JP2014204141A - Multi-hop wireless device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly establish a communication path in a multi-hop communication system.SOLUTION: A master wireless unit determines a communication frequency to transmit and receive packets. In the case where the master wireless unit receives a request packet transmitted by a slave wireless unit at the communication frequency, it transmits a response packet at the communication frequency when it permits the slave wireless unit to establish a communication path. If the slave wireless unit receives the response packet, it recognizes a frequency at which the response packet is received as a communication frequency. If the slave wireless unit does not receive a response packet, it repeatedly transmits a request packet while changing the frequency until a response packet is received. When a response packet is received, the slave wireless unit recognizes a frequency at which the response packet is received as a communication frequency and establishes a communication path to the master wireless unit.

Description

  The present invention relates to a multi-hop wireless device, and more particularly to processing for establishing a communication path.

  Multi-hop communication systems that transmit packets by relay transmission of a plurality of wireless devices are widely used. A communication path of a multi-hop communication system includes a tree shape in which one of a plurality of wireless devices is a basic node and another wireless device is a branch node or a terminal node. The core node forms the root of a tree shape. A branch node is a branch point in the tree shape or a relay point without a branch, and a terminal node is a terminal in the tree shape.

Route information that defines the communication route of the multi-hop communication system is stored in the radio of each node. The radio | wireless machine of a basic node has memorize | stored ID (Identification) of the radio | wireless machine adjacent to the terminal node side as routing information. Further, the branch node radio stores the ID of the radio adjacent to the trunk node and the ID of the radio adjacent to the end node as route information. And the radio | wireless machine of a terminal node has memorize | stored ID of the radio | wireless machine adjacent to the trunk | node side as routing information. Each wireless device transmits and receives packets to and from other wireless devices adjacent to each other in the communication path in accordance with the path information stored by itself. In addition, the wireless device of the basic node stores information regarding the entire tree-shaped communication path, and gives an instruction on the packet transmission destination to other wireless devices according to the information.

  Note that Patent Document 1 describes a wireless communication system. In this system, wireless communication is performed between a base station and a plurality of mobile stations, and wireless communication is performed between a plurality of mobile stations. The base station selects one frequency channel from among a plurality of frequency channels given to the system as a frequency channel used by the own station. Then, wireless communication is performed with each mobile station using the frequency channel. A plurality of mobile stations perform wireless communication using the same frequency channel as the frequency channel used for wireless communication with the base station.

  Patent Document 2 describes a multi-hop communication system. In this system, information that defines a communication path is generated by a parent node. There are a plurality of communication paths from the child node to the parent node, and a communication path having a good communication status is selected from among the communication paths.

JP-A-10-66140 JP 2011-223442 A

  In a multi-hop communication system, a communication path is established before packet transmission / reception is performed. Each wireless device performs wireless communication for establishing a communication path with another wireless device, and determines an adjacent wireless device. However, when a plurality of wireless devices simultaneously perform wireless communication for establishing a communication path, there is a problem that congestion occurs in each wireless device and processing in each wireless device is delayed.

  An object of the present invention is to quickly establish a communication path in a multi-hop communication system.

  The present invention relates to a request packet transmitter for transmitting a request packet for requesting establishment of a communication path to another radio device in a multi-hop radio device used as one of a plurality of radio devices performing multi-hop communication. And when a response packet having the same frequency as the frequency of the request packet is transmitted from another wireless device to the request packet, a response packet receiving unit that receives the response packet, and the response packet A main side next hop determination unit that determines, when received, the other radio that has transmitted the response packet as a next hop radio on the main side in the communication path, and the request packet transmission unit includes: When a response packet is not received, the transmission frequency is changed and the request packet is transmitted again.

  The multi-hop radio according to the present invention preferably has a frequency recognition unit that recognizes a frequency of the response packet as a communication frequency used in the multi-hop communication when the response packet is received; After the request packet receiver that receives the second request packet that is transmitted from the radio and has the same frequency as the communication frequency and requests establishment of a communication path, and the next-hop radio on the backbone side are determined, A terminal-side next hop determination unit that determines another wireless device that has transmitted the second request packet as a terminal-side next-hop wireless device in the communication path when the second request packet is received;

  In addition, the multi-hop radio according to the present invention is preferably a confirmation packet indicating the status of the communication path, the confirmation packet receiving unit receiving the confirmation packet transmitted from the next-hop radio on the backbone side, A backbone next hop re-determination unit that re-determines a radio serving as a backbone next-hop radio when a confirmation packet has not been received for a predetermined time, and the backbone-side next hop redetermination The unit uses the request packet transmission unit, the response packet reception unit, and the backbone next hop determination unit to re-determine a wireless device to be a backbone next hop wireless device.

