JP5654942B2 - Wireless relay transmission system - Google Patents

Description

  The present invention relates to a wireless relay transmission system including a plurality of slave units arranged in the relay order and a master unit that collects information acquired by each slave unit, wherein the slave unit relays information via another slave unit.

  Conventionally, in order to collect information by acquiring a variety of information by a plurality of slave units having sensors, and relaying this information sequentially in the direction in which the slave units are arranged and wirelessly transmitting to the master unit at the end of the slave unit row A wireless relay transmission system using a wireless device is known. For example, Patent Literature 1 discloses an overhead power transmission line tower-based monitoring system that monitors the state of an overhead power transmission line such as a power transmission line, a power pole, or a lamp using a wireless device. This monitoring system avoids the problem that relay transmission is interrupted when any one of the tower radios (slave units) in the tower row becomes unable to communicate for some reason. When an information collection station (master unit) is arranged and a failure that prevents relay transmission occurs in any of the wireless devices, the wireless devices before and after the failure are directed to the front and rear ends of the tower row 2 The direction of the relay transmission route is formed, the information of the sensors of each tower on the relay transmission route is collected by the information collection station by the relay transmission route toward the tip, and the information of each tower is collected by the relay transmission route toward the rear end. Sensor information is collected by an information collection station on the rear end side.

  Although the above system is capable of relay transmission even if a certain radio device breaks down, it is not a so-called polling system in which the master unit collects the status of slave units as needed for unidirectional transmission. Is a relay transmission method. By performing relay transmission periodically, it is possible to collect the state in almost real time, but extra communication to the slave unit may occur. On the other hand, as a communication method capable of multi-hop transmission and performing polling, there is a communication protocol called AODV as shown in Non-Patent Document 1.

JP 2005-229715 A

AODV (Ad-hoc On-Demand Distance Vector Routing): RFC3561

  FIG. 17 shows a conventional wireless relay transmission system 100 that collects information up to the slave units 102-1 to 102-n in response to a request from the master unit 101. In this wireless relay transmission system 100, when polling is performed for each slave unit using the transmission method of Non-Patent Document 1, the number of transmissions / receptions of slave units around the master unit inevitably increases and current consumption increases. In particular, a slave unit 102 that operates with a solar cell and a secondary battery increases the communication load of the slave unit 102-1 disposed in the vicinity of the master unit 101 by polling the specific slave unit 102. The slave unit 102-1 may not be able to operate due to an increase in current consumption. Further, when polling each slave unit (102-1 to 102-n), it takes time to collect the status from each slave unit 102. On the other hand, in order to reduce the power consumption of the wireless device, the power consumption can be reduced by intermittent reception. On the other hand, if polling is performed on the slave device for intermittent reception, more time is required.

  Therefore, in the present invention, in a system having a slave unit and a master unit that relays and relays information, the relay transmission route is optimized to reduce the power consumption of the slave unit and to shorten the state collection time from the slave unit. An object of the present invention is to provide a wireless relay transmission system that can perform such a process.

  In order to achieve the above object, a wireless relay transmission system according to the present invention includes a plurality of slave units arranged in the relay order and a master unit that collects information acquired by each slave unit. In a wireless relay transmission system that relays information via other slave units, the slave unit receives a route construction message in which the relay order from the master unit to the terminal slave unit is recorded from the master unit, and the next relay destination The message relay means to be transmitted to the slave unit and whether the route construction message transmitted by other slave units can be received, and if it can be received, the relay destination information that can be communicated is extracted from the route construction message Extracting means, and storage means for storing the relay destination information extracted by the extracting means, and each slave unit sequentially relays the route route from the parent device to the terminal device and transmits a route construction message. The upstream route from the terminal unit to the base unit is recorded in the storage means. Characterized in that it utilizes a small path number of relays in comparison with the downlink path based on the communication can be a relay destination information.

  Further, in the wireless relay transmission system according to the present invention, the slave unit determines that the slave unit does not relay the message to the next slave unit by the extraction unit after transmitting the telegram to the relay destination slave unit that can communicate. In this case, a message is transmitted to a slave unit whose relay order is increased by one in the case of a downlink route, and to a slave unit whose relay order is reduced by one in the case of an uplink route.

  Further, in the wireless relay transmission system according to the present invention, when the slave unit determines that the relay unit cannot relay to the terminal slave unit using the relay destination information stored in the storage unit in the downlink route, the uplink route It is characterized by transmitting a message.

  Further, in the wireless relay transmission system according to the present invention, another master unit is arranged at the end of the downstream path from the master unit to the terminal slave unit.

