JP2015211272A - Radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication system that can reduce the probability of data collision when a communication path is constructed, and enables selection of a transmission destination node from plural candidate nodes.SOLUTION: Each of a slave unit 10 and a relay unit 30 transmits data through broadcast when a transmission destination node is not determined. Upon reception of data from any one of the slave unit 10 and the relay unit 30, a master unit 20 adds final destination information to ACK, and transmits the ACK to a transmission source node. Upon reception of ACK added with final destination information from an upper node of the communication passage, each of the slave unit 10 and the relay unit 30 sets the transmission source node of ACK as a transmission destination candidate node for next transmission. When receiving ACK added with final destination information at a predetermined number of times, each of the slave unit 10 and the relay unit 30 determines the transmission destination node for next transmission from candidate nodes from which the final destination information corresponding to the predetermined number of times are transmitted, and transmits data to a transmission destination node by unicast for subsequent communications.

Description

  The present invention relates to a wireless communication system, and more particularly, to a wireless communication system that relays and transmits communication between nodes using a relay node.

  Conventionally, a network system that performs multi-hop wireless communication between a base station node device and a plurality of child node devices has been proposed (see, for example, Patent Document 1).

  In this network system, a measuring device is connected to each of a plurality of child node devices. When a base station node device requests data from a child node device connected to a certain measuring device, if the connection relationship with this child node device is unknown, a request packet for requesting data is sent to the transmission destination. It transmits by broadcast without specifying the child node device to be.

  When the child node device receives the request packet from the base station node device, if the transmission destination address of the request packet does not match the device ID, the child node device functions as a relay node and sends the request packet to another child device. Broadcast transmission to the node device. As described above, the reception and broadcast transmission of the request packet by the child node device are repeated, so that the request packet is eventually received by the child node device to which the destination measuring device is connected. The child node device connected to the transmission destination measurement device creates a response packet to the request packet from the base station node device, specifies the transmission destination node device, and transmits it by unicast. Here, the header of the response packet includes the device ID of the child node device that created the response packet and the communication path to the base station node device, and reception and unicast transmission by the child node device are repeated. Thus, the data is finally transmitted to the base station node device.

JP 2013-74355 A

  In the network system of Patent Document 1, when a request packet is broadcast from a base station node device to a specific child node device, relay processing is performed between the nodes, so that the transmission destination child node device and the base station node device The connection relationship between them is specified. For this reason, there is a possibility that subsequent communication may be performed on the communication path that succeeded in communication first, even though there are other communication paths with good communication conditions.

  The present invention has been made in view of the above problems, and provides a wireless communication system that can reduce the possibility of transmission data colliding when constructing a communication path and can select a destination node from a plurality of candidate nodes. The purpose is to do.

  The wireless communication system of the present invention performs wireless communication between a first node of a transmission source having a wireless communication function, a second node of a transmission destination having a wireless communication function, and the first node and the second node. A plurality of third nodes having a relay function. In a state where a communication path for transmitting data from the first node to the second node is not established, the first node and the third node are configured to transmit data by broadcast. When the second node receives data from any one of the first node and the third node, the second node adds final destination information indicating that communication with the second node is possible to the ACK, and is a source node Configured to send to. When each of the first node and the third node receives the ACK to which the final destination information is added from an upper node of a communication path, the ACK transmission source node is set as a transmission destination candidate node at the next transmission time. It is comprised so that. When each of the first node and the third node receives the ACK to which the final destination information is added a predetermined number of times, each of the first node and the third node transmits the next time from among the candidate nodes that have transmitted the final destination information for the predetermined number of times. It is configured to determine the destination node at the time. Each of the first node and the third node is configured to transmit data to the transmission destination node by unicast in subsequent communication.

  In this wireless communication system, each of the first node and the third node preferably determines the candidate node having the smallest number of relay hops as the transmission destination node from among the candidate nodes.

  In this wireless communication system, each of the first node and the third node sets an arrival delay time required for data to reach from the first node to the second node under a condition for determining the transmission destination node. It is also preferable to combine them.

  In this wireless communication system, each of the first node and the third node includes a plurality of relay hop numbers, received signal strengths, and arrival delay times required for data to reach from the first node to the second node. It is also preferable that the destination node is determined from the candidate nodes based on the above condition.

  In this wireless communication system, when each of the first node and the third node receives the ACK with the final destination information added, and the received signal strength of the ACK is less than a predetermined threshold, It is also preferable to discard the final destination information added to the ACK. Each of the first node and the third node is preferably configured not to set the ACK transmission source node as the candidate node.

  In this wireless communication system, each of the first node, the second node, and the third node preferably includes a setting unit for setting the predetermined number of times to a desired number.

  In this wireless communication system, it is also preferable that the third node is configured not to transmit the final destination information to a lower node of the communication path until the transmission destination node is determined.

  In this wireless communication system, each of the first node and the third node is unicast to the destination node when data transmission to the destination node fails in a state determined by the destination node. When the data transmission fails again, it is also preferable that the data is transmitted by broadcasting to reconstruct the communication path to the second node.

  In this wireless communication system, each of the first node and the third node has the candidate node that received the final destination information last as the transmission destination node if the communication conditions of the candidate nodes are the same. It is also preferred to be configured to determine as

  In this wireless communication system, when each of the first node and the third node determines the transmission destination node, it adds route information for specifying a communication route to the data when transmitting data next time. It is also preferably configured to transmit.

  According to the present invention, a destination node can be selected from a plurality of candidate nodes. In addition, since the node determined as the destination node among the first node and the third node transmits data by unicast, the number of ACKs to be transmitted is reduced as compared with the case of transmitting by broadcast. Decreases, and the probability that transmission data collides decreases.

It is explanatory drawing which shows an example of the communication procedure by the radio | wireless communications system of this embodiment. It is a block diagram of the subunit | mobile_unit of this embodiment. It is a block diagram of the main | base station of this embodiment. It is a block diagram of the relay machine of this embodiment. It is explanatory drawing which shows an example of the communication procedure by the radio | wireless communications system of this embodiment. It is explanatory drawing which shows an example of the communication procedure by the radio | wireless communications system of this embodiment. It is explanatory drawing which shows an example of the communication procedure by the radio | wireless communications system of this embodiment. It is explanatory drawing which shows an example of the communication procedure by the radio | wireless communications system of this embodiment. It is explanatory drawing which shows an example of the communication procedure by the radio | wireless communications system of this embodiment. It is explanatory drawing which shows an example of the communication procedure by the radio | wireless communications system of this embodiment.

  An embodiment of a wireless communication system according to the present invention will be described with reference to the drawings.

  FIG. 1 shows a schematic configuration of the wireless communication system of the present embodiment. The wireless communication system according to the present embodiment includes a plurality of (for example, three in the illustrated example) slave units (first node) 10 that are data transmission sources and a master unit (second node) 20 that is a data transmission destination. And a plurality of relay machines (third nodes) 30 (for example, nine in the illustrated example). Note that the wireless communication system of the present embodiment includes nine repeaters 30, but the number of repeaters 30 is not limited to nine, and it is sufficient if there is a necessary number for signal relay. In addition, the wireless communication system of the present embodiment includes three slave units 10 that are data transmission sources, but the number of slave units 10 is not limited to three, and can be changed as appropriate. .