  In addition, the multi-hop wireless device according to the present invention is preferably a wireless device that becomes a next-hop wireless device on the backbone side with respect to another wireless device when the confirmation packet is not received for a predetermined time. A broadcast unit that broadcasts route establishment command information for re-determination.

  The multi-hop wireless device according to the present invention preferably includes a route establishment command receiving unit that receives route establishment command information for instructing re-determination of a wireless device to be a next-hop wireless device on the backbone side, and the route establishment command. A main-side next-hop re-determination unit that re-determines a radio serving as a main-side next-hop radio when information is received, and the main-unit next-hop re-determination unit includes the request packet transmission unit The response packet reception unit and the backbone next hop determination unit re-determine a wireless device to be the backbone next hop wireless device.

  Further, the present invention is used as one of a plurality of radio devices performing multi-hop communication, and the multi-hop communication is communication in which one of the plurality of radio devices is a basic radio device. A confirmation packet receiving unit that receives a confirmation packet indicating a status of a communication path in a multi-hop wireless device and transmitted from a wireless device that has been determined as a next-hop wireless device on the backbone side, and the confirmation If the packet is not received for a predetermined time, the next-hop re-determination unit for re-determining the radio serving as the next-hop radio on the main side, and the confirmation packet is received for a predetermined time If this is not the case, a broadcast that broadcasts route establishment command information that causes another radio to redetermine the radio that will be the next-hop radio on the trunk side is performed. Characterized in that it comprises a cast part.

  According to the present invention, a communication path in a multi-hop communication system can be quickly established.

It is a figure which shows the communication system which concerns on embodiment of this invention. It is a figure which shows the structure of a main radio | wireless machine and a sub radio | wireless machine. It is a figure which shows route information notionally. It is a figure which shows the structural example of a packet. It is a flowchart of a main | base station and a route establishment process. It is a flowchart of a subunit | mobile_unit and route establishment process. It is a flowchart of a terminal side ID acquisition process. It is a figure which shows the structure of an information collection | recovery / parent radio | wireless machine. It is a figure which shows the structure of a sensor and a subunit | mobile_unit radio | wireless machine.

(1) Configuration of Multihop Communication System FIG. 1 shows a communication system according to an embodiment of the present invention. The communication system includes multi-hop communication systems 10 and 12. Each of the multi-hop communication systems 10 and 12 performs multi-hop communication with a plurality of wireless devices. The multi-hop communication systems 10 and 12 are connected to a communication network 14 including a host computer H, and transmit / receive packets to / from each other.

  The multihop communication system 10 includes a master radio device A0 and slave radio devices B1 to B8. The parent radio device A0 is connected to the communication network 14 and operates as a core node. A straight line connecting between the wireless devices means that wireless communication is performed between the wireless devices at both ends of the straight line. FIG. 1 shows a state in which the child radio devices B1, B4, and B7 operate as branch nodes and the child radio devices B2, B3, B5, B6, and B8 operate as terminal nodes.

  The multi-hop communication system 12 includes a master radio device A1 and slave radio devices B9 to B12. The parent radio device A1 is connected to the communication network 14 and operates as a core node. FIG. 1 shows a state in which the slave radio B10 operates as a branch node and the slave radios B9, B11, and B12 operate as end nodes.

  In each multi-hop communication system, a plurality of channels having different communication frequencies are defined. Here, n channels having frequencies f1 to fn as communication frequencies are defined. Each wireless device transmits and receives a packet by a wireless signal having a communication frequency determined by the multihop communication system to which the wireless device belongs. The communication frequency of each multi-hop communication system, and which child radio is a branch node and which child radio is a terminal node are determined by a route establishment process described later.

  The parent radio devices A0 and A1 and the child radio devices B1 to B12 are configured by similar hardware. FIG. 2A shows the configuration of the parent radio device. FIG. 2B shows the configuration of the slave radio. The parent radio device includes a transmission / reception unit 16p, a control unit 18p, and a storage unit 20p. The control unit 18p is connected to the communication network 14.

