And ROM stores the program for performing operation | movement of each wireless node 1-7. When the operations of the wireless nodes 1 to 7 are performed, the CPUs of the wireless nodes 1 to 7 read the program from the ROM and execute the read program. The RAM is used to perform necessary calculations when the CPU is executing a program and to store the calculated results.

  FIG. 30 is a flowchart illustrating a program for causing a computer (CPU) to execute the operations of the wireless nodes 1 to 7.

  Referring to FIG. 30, a program PROG for causing a computer (CPU) to execute the operations of the wireless nodes 1 to 7 includes steps S101 to S107. When the operations of the wireless nodes 1 to 7 are started, the CPU reads the program PROG from the ROM and executes it.

  Then, a frame transmission number N, which is the number of radio frames transmitted in a desired time length, is determined (step S101).

Thereafter, suitable sampling when the total power amount, which is the sum of the received power amount when receiving a radio frame and the transmission power amount when transmitting a radio frame, is minimized. The interval T _{interval_min} is determined according to the determined frame transmission number N by the above-described method (step S102). In this case, a suitable sampling interval T _{interval_min} may be determined corresponding to the number N of frame transmissions using the correspondence table TBL1.

Then, a suitable sampling interval T _{interval_min} or frame transmission number N is adjusted using topology information indicating the topology of the wireless device in the wireless network (step S103). In this case, adjustment of a suitable sampling interval T _{interval — min} or the number N of frame transmissions is performed according to the flowchart shown in FIG.

  After step S103, it is determined whether or not to use the wakeup signal reception unit 17 and the wakeup signal determination unit 18 based on either the number N of frame transmissions or the topology information indicating the topology of the wireless device in the wireless network. (Step S104). When it is determined whether to use the wakeup signal receiving unit 17 and the wakeup signal determining unit 18 based on the number N of frame transmissions, the determination operation is executed according to the flowchart shown in FIG. When it is determined whether or not to use the wakeup signal receiving unit 17 and the wakeup signal determining unit 18 based on the above, the determination operation is executed according to the flowchart shown in FIG.

  When it is determined in step S104 that the wakeup signal receiving unit 17 and the wakeup signal determining unit 18 are not used, the series of operations proceeds to step S106.

On the other hand, when it is determined in step S104 that the wakeup signal reception unit 17 and the wakeup signal determination unit 18 are to be used, the wakeup signal reception unit 17 and the wakeup signal determination unit 18 receive the radio frame and are preferable. The sampling interval T _{interval_min} is operated (step S105).

  In step S104, when it is determined not to use the wakeup signal receiving unit 17 and the wakeup signal determining unit 18, or after step S105, the MAC address of the wireless device (= any of the wireless nodes 1 to 7). Based on the above, the frame length indicating the identification information is acquired from the correspondence table TBL3 or TBL5 indicating the correspondence between the frame length and the bit value (step S106).

  Thereafter, a radio frame having the acquired frame length is transmitted (step S107). As a result, a series of operations is completed.

  In step S101, the frame transmission number N is determined by one of two methods. The first method includes a predetermined data collection cycle, a transmission cycle of control packets DIO and DAO for building and / or maintaining a topology of a wireless device in a wireless network, a tree size (= topology is hierarchical structure) The total number of wireless devices existing in a lower layer than the wireless device on which the program PROG is executed and located at one hop or more from the wireless device on which the program PROG is executed). This is a method of calculating the frame transmission number N by calculating the total number of frames and increasing the total number of radio frames in consideration of link communication quality with respect to the calculated total number of radio frames.

  The second method is a method of detecting the number N of frame transmissions by measuring the number of transmissions of radio frames in a desired time length.

In step S102, a suitable sampling interval T _{interval_min} may be determined periodically.

  In the embodiment of the present invention, the program PROG only needs to include at least steps S102 and S105. This is because if at least steps S102 and S105 are executed, the overall power consumption of the wireless device (= any of wireless nodes 1 to 7) can be reduced.

In the embodiment of the present invention, the sampling interval determination unit 16 that determines the sampling interval T _{interval — min} constitutes “determination means”.

