JP2012257016A - Radio system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio system that can collect measurement data measured by a measuring terminal without losing it in the course of communication.SOLUTION: A radio network is comprised of: a measuring terminal 1 which measures a prescribed physical quantity and wirelessly transmits measurement data; a main device 2 which collects the measurement data transmitted by the measuring terminal 1; and a relay device 3 which intervenes between the measuring terminal 1 and the main device 2 to relay the measurement data. The relay device 3 comprises a storage unit which stores the measurement data transmitted by the measuring terminal 1 with which its own device has established connection. The relay device transmits in block a data group including multiple times of the measurement data stored in the storage unit to another relay device which has established connection with its own device and is closer to the main device than the own device.

Description

  The present invention relates to a wireless system that performs multi-hop wireless communication.

  Currently, a multi-hop wireless network method has been proposed in which a network is formed by a plurality of wireless terminals, and packets are relayed between adjacent wireless terminals, thereby enabling communication between wireless terminals that do not receive direct radio waves. . A sensor network system (wireless system) employing such a multi-hop wireless network system is disclosed in, for example, Patent Document 1.

  The conventional example described in Patent Document 1 includes a backbone device and a plurality of wireless devices. The backbone device is, for example, a computer having a wireless communication function, and manages the sensor information reported from each wireless device, and establishes and controls the path of the sensor network system. Prior to communication with a plurality of wireless devices, the backbone device executes a process of joining the wireless device to the wireless network to form a route. This route has a tree-like hierarchical relationship with the backbone device as the root.

  Each wireless device acquires various sensor information according to the sensor function of each wireless device, and reports to the backbone device. Prior to such a reporting process, the wireless device first executes a joining process to join the sensor network. In the participation process, the wireless device selects another wireless device that should form a parent-child relationship. At this time, the backbone device may be selected instead of another wireless device. This selection is performed so that the number of other wireless devices existing with the backbone device is minimized.

  And in this prior art example, the collision of radio packets at the time of relay processing is avoided by defining a specific transmission timing for each radio device constituting the network.

JP 2008-228176 A

  By the way, in the wireless system as in the above-described conventional example, the wireless device at the lowest level (position farthest from the backbone device) does not relay the wireless packet from the other wireless device, and does not relay the sensor information (measurement data). There is a case where only acquisition is performed, that is, a measurement terminal is used. And in such a measurement terminal, in order to make it easy to carry the terminal to a desired measurement location, it is common to use a battery provided for itself as an operating power supply without receiving an operating power supply from an external power supply. It is. For this reason, in such a measurement terminal, measurement data is transmitted at a predetermined interval so that it can be used for a long time with reduced battery consumption, and after transmission, the communication function is stopped until the next transmission, that is, in the sleep state Those that move to are common.

  However, in the above case, when measuring data transmitted from the measuring terminal is transmitted, there is a risk that the measured data may be lost during communication due to external noise or collision between radio signals. When the measurement data is lost in this way, the measurement terminal that has transmitted the measurement data is in the sleep state and cannot perform the retransmission process of the measurement data. Therefore, there is a problem that the lost measurement data cannot be collected by the backbone device.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a wireless system capable of collecting measurement data measured by a measurement terminal without being lost during communication.

  The wireless system of the present invention measures a predetermined physical quantity and wirelessly transmits measurement data including a measured value. When the measurement data is transmitted, at least the communication function is stopped until the next measurement data is transmitted. A wireless network including a plurality of measurement terminals, a main device that collects the measurement data of the measurement terminal, and one or more relay devices that are interposed between the measurement terminal and the main device and relay the measurement data The relay device includes a storage unit that stores the measurement data transmitted from the measurement terminal that has established a connection with itself, and the measurement terminal includes the measurement data in the measurement data. Time information based on the time at which data is measured is included, and the storage unit includes a volatile memory and a nonvolatile memory, and stores the same data in both memories.

  In this radio system, the relay device transmits and receives radio signals to and from the measurement terminal, and the measurement terminal and the relay device each include an electric field strength measurement unit that measures the electric field strength of the received radio signal. It is preferable that a wireless signal including information on the measured electric field strength is returned to the measurement terminal or the relay device.

  In this wireless system, the relay device includes a plurality of measurement data stored in the storage unit with respect to another relay device that establishes a connection with itself and is closer to the main device than itself. It is preferable to transmit the data group in a batch.

  In this wireless system, it is preferable that the measurement data is transmitted in a packet having a maximum packet size that can be allowed by a communication protocol.