  The control unit 18p generates a packet to be transmitted by multihop communication based on the information stored in the storage unit 20p. The control unit 18p outputs the packet to the transmission / reception unit 16p. The transmission / reception unit 16p transmits a packet according to the control of the control unit 18p. The packet is transmitted to the destination radio device by multi-hop communication by another radio device.

  Further, the transmission / reception unit 16p receives a packet transmitted from another wireless device and outputs the packet to the control unit 18p. The control unit 18p executes processing for the packet output from the transmission / reception unit 16p based on the information stored in the storage unit 20p. That is, the transmission / reception unit 16p is controlled to perform relay transmission for the packet, or acquire information included in the packet. The control unit 16p performs communication in the communication network 14 in addition to performing control related to multi-hop communication.

  The slave radio device includes a transmission / reception unit 16c, a control unit 18c, and a storage unit 20c. The transmission / reception unit 16c and the storage unit 20c have functions similar to those of the transmission / reception unit 16p and the storage unit 20p provided in the parent wireless device, respectively. The control unit 18c has the same function as the control unit 18p of the parent radio device except for the function of performing communication in the communication network 14.

(2) Multi-hop communication Multi-hop communication using route information and routing information stored in each wireless device will be described. The route information includes a communication frequency, a backbone ID, and a terminal ID. The backbone ID is the ID of the next hop radio adjacent to the backbone node. The terminal side ID is the ID of the next hop radio adjacent to the terminal node side. Note that the base side ID is not stored in the parent wireless device, and the terminal side ID is not stored in the child wireless device operating as the terminal node. FIG. 3 conceptually shows route information a0, b1, and b3 stored in the storage units of the parent radio device A0 and the child radio devices B1 and B3 as examples of route information.

  The routing information stored in each radio is information for obtaining the ID of the next hop radio with respect to the destination ID of the packet, and is generated in advance by communication between a plurality of radios. It is stored in the storage unit of the machine.

  Here, an example in which the parent radio device A0 transmits a packet with the radio device B2 as a destination will be described. FIG. 4 shows a packet configuration example. The packet includes a destination ID part, a next hop ID part, and a payload part. In the destination ID section, the ID of the destination wireless device is described. In the next hop ID section, the ID of the next hop radio is described. In the payload portion, substantive information (transmission target information) to be transmitted is described.

  The parent radio device A0 generates a packet in which the transmission target information is described in the payload portion. Further, the master radio device A0 describes “B2” in the destination ID section as the ID of the slave radio device that is the destination. Further, the parent radio device A0 acquires “B1” as the ID of the next hop radio device based on the destination ID, the route information and routing information stored by itself, and describes it in the next hop ID section. The parent radio device A0 transmits a packet at a communication frequency according to the path information stored by itself.

  When receiving the packet, the slave radio except for the slave radio B1 recognizes that the next hop ID of the received packet does not match its own ID, and ends the processing for the packet. On the other hand, the child radio B1 receives the packet, recognizes that the next hop ID of the received packet matches its own ID, and further recognizes that the destination ID does not match its own ID as follows. Perform relay transmission.

  The slave radio B1 acquires “B2” as the ID of the next hop radio from the destination ID, the route information stored by itself, and the routing information. Then, the description of the next hop ID part is rewritten from “B1” to “B2”. The slave radio B1 wirelessly transmits the packet at a communication frequency according to the path information stored by itself.

  When receiving the packet, the slave radio except for the slave radio B2 recognizes that the next hop ID of the received packet does not match its own ID, and ends the processing for the packet. On the other hand, when the child radio device B2 receives the packet and recognizes that the next hop ID of the received packet matches its own ID and that the destination ID matches its own ID, it is described in the payload portion. Obtained transmission target information. As a result, the transmission target information included in the packet is transmitted in the order of the master radio device A0, the slave radio devices B1, and B2, and is acquired by the slave radio device B2.

  As described above, the radio as the packet transmission source transmits a packet describing the destination ID, the next hop ID, and the transmission target information. Each wireless device ends the processing for the packet when the next hop ID of the received packet does not match its own ID. Also, each wireless device rewrites the next hop ID and relays the packet when the next hop ID of the received packet matches its own ID and the destination ID does not match its own ID. Further, each wireless device acquires the transmission target information described in the payload portion when the next hop ID of the received packet matches its own ID and the destination ID matches its own ID. Thus, the packet is transmitted from the transmission source radio to the destination radio by multi-hop communication.