  In the embodiment of the present invention, wakeup signal receiver 17 and wakeup signal determiner 18 constitute a “receiver”.

  Furthermore, in the embodiment of the present invention, the sampling interval determination unit 16 that calculates the number N of frame transmissions constitutes “calculation means”.

  Furthermore, in the embodiment of the present invention, the wireless communication unit 13 that measures the number N of frame transmissions constitutes “detection means”.

Furthermore, in the embodiment of the present invention, the sampling interval T _{interval — min} constitutes a “suitable sampling interval”.

Furthermore, in the embodiment of the present invention, the sampling interval determination unit 16 that adjusts the sampling interval T _{interval_min} or the frame transmission number N using the topology information constitutes “adjustment means”.

  Furthermore, in the embodiment of the present invention, based on the MAC address of the wireless node for shifting from the sleep state to the activated state, the wireless node for shifting from the sleep state to the activated state from the correspondence table TBL3 or the correspondence table TBL5 The control unit 14 that acquires the frame length indicating the identification information constitutes “acquisition means”.

  Furthermore, in the embodiment of the present invention, the correspondence table TBL1 constitutes a “first correspondence table”, and the correspondence table TBL3 or the correspondence table TBL5 constitutes a “second correspondence table”.

  Furthermore, in the embodiment of the present invention, it is determined whether or not to use the wakeup signal receiving unit 17 and the wakeup signal determining unit 18 (receiver) based on either the frame transmission number N or the topology information. The control unit 14 constitutes “determination means”.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  The present invention is applied to a radio apparatus, a radio communication system including the radio apparatus, and a program executed in the radio apparatus.

  1 to 7 wireless nodes, 10 wireless sensor networks, 11 and 12 antennas, 13 wireless communication units, 14 control units, 15 path control units, 16 sampling interval determination units, 17 wakeup signal reception units, 18 wakeup signal determination units, 19 Frame length correspondence table.

Claims (19)