  By using the wireless relay transmission system according to the present invention, it is possible to reduce the power consumption of the slave unit that does not relay by making the uplink route transmitted from the terminal slave unit to the master unit a route having a smaller number of relays than the downlink route. It becomes possible to reduce power shortage. Further, there is an effect that the transmission time can be shortened by reducing the number of times of relaying the upstream route.

It is a block diagram which shows the structure of the wireless relay transmission system which has a main | base station and a subunit | mobile_unit which concerns on embodiment of this invention. It is explanatory drawing explaining the communication timing of the radio relay transmission system which concerns on embodiment of this invention. It is explanatory drawing explaining the content of the message | telegram used with the radio relay transmission system of FIG. It is explanatory drawing explaining the outline | summary of the path | route construction process which concerns on the 1st Embodiment of this invention. FIG. 5 is an explanatory diagram for explaining a routing table creation process in the route construction process shown in FIG. 4. It is explanatory drawing explaining the process which relays an upstream path | route with the small frequency | count of relaying using the routing table shown in FIG. It is explanatory drawing in the case of performing return transmission in the middle of a downstream path | route using the routing table shown in FIG. It is a flowchart figure which shows the flow of the path | route construction process shown in FIGS. It is explanatory drawing explaining the outline | summary of the state collection process which concerns on this embodiment. It is explanatory drawing explaining the flow of a process when the relay failure generate | occur | produces in the state collection process shown in FIG. It is a flowchart figure which shows the flow of the state collection process of FIGS. It is explanatory drawing explaining the outline | summary of the state collection process which concerns on the 2nd Embodiment of this invention. It is explanatory drawing explaining the flow of a process when a relay failure generate | occur | produces in the state collection process shown in FIG. FIG. 14 is an explanatory diagram for explaining a flow of return transmission that cannot be relayed in the state collection processing shown in FIG. 13. It is a flowchart figure which shows the flow of the state collection process of FIGS. It is explanatory drawing explaining the outline | summary of the state collection process which concerns on the modification of this invention. It is explanatory drawing explaining the flow of the conventional wireless relay transmission process.

  Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings.

  FIG. 1 shows a wireless relay transmission system 1 having a parent device 10 and a plurality of child devices 20 used in the present embodiment. The base unit 10 is a radio unit connected to a management computer (PC), and is connected to the conversion unit 14 for connecting to the PC, the radio unit 12 for performing radio communication, and the radio unit 12. Controlling the antenna 11, the radio unit 12 and the conversion unit 14, a control unit 13 having a CPU, a RAM, and a ROM, and a power supply unit 15 for supplying power to the master unit with a DC power supplied from the outside. Have. Moreover, the subunit | mobile_unit 20 has a sensor which measures the temperature of an agricultural land, humidity, sunshine, and rainfall, and comprises the radio | wireless machine of the agricultural environment measuring machine which transmits measurement data to the main | base station 10. FIG. The subunit | mobile_unit 20 produces | generates electric power by the conversion part 24 which converts the input from various sensors into digital data, the radio | wireless part 22 for performing wireless communication, the antenna 21 connected to the radio | wireless part 22, and sunlight. A solar battery 26, a storage battery 27 for storing the power generated by the solar battery 26, a DC power input, a power supply section 25 having a charge control section for controlling the solar battery and the storage battery 27, a radio section 22, a conversion section 24, and a power supply section And a control unit 23 having a CPU, a RAM, and a ROM.

  The radio used in this embodiment uses a specific low power radio (400 MHz band, 950 MHz band, etc.) that can transmit at a line-of-sight distance and has low power consumption, and has a communication speed of 1200 bps and 4800 bps according to the amount of data to be transmitted and received. If the communication speed is about 50 kbps and 100 kbps, the frequency band of 950 MHz is used.

  In this embodiment, it was set as the structure which arrange | positions and arrange | positions the subunit | mobile_unit 20 in a farm land division in order at predetermined intervals, and collects the information of each division with the management computer connected to the main | base station 10. FIG. For this reason, a DC power supply cannot be connected to the subunit | mobile_unit 20, It is necessary to drive with the electric power of a solar cell. Therefore, the communication timing by intermittent reception as shown in FIG. 2 is adopted for the purpose of reducing the power consumption of the slave unit 20. The horizontal axis in FIG. 2 is a time axis, and the transmission timing on the reception side is shown on the upper side and the transmission / reception timing on the transmission side is shown on the lower side. In this embodiment, in order to reduce the power consumption in the reception process, for example, the reception operation is executed at N = 500 ms, and the rest is set in the sleep state to reduce the power consumption. In the transmission process, the preamble is repeatedly transmitted for Nmsec or more before the actual message is transmitted, so that the message transmitted after the preamble can be received even in intermittent reception.