  The present invention has an effect that measurement data measured by a measurement terminal can be collected without being lost during communication.

1A and 1B are diagrams illustrating an embodiment of a wireless system according to the present invention, in which FIG. 1A is a schematic diagram in a normal state, and FIG. 1B is a schematic diagram in a case where a relay device fails. It is a schematic block diagram which shows the structure of each part in a radio | wireless system same as the above, (a) is a schematic block diagram of a measurement terminal, (b) is a schematic block diagram of a main apparatus, (c) is a schematic block diagram of a relay apparatus. is there.

  Embodiments of a wireless system according to the present invention will be described below with reference to the drawings. As shown in FIG. 1A, the present embodiment includes a plurality (three in the figure) of measurement terminals 1, a main apparatus 2, and a plurality (four in the figure) of relay apparatuses 3, and these measurements. The terminal 1, the main device 2, and the relay device 3 (hereinafter collectively referred to as “wireless devices”) constitute a wireless network. In the following description, in order to distinguish between the plurality of measuring terminals 1, the measuring terminal 1 is represented by reference numerals 1 </ b> A to 1 </ b> C as necessary, and in order to distinguish between the plurality of relay apparatuses 3, the relay apparatus as necessary. 3 is represented by reference numerals 3A to 3D.

  As shown in FIG. 2A, the measurement terminal 1 is a radio that transmits and receives radio signals to and from a measurement unit 10 that measures a predetermined physical quantity (temperature, power consumption, flow rate) such as a thermometer, a power meter, and a gas meter. A transmission / reception unit 11, a control unit 12 that controls each unit, and a battery 13 that is a driving power source are provided. In addition, the measurement terminal 1 includes an electric field strength measurement unit 14 that measures the electric field strength of a radio signal received by the radio transmission / reception unit 11.

  The radio transmission / reception unit 11 includes a transmission circuit unit (not shown) that transmits a radio signal via an antenna (not shown) and a reception circuit unit (not shown) that receives a radio signal via the antenna. To do. Since the configuration of the wireless transmission / reception unit 11 is well known in the art, detailed description thereof is omitted here.

  The control unit 12 includes, for example, a microcomputer and implements various functions by executing programs stored in the memory. The control unit 12 causes the measurement unit 10 to perform measurement processing at regular intervals, and acquires measurement data including the measured values. Then, the control unit 12 causes the wireless signal including the measurement data to be transmitted from the wireless transmission / reception unit 11 to the relay apparatus 3 that has established a connection with the wireless signal (set in the communication path).

  Here, in order to make it easy to carry the terminal to a desired measurement location, the measurement terminal 1 obtains the operating power from the battery 13 provided in the measuring terminal 1 without receiving the operating power from the external power source. ing. Further, when transmitting the measurement data, the control unit 12 shifts the wireless transmission / reception unit 11 to a sleep state in which the operation is stopped until the next measurement data is transmitted. Thereby, the power consumption in the wireless transmission / reception unit 11 is reduced, and the battery 13 can be used for a long time while suppressing the consumption of the battery 13.

  In this embodiment, each wireless device has a unique address (MAC address and network address), and the transmission destination and transmission source of the wireless signal can be specified by the MAC address and network address. For this reason, the MAC address and network address of each wireless device are stored in the memory of the control unit 12.

  The electric field strength measurement unit 14 includes a relay device 3 that establishes a connection with itself, and a measurement circuit (not shown) that measures the electric field strength of a radio signal received in a communication path between itself. . In this embodiment, an LQI (Link Quality Indication) value is used as an index of electric field strength. The control unit 12 determines the connection status with the relay device 3 based on the LQI value measured by the electric field strength measurement unit 14. For example, if the LQI value becomes zero or a value close to zero, the control unit 12 determines that the connection with the relay device 3 that has established a connection with itself is disconnected.

  As shown in FIG. 2B, the main device 2 includes a wireless transmission / reception unit 20 that transmits and receives wireless signals, and a collection unit 21 that collects and stores measurement data from each measurement terminal 1. The main device 2 includes a communication unit 22 that communicates with a management server (not shown) via a host network and a control unit 23 that controls each unit.

  The wireless transmission / reception unit 20 has the same configuration as the wireless transmission / reception unit 10 of the measurement terminal 1. The collection unit 21 includes, for example, a rewritable nonvolatile memory (for example, a flash memory), and collects the measurement data from each measurement terminal 1 by storing the measurement data for each measurement terminal 1.