From the plurality of frame lengths including the frame length obtained by adding / subtracting the desired frame length interval to / from the average frame length that becomes longer as the sampling interval when detecting the frame length becomes longer and becomes shorter as the sampling interval becomes shorter A wireless device that represents wireless device identification information by at least one selected frame length, and transmits and receives a first wireless frame having a frame length representing the identification information,
The total power amount that is the sum of the reception power amount that is the power consumption amount when receiving the first radio frame and the transmission power amount that is the power consumption amount when transmitting the first radio frame is minimized. Determining means for determining a suitable sampling interval corresponding to the number of frame transmissions that is the number of transmissions of the first radio frame in a desired time length;
And a receiver that receives the first radio frame and operates at the preferred sampling interval. Pre-determined data collection period, transmission period of control packets for establishing and / or maintaining the topology of the wireless device in the wireless network, and existing in a lower layer than the wireless device when the topology has a hierarchical structure In addition, the total number of radio frames is calculated using the total number of radio devices existing at a position of 1 hop or more from the radio device, and the communication quality of the link is considered with respect to the calculated total number of radio frames. Further comprising computing means for computing the number of frame transmissions by increasing the total number of radio frames;
The radio apparatus according to claim 1, wherein the determining unit determines the suitable sampling interval corresponding to the number of frame transmissions calculated by the calculating unit. Detecting means for detecting the number of frame transmissions by measuring the number of transmissions of the first radio frame in the desired time length;
The radio apparatus according to claim 1, wherein the determination unit determines the suitable sampling interval corresponding to the number of frame transmissions detected by the detection unit.   The wireless device according to any one of claims 1 to 3, wherein the determining unit periodically determines the suitable sampling interval.   The determination unit holds a first correspondence table indicating a correspondence relationship between the number of frame transmissions and the sampling interval, and determines the suitable sampling interval with reference to the first correspondence table. The wireless device according to any one of claims 1 to 3.   6. The wireless device according to claim 1, further comprising an adjusting unit that adjusts the suitable sampling interval or the number of frame transmissions using topology information indicating a topology of a wireless device in a wireless network. .   The topology information includes, when the topology has a hierarchical structure, a cost value indicating a proximity to a radio device located at the highest level, a hop number indicating a proximity to the radio device located at the highest level, and The wireless device according to claim 6, comprising at least one of a total number of wireless devices existing in a lower layer than the wireless device and located at a position of 1 hop or more from the wireless device.   Corresponding to each sampling interval, a second correspondence table indicating a correspondence relationship between a frame length and a bit value is held, and the identification information is obtained from the second correspondence table based on the MAC address of the wireless device. The radio apparatus according to claim 1, further comprising an acquisition unit configured to acquire a frame length indicating   The determination unit according to any one of claims 1 to 8, further comprising determination means for determining whether to use the receiver based on either the number of frame transmissions or topology information indicating a topology of a wireless device in a wireless network. The wireless device according to item 1.   A wireless communication system comprising the wireless device according to any one of claims 1 to 9. From the plurality of frame lengths including the frame length obtained by adding / subtracting the desired frame length interval to / from the average frame length that becomes longer as the sampling interval when detecting the frame length becomes longer and becomes shorter as the sampling interval becomes shorter A program for causing a computer to execute identification in a wireless device that transmits and receives a first wireless frame having a frame length representing the identification information, representing the identification information of the wireless device by at least one selected frame length,
The total power amount that is the sum of the reception power amount that is the power consumption amount when receiving the first radio frame and the transmission power amount that is the power consumption amount when transmitting the first radio frame is minimized. A first step of determining a suitable sampling interval corresponding to the number of frame transmissions that is the number of transmissions of the first radio frame in a desired time length;
A program for causing a computer to execute a second step of receiving the first radio frame and operating at the preferred sampling interval. From a data collection cycle determined in advance, a transmission cycle of a control packet for constructing and / or maintaining a topology of a wireless device in a wireless network, and a wireless device on which the program is executed when the topology has a hierarchical structure And the total number of radio frames using the total number of radio devices existing in the lower layer and located at a position of 1 hop or more from the radio device on which the program is executed. On the other hand, the computer further executes a third step of calculating the number of frame transmissions by increasing the total number of the radio frames in consideration of the communication quality of the link,
12. The program for causing a computer to execute according to claim 11, wherein in the first step, the suitable sampling interval is determined in accordance with the number of frame transmissions calculated in the third step. Causing the computer to further execute a fourth step of measuring the number of transmissions of the first radio frame in the desired time length and detecting the number of frame transmissions;
The computer-executable program according to claim 11, wherein in the first step, the suitable sampling interval is determined in correspondence with the number of frame transmissions detected in the fourth step.   The program for causing a computer to execute the computer according to any one of claims 11 to 13, wherein in the first step, the suitable sampling interval is periodically determined.   14. The method according to claim 11, wherein in the first step, the suitable sampling interval is determined with reference to a first correspondence table indicating a correspondence relationship between the number of frame transmissions and the sampling interval. A program for causing a computer according to claim 1 to execute.   16. The computer according to any one of claims 11 to 15, further causing a computer to execute a fifth step of adjusting the suitable sampling interval or the number of frame transmissions using topology information indicating a topology of a wireless device in a wireless network. A program to be executed by the computer described in 1.   The topology information includes, when the topology has a hierarchical structure, a cost value indicating a proximity to a radio device located at the highest level, a hop number indicating a proximity to the radio device located at the highest level, and 17. The wireless device according to claim 16, comprising at least one of a total number of wireless devices that exist in a lower layer than a wireless device on which a program is executed and are located at one hop or more from a wireless device on which the program is executed. To run on a computer.   A sixth step of acquiring a frame length indicating the identification information from a second correspondence table indicating a correspondence relationship between the frame length and the bit value corresponding to each sampling interval based on the MAC address of the wireless device; A program for causing a computer to execute the program according to any one of claims 11 to 17.   12. The computer further executes a seventh step of determining whether to use the receiver based on either the number of frame transmissions or topology information indicating a topology of a wireless device in a wireless network. Item 19. A program for causing a computer according to any one of items 18 to execute.

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