  Here, the processing when each wireless device stores the routing information has been described. In addition to such processing, routing information may be included in the payload portion of the packet, and each wireless device may refer to the routing information and transmit the packet. In this case, it is assumed that the radio device of the transmission source has information on the communication path of the entire multihop communication system. For example, the routing information indicates the order in which packets are transmitted. When a packet is transmitted from the parent radio device A0 to the child radio device B5, the routing information is expressed as (A0, B1, B4, B5).

  In addition, the destination ID may be a broadcast ID that is addressed to all the wireless devices. In this case, the wireless device of the branch node whose next hop ID matches its own ID performs relay transmission, and acquires transmission target information described in the payload portion. Further, a command for controlling a destination radio device may be described in the payload portion. For example, the transmission source radio device may describe a reply command for requesting a packet reply in the payload portion. The destination wireless device that has acquired the reply command from the packet transmits a reply packet with the packet transmission source wireless device as the destination.

  Note that the parent radio devices A0 and A1 perform packet transmission / reception via the host computer H or directly according to the communication protocol defined by the communication network 14.

(3) Route establishment processing The route establishment processing is processing in which a plurality of wireless devices establish communication paths by mutually transmitting and receiving communication path establishment packets. The communication path establishment packet includes a request packet for requesting establishment of a communication path from another wireless device and a response packet for permitting establishment of the communication route to the wireless device that has transmitted the request packet.

  In the route establishment process, the parent radio device and each child radio device execute the following processing. First, the parent radio determines a communication frequency for transmitting and receiving packets. The determination of the communication frequency is performed by a user operation, for example. In addition, the parent radio device may randomly determine the communication frequency. When the parent radio device receives the request packet transmitted from the child radio device at the communication frequency, the parent radio device transmits a response packet at the communication frequency when permitting the child radio device to establish a communication path. The child radio device that has received the response packet recognizes the frequency at which the response packet is received as the communication frequency.

  As described above, the parent wireless device receives the request packet at the communication frequency determined by itself. Therefore, when the frequency of the request packet transmitted from the child radio device does not match the communication frequency, the request packet is not received by the parent radio device. In this case, no response packet is transmitted from the parent radio device, and no response packet is received by the child radio device. Therefore, when the response packet is not received, the slave radio device changes the frequency and repeatedly transmits the request packet until the response packet is received. When the response packet is received, the slave radio device recognizes the frequency at which the response packet is received as a communication frequency, and establishes a communication path to the master radio device.

  When the slave radio device (first slave radio device) that has recognized the communication frequency receives a request packet transmitted from another slave radio device (second slave radio device) at the communication frequency, When allowing the wireless device to establish a communication path, a response packet is transmitted at the communication frequency. The second child radio device that has received the response packet recognizes the frequency at which the response packet is received as the communication frequency. Similar to the first slave radio, when the response packet is not received, the second slave radio changes the frequency and repeatedly transmits the request packet until the response packet is received. When the response packet is received, the second child radio device recognizes the frequency at which the response packet is received as a communication frequency, and establishes a communication path to reach the parent radio device. By such processing, the second slave radio recognizes the communication frequency determined by the master radio and establishes a communication path to the master radio.

  Similarly, the Nth sub-radio device that has recognized the communication frequency and the other sub-radio devices (N + 1th sub-radio device) transmit / receive packets for establishing a communication path to / from each other. As a result, the (N + 1) th child radio device recognizes the communication frequency determined by the parent radio device and establishes a communication path to the parent radio device.

  Note that the request packet and the response packet include the ID of the transmitter radio. The parent radio device and each child radio device acquire the ID included in the request packet as the terminal side ID. Further, each child radio device acquires the ID included in the response packet as the backbone ID.

  According to such processing, a communication path is established in order from the basic node to the end node, and the next hop radio is determined in each radio. The communication frequency is determined by the parent radio device and recognized by each child radio device together with the establishment of the communication path. Therefore, it is not necessary to set the communication frequency in advance in each slave radio. Further, the child radio device repeatedly transmits the request packet while changing the frequency, independently of the processing of the other child radio devices. Therefore, the frequency at which a plurality of request packets having the same frequency are received at the parent radio device or the child radio device is reduced. As a result, the burden of processing executed by the parent radio device or the child radio device is reduced, and processing for establishing a communication path is quickly performed. Further, since each child radio device autonomously establishes a communication path, the processing amount in the parent radio device is reduced.