  The communication unit 22 includes, for example, a wired LAN adapter, a wireless LAN adapter, and the like, and performs wired or wireless communication with an upper network. Therefore, for example, the measurement data of each measurement terminal 1 collected by the collection unit 21 can be transmitted to the management server via the host network. The management server can collectively manage all measurement terminals 1 including other main devices 2.

  The control part 23 consists of microcomputers (microcomputer), for example, and implement | achieves various functions by running the program stored in memory. When the wireless signal transmitted from each relay device 3 is received by the wireless transmission / reception unit 20, the control unit 23 causes the collection unit 21 to store the measurement data included in the wireless signal for each measurement terminal 1. Note that the MAC address and network address of each wireless device are stored in the memory of the control unit 23 as in the measurement terminal 1.

  The relay apparatus 3 is interposed between the measurement terminal 1 and the main apparatus 2 and relays measurement data. As shown in FIG. 2C, the relay apparatus 3 transmits and receives radio signals. A storage unit 31 that stores measurement data and a control unit 32 that controls each unit are provided. In addition, the relay device 3 includes an electric field strength measurement unit 33 that measures the electric field strength of a radio signal received by the radio transmission / reception unit 30.

  The wireless transmission / reception unit 30 has the same configuration as the wireless transmission / reception units 11 and 20 of the measurement terminal 1 and the main device 2. The storage unit 31 includes, for example, a rewritable volatile memory (for example, DRAM) and a rewritable non-volatile memory (for example, flash memory), and is transmitted from the measurement terminal 1 that establishes a connection with itself. Memorize measurement data. The storage unit 31 stores not only the latest measurement data of each measurement terminal 1 but also a plurality of measurement data received in the past. In addition, these measurement data are stored in both the volatile memory and the nonvolatile memory constituting the storage unit 31.

  The control unit 32 is composed of, for example, a microcomputer (microcomputer), and realizes various functions by executing a program stored in a memory. When the wireless transmission / reception unit 30 receives a wireless signal transmitted from the measurement terminal 1 that has established a connection with itself, the control unit 32 stores the measurement data included in the wireless signal in the storage unit 31. Remember every time. Note that the MAC address and network address of each wireless device are stored in the memory of the control unit 32 as in the measurement terminal 1 and the main device 2. In addition, the control unit 32 sets a data group including measurement data for each measurement terminal 1 accumulated in the storage unit 31 at a higher level (that is, establishes a connection with itself and is higher than itself). As the relay device 3 on the side close to the main device 2, the wireless transmission / reception unit 30 transmits the relay device 3 at a time. Note that the timing at which the measurement data is collectively transmitted may be, for example, a point in time at which each relay device 3 receives the measurement data of each measurement terminal 1 a predetermined number of times, or simply every predetermined time.

  The electric field strength measurement unit 33 has a measurement circuit (not shown) similar to the electric field strength measurement unit 14 of the measurement terminal 1 and is a radio signal transmitted from the measurement terminal 1 that establishes a connection with itself. Measure the electric field strength. The control unit 32 determines the connection status with the measurement terminal 1 based on the LQI value measured by the electric field strength measurement unit 33. For example, if the LQI value becomes zero or a value close to zero, the control unit 32 determines that the measurement terminal 1 that has established a connection with itself has left the connection.

  In the present embodiment, it is assumed that a wireless network has already been automatically configured between the wireless devices according to the communication path indicated by the broken line in FIG. Since the technology for automatically configuring a wireless network is well known in the art, detailed description thereof is omitted here.

  In the present embodiment, the relay device 3C has established a connection with the measurement terminal 1A and stores measurement data of the measurement terminal 1A. The relay device 3D establishes connection with the measurement terminals 1B and 1C, and stores measurement data of the measurement terminals 1B and 1C. The relay device 3B establishes connection with the relay devices 3C and 3D, and stores the measurement data of each measurement terminal 1 accumulated in each of the relay devices 3C and 3D. The relay device 3A establishes a connection between the relay device 3B and the main device 2, stores the measurement data of each measurement terminal 1 accumulated in the relay device 3B, and stores the measurement data in the main device 2 Relay to. In this embodiment, the communication path is not set, but the relay apparatus 3B can also perform wireless communication with the main apparatus 2.