  FIG. 3 shows the data structure of an actual message. In the preamble, bit synchronization, frame synchronization, system ID, transmission destination ID, transmission source ID, and error check CRC are repeatedly transmitted. After the receiver side is ready, bit synchronization, frame synchronization, system ID, transmission source ID , Transmission destination ID, message type, data length, data and CRC are transmitted. The message types include a route construction message and a status collection message described later.

  (First Embodiment): In the first embodiment, the routing table of each slave unit is created using the route construction syntax, thereby reducing the number of relays of the slave units and reducing power consumption. FIG. 8 is a flowchart showing the flow of the route construction process. Hereinafter, the flow of the route construction process will be described with reference to FIGS.

  When step S10 of FIG. 8 is executed, the relay order is transmitted from the parent device 10 to the child device 20. In this process, the communication status of the slave unit is confirmed using the instruction from the master unit 10 as a trigger, and the relay information to each slave unit is checked. As shown in FIG. 4, the base unit 10 stores the “route construction message” in which the relay order from the first slave unit 20-1 close to the master unit 10 to the terminal slave unit 20-n is stored once before starting normal operation. "Is relayed from the first slave unit 20-1 to the last slave unit 20-n. In the wireless relay transmission system, when the slave unit 20 is arranged for each line-of-sight distance from the master unit 10, since the preset slave unit ID and arrangement order are known, this information is stored in the management computer, Based on the arrangement order, the route construction telegram 31 is transmitted from the parent device 10 to the child device 20-1.

  In step 12 of FIG. 8, the slave unit 20-1 refers to the relay order of the route construction message received from the master unit 10, and extracts that the relay destination is the slave unit 20-2 (identifier: slave unit 2ID). Then, the route construction message 31 is transmitted to the child device 20-2. Similarly, the slave unit 20-2 is relayed from the slave unit 20-3,..., The slave unit 20-n-1, and the terminal slave unit 20-n. At this time, the handset 20 tries to receive information on the route construction telegram 31 and wireless communication from the handset in the vicinity of the own device.

  5 extracts the routing table of the upstream path 32 and the routing table of the downstream path 33 from the path construction message 31 and receives a transmission signal having an electric field strength that can be received by intermittent reception. The communication status of the slave unit in the vicinity of its own device (slave unit 20-5) is checked. From this routing table, it can be seen that the slave units 20-2 (slave unit 2ID) and slave unit 20-7 (slave unit 7ID) are far from the own device (step S14 in FIG. 8).

  In step S16 of FIG. 8, it is determined whether or not relaying has been performed to the terminal slave unit 20-n. If relaying has not been performed to the terminal, relaying is continued. The relay to the terminal 20-n is completed, and the slaves (20-3, 20-5, 20-7) can obtain the routing tables 34, 35, 36 of FIG. In step S18 of FIG. 8, for example, when the slave unit 20-7 (slave unit 7ID) performs route construction statement transmission on the uplink route, the slave device 20-5 (slave device 5ID) on the uplink route of the routing table 36. ) Is selected, and in step S20, a route construction message is transmitted to the remote child device. Similarly, the slave unit 20-5 (slave unit 5ID) selects the slave unit 20-3 (slave unit 3ID) on the upstream path of the routing table 34 and transmits a route construction message, and the slave unit 20-3 (slave unit 20-3) (Machine 3ID) selects the slave 20-1 (slave 1ID) in the upstream route of the routing table 35 and transmits a route construction message. Finally, after transmitting the route construction message to the parent device 10, the child device 20-1 (child device 1 ID) determines that it has relayed to the parent device 10 in step S <b> 22 of FIG. 8, and the series of processing ends. Therefore, as shown in FIG. 6, in the up route, the route construction message is returned to the base unit 10 with a smaller number of relays (2 times) than in the down route.

  Next, processing when a communication failure occurs in the slave unit will be described. FIG. 7 shows a case in which return transmission is performed in the middle of the downstream path using the routing table. When the power of the storage battery decreases due to lack of sunshine or an increase in data relay, communication failure occurs. 7 tries to relay to the slave unit 20-6 (slave unit 6ID) or the slave unit 20-7 (slave unit 7ID), but the slave unit 20-6 (slave unit 6ID). If it is determined that the communication device 6ID) or the slave device 20-7 (slave device 7ID) is not communicating with the next slave device, it is determined that there is a relay failure in the downstream route, and the route construction message is switched to the upstream route. Relay in the direction of the main unit. By this processing, the parent device 10 can recognize the completion of the routing table creation up to the child device 20-5. In this way, the “route construction message” can be used as a monitor of the communication status by using it before normal operation or when the route configuration is changed by adding or deleting a slave unit.