  Next, specific processing executed by the parent radio device and each child radio device will be described. The route establishment process includes a parent device / route establishment process executed by the parent wireless device and a child device / route establishment process executed by the child wireless device.

  FIG. 5 shows a flowchart of the master / route establishment process. Here, with reference to FIG. 2 (A) and FIG. 5, the process which the control part 18p and transmission / reception part 16p with which a parent radio apparatus is provided is demonstrated.

  The control unit 18p determines one of n predetermined frequencies f1 to fn as a communication frequency (S101). The determination of the communication frequency is performed by a user operation, for example. Moreover, the control part 18p may determine a communication frequency at random. The control unit 18p stores the determined communication frequency in the storage unit 20p (S102). Then, the frequency at which the transmission / reception unit 18p transmits / receives a packet (transmission / reception frequency) is set as the communication frequency (S103). Thereafter, the parent radio device executes a terminal ID acquisition process SA including the processes of steps S104 to S107.

  The control unit 18p determines whether or not the request packet is received by the transmission / reception unit 16p (S104). This determination is performed based on, for example, whether a request packet has been received within a predetermined time. If the control unit 18p determines that the request packet has not been received, the control unit 18p ends the parent radio / route establishment process. On the other hand, if it is determined that the request packet has been received, the ID included in the request packet is acquired as the terminal ID and stored in the storage unit 20p (S105). The control unit 18p generates a response packet (S106) and outputs it to the transmission / reception unit 16p. The transmission / reception unit 16p transmits a response packet at the communication frequency (S107), and returns to the process of step S104.

  Through such processing, the master radio determines the communication frequency and, when receiving a request packet from the slave radio, acquires the ID included in the request packet as the terminal ID. Further, when the master radio device receives a plurality of request packets transmitted from a plurality of child radio devices by the processing loop of steps S104 to S107, the master radio device acquires the ID included in each request packet as a terminal ID. . As a result, the parent radio determines one or more next-hop radios on the end node side.

  FIG. 6 shows a flowchart of the slave unit / route establishment process. Here, with reference to FIG. 2 (B) and FIG. 6, the process which the control part 18c and transmission / reception part 16c with which a sub radio | wireless machine is provided is demonstrated.

  The control unit 18c generates a request packet (S201) and outputs the request packet to the transmission / reception unit 16c. The controller 18c randomly selects one of n predetermined frequencies f1 to fn, and determines the selected frequency as a temporary frequency (S202). The control unit 18c sets the transmission / reception frequency of the transmission / reception unit 16c to a temporary frequency (S203). The transmission / reception unit 16c transmits the request packet at the temporary frequency (S204).

  The parent radio device executes the above-described terminal ID acquisition process SA (S205). The parent radio device transmits a response packet when permitting the child radio device to establish a communication path. Further, the other child radio devices execute the terminal side ID acquisition process in the same manner as the parent radio device (S205). Other child radio devices transmit a response packet when permitting establishment of a communication path.

  The control unit 18c determines whether or not a response packet has been received by the transmission / reception unit 16c (S206). When it is determined that the response packet has not been received, the control unit 18c changes the temporary frequency. That is, the control unit 18c changes the temporary frequency to the frequency f1 to fn that has not been previously set as the temporary frequency (S207). For example, if the previous temporary frequency is fj and j + 1 is a value equal to or smaller than n, the changed temporary frequency f is set to fj + 1. When j + 1 exceeds n, the temporary frequency after change is set to f1. Alternatively, the frequency f1 to fn that has not been previously set as the temporary frequency may be selected at random and set as the changed temporary frequency. After changing the temporary frequency in step S207, the control unit 18c returns to the process in step S203.

  When it is determined in step S206 that the transmission / reception unit 16c has received the response packet, the control unit 18c acquires the ID included in the response packet as the backbone ID and stores it in the storage unit 20c (S209). Further, the temporary frequency at this time is stored in the storage unit 20c as the communication frequency (S210).