  Hereinafter, the operation of the present embodiment will be described with reference to the drawings. As shown in FIG. 1A, the measurement terminal 1A that establishes a connection with the relay device 3C periodically transmits a radio signal including measurement data measured by itself to the relay device 3C. . When the relay device 3C receives the radio signal, the relay device 3C stores the measurement data included in the radio signal in the storage unit 31 and returns a confirmation signal (ACK) notifying that the measurement data has been received to the measurement terminal 1A. At this time, the confirmation signal includes the LQI value measured by the electric field strength measurement unit 33. By receiving the confirmation signal, the measurement terminal 1A can confirm that the relay device 3C has received the measurement data, and can determine the connection status with the relay device 3C.

  In addition, the measurement terminals 1B and 1C that have established a connection with the relay device 3D periodically transmit a radio signal including measurement data to the relay device 3D, similarly to the measurement terminal 1A. Then, the relay device 3D stores the measurement data included in the wireless signals from the measurement terminals 1B and 1C in the storage unit 31 and returns a confirmation signal to the measurement terminals 1B and 1C. The measurement terminals 1B and 1C can confirm that the relay device 3D has received the measurement data by receiving the confirmation signal, and can determine the connection status with the relay device 3D. . By repeating the above operation, the measurement data of the measurement terminals 1A to 1C is accumulated in the relay devices 3C and 3D.

  Here, the measurement data stored in the storage unit 31 of each relay device 3 includes a time stamp (time information) indicating the acquisition time of the measurement data. The time stamp is stored as, for example, a difference between a reference time measured by each relay device 3 itself and a time when a radio signal transmitted from each measurement terminal 1 is received, that is, an elapsed time from the reception time. In this case, each measuring terminal 1 does not need to include the time information in the measurement data and transmit it to each relay device 3, so that the transmission load of each measuring terminal 1 does not increase.

  The relay devices 3C and 3D periodically transmit a data group including a plurality of times of measurement data stored in itself to the upper relay device 3B in a batch. In the relay device 3B, the measurement data for a plurality of times included in the radio signals from the relay devices 3C and 3D are stored in the storage unit 31. Therefore, the measurement data for a plurality of times of all the measurement terminals 1 is stored in the storage unit 31 of the relay device 3B in a lump. At this time, the relay device 3B may return a confirmation signal to each of the relay devices 3C and 3D.

  Further, the relay device 3B periodically transmits a data group including a plurality of times of measurement data of all the measurement terminals 1 accumulated therein to the upper relay device 3A in a batch. Thereby, the measurement data for a plurality of times of all the measurement terminals 1 are also stored in the storage unit 31 of the relay device 3A. Therefore, if the relay device 3A periodically transmits a data group including a plurality of measurement data of all the measurement terminals 1 accumulated in itself to the main device 2, the main device 2 The measurement data for a plurality of times of the measurement terminal 1 can be collected. Of course, the measurement data is not periodically transmitted from the relay device 3A, but the main device 2 transmits a request signal for requesting transmission of measurement data to the relay device 3A, and the relay device 3A returns all of the requests as a reply. A method of transmitting measurement data of the measurement terminal 1 for a plurality of times to the main apparatus 2 may be used.

  Here, as shown in FIG. 1B, assuming that the relay device 3A has failed, it is conceivable that the main device 2 establishes a connection with the relay device 3B capable of wireless communication. In this case, conventionally, after establishing the connection between the main device 2 and the relay device 3B, the measurement data is transmitted to the relay devices 3C and 3D to collect the measurement data of each measurement terminal 1 again. The measurement data collection efficiency is poor. On the other hand, in this embodiment, since the measurement data for a plurality of times of all the measurement terminals 1 are already stored in the storage unit 31 of the relay device 3B, the main device 2 transmits the measurement data. It is possible to collect measurement data for a plurality of times of all the measurement terminals 1 simply by requesting. Therefore, in this embodiment, the collection efficiency of measurement data can be improved compared to the conventional case.

  In the present embodiment, it is assumed that wireless communication is possible between the main device 2 and the relay device 3B. However, even when wireless communication is not possible, when the relay device 3A is restored or replaced with a new relay device 3, the main device 2 measures the measurement data for all the measurement terminals 1 from the relay device 3B. Can be collected at once, and the collection efficiency of measurement data is improved.

