JP5924074B2 - COMMUNICATION SYSTEM AND COMMUNICATION SYSTEM CONTROL METHOD - Google Patents

Description

  The present invention relates to a communication system that includes a plurality of wireless tags that perform wireless communication using the same communication frequency band, and a plurality of communication devices that perform wireless communication with these wireless tags.

  For example, in order to measure physical phenomena such as water level and temperature, wireless sensor tags (also referred to as “wireless tags” in the present application) that incorporate a sensor circuit and transmit data wirelessly are used. In addition, in order to collect data by performing wireless communication with the wireless sensor tag, a data collecting device (in this application, also referred to as “communication device”) connected to an antenna installed at a short distance from the wireless sensor tag through a wire. Is used).

  In order to measure a physical phenomenon in a wide range, a plurality of wireless sensor tags are required, and accordingly, a large number of data collection devices are required. Therefore, a plurality of antennas can be connected to each data collection device corresponding to a plurality of wireless sensor tags. However, since these wireless sensor tags use the same communication frequency band, there is a problem of which wireless sensor tag and which antenna perform communication in order to ensure good communication quality.

  As a related prior art, in Patent Document 1, when performing wireless communication with a master station apparatus that sequentially switches a plurality of antennas having directivity and transmits a notification signal, the notification signal is transmitted from the plurality of antennas having directivity. A slave station device is disclosed that can select the antenna having the best reception state and wirelessly communicate with the master station device.

  The slave station device is based on a plurality of antennas having directivity, a detection unit that detects a reception state of a notification signal for at least one cycle of antenna switching of the master station device for each antenna, and a detection result by the detection unit Antenna selection means for selecting the antenna having the best reception state of the broadcast signal and communication means for wirelessly communicating with the master station apparatus using the selected antenna are provided.

  Patent Document 2 also measures the communication quality of all combinations of transmission and reception antennas in a wireless communication system that performs communication by selecting an antenna that can ensure the best communication quality among wireless stations having a plurality of antennas. In addition, it is disclosed that by selecting a combination of antennas with good communication quality, the number of antenna combinations to be transmitted / received can be reduced to shorten the transmission / reception delay time.

  According to this wireless communication system, when one of the wireless stations selects an antenna, the rotation period of the antenna is set to an integral multiple of the rotation period of the antenna of the communication partner station, and is subordinately synchronized with the signal of the communication partner station. Receives all combinations of antennas and antennas of the communication partner station, measures the communication quality at that time, stores the antenna of the local station having communication quality capable of communication, and the timing thereof. The local station antenna to be used and the switching timing thereof are determined from the above information, and then the antenna switching cycle is made the same as the rotation cycle of the antenna of the communication partner station.

  These conventional techniques are common in that they find a combination of antennas that improve communication quality between a master station having a plurality of antennas and a slave station having a plurality of antennas. However, when a plurality of slave stations use the same communication frequency band as in a wireless sensor tag, if a plurality of slave stations communicate with a plurality of master stations at the same time, antennas close to each other There is a problem that communication quality deteriorates due to interference. In such a case, it is not possible to solve the problem only by finding a combination of antennas that individually improve the communication quality.

JP 2001-16149 A (paragraph 0011, claim 1) JP-A-11-55174 (paragraph 0024, abstract)

  In some aspects of the present invention, when a plurality of wireless tags communicate with a plurality of communication devices using the same communication frequency band, a plurality of antennas and a plurality of wireless tags connected to the plurality of communication devices. It is a problem to automatically determine an appropriate combination with.

  In order to solve the above problems, a communication system according to a first aspect of the present invention includes a first wireless tag and a second wireless tag that perform wireless communication using the same communication frequency band, and a first antenna. A first communication device capable of wireless communication with the first wireless tag using the second antenna, and a second communication device capable of wireless communication with the second wireless tag using the second antenna, wherein the first antenna Communication between the first communication device using the first wireless tag and the first wireless tag and communication between the second communication device using the second antenna and the second wireless tag are possible simultaneously. And a second communication device for investigating whether or not there is.

  In addition, a communication system according to a second aspect of the present invention includes a plurality of wireless tags that perform wireless communication using the same communication frequency band, and a plurality of communication devices each connected to a plurality of antennas, One of a plurality of communication devices investigates a combination of an antenna and a wireless tag that can wirelessly communicate between each communication device and each wireless tag, and can further perform wireless communication at the same time for those combinations. It is investigated whether or not there is, and one antenna and a minimum communication time slot are allocated to each of the plurality of wireless tags based on the investigation results.

  Here, when one of the plurality of communication devices assigns an antenna and a communication time slot to the plurality of wireless tags, the wireless tag capable of wireless communication only through one antenna may be given priority. In addition, when there are a plurality of combinations of antennas and wireless tags capable of assigning one antenna and a minimum communication time slot to each of the plurality of wireless tags, one of the plurality of communication devices is A combination having a larger minimum value of received signal strength obtained by a plurality of antennas to be compared may be selected.