  Through such processing, the slave radio device repeatedly transmits the request packet while changing the temporary frequency until a response packet transmitted from another radio device is received. When a response packet to the request packet is received, the backbone ID is acquired from the response packet, and the provisional frequency at that time is acquired as the communication frequency. That is, the slave radio determines the next hop radio on the trunk node side and recognizes the communication frequency of the multihop communication system to which the slave radio belongs.

  After storing the backbone ID and the communication frequency in the storage unit 20c, the control unit 18c executes a terminal ID acquisition process (S211). FIG. 7 shows a flowchart of the terminal ID acquisition process. This process is the same as the terminal side ID acquisition process SA shown in FIG. Steps S301 to S304 correspond to steps S104 to S107 shown in FIG.

  The control unit 18c determines whether or not the request packet is received by the transmission / reception unit 16c (S301). When determining that the request packet has not been received, the control unit 18c ends the terminal-side ID acquisition process, and further ends the slave unit / path establishment process. On the other hand, if it is determined that the request packet has been received, the ID included in the request packet is acquired as the terminal side ID and stored in the storage unit 20c (S302). The control unit 18c generates a response packet (S303) and outputs it to the transmission / reception unit 16c. The transmission / reception unit 16c transmits the response packet at the communication frequency (S304), and returns to the process of step S301.

  By such processing, the slave radio device that executes the terminal side ID acquisition processing acquires the ID included in the request packet as the terminal side ID when receiving the request packet from another child radio device. Further, when the slave radio that executes the terminal side ID acquisition process receives a plurality of request packets transmitted from a plurality of other slave radios by the processing loop of steps S301 to S304, The included ID is acquired as the terminal ID. That is, the child radio device that executes the terminal-side ID acquisition process determines one or more next-hop wireless devices on the terminal node side.

  In addition, after memorize | storing path | route information, each sub radio | wireless machine may transmit own path | route information to a parent radio | wireless machine via the next hop radio | wireless by the main node side. As a result, the parent radio device can acquire communication path information of the entire multi-hop communication system and generate routing information in the multi-hop communication.

(4) Route Re-Establishment Process The parent radio device according to the present embodiment transmits a confirmation packet with a destination ID as a broadcast ID at a predetermined time interval by the multihop communication described above. If there is no problem in the communication path between the parent radio device and the child radio device, a confirmation packet is received by the child radio device. By receiving the confirmation packet transmitted from the parent wireless device, the child wireless device recognizes that there is no problem in the communication path from the parent wireless device to itself. However, if a problem occurs in the communication path between the parent radio device and the child radio device due to the appearance of an obstacle or the occurrence of an interference wave, the confirmation packet may not be received by the child radio device. It can be said that the confirmation packet is a packet indicating that the state of the communication path is good for the slave radio device.

  Each slave radio device performs a route re-establishment process when a confirmation packet is not received for a predetermined time or more. The route re-establishment process is a process for invalidating the route information stored by itself at this time, performing the slave unit / route establishment process shown in FIGS. 6 and 7, and broadcasting the route establishment command information. Here, the route establishment command information is information for instructing other child radio devices to execute the child device / route establishment processing while invalidating the current route information. Broadcast is a process of transmitting information to an unspecified child radio device at a predetermined frequency without following the communication path of multi-hop communication. The slave radio device that has received the route establishment command information invalidates the route information stored by itself at the present time, and executes the slave device / route establishment process.

  According to such processing, a slave radio device that does not receive a confirmation packet for a predetermined time or longer executes a process of newly establishing a communication route, and newly sets a communication route to other slave radio devices. Prompt execution of the process to be established. As a result, the communication status deteriorates due to the appearance of obstacles, the occurrence of jamming waves, etc., and the communication route to the parent wireless device is interrupted. The establishing process is executed again.

  Each child radio device that executes the route re-establishment process autonomously establishes a communication route independently of the parent radio device. Therefore, it is not necessary for each slave radio to communicate with the master radio, and a communication path is quickly established.

(5) Change of communication frequency by parent radio device The parent radio device may execute a process of changing the communication frequency according to the state of the communication path. In this case, the parent radio device determines whether or not the state of the communication path to the child radio device is good by transmitting and receiving packets with the child radio device. When determining that the communication path to the child radio device is not good, the parent radio device changes the communication frequency.

  When the parent radio changes the communication frequency, each slave radio does not receive a confirmation packet for a predetermined time or longer. As a result, each child radio device executes the above-described route re-establishment process and establishes a communication route to the parent radio device.