  As described above, in the present embodiment, the measurement data of each measurement terminal 1 and the time stamp (time information) based on the time when the measurement data is measured are stored in the storage unit 31 of each relay device 3. Therefore, when the main device 2 collects the measurement data of each measurement terminal 1, even if the measurement data is lost during communication due to external noise or the like, the main device 2 transmits the measurement data to the relay device 3 again. Measurement data can be collected in the apparatus 2. In addition, the measurement data includes a time stamp (time information) based on the time measured by the measurement terminal 1. For this reason, even if the measurement data is lost during communication, when the main device 2 reacquires the lost measurement data, the main device 2 rearranges the measurement data in time series based on the time stamp included in the measurement data. be able to. That is, the main device 2 can collect measurement data along a time series regardless of the measurement data acquisition order.

  Furthermore, in this embodiment, the memory | storage part 31 of each relay apparatus 3 consists of a volatile memory and a non-volatile memory, and memorize | stores the same measurement data of each measurement terminal 1 in both memory. Therefore, even if a power failure or an instantaneous power failure occurs and the power supply to each relay device 3 stops, the measurement data stored in the nonvolatile memory does not disappear, and therefore the measurement data of each measurement terminal 1 may be damaged. Absent.

  In addition, each measurement terminal 1 and each relay device 3 of the present embodiment include electric field strength measurement units 14 and 33 that measure the electric field strength of the received radio signal. Each measurement terminal 1 and each relay device 3 return a radio signal including information on the measured electric field strength (LQI value) to the measurement terminal 1 or relay device 3 that is the transmission source. For this reason, each measuring terminal 1 and each relay device 3 can grasp the connection status with the measuring terminal 1 or the relay device 3 that has established a connection with itself.

  Moreover, in this embodiment, each relay apparatus 3 transmits the data group containing the measurement data for several times memorize | stored in the memory | storage part 31 with respect to the high-order relay apparatus 3 collectively. For this reason, the storage unit 31 of the higher-level relay device 3 can collectively store the measurement data for a plurality of times of all the measurement terminals 1 existing on the lower side (far side from the main device 2) than itself. . Therefore, even if one of the relay devices 3 breaks down and the communication is interrupted, the main device 2 requests the transmission of measurement data to any one of the higher-level relay devices 3, so that a plurality of measurement terminals 1 The measurement data for the batch can be collected at once, and the collection efficiency of the measurement data can be improved.

  By the way, when the relay device 3 collectively transmits measurement data for a plurality of times to the upper relay device 3 as described above, if the size of the data group including the measurement data is large, the measurement data is divided into a plurality of data. It is necessary to divide and send. For this reason, it takes time to transmit all the measurement data, and there may be a problem that wireless communication cannot be performed with another relay device 3 or the measurement terminal 1 during the period.

  Therefore, it is desirable to transmit the measurement data in a packet having a maximum packet size that can be allowed by the communication protocol. In this case, since the amount of data that can be transmitted in one communication can be increased, the time required until all measurement data is transmitted can be shortened. Therefore, it is possible to shorten a period during which wireless communication cannot be performed with another relay device 3 or the measurement terminal 1. Further, since the number of transmissions when measuring data is transmitted can be reduced, the probability that a communication error occurs can also be reduced.

DESCRIPTION OF SYMBOLS 1 (1A-1C) Measuring terminal 14 Electric field strength measurement part 2 Main apparatus 3 (3A-3D) Relay apparatus 31 Memory | storage part 33 Electric field strength measurement part

Claims (4)

  One or a plurality of measurement terminals that measure a predetermined physical quantity and wirelessly transmit measurement data including a measurement value, and stop the communication function at least until the measurement data is transmitted next when the measurement data is transmitted; A wireless network is configured by a main device that collects the measurement data of a measurement terminal and one or more relay devices that are interposed between the measurement terminal and the main device and relay the measurement data, and the relay device Includes a storage unit that stores the measurement data transmitted from the measurement terminal that has established a connection with itself, and the measurement data is based on the time at which the measurement terminal measured the measurement data. A wireless system including time information, wherein the storage unit includes a volatile memory and a nonvolatile memory, and stores the same data in both memories.   The relay device transmits and receives radio signals to and from the measurement terminal, and the measurement terminal and the relay device each include an electric field strength measurement unit that measures the electric field strength of a radio signal to be received. The wireless system according to claim 1, wherein a wireless signal including information on the measured electric field strength is returned to the relay device.   The relay device establishes a connection with itself and batches a data group including the measurement data for a plurality of times stored in the storage unit with respect to another relay device closer to the main device than itself. The wireless system according to claim 1, wherein the wireless system transmits the data.   4. The wireless system according to claim 3, wherein the measurement data is transmitted in a packet having a maximum packet size that can be permitted by a communication protocol.

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