  Each of the slave unit 10, the master unit 20, and the relay unit 30 includes a radio communication unit that does not require a radio license (for example, a specific low-power radio module, a radio communication unit that conforms to the IEEE 802.15.1 standard, IEEE 802.15. Wireless communication unit compliant with the standard No. 4). Here, if the child device 10 and the parent device 20 are within communication ranges of each other and the communication environment between the child device 10 and the parent device 20 is good, the wireless communication between the child device 10 and the parent device 20 is performed. Communication takes place directly. However, if the handset 10 and the base unit 20 cannot communicate directly, or if communication is possible but the communication environment is not good, wireless communication between the handset 10 and the base unit 20 via the relay device 30 is possible. Done. Therefore, the plurality of relay devices 30 are arranged so that other adjacent relay devices 30 exist in the communication area so that the wireless communication between the child device 10 and the parent device 20 can be relayed. A relay communication network is constructed by 10, parent device 20, and a plurality of relay devices 30. Individual node numbers are assigned to the child device 10, the parent device 20, and the relay device 30 in order to identify individual nodes in the network. In the wireless communication system of the present embodiment, the node number of the master unit 20 is set to “0”, the node numbers “1” to “9” are set to each of the nine repeaters 30, and three child units are set. Node numbers “11”, “12”, and “13” are set for each of the machines 10. In FIG. 1 and FIGS. 5 to 10, the numbers in the squares indicating the child device 10, the parent device 20, and the relay device 30 are assigned to the child device 10, the parent device 20, and the relay device 30, respectively. Indicates the node number.

  Next, the structure of the subunit | mobile_unit 10, the main | base station 20, and the relay machine 30 is demonstrated based on FIGS.

  As shown in FIG. 2, the slave unit 10 includes an MCU (Micro Control Unit) 100, a measurement unit 101, a storage unit 102, a wireless communication unit 103, an antenna 104, an operation unit 105, a display unit 106, A power supply unit 107 and a wired communication unit 108. The subunit | mobile_unit 10 wirelessly transmits the data which the measurement part 101 measured with the predetermined measurement timing to the main | base station 20. FIG.

  The MCU 100 performs overall control of the slave unit 10.

  The measuring unit 101 is for measuring temperature, for example, and includes a thermistor whose electric resistance changes according to the ambient temperature, and measures the ambient temperature by measuring the resistance value of the thermistor. Note that the measurement target of the measurement unit 101 is not limited to temperature, and a physical quantity corresponding to the purpose of use or application such as ambient humidity and illuminance may be measured.

  The storage unit 102 is configured by an electrically rewritable nonvolatile memory such as an EEPROM (electrically erasable and programmable read-only memory) or a flash memory. The storage unit 102 writes and reads data by the MCU 100, and stores identification information (address and node number) assigned to the child device 10, measurement data by the measurement unit 101, communication path information, and the like.

  The wireless communication unit 103 includes a wireless module that conforms to a specific low power wireless communication standard, for example, and transmits or receives a wireless signal via the antenna 104.

  The wired communication unit 108 is connected to a device such as a setting device (not shown) via a communication line, for example, and performs communication using a wired communication method.

  The operation unit 105 is used, for example, for setting a lower limit value and an upper limit value of a measurement range by the measurement unit 101, a measurement interval, and a measurement data transmission interval. The operation unit 105 is also used to set the number of final destination information received when determining a transmission destination node, that is, the number of ACKs (predetermined number of times) to which the final destination information is added.

  The display unit 106 includes, for example, one or more light emitting diodes, and lighting / extinguishing is controlled by the MCU 100.

  The power supply unit 107 supplies power necessary for the operation to the internal circuit of the slave unit 10 using, for example, a battery as a power source.

  As shown in FIG. 3, the base unit 20 includes an MCU 200, a storage unit 201, a wireless communication unit 202, an antenna 203, a wired communication unit 204, an operation unit 205, a display unit 206, and a power supply unit 207. It has.

  The MCU 200 performs overall control of the parent device 20.

  The storage unit 201 is configured by an electrically rewritable nonvolatile memory such as an EEPROM or a flash memory. The storage unit 201 writes and reads data by the MCU 200, and stores identification information assigned to the parent device 20, measurement data collected from the child device 10, communication path information, and the like.

  The wireless communication unit 202 includes, for example, a wireless module conforming to a specific low power wireless communication standard, and transmits or receives a wireless signal via the antenna 203.

  The wired communication unit 204 is connected to, for example, a server (not shown) via a communication line, and transmits data collected from the child device 10 to the server by a wired communication method.

  The operation unit 205 is used, for example, for performing operation settings of the parent device 20. In addition, when the base unit 20 is the transmission source, the operation unit 205 determines the number of final destination information received when determining the transmission destination node, that is, the number of ACKs with the final destination information added (predetermined number of times). Also used to set.

  The display unit 206 includes, for example, one or a plurality of light emitting diodes, and lighting / extinguishing is controlled by the MCU 200.

  The power supply unit 207 receives power supplied from, for example, a commercial power supply, and supplies power necessary for operation to the internal circuit of the parent device 20.

  As shown in FIG. 4, the repeater 30 includes an MCU 300, a storage unit 301, a wireless communication unit 302, an antenna 303, an operation unit 304, a display unit 305, a power supply unit 306, and a wired communication unit 307. It has.

  The MCU 300 performs overall control of the repeater 30.

  The storage unit 301 is configured by an electrically rewritable nonvolatile memory such as an EEPROM or a flash memory. The storage unit 301 writes and reads data by the MCU 300, identification information assigned to the own device, data received by the wireless communication unit 302, data transmitted by the wireless communication unit 302 in the past, communication path This information is stored.

  The wireless communication unit 302 includes, for example, a wireless module that conforms to a specific low-power wireless communication standard, and transmits or receives a wireless signal via the antenna 303.

  The wired communication unit 307 is connected to a device such as a setting device (not shown) via a communication line and performs communication using a wired communication method.

  The operation unit 304 is used, for example, for setting the operation of the relay machine 30. The operation unit 304 is also used to set the number of final destination information received when determining the transmission destination node, that is, the number of ACKs to which the final destination information is added (a predetermined number of times).

  The display unit 305 includes, for example, one or more light emitting diodes, and lighting / extinguishing is controlled by the MCU 300.

  The power supply unit 306 supplies power necessary for operation to the internal circuit of the repeater 30 using, for example, a battery as a power source. Since the relay machine 30 is powered by a battery, the relay machine 30 can be installed and used in any place. The power supply unit 306 may receive power supplied from a commercial power supply and supply power necessary for operation to the internal circuit of the repeater 30.

  Next, in the wireless communication system of the present embodiment, data (for example, measurement data) is transmitted from the child device 10 to the parent device 20 in a state where the communication path between the child device 10 and the parent device 20 is not established. Processing will be described with reference to FIGS. 1 and 5 to 10. Note that a separate node number is assigned to each of the slave unit 10, the master unit 20, and the plurality of relay units 30, and in the following, the node numbers are used to distinguish and describe the plurality of relay units 30. To explain. For example, the relay device 30 with the node number “2” is expressed as the second relay device 30, and the child device 10 with the node number “11” is expressed as the eleventh child device 10. 1 and 5 to 10 indicate communication between nodes, a solid arrow line indicates a data transmission process, and a dotted arrow line indicates an ACK transmission process. Further, when X is added to the head of the dotted arrow line, it means that the transmission of ACK is stopped.

  Refer to FIG. 1 for the communication procedure when the eleventh slave unit 10 transmits measurement data for the first time in a state where the communication path for transmitting data from the eleventh slave unit 10 to the master unit 20 is not established. I will explain.

  The MCU 100 of the eleventh handset 10 starts from the sleep mode at a predetermined sampling interval (for example, an interval of several seconds to several minutes), and causes the measurement unit 101 to measure the temperature. Since the transmission destination node is not determined, the eleventh child device 10 transmits data by broadcast. That is, the MCU 100 of the slave unit 10 stores the measurement data of the measurement unit 101 and the individual sequence numbers assigned to the transmission data, the destination address as the broadcast address, the transmission source address and the data source address as the address of its own unit. Create the transmitted data. An individual node number assigned to each node is used as the address. And MCU100 of the subunit | mobile_unit 10 transmits the produced transmission data by the broadcast from the wireless communication part 103 (process T1 of FIG. 1).