  According to such a process, even if the parent radio device changes the communication frequency according to the communication status, a communication path is autonomously established by each child radio device.

(6) Application Example of Multihop Communication System (6-1) Configuration of Information Recovery System The multihop communication system according to the present invention can be used for an information recovery system. The information collection system includes an information collection / master radio and a plurality of sensors / slave radios. The information collection / parent wireless device corresponds to the above-described parent wireless device, and the sensor / slave wireless device corresponds to the above-described slave wireless device.

  Each sensor / slave radio is provided with a sensor for detecting temperature, humidity and the like. The sensor / slave radio is provided in, for example, a buoy disposed in the sea, a lake, a river, or a warehouse where quality control is performed. The sensor may be a power meter, a gas meter or the like provided in each household of the apartment house. In this case, the sensor / slave radio is installed in each home. The information collection / master radio device collects detection data from each sensor / slave radio device by multi-hop communication. The communication frequency used in the information collection / master radio and sensor / slave radio is, for example, a 400 MHz band and a 920 MHz band defined by the standard ARIB-STD T108.

  FIG. 8 shows a configuration example of the information collection / parent wireless device 22. The same components as those shown in FIG. 2A are denoted by the same reference numerals. The information collection / parent wireless device 22 includes a computer 24 and a main body 25. As the computer 24, for example, a personal computer or a large computer for business use is used. The computer 24 is connected to the communication network 14.

  The main unit 25 includes an interface 26, a parent radio processor 28, a transmission / reception unit 16 p, and a power supply unit 30. These components may be accommodated in the same housing. The interface 26 connects the parent radio processor 28 to the computer 24. The parent radio processor 28 exchanges packets with the transmission / reception unit 16p or controls the transmission / reception unit 16p based on a command from the computer 24 or a program stored by itself. The power supply unit 30 supplies power to the parent radio processor 28 and the transmission / reception unit 16p. The power supply unit 30 may include a battery or may be supplied with power from a commercial power supply.

  The computer 24, the interface 26, and the parent radio processor 28 have the same functions as the control unit 18p of the parent radio shown in FIG. Further, the memory 32 included in the computer 24 has a function similar to that of the storage unit 20p illustrated in FIG.

  FIG. 9 shows a configuration example of the sensor / slave radio 34. The same components as those shown in FIG. 2B are denoted by the same reference numerals. The sensor / slave radio 34 includes a sensor 36, an information input unit 38, a slave radio processor 40, a memory 42, a transmission / reception unit 16 c, and a power supply unit 44. These components may be accommodated in the same housing. The sensor 36 is connected to the slave radio processor 40 by the information input unit 38.

  The sensor 36 detects temperature, humidity, etc., and outputs the detected data to the slave radio processor 40 via the information input unit 38. The slave radio processor 40 exchanges packets with the transmission / reception unit 16c or controls the transmission / reception unit 16c based on the memory 42 or a program stored by itself. The power supply unit 44 supplies power to the slave radio processor 40 and the transmission / reception unit 16c. The power supply unit 44 may include a battery, or may be supplied with power from a commercial power supply. A battery is used when it is difficult to acquire power from a commercial power source such as a buoy arranged in the sea, a lake, a river, or the like. As the battery, a secondary battery that can be repeatedly charged and discharged, such as a lithium ion battery or a nickel metal hydride battery, may be used, or a solar battery may be used.

  The slave radio processor 40 has the same function as the control unit 18c of the slave radio shown in FIG. The memory 42 has a function similar to that of the storage unit 20c illustrated in FIG.

(6-2) Process Performed by Information Collection System A process in which the information collection / master radio device 22 collects detection data from the sensor / slave radio device 34 will be described. The information collection / parent radio device 22 describes the ID of the detection data collection destination sensor / child radio device 34 in the destination ID portion, and generates an information collection packet in which the information collection command is written in the payload portion. Here, the information collection command is a command for instructing that a packet including detection data should be returned. The information collection / master radio 22 transmits an information collection packet to the destination sensor / slave radio 34 by multi-hop communication.

  The destination sensor / slave radio 34 generates a detection data return packet in accordance with the information collection command described in the payload portion. The detection data return packet is a packet in which the ID of the information collection / parent wireless device is described in the destination ID portion, and the detection data acquired by the sensor 36 is described in the payload portion.