  Next, information collection by the status collection message will be described with reference to the flowchart of FIG. 11 and FIGS. 9 to 12. When the state collection is started, in step S30 in FIG. 11, the base unit 10 acquires the sensor information from the handset and adds the state data of each handset to the data portion of the state collection message. The collection message 41 is set to have the transmission source as the parent device 10 and the transmission destination as the terminal child device 20-n, and the status collection message 41 is sent to the child device 20-1 (child device 1 ID). Further, the slave unit 20-1 relays to the slave unit 20-2 (step S32).

  The subunit | mobile_unit 20-1 has a routing table, and in the down path | route, the status collection message | telegram 41 transmits to the nearest subunit | mobile_unit 20-2 in the routing table of the downstream path | route of the subunit | mobile_unit 20-1. Next, the slave unit 20-2 stores the status of the own device in the status collection message 41, and refers to the routing table of the own device, and the status of the slave unit closest to the own device on the downstream path (step S34). A collected message is transmitted (step S38). If a message cannot be transmitted to the nearest child device, a status collection message is then transmitted to the child device closest to the own device (step S36).

  When the relayed state collection telegram 41 does not reach the terminal slave unit 20-n, it returns at step S40. When the terminal unit 20-n is reached, the process proceeds to step S42, and the farthest slave unit 20-6 is selected from the routing table for the upstream route so that the number of relays for the upstream route is reduced. In S44, the state collection telegram 41 is transmitted. If it is not possible to transmit to the farthest slave unit in step S44, a message is transmitted to the next distant slave unit (front side) and a status collection message is transmitted to the master unit 10. That is, the child device 20 creates a routing table based on the route construction message, and confirms the communication status in the vicinity of the child device 20 and reduces the number of relays based on the routing table, whereby each child device in the subsequent state collection message. It is possible to reduce the number of relays even when collecting the information. If relayed to the parent device, the series of processing ends (step S46).

  (Second Embodiment): In the second embodiment, the status collection message is transmitted according to the relay order of the slave units without separately transmitting the route construction message and the status collection message that were performed in the first embodiment. The number of relays can be reduced in the upstream path from the terminal slave unit to the master unit by searching for the slave units that can communicate with each other. With such processing, the route construction message and the state collection message can be transmitted by one message transmission, and the routing table is not used. Furthermore, the position of the parent device can be changed at any time without using a route construction message by disposing another parent device at a communicable distance ahead of the terminal device.

  Information collection by the state collection message will be described with reference to the flowchart of FIG. 15 and FIGS. FIG. 12 shows an overview of the state collection process according to the second embodiment. In the composite message 42 in which the relay order and status information of FIG. 12 are recorded, the relay destination ID of the slave unit and the status of the slave unit can be stored. Therefore, relay and status collection can be performed using this composite message 42. It becomes possible. When the state collection of FIG. 15 is started, in step S50, the base unit 10 stores the relay order up to the terminal unit and the state information in the composite message 42 and transmits it to the slave unit 20-1. Next, in step S52, the slave unit refers to the relay order in the status collection message, sets the status of the slave unit in the composite message 42, and transmits it to the next slave unit 20-2 (step S54). In step S56, the slave unit attempts to receive a message transmitted from the next slave unit 20-2, and determines whether or not the slave unit 20-2 relays. If the slave unit 20-2 relays, information is added to the message (step S58). If the relay to the terminal slave unit is not completed in step S64, the process returns to step S52.

  Next, processing when communication failure occurs will be described with reference to FIG. FIG. 13 shows a situation in which the slave unit 20-3 (slave unit 3ID) has a communication failure. In step S56 of FIG. 15, transmission from the child device 20-2 to the child device 20-3 is confirmed. When the handset 20-2 determines that the handset 20-3 does not transmit anything over several cycles of intermittent reception in step S56, the handset 20-2 transmits to the next handset 20-4 next to step S60, If it is transmitted normally, information is added to the composite message (step S62). In this case, the status collection of the slave unit 20-3 (slave unit 3ID) is recorded as “error: X”, that is, information is not added to the composite message, and the following processing is continued. By performing such processing, it is possible to continue relaying by jumping over the slave unit in which communication failure has occurred. Next, the flow of processing when the slave units 20-4 and 20-5 have a communication failure will be described with reference to FIG.