  In the example of FIG. 1, there are six relay devices 30 with node numbers 4 to 9 in the communication range of the eleventh slave device 10, and the data transmitted from the eleventh slave device 10 is the data of these six slave devices 10. Received by the wireless communication unit 302 of the repeater 30. The MCU 300 of each repeater 30 extracts measurement data, a sequence number, a destination address (broadcast address), a transmission source address, and a data source address from the received data. In the present embodiment, the MCU 300 of each relay device 30 sets a wait time until an ACK (acknowledgement) is transmitted to a random time when data is received. In the example of FIG. 1, the wait time of the fourth repeater 30 is shorter than the wait time of the other repeaters 30. For this reason, the MCU 300 of the fourth repeater 30 controls the wireless communication unit 302 after the wait time elapses earlier than the other repeaters 30, and transmits an ACK to the transmission source child device 10 (FIG. 1). Process T2). When receiving the ACK transmitted after the data transmission, the slave unit 10 switches to the sleep mode after a predetermined time and reduces power consumption.

  The 5th and 6th relay devices 30 and the slave device 10 exist within the communication range of the 4th relay device 30, and the ACK transmitted by the 4th relay device 30 is not only the slave device 10 but also the 5th. , Are also received by the wireless communication unit 302 of the sixth repeater 30. The MCU 300 of the 5th and 6th relay devices 30 stops the relay operation and does not transmit ACK because the 4th relay device 30 transmits ACK to the transmission data from the child device 10. Note that the seventh to ninth repeaters 30 perform the relay operation because they cannot receive the ACK transmitted by the fourth repeater 30. However, since there is no communication path for data to reach from the 7th to 9th relay devices 30 to the parent device 20, the 7th to 9th relay devices 30 wait for reception after repeating the relay process a prescribed number of times. It becomes.

  The MCU 300 of the fourth relay device 30 extracts the measurement data, the sequence number, the destination address, the transmission source address, and the data source address from the transmission data from the child device 10. The MCU 300 of the fourth relay device 30 includes the measurement data extracted from the transmission data and the sequence number, the destination address is the broadcast address, the transmission source address is the own device address, and the data source address is the eleventh child device 10 address. Create the transmission data. Then, the MCU 300 of the fourth repeater 30 causes the wireless communication unit 302 to transmit the transmission data by broadcast when the wait time has elapsed from the time of data reception (process T3 in FIG. 1). In the example of FIG. 1, the 1st, 2nd, 5th relays 30 and the slave unit 10 exist in the communication area of the 4th relay 30 and the data transmitted by broadcast from the 4th relay 30 Are received by the wireless communication unit 302 of the first, second, and fifth repeaters 30. Since the handset 10 is switched to the sleep mode when receiving ACK after data transmission, the data transmitted from the fourth relay device 30 is not received by the handset 10. Note that the wait time from when the relay device 30 receives data from the lower node to when the received data is relay-transmitted may be set to a random time or may be set to a certain time.

  When the wireless communication unit 302 of the No. 1, No. 2, No. 5 repeater 30 receives transmission data from the No. 4 repeater 30, the MCU 300 of these No. 30 repeaters receives measurement data and a sequence from the received data. The number, destination address, source address and data source address are extracted. As described above, the wait time until each repeater 30 transmits an ACK is set to a random time. In the example of FIG. 1, the wait time of the first repeater 30 is the second, fifth. It is shorter than the wait time of the repeater 30. Therefore, the MCU 300 of the first repeater 30 controls the wireless communication unit 302 after the wait time elapses earlier than the other repeaters 30, and transmits an ACK to the fourth repeater 30 of the transmission source ( Process T4 in FIG. 1). The ACK transmitted from the first repeater 30 to the fourth repeater 30 is received not only by the fourth repeater 30 but also by the wireless communication unit 302 of the second and fifth repeaters 30. Since the MCU 300 of the second and fifth repeaters 30 transmits an ACK to the transmission data from the fourth repeater 30 by another repeater (in this case, the first repeater 30), the relay operation is performed. And no ACK is sent.

  Thereafter, the MCU 300 of the first relay device 30 extracts the measurement data and the sequence number from the transmission data from the fourth relay device 30. The MCU 300 of the first relay device 30 includes the measurement data and the sequence number, the destination address is the broadcast address, the transmission source address is the address of the own device, and the data source address is the address of the eleventh child device 10. Create transmission data. Then, the MCU 300 of the first relay device 30 transmits this transmission data by broadcast from the wireless communication unit 302 when a random wait time has elapsed since the transmission of the ACK (process T5 in FIG. 1). Since the parent device 20 exists within the communication range of the first relay device 30, data transmitted by broadcast from the first relay device 30 is received by the parent device 20.

  When the wireless communication unit 202 receives the transmission data from the first relay device 30, the MCU 200 of the parent device 20 takes in the measurement data, the sequence number, the transmission source address, and the data source address from the received data. Then, the MCU 200 of the parent device 20 sends an ACK with final destination information indicating that communication with the parent device 20 is possible from the wireless communication unit 202 to the transmission source relay device 30 (in this case, the first relay device 30). Transmit (process T6 in FIG. 1). In the present embodiment, the base unit 20 is configured to transmit ACK without providing a wait time. When the base unit 20 receives data, the base unit 20 receives an ACK earlier than the other relay units 30. Sent. In the present embodiment, the final destination information is the number of relay hops to the base unit 20, and the number of relay hops to the base unit 20, that is, data "1" is added to the first relay unit 30. ACK is sent. Note that when the 4th and 1st relays 30 transmit ACKs in the processes T2 and T4, respectively, the 4th and 1st relays 30 have not received the final destination information from the upper node, so the 4th and 1st The final destination information is not added to the ACK transmitted from the first repeater 30. In other words, data indicating that the number of relay hops is zero is added to the ACK transmitted from the fourth repeater 30 in process T2.

  When the wireless communication unit 302 of the first relay device 30 receives the ACK transmitted from the parent device 20, the MCU 300 of the relay device 30 determines that the final destination information added to the ACK is 1, so that the parent device 20 is determined to be able to communicate directly with 20 and the next transmission destination node is determined as the parent device 20. That is, the MCU 300 of the first relay device 30 transmits data to the parent device 20 by unicast after the next time.

  Here, in the series of communications shown in FIG. 1, information obtained by the eleventh slave unit 10 and the first and fourth relay units 30 is as shown in Table 1 below. Only get the final destination information.

  Next, a communication procedure when the eleventh handset 10 transmits measurement data for the second time will be described with reference to FIG. Note that description of communication procedures common to the communication procedures described with reference to FIG. 1 is omitted.

  At the next transmission timing, the eleventh handset 10 starts from the sleep mode and transmits transmission data storing the measurement data and the sequence number by broadcast (process T11 in FIG. 5).

  In the example of FIG. 5, the MCU 300 of the sixth repeater 30 controls the wireless communication unit 302 after the wait time elapses earlier than the other repeaters 30 to transmit an ACK to the transmission slave unit 10 ( Process T12 in FIG. 5). When receiving the ACK transmitted after the data transmission, the slave unit 10 switches to the sleep mode after a predetermined time and reduces power consumption.

  Within the communication area of the 6th relay device 30, the 4th, 5th relay device 30 and the child device 10 exist, and the ACK transmitted by the 6th relay device 30 is not only the child device 10 but also the 4th device. It is also received by the wireless communication unit 302 of the fifth repeater 30. The MCU 300 of the 4th and 5th relay devices 30 stops the relay operation and does not transmit the ACK because the 6th relay device 30 transmits the ACK for the same data as the received data.