  The sensor / slave radio 34 transmits a detection data return packet to the information collection / master radio 22 by multi-hop communication. When the information collection / master radio 22 receives the detection data return packet, the information collection / master radio 22 acquires the detection data from the payload portion. By such processing, the information collection / radio device 22 acquires detection data from the sensor / child radio device 34 that is the detection data collection destination.

  According to the information collection system, detection data is collected by the information collection / master radio device 22 from each of a plurality of scattered sensors / sub-radio devices 34, and each sensor / sub-radio device 34 is arranged. Detection data at a place can be acquired at one place.

  10, 12 multi-hop communication system, 14 communication network, 16p, 16c transmission / reception unit, 18p, 18c control unit, 20p, 20c storage unit, 22 information collection / parent radio unit, 24 computer, 25 main unit, 26 interface, 28 Parent radio processor, 30, 44 Power supply unit, 32, 42 Memory, 34 Sensor / child radio device, 36 Sensor, 38 Information input unit, 40 Child radio processor.

Claims (6)

In a multi-hop radio used as one of a plurality of radios performing multi-hop communication,
A request packet transmitter for transmitting a request packet for requesting establishment of a communication path to another wireless device;
A response packet receiving unit that receives a response packet when a response packet having the same frequency as the frequency of the request packet is transmitted from another wireless device to the request packet;
When the response packet is received, another wireless device that has transmitted the response packet is determined as a next-hop wireless side on the backbone side that determines the next-hop wireless device on the communication side,
With
The request packet transmission unit changes a transmission frequency and transmits the request packet again when the response packet is not received. The multi-hop wireless device according to claim 1,
A frequency recognizing unit that recognizes the frequency of the response packet as a communication frequency used in the multi-hop communication when the response packet is received;
A request packet receiver that receives a second request packet that is transmitted from another wireless device, has the same frequency as the communication frequency, and requests establishment of a communication path;
When the second request packet is received after the next-hop radio on the backbone side is determined, the other radio that has transmitted the second request packet is used as the next-hop radio on the end side in the communication path. A terminal next hop determination unit to determine,
A multi-hop wireless device comprising: The multi-hop wireless device according to claim 1 or 2,
A confirmation packet indicating the status of the communication path, a confirmation packet receiving unit that receives the confirmation packet transmitted from the next-hop wireless device on the backbone side;
When the confirmation packet has not been received for a predetermined time, a trunk side next hop re-determination unit that re-determines a radio serving as a trunk side next-hop radio;
With
The backbone next hop re-determination unit is
A multi-hop wireless device, wherein the request packet transmitting unit, the response packet receiving unit, and the backbone-side next hop determining unit re-determine a wireless device that becomes a backbone-side next-hop wireless device. The multi-hop wireless device according to claim 3,
A broadcast unit that broadcasts route establishment command information that, when the confirmation packet has not been received for a predetermined time, causes another wireless device to re-determine a wireless device that is a next-hop wireless device on the backbone side;
A multi-hop wireless device comprising: The multi-hop wireless device according to claim 1 or 2,
A route establishment command receiving unit for receiving route establishment command information for instructing re-determination of a wireless device to be a next-hop wireless device on the backbone side;
When the route establishment command information is received, a backbone side next hop re-determination unit that re-determines a wireless device that becomes a backbone side next-hop wireless device,
With
The backbone next hop re-determination unit is
The multi-hop wireless device, wherein the request packet transmitting unit, the response packet receiving unit, and the backbone-side next hop determining unit re-determine a wireless device that becomes the backbone-side next-hop wireless device. In a multi-hop wireless device that is used as one of a plurality of wireless devices that perform multi-hop communication, and the multi-hop communication is communication using one of the plurality of wireless devices as a core wireless device ,
A confirmation packet indicating the status of the communication path, a confirmation packet receiving unit for receiving a confirmation packet transmitted from a radio determined as the next-hop radio on the backbone side;
When the confirmation packet has not been received for a predetermined time, a trunk side next hop re-determination unit that re-determines a radio serving as a trunk side next-hop radio;
A broadcast unit that broadcasts route establishment command information that causes another wireless device to re-determine a wireless device that is to be the next-hop wireless device on the backbone side when the confirmation packet has not been received for a predetermined time; ,
A multi-hop wireless device comprising:

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