  In step 56 of FIG. 15, communication from the slave unit 20-3 (slave unit 3ID) to the slave unit 20-4 (slave unit 4ID) fails, and in step S60, the slave unit 20-5 (slave unit 5ID). When communication to the network fails, relaying to the downstream path is not possible. Here, it is assumed that the slave unit 20-3 (slave unit 3ID) has received the composite telegram 42 to the slave units 20-2 and 20-1. When sending an electronic message to the parent device 10 on the upstream route, the number of relays to the parent device 10 is less when transmitted to the child device 20-1 farthest than the child device 20-2. The composite message 42 is transmitted to the child device 20-1 which is a distant child device, and the relay is repeated to the parent device 10 in step S70. As described above, the slave unit 20 can realize a function corresponding to the routing table by recording the farthest relay destination slave unit having a small number of relays on the upstream route as a pair with the composite message. In FIG. 14, since it is difficult to collect the status from the slave unit 20-6 and the slave unit 20-7 to the terminal slave unit 20-n, an application example of this embodiment is shown in FIG.

  FIG. 16 is a diagram in which the parent device A is arranged at a distance that allows communication with the terminal device 20-n. The parent device A (10A) collects the state from the child device 1A to the terminal device 20A-n, but from the child device 20-6, the child device 20-7 to the terminal child device 20-n as necessary. It is also possible to perform state collection. Normally, the master unit 10 and the master unit A (10A) can communicate with each other via a management computer. Therefore, the master unit A (10A) is notified of a malfunction from the master unit 10 and the remaining slave units 20-7. It is possible to collect the state collection from the terminal device 20-n.

  As described above, using the wireless relay transmission system according to this embodiment has the following five effects. (1) Information on each slave unit can be collected in the shortest time by sequentially setting the downlink route as a relay and the uplink route as a route with a small number of relays. Thereby, the current consumption of each slave unit can also be reduced. (2) Temporary radio interference and abnormalities in specific slave units can be communicated using alternative routes. (3) Since the alternative route is automatically set, it is not necessary to set the communication route to each slave unit. (4) Even when relay transmission from the parent device to the terminal child device is impossible, it can be turned back in the middle, so that reduction operation is possible. (5) In the case of FIG. 16, communication is possible even if the position of the master unit is changed. Even if it is not possible to collect the status up to the terminal slave unit due to an abnormality of the slave unit by using this, if the status is collected from the reverse side, the status of each slave unit except the abnormal slave unit can be collected Is also possible.

  In the present embodiment, a system related to information collection from agricultural sensors has been described. However, the present invention is not limited to this, and the present invention may be applied to a system that monitors the state of utility poles, street lamps, and the like.

  DESCRIPTION OF SYMBOLS 1,100 Wireless relay transmission system 10,101 Main | base station, 11,21 Antenna, 12,22 Radio | wireless part, 13,23 Control part, 14,24 Conversion part, 15,25 Power supply part, 20, 20A, 102 , 26 solar cell, 27 storage battery, 31 route construction message, 32 slave device uplink route, 33 slave device downlink route, 34, 35, 36 routing table, 41 status collection message, 42 composite message.

Claims (4)

In a wireless relay transmission system that includes a plurality of slave units arranged in the relay order, and a master unit that collects information acquired by each slave unit, the slave unit relays information via other slave units,
The handset is
A message relay means for receiving a route construction message in which the relay order from the parent device to the terminal child device is recorded from the parent device, and transmitting it to the child device as the next relay destination;
It is determined whether or not a route construction message transmitted by another slave unit can be received, and if it can be received, an extraction unit that extracts relay destination information that can be communicated from the route construction message;
Storage means for storing relay destination information extracted by the extraction means;
Have
The downstream route from the parent device to the terminal device is sequentially relayed by each slave device to transmit the route construction message, and the upstream route from the terminal device to the parent device is the communicable relay destination stored in the storage means. A wireless relay transmission system using a route having a smaller number of relays than a downlink route based on information. The wireless relay transmission system according to claim 1,
After transmitting the message to the relay device that can communicate with the child device, if it is determined by the extraction means that the child device is not relaying the message to the next child device,
A radio relay transmission system characterized in that a telegram is transmitted to a slave unit whose relay order is increased by one in the case of a downlink route, and a slave unit whose relay order is decremented by one in the case of an uplink route. In the wireless relay transmission system according to claim 1 or 2,
If the slave unit determines that relaying to the terminal slave unit is not possible using the relay destination information stored in the storage unit in the downlink route, the slave device transmits a message on the uplink route Transmission system. In the radio relay transmission system according to any one of claims 1 to 3,
A wireless relay transmission system characterized in that another master unit is arranged at the end of a downstream path from a master unit to a terminal unit.

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