  The MCU 300 of the sixth relay device 30 extracts the measurement data, the sequence number, the destination address, the transmission source address, and the data source address from the transmission data from the child device 10. The MCU 300 of the sixth relay device 30 includes the measurement data extracted from the transmission data and the sequence number, the destination address is the broadcast address, the transmission source address is the own device address, and the data source address is the eleventh child device 10. Create transmission data with addresses. Then, the MCU 300 of the sixth repeater 30 causes the wireless communication unit 302 to transmit the transmission data by broadcast when a random wait time has elapsed since the transmission of the ACK (process T13 in FIG. 5). In the example of FIG. 5, the second, third, fifth, and eleventh slave devices 10 and the tenth child device 10 exist in the communication area of the sixth relay device 30 and are transmitted from the sixth relay device 30 by broadcast. The received data is received by the wireless communication unit 302 of the second, third, and fifth repeaters 30. The 11th handset 10 is switched to the sleep mode when receiving ACK after data transmission, and therefore the data sent from the 6th repeater 30 is not received by the 11th handset 10.

  When the wireless communication unit 302 of the second, third, and fifth repeaters 30 receives the transmission data from the sixth repeater 30, the MCU 300 of these repeaters 30 determines the measurement data and sequence from the received data. The number, destination address, source address and data source address are extracted. As described above, the wait time until each repeater 30 transmits an ACK is set to a random time. In the example of FIG. 5, the wait time of the third repeater 30 is the second, fifth. It is shorter than the wait time of the repeater 30. Therefore, the MCU 300 of the third repeater 30 controls the wireless communication unit 302 after the wait time elapses earlier than the other repeaters 30, and transmits an ACK to the sixth repeater 30 of the transmission source (FIG. 5 process T14). The ACK transmitted from the third repeater 30 to the sixth repeater 30 is also received by the second and fifth repeaters 30. The second and fifth repeaters 30 stop the relay operation and do not transmit ACK because the third repeater 30 transmits ACK for the transmission data from the sixth repeater 30.

  Thereafter, the MCU 300 of the third relay device 30 extracts the measurement data, the sequence number, the destination address, the transmission source address, and the data source address from the transmission data from the sixth relay device 30. The MCU 300 of the third relay device 30 includes transmission data including the measurement data and the sequence number, the destination address as the broadcast address, the transmission source address as the own device address, and the data source address as the eleventh child device 10 address. create. Then, the MCU 300 of the third repeater 30 causes the wireless communication unit 302 to transmit this transmission data by broadcast when a random wait time has elapsed since the transmission of the ACK (process T15 in FIG. 5). Since the parent device 20 exists within the communication range of the third relay device 30, data transmitted by broadcast from the third relay device 30 is received by the parent device 20.

  When the wireless communication unit 202 receives transmission data from the third relay device 30, the MCU 200 of the parent device 20 captures measurement data, sequence number, destination address, transmission source address, and data source address from the received data. Then, the MCU 200 of the parent device 20 transmits the ACK to which the final destination information is added from the wireless communication unit 202 to the transmission source relay device 30 (in this case, the third relay device 30) (process T16 in FIG. 1). .

  When the wireless communication unit 302 of the third relay device 30 receives the ACK transmitted from the parent device 20, the MCU 300 of the relay device 30 determines that the final destination information added to the ACK is 1, so that the parent device 20 is determined to be able to communicate directly with 20 and the next transmission destination node is determined as the parent device 20. That is, the MCU 300 of the third relay device 30 transmits data to the parent device 20 by unicast from the next time.

  Here, in the series of communications shown in FIG. 5, the information obtained by the eleventh slave unit 10 and the third and sixth repeaters 30 is as shown in Table 2 below. The machine 30 acquires final destination information.

  Next, a communication procedure when the eleventh handset 10 transmits measurement data for the third time will be described with reference to FIG. Note that description of communication procedures common to the communication procedures described with reference to FIGS. 1 and 5 is omitted.

  At the next transmission timing, the eleventh handset 10 starts from the sleep mode and transmits transmission data storing the measurement data and the sequence number by broadcast (process T21 in FIG. 6).

  In the example of FIG. 6, the MCU 300 of the fifth relay device 30 controls the wireless communication unit 302 to transmit an ACK to the transmission source child device 10 after the wait time elapses earlier than the other relay devices 30 ( Process T22 in FIG. 6). When receiving the ACK, the eleventh handset 10 shifts to the sleep mode after a predetermined time has elapsed.

  The ACK transmitted by the fifth relay device 30 is also received by the fourth and sixth relay devices 30. The fourth and sixth repeaters 30 stop the relay operation and do not transmit ACK because the fifth repeater 30 transmits ACK for the same data as the received data.

  The MCU 300 of the fifth relay device 30 extracts the measurement data, the sequence number, the destination address, the transmission source address, and the data source address from the transmission data from the child device 10. The MCU 300 of the fifth relay device 30 includes the measurement data extracted from the transmission data and the sequence number, the destination address is the broadcast address, the transmission source address is its own address, and the data source address is the eleventh slave device 10. Create transmission data with addresses. Then, the MCU 300 of the fifth repeater 30 causes the transmission data to be broadcast from the wireless communication unit 302 when a random wait time has elapsed since the transmission of the ACK (process T23 in FIG. 6). In the example of FIG. 6, the first, second, third, fourth, and sixth relay devices 30 and the slave device 10 exist in the communication area of the fifth relay device 30, and the fifth relay device 30. Is transmitted by the wireless communication unit 302 of the 1st to 4th and 6th repeaters 30. Since the handset 10 is switched to the sleep mode when receiving ACK after data transmission, the data transmitted from the fifth relay device 30 is not received by the handset 10.

  When the wireless communication unit 302 of the 1st to 4th and 6th repeaters 30 receives the transmission data from the 5th repeater 30, the MCU 300 of these repeaters 30 determines the measurement data and the sequence number from the received data. Then, the destination address, source address, and data source address are extracted. As described above, the wait time until each repeater 30 transmits an ACK is set to a random time. In the example of FIG. 6, the wait time of the second repeater 30 is the first, third. The time is shorter than the wait time of the fourth and sixth repeaters 30. Therefore, the MCU 300 of the second repeater 30 controls the wireless communication unit 302 after the wait time elapses earlier than the other repeaters 30, and transmits an ACK to the fifth repeater 30 of the transmission source (FIG. Process T24 of 6). The ACK transmitted from the second relay device 30 to the fifth relay device 30 is not only the fifth relay device 30 but also the wireless communication unit 302 of the first, third, fourth, and sixth relay devices 30. Also received by. The No. 1, No. 3, No. 4 and No. 6 relay devices 30 have transmitted an ACK to the same data (the transmission data from the No. 5 relay device 30) as the data received by the No. 2 relay device 30. In addition, the relay operation is stopped and no ACK is transmitted.

  Thereafter, the MCU 300 of the second relay unit 30 extracts the measurement data, the sequence number, the destination address, the transmission source address, and the data source address from the transmission data from the fifth relay unit 30. The MCU 300 of the second repeater 30 includes the transmission data including the measurement data and the sequence number, the destination address as the broadcast address, the transmission source address as its own address, and the data source address as the eleventh slave unit 10 address. create. Then, the MCU 300 of the second relay device 30 transmits the created transmission data by broadcast from the wireless communication unit 302 when a random wait time has elapsed since the transmission of the ACK (process T25 in FIG. 6). Since the parent device 20 exists within the communication range of the second relay device 30, data transmitted by broadcast from the second relay device 30 is received by the parent device 20.

  When the wireless communication unit 202 receives the transmission data from the second relay device 30, the MCU 200 of the parent device 20 takes in the measurement data, sequence number, transmission source address, and data source address from the received data. The MCU 200 of the parent device 20 causes the wireless communication unit 202 to transmit the ACK added with the final destination information to the second relay device 30 that is the transmission source (process T26 in FIG. 6).

  When the wireless communication unit 302 of the second relay device 30 receives the ACK transmitted from the parent device 20, the MCU 300 of the relay device 30 determines that the final destination information added to the ACK is 1, so that the parent device 20 is determined to be able to communicate directly with 20 and the next transmission destination node is determined as the parent device 20. That is, the MCU 300 of the second relay device 30 transmits data to the parent device 20 by unicast from the next time.

  Here, in the series of communications shown in FIG. 6, the information obtained by the eleventh slave unit 10 and the second and fifth repeaters 30 is as shown in the following Table 3. The machine 30 acquires final destination information.

  Next, a communication procedure when the eleventh handset 10 transmits measurement data for the fourth time will be described with reference to FIG. Note that description of communication procedures common to those described with reference to FIGS. 1, 5, and 6 is omitted.

  The eleventh handset 10 starts from the sleep mode at the next transmission timing, and transmits transmission data including the measurement data and the sequence number by broadcast (process T31 in FIG. 7).

  Data transmitted from the eleventh slave unit 10 is received by the fourth to ninth relay units 30. In the example of FIG. 7, the MCU 300 of the fourth repeater 30 controls the wireless communication unit 302 to transmit an ACK to the transmission source child device 10 after the wait time elapses earlier than the other repeaters 30. (Process T32 in FIG. 7). When receiving the ACK, the slave unit 10 shifts to the sleep mode after a predetermined time has elapsed.

  The ACK transmitted by the fourth relay device 30 is received not only by the child device 10 but also by the fifth and sixth relay devices 30. The 5th and 6th relay devices 30 stop the relay operation because the 4th relay device 30 transmits an ACK to the same data (the transmission data from the 11th slave device 10) as the received data. ACK is not transmitted.

  The MCU 300 of the fourth relay device 30 extracts the measurement data, the sequence number, the destination address, the transmission source address, and the data source address from the transmission data from the child device 10. The MCU 300 of the fourth relay device 30 includes the measurement data and the sequence number, the transmission data having the destination address as the broadcast address, the transmission source address as the own device address, and the data source address as the eleventh child device 10 address. Create Then, the MCU 300 of the fourth repeater 30 causes the wireless communication unit 302 to transmit this transmission data by broadcast when a random wait time has elapsed since the transmission of the ACK (process T33 in FIG. 7). In the example of FIG. 7, the 1st, 2nd, 5th relays 30 and the 11th handset 10 exist within the communication range of the 4th relay 30 and are transmitted from the 4th relay 30 by broadcast. The received data is received by the wireless communication unit 302 of the first, second, and fifth repeaters 30. Since the 11th handset 10 is switched to the sleep mode when ACK is received after data transmission, the data sent from the 4th repeater 30 is not received by the handset 10.

  When the wireless communication unit 302 of the No. 1, No. 2 and No. 5 repeaters 30 receives the transmission data from the No. 4 repeater 30, the MCU 300 of these repeaters 30 determines the measurement data and sequence from the received data. The number, destination address, source address and data source address are extracted. As described above, the wait time until each repeater 30 transmits an ACK is set to a random time. In the example of FIG. 7, the wait times of the second repeater 30 are No. 1 and No. 5. It is shorter than the wait time of the repeater 30. Therefore, the MCU 300 of the second repeater 30 controls the wireless communication unit 302 after the wait time elapses earlier than the other repeaters 30, and transmits an ACK to the fourth repeater 30 as the transmission source (FIG. 7 processing T34). Here, since the second relay device 30 has acquired the final destination information from the parent device 20 in the previous communication, the number of relay hops obtained by adding 1 to the number of relay hops of the own device as the final destination information (in this case) 2) is added to the ACK and transmitted to the fourth repeater 30.

  When the wireless communication unit 302 of the fourth repeater 30 receives the ACK transmitted from the second repeater 30, the MCU 300 of the fourth repeater 30 determines the second destination information from the final destination information added to the ACK. The relay device 30 determines that the node can communicate with the parent device 20, and sets the node as a transmission destination candidate node. In the present embodiment, when receiving an ACK to which final destination information is added, the MCU 300 of each relay device 30 sets a node that is a transmission source of this ACK as a candidate node that is a transmission destination. The MCU 300 of each repeater 30 transmits data by broadcast in subsequent communications until the destination node is determined. When receiving the final destination information a predetermined number of times, for example, three times in this embodiment, the MCU 300 of each relay device 30 selects a destination node based on communication conditions from among candidate nodes that have transmitted the final destination information for three times. To decide. Then, the MCU 300 of each relay device 30 is configured to transmit data by unicast to an upper node (transmission destination node) determined as a transmission destination in subsequent communication. In the present embodiment, when the relay device 30 that has received the final destination information can directly communicate with the parent device 20, the relay device 30 determines the parent device 20 as a transmission destination node.

  In addition, the ACK transmitted from the second repeater 30 to the fourth repeater 30 is also received by the first and fifth repeaters 30. Since the 1st and 5th relays 30 are transmitting the ACK for the same data as each received data (the transmission data from the 4th relay 30), the 2nd relay 30 transmits the ACK. And no ACK is sent.

  Thereafter, the MCU 300 of the second relay device 30 extracts the measurement data, the sequence number, the destination address, the transmission source address, and the data source address from the transmission data from the fourth relay device 30. The MCU 300 of the second relay device 30 includes the measurement data and the sequence number, the destination address is the address of the master device 20, the transmission source address is the address of its own device, and the data source address is the eleventh slave device 10 address. Create data. Then, the MCU 300 of the second relay device 30 transmits the transmission data from the wireless communication unit 302 to the parent device 20 by unicast when a random wait time has elapsed since the ACK was transmitted (FIG. 7). Process T35).

  When the wireless communication unit 202 receives the transmission data from the second relay device 30, the MCU 200 of the parent device 20 takes in the measurement data, sequence number, transmission source address, and data source address from the received data. Then, the MCU 200 of the parent device 20 transmits an ACK with the final destination information added from the wireless communication unit 202 to the second relay device 30 that is the transmission source (processing T36 in FIG. 7).

  Here, in the series of communications shown in FIG. 7, the information newly obtained by the No. 4 relay machine 30 is as shown in the following Table 4, and the No. 2 relay machine 30 newly acquires the final destination information. .

  Next, a communication procedure when the eleventh handset 10 transmits measurement data for the fifth time will be described with reference to FIG. In addition, description is abbreviate | omitted about the communication procedure which is common with the communication procedure demonstrated with reference to FIG. 1, FIG.

  At the next transmission timing, the eleventh handset 10 starts from the sleep mode, and transmits the transmission data storing the measurement data and the sequence number by broadcast (process T41 in FIG. 8).

  Data transmitted from the eleventh slave unit 10 by broadcast is received by the fourth to ninth relay units 30. In the example of FIG. 8, the sixth relay device 30 transmits ACK to the transmission child device 10 after the wait time elapses earlier than the other relay devices 30 (process T42 in FIG. 8). When receiving the ACK, the slave unit 10 shifts to the sleep mode after a predetermined time has elapsed.

  The ACK transmitted by the sixth relay device 30 is received not only by the eleventh child device 10 but also by the wireless communication unit 302 of the fourth and fifth relay devices 30. The MCU 300 of the 4th and 5th repeaters 30 performs the relay operation because the 6th repeater 30 transmits an ACK for the same data (the transmission data from the 11th slave unit 10) as the received data. Cancel and do not send ACK.

  The MCU 300 of the sixth relay device 30 extracts the measurement data, the sequence number, the destination address, the source address, and the data source address from the transmission data from the eleventh slave device 10. The MCU 300 of the sixth relay device 30 includes the measurement data and the sequence number, the transmission data having the destination address as the broadcast address, the transmission source address as the own device address, and the data source address as the eleventh slave device 10 address. Create Then, the MCU 300 of the sixth repeater 30 causes the wireless communication unit 302 to transmit the transmission data by broadcast when a random wait time has elapsed since the transmission of the ACK (process T43 in FIG. 8). Data transmitted by broadcast from the sixth relay 30 is received by the wireless communication unit 302 of the second, third and fifth relays 30. The 11th handset 10 is switched to the sleep mode when receiving ACK after data transmission, and therefore the data sent from the 6th repeater 30 is not received by the 11th handset 10.

  When the wireless communication unit 302 of the No. 2, No. 3, and No. 5 repeaters 30 receives the transmission data from the No. 6 repeater 30, the MCU 300 of these repeaters 30 determines the measurement data and sequence from the received data. The number, destination address, source address and data source address are extracted. As described above, the wait time until each repeater 30 transmits an ACK is set to a random time. In the example of FIG. 8, the wait time of the third repeater 30 is the second, fifth. It is shorter than the wait time of the repeater 30. Therefore, the third relay device 30 transmits ACK to the sixth relay device 30 as the transmission source after the wait time elapses earlier than the other relay devices 30 (process T44 in FIG. 8). Here, since the third relay device 30 has acquired the final destination information from the parent device 20 in the previous communication, the number of relay hops obtained by adding 1 to the number of relay hops of the own device as the final destination information (in this case) 2) is added to the ACK and transmitted to the sixth repeater 30.

  When the wireless communication unit 302 of the 6th repeater 30 receives the ACK transmitted from the 3rd repeater 30, the MCU 300 of the 6th repeater 30 receives the 3rd destination information from the final destination information added to the ACK. The relay device 30 determines that the node can communicate with the parent device 20, and sets the node as a transmission destination candidate node. The MCU 300 of the sixth relay device 30 sets the third relay device 30 as a candidate node, but transmits data by broadcast in subsequent communications until the destination node is determined. When receiving the final destination information three times (predetermined number of times), for example, the MCU 300 of the sixth relay device 30 selects a destination node based on communication conditions from among candidate nodes that have transmitted the final destination information for three times. To decide.

  The ACK transmitted from the third relay 30 to the sixth relay 30 is also received by the second and fifth relays 30. The second and fifth repeaters 30 cancel the relay operation because the third repeater 30 transmits an ACK to the same data (the transmission data from the sixth repeater 30) as the data received by each. However, ACK is not transmitted.

  Thereafter, the MCU 300 of the third relay device 30 extracts the measurement data, the sequence number, the destination address, the transmission source address, and the data source address from the transmission data from the sixth relay device 30. The MCU 300 of the third relay device 30 includes the measurement data and the sequence number, the destination address is the address of the parent device 20, the transmission source address is the address of the own device, and the data source address is the address of the eleventh child device 10. Create the transmitted data. Then, the MCU 300 of the third relay device 30 transmits this transmission data from the wireless communication unit 302 to the parent device 20 by unicast when a random wait time has elapsed since the transmission of the ACK (FIG. 8). Process T45).

  When the wireless communication unit 202 receives the transmission data from the third relay device 30, the MCU 200 of the parent device 20 takes in the measurement data, sequence number, transmission source address, and data source address from the received data. The MCU 200 of the parent device 20 transmits an ACK to which the final destination information is added from the wireless communication unit 202 to the third relay device 30 that is the transmission source (process T46 in FIG. 8).

  Here, in the series of communications shown in FIG. 8, the information newly obtained by the sixth relay device 30 is as shown in the following Table 5, and the sixth relay device 30 newly acquires the final destination information. .

  As described above, the eleventh slave unit 10 repeats the transmission of the measurement data every time the predetermined transmission timing comes. As a result of the data transmission from several times to a dozen times, for example, the fourth relay unit 30 Assume that the final destination information is received three times, for example. At this point, it is assumed that the slave unit 10 and the relay unit 30 have obtained information as shown in Table 6 below.

  When receiving the final destination information three times, the MCU 300 of the fourth repeater 30 determines a transmission destination node based on communication conditions and the like from candidate nodes that have transmitted the final destination information for three times. In this embodiment, the MCUs 100 and 300 of the child device 10 and the relay device 30 determine the candidate node having the smallest number of relay hops as the transmission destination node from among the candidate nodes that have transmitted the final destination information for three times.

  Note that the communication condition for determining the destination node from among the candidate nodes is not limited to the number of relay hops. The wireless communication units 103 and 302 of the slave unit 10 and the relay unit 30 have a reception signal strength measurement function, and the MCUs 100 and 300 of the slave unit 10 and the relay unit 30 have transmitted candidate destination information for three times. Therefore, the node having the highest received signal strength may be determined as the destination node. Further, the slave unit 10 includes the transmission time information in the transmission data, and the master unit 20 obtains the arrival delay time from the difference between the transmission time included in the received data and the data reception time. You may transmit by adding to ACK. Here, the arrival delay time is a time required for data to reach from the first node of the transmission source (the child device 10 in the present embodiment) to the second node of the transmission destination (the parent device 20 in the present embodiment). . Then, the MCUs 100 and 300 of the slave unit 10 and the relay unit 30 have the shortest arrival delay time among the candidate nodes that have transmitted the final destination information for three times based on the arrival delay time added to the ACK. The node may be determined as a destination node. Further, when determining the transmission destination node from among the candidate nodes, the MCUs 100 and 300 of the child device 10 and the relay device 30 may determine the candidate node having a smaller number of nodes that relay data as the transmission destination node. Good. Further, the MCUs 100 and 300 of the slave unit 10 and the relay unit 30 may determine a destination node from among candidate nodes based on a plurality of conditions among the above-described number of relay hops, received signal strength, and arrival delay time. Good. Further, the MCUs 100 and 300 of the slave unit 10 and the relay unit 30 may determine the candidate node that received the final destination information last as the transmission destination node if the communication conditions are the same among the candidate nodes.

  As described above, the fourth relay device 30 determines the transmission destination node. As a result of the data transmission by the eleventh child device 10 a plurality of times, the fifth and sixth devices 6 and 6 communicate directly with the eleventh child device 10. It is assumed that each of the numbered repeaters 30 also acquires the final destination information for a predetermined number of times and determines the transmission destination node. At this time, it is assumed that the slave unit 10 and the relay unit 30 have obtained information as shown in Table 7 below.

  A communication procedure in the case where the eleventh handset 10 transmits measurement data from this state will be described with reference to FIG. Note that a description of communication procedures common to those described with reference to FIGS. 1 and 5 to 8 will be omitted.

  The eleventh handset 10 starts from the sleep mode at the next transmission timing, and transmits the transmission data storing the measurement data and the sequence number by broadcast (process T51 in FIG. 9).

  Data transmitted from the eleventh slave unit 10 by broadcast is received by the fourth to ninth relay units 30. In the example of FIG. 9, the fourth relay device 30 transmits an ACK to the transmission source child device 10 after the wait time elapses earlier than the other relay devices 30 (process T52 in FIG. 9). At this time, since the No. 4 relay station 30 has determined the transmission destination node, the No. 4 relay station 30 adds the final destination information (data “2” of the number of relay hops in this embodiment) to the ACK. Is transmitted to the 11th child device 10 which is the transmission source. Upon receiving the ACK with the final destination information from the 4th relay device 30, the 11th child device 10 sets the 4th relay device 30 as a transmission destination candidate node, and shifts to the sleep mode after a predetermined time. To do. Note that the MCU 100 of the slave unit 10 transmits data by broadcast in subsequent communications until the destination node is determined. When the MCU 100 of the child device 10 receives the final destination information a predetermined number of times, for example, three times in this embodiment, the MCU 100 of the transmission destination node among the candidate nodes that have transmitted the final destination information for three times based on communication conditions and the like To decide.

  The ACK transmitted by the fourth relay device 30 is received not only by the slave device 10 but also by the wireless communication unit 302 of the fifth and sixth relay devices 30. The MCU 300 of the fifth and sixth repeaters 30 performs the relay operation because the fourth repeater 30 transmits an ACK for the same data (the transmission data from the eleventh slave unit 10) as the data received by each. Cancel and do not send ACK.

  The MCU 300 of the fourth relay device 30 extracts the measurement data, the sequence number, the destination address, the source address, and the data source address from the transmission data from the eleventh slave device 10. The MCU 300 of the fourth relay device 30 includes the measurement data and the sequence number, the destination address is the address of the first relay device 30, the transmission source address is the address of its own device, and the data source address is the eleventh child device. Transmission data with 10 addresses is created. Then, the MCU 300 of the fourth relay device 30 transmits the transmission data from the wireless communication unit 302 to the first relay device 30 by unicast (process T53 in FIG. 9).

  When the first repeater 30 receives the transmission data transmitted from the fourth repeater 30 by unicast, the first repeater 30 transmits ACK to the fourth repeater 30 of the transmission source (process T54 in FIG. 9).

  Also, the first relay device 30 extracts the measurement data, the sequence number, the destination address, the transmission source address, and the data source address from the transmission data from the fourth relay device 30. The first relay device 30 includes the measurement data and the sequence number, the destination address is the address of the parent device 20, the transmission source address is the address of the own device, and the data source address is the address of the eleventh child device 10. Create transmission data. Then, the MCU 300 of the first relay device 30 transmits the transmission data from the wireless communication unit 302 to the parent device 20 by unicast (process T55 in FIG. 9).

  When the base unit 20 receives the transmission data from the first relay unit 30, the base unit 20 captures the measurement data, sequence number, transmission source address, and data source address from the received data, and sends the ACK with the final destination information at the transmission source. The data is transmitted to a certain first repeater 30 (process T56 in FIG. 9).

  Thereby, one-time data transmission from the child device 10 to the parent device 20 is completed. In the series of communications shown in FIG. 9, the information newly obtained by the slave unit 10 and the relay unit 30 is as shown in the following Table 8, and the 11th slave unit 10 and the 4th relay unit 30 are newly finalized. Get destination information.

  After that, the eleventh slave unit 10 repeats the transmission of the measurement data every time the predetermined transmission timing comes, and as a result of two more data transmissions, the eleventh slave unit 10 is added with the final destination information. ACK can be received three times. At this time, it is assumed that the slave unit 10 and the relay unit 30 have obtained information as shown in Table 9 below.

  In this way, when the MCU 100 of the eleventh child device 10 receives the ACK to which the final destination information is added three times, the candidate nodes (Nos. 4, 5, and 6 that have transmitted the final destination information for the third time are received. The destination node for the next transmission is determined from the relay station 30). Here, when the MCU 100 of the child device 10 determines the transmission destination node to be the sixth relay device 30 from the communication results of receiving the final destination information for three times, the MCU 100 of the child device 10 is connected to the sixth relay device 30 in the subsequent communication. Send data by unicast.

  FIG. 10 shows a communication procedure when communication is performed from the child device 10 to the parent device 20 by unicast.

  The eleventh slave unit 10 starts from the sleep mode at the next transmission timing, and sends the transmission data storing the measurement data, the sequence number, the destination address, the source address, and the data source address to the sixth relay unit 30. Transmission is performed by unicast (process T61 in FIG. 10).

  When receiving the transmission data from the eleventh slave unit 10, the sixth relay unit 30 transmits an ACK to which the final destination information is added to the source slave unit 10 (process T62 in FIG. 10).

  The sixth relay device 30 extracts the measurement data and the sequence number from the transmission data from the child device 10, and includes the measurement data and the sequence number, and the destination address is the address of the third relay device 30 and the transmission source. Create transmission data with the address as your own address. Then, the sixth relay device 30 transmits this transmission data to the third relay device 30 by unicast (process T63 in FIG. 10).

  When the third relay device 30 receives the transmission data transmitted from the sixth relay device 30 by unicast, the third relay device 30 transmits an ACK to the sixth relay device 30 of the transmission source (process T64 in FIG. 10).

  In addition, the third relay device 30 extracts the measurement data, the sequence number, the destination address, the transmission source address, and the data source address from the transmission data from the sixth relay device 30. The third relay device 30 includes the measurement data and sequence number extracted from the transmission data from the sixth relay device 30, the destination address is the address of the master device 20, the transmission source address is the address of the own device, and the data source Transmission data with the address as the address of the eleventh handset 10 is created. Then, the third relay device 30 transmits this transmission data to the parent device 20 by unicast. When receiving the data transmitted from the third repeater 30, the master unit 20 transmits an ACK to the third repeater 30. As described above, when the transmission destination node is determined in all the nodes constituting the communication path from the child device 10 to the parent device 20, each node transmits data by unicast, so each node transmits data by broadcast. Compared to the case, the number of ACKs transmitted decreases. As a result, the amount of communication decreases and the probability that transmission data collides decreases.

  Note that the order in which the transmission destination nodes are determined in each of the child device 10 and the relay device 30 is not limited to the description of FIGS. 1 and 5 to 10, and varies depending on the communication environment and the like.

  As described above, the wireless communication system according to the present embodiment includes a transmission source first node (slave unit 10 in this embodiment), a transmission destination second node (base unit 20 in this embodiment), a plurality of nodes. And a third node (in this embodiment, the relay machine 30). Each of the first node and the second node has a wireless communication function. Each of the plurality of third nodes has a function of relaying wireless communication between the first node and the second node. Each of the first node and the third node is configured to transmit data by broadcast when a transmission destination node is not determined. When the second node receives data from either the first node or the third node, the second node is configured to add the final destination information to the ACK and transmit it to the transmission source node. When the third node receives an ACK to which the final destination information is added from an upper node of the communication path, the third node is configured so that the ACK transmission source node is a transmission destination candidate node for the next transmission. The third node is configured to transmit ACK to which the final destination information is added to the lower node when data is received next time from the lower node of the communication path. When each of the first node and the third node receives the ACK with the final destination information added a predetermined number of times, the first node and the third node determine the destination node for the next transmission from among the candidate nodes that have transmitted the final destination information for the predetermined number of times. Configured to do. Each of the first node and the third node is configured to transmit data to the transmission destination node by unicast in subsequent communication.

  In this way, in the state where the destination node is not determined in each of the first node and the third node, the first node and the third node are transmitting data by broadcasting, and thus transmitted from the first node. The data is transmitted to the second node directly or via the third node. Since the node determined by the destination node among the first node and the third node transmits data by unicast, the number of ACKs to be transmitted is reduced compared to the case where each node transmits by broadcast. As a result, the amount of communication decreases and the probability that transmission data collides decreases. Furthermore, since each of the first node and the third node determines a destination node from among candidate nodes that have transmitted the final destination information for a predetermined number of times, a candidate node with better communication conditions is selected as the destination. Can be determined on the node.

  In the present embodiment, the case where data is transmitted from the child device 10 to the parent device 20 has been described as an example. However, when a sensor that measures a predetermined physical quantity is connected to the relay device 30, the parent device 20 is connected to the relay device. Request data for requesting sensor measurement data may be transmitted to 30. In this case, the parent device 20 becomes the first node of the transmission source, and the relay device 30 that requests the measurement data becomes the second node of the transmission destination.

  In the wireless communication system of the present embodiment, each of the first node and the third node may determine a candidate node having the smallest number of relay hops as a transmission destination node from among candidate nodes. As a result, the number of times data is relayed and transmitted while data is transmitted from the first node to the second node is reduced, so that the amount of communication is reduced and the possibility of collision of transmission data is reduced.

  In the wireless communication system according to the present embodiment, each of the first node and the third node may combine the arrival delay time with the condition for determining the transmission destination node. Here, the arrival delay time is a time required for data to reach from the first node to the second node. Thereby, each of the first node and the third node can determine the transmission destination node based on the arrival delay time in each candidate node, for example, transmits a candidate node having a shorter arrival delay time. The destination node can be determined.

  In the wireless communication system of the present embodiment, each of the first node and the third node is a destination node from among candidate nodes based on a plurality of conditions among the number of relay hops, the received signal strength, and the arrival delay time. May be determined. Here, the arrival delay time is a time required for data to reach from the first node to the second node. As a result, each of the first node and the third node selects a node having a good communication condition from among candidate nodes based on a plurality of conditions among the number of relay hops, received signal strength, and arrival delay time. Can be determined.

  Moreover, it is also preferable that the radio communication system of the present embodiment is configured as follows. Each of the first node and the third node discards the final destination information added to the ACK if the received signal strength of the ACK is less than a predetermined threshold when receiving the ACK with the final destination information added. Configured as follows. Each of the first node and the third node is configured so that the node from which the ACK is transmitted is not a candidate node.

  That is, the wireless communication unit 103 of the child device 10 has a function of measuring the signal strength (reception signal strength) of the received signal, and outputs the measurement result (received signal strength) to the MCU 100. When the wireless communication unit 103 receives data, the MCU 100 of the child device 10 compares the received signal strength of the data with a predetermined threshold value. If the received signal strength is less than the threshold value, the MCU 100 of the slave unit 10 is configured to discard the final destination information added to the ACK and not set the ACK transmission source node as a candidate node, and the communication state is An unstable node is less likely to be selected as a candidate node. Similarly, the wireless communication unit 302 of the repeater 30 has a function of measuring the signal strength (received signal strength) of the received signal, and outputs the measurement result (received signal strength) to the MCU 300. When the wireless communication unit 302 receives data, the MCU 300 of the repeater 30 compares the received signal strength of this data with a predetermined threshold. If the received signal strength is less than the threshold value, the MCU 300 of the relay device 30 is configured to discard the final destination information added to the ACK and not set the node that transmitted the ACK as a candidate node, and the communication state is An unstable node is less likely to be selected as a candidate node.

  In the wireless communication system according to the present embodiment, each of the first node, the second node, and the third node may include a setting unit for setting the predetermined number of times to a desired number. Here, the predetermined number of times set using the setting unit is the number of times of receiving the ACK to which the final destination information is added, and the transmission destination node is determined from the candidate nodes that have transmitted the final destination information for the predetermined number of times. The For example, when setting a predetermined number of times in the slave unit 10, when a setting value is input using the operation unit 105, the MCU 100 stores the setting value input from the operation unit 105 in the storage unit 102. The number of times can be set to a desired number. Further, when setting a predetermined number of times in the base unit 20, when a setting value is input using the operation unit 205, the MCU 200 stores the setting value input from the operation unit 205 in the storage unit 201. The number of times can be set to a desired number. Further, when setting a predetermined number of times in the relay machine 30, when a setting value is input using the operation unit 304, the MCU 300 stores the setting value input from the operation unit 304 in the storage unit 102. The number of times can be set to a desired number. The same number of times may be set as the predetermined number of times for the first node, the second node, and the third node, or different numbers may be set for each node. Here, a setting unit is realized by the operation units 105, 205, 304, and the like.

  In the wireless communication system according to the present embodiment, the third node may be configured not to transmit the final destination information to the lower nodes of the communication path until the transmission destination node is determined. Since the number of relay hops and arrival delay time are undecided when the destination node is not determined, the third node does not transmit the final destination information to the lower nodes of the communication path, and the destination node is determined. The final destination information may be transmitted later to the lower node.

  The wireless communication system according to the present embodiment may further include the following configuration. Each of the first node and the third node resends data to the transmission destination node by unicast when data transmission to the transmission destination node fails while the transmission destination node is determined. When the data transmission fails again, each of the first node and the third node transmits data by broadcasting and reconstructs the communication path to the second node.

  As described above, when the data transmission to the destination node fails, each of the first node and the third node first retransmits the data to the destination node by unicast. Therefore, in the case of a single communication error, the possibility of transmitting data to the destination node increases by retransmitting the data to the destination node by unicast. In addition, when each of the first node and the third node fails to transmit data again, the communication environment has changed because the communication path to the second node is reconstructed by transmitting data by broadcasting. In this case, communication to the second node can be performed through a new communication path.

  Also, in the wireless communication system of the present embodiment, each of the first node and the third node has the candidate node that received the final destination information last as the transmission destination node if the communication conditions are the same in each of the candidate nodes. You may decide. If each candidate node has the same communication condition, the candidate node that has received the latest final destination information as the destination node can be used as the transmission destination node, so that communication can be performed under better conditions even when the communication environment changes. Get higher.

10 Slave unit (first node)
20 Master unit (second node)
30 Repeater (3rd node)

Claims (10)

A first node of a transmission source having a wireless communication function;
A destination second node having a wireless communication function;
A plurality of third nodes having a function of relaying wireless communication between the first node and the second node;
In a state where a communication path for transmitting data from the first node to the second node is not established, the first node and the third node are configured to transmit data by broadcast,
When the second node receives data from any one of the first node and the third node, the second node adds final destination information indicating that communication with the second node is possible to the ACK, and is a source node Configured to send to
When each of the first node and the third node receives the ACK to which the final destination information is added from an upper node of a communication path, the ACK transmission source node is set as a transmission destination candidate node at the next transmission time. And is configured to
When each of the first node and the third node receives the ACK to which the final destination information is added a predetermined number of times, each of the first node and the third node transmits the next time from among the candidate nodes that have transmitted the final destination information for the predetermined number of times. A wireless communication system configured to determine a transmission destination node at a time and transmit data to the transmission destination node by unicast in subsequent communication.   The each of the first node and the third node is configured to determine the candidate node having the smallest number of relay hops as the transmission destination node from among the candidate nodes. The wireless communication system described.   Each of the first node and the third node is configured to combine the arrival delay time required for data to reach from the first node to the second node with the condition for determining the destination node. The wireless communication system according to claim 2.   Each of the first node and the third node is based on a plurality of conditions among the number of relay hops, received signal strength, and arrival delay time required for data to reach from the first node to the second node. The wireless communication system according to claim 1, wherein the transmission destination node is determined from the candidate nodes.   Each of the first node and the third node is added to the ACK if the received signal strength of the ACK is less than a predetermined threshold when receiving the ACK with the final destination information added. 5. The wireless communication system according to claim 1, wherein the final destination information is discarded, and the node that has transmitted the ACK is not set as the candidate node. 6.   6. The method according to claim 1, wherein each of the first node, the second node, and the third node includes a setting unit that sets the predetermined number of times to a desired number. A wireless communication system according to the item.   The said 3rd node is comprised so that the said final destination information may not be transmitted to the low-order node of the said communication path | route until it determines the said transmission destination node. The wireless communication system according to 1.   Each of the first node and the third node retransmits data to the transmission destination node by unicast when data transmission to the transmission destination node fails in a state determined by the transmission destination node. 8. The apparatus according to claim 1, wherein when transmission fails again, data is transmitted by broadcast to reconstruct a communication path to the second node. 9. Wireless communication system.   Each of the first node and the third node is configured to determine the candidate node that received the final destination information last as the transmission destination node if the communication conditions are the same in each of the candidate nodes. The wireless communication system according to claim 1, wherein the wireless communication system is a wireless communication system.   When each of the first node and the third node determines the transmission destination node, the first node and the third node are configured to add route information for specifying a communication route to the data and transmit the next time data is transmitted. The wireless communication system according to claim 1, wherein the wireless communication system is a wireless communication system.

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