  According to the first or second aspect of the present invention, a plurality of communication devices are investigated whether or not communication with a plurality of wireless tags performing wireless communication using the same communication frequency band is possible at the same time. An appropriate combination of a plurality of antennas and a plurality of wireless tags connected to the can be automatically determined.

The figure which shows the structural example of the communication system which concerns on one Embodiment of this invention. The block diagram which shows the structural example of the wireless sensor tag shown in FIG. The block diagram which shows the structural example of the data collection device shown in FIG. The flowchart of the operation | movement of the communication system which concerns on one Embodiment of this invention. The figure which shows the communicable tag table regarding node N1. The figure which shows the communication possible tag table regarding node N2. The figure which shows an antenna competition table. The flowchart for demonstrating the content of the allocation process. The figure which shows a communicable antenna table. The figure which shows a combination list.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration example of a communication system according to an embodiment of the present invention. The communication system according to the present embodiment includes a plurality of data collection devices 11, 12,..., A plurality of antennas 21, 22, 23, 24, and a plurality of wireless sensor tags 31, 32, 33, 34. ... and so on.

  The data collection devices 11, 12,... Are connected to each other via a network such as a wireless LAN (local area network) or a wired LAN. One of these data collection devices (data collection device 11 in FIG. 1) is used as a master, and the other is used as a slave.

  The antennas 21, 22, 23, 24,... Are connected to any of the data collection devices via wires. It is possible to connect a plurality of antennas to one data collection device. In FIG. 1, for example, the antennas 21 and 22 are connected to the data collection device 11, and the antennas 23 and 24 are connected to the data collection device 12. Has been. However, one data collection device cannot use a plurality of antennas at the same time.

  The wireless sensor tags 31, 32, 33, 34... Can perform wireless communication with at least one data collection device via at least one antenna. These wireless sensor tags may be, for example, an active sensor device incorporating a battery or a generator, or may be a passive sensor device that operates by being supplied with energy from a magnetic field or an electromagnetic field from at least one antenna.

  FIG. 2 is a block diagram illustrating a configuration example of the wireless sensor tag illustrated in FIG. In FIG. 2, a configuration example of the wireless sensor tag 31 is shown, but the configuration of the wireless sensor tags 32, 33, 34,.

  As shown in FIG. 2, the wireless sensor tag 31 includes a sensor circuit 311, a timing circuit 312, a control circuit 313, a storage circuit 314, and a communication circuit 315. A sensor element 310 is connected to the sensor circuit 311. The sensor element 310 is an element for measuring an environmental physical phenomenon, and may be a water level sensor, a temperature sensor, a tilt sensor, or a strain sensor.

  For example, in order to measure the position of the interface of an object to be measured such as water stored in a water tank or concrete filled in a formwork, a parallel two-core cable having a pair of core wires covered with an insulator is used. A sensor cable subjected to terminal treatment is used as the sensor element 310. The sensor cable is disposed along a vertical line in the water tank or the mold.

  Assuming that the capacitance between the core wires in the portion where the air exists around the sensor cable is 1, the capacitance between the core wires in the portion where the liquid substance exists around the sensor cable is about 80. When soft concrete still soft is present around the sensor cable, it is the same as when liquid material is present.

  Therefore, the position of the interface of the liquid substance or concrete can be calculated by measuring the capacitance between the core wires of the sensor cable. In particular, when confirming the state of filling when placing concrete, it is possible to continuously grasp the filling state of concrete in a wide range by placing active wireless sensor tags that operate on batteries. Become.

  The sensor circuit 311 measures an environmental physical phenomenon using the sensor element 310 and generates measurement data representing a measurement result. For example, the sensor circuit 311 includes an RC oscillation circuit in which the oscillation frequency changes depending on the capacitance between the cores of the sensor cable, and a counter that counts the number of pulses of the clock signal in a period that is an integral multiple of the oscillation period of the RC oscillation circuit. Measurement data representing the count value is generated. Since this count value has a predetermined relationship with the capacitance between the core wires of the sensor cable, the position of the interface of the liquid substance or concrete can be calculated based on the count value.

  The clock circuit 312 includes, for example, an oscillation circuit that performs an oscillation operation using a crystal resonator or the like, and measures time based on a clock signal generated by the oscillation circuit to generate clock data. The timer circuit 312 supplies a clock signal to the sensor circuit 311.

  The control circuit 313 controls each circuit of the wireless sensor tag 31 according to a preset program. The control circuit 313 stores the measurement data generated by the sensor circuit 311 in the storage circuit 314 in association with the time measurement data generated by the time measurement circuit 312. The storage circuit 314 is configured by a memory or the like.

  The communication circuit 315 has an antenna, and performs wireless communication with any one of the data collection devices 11, 12,... Shown in FIG. Is transmitted to the data collection device together with identifier information representing a unique identifier (ID).

  Considering the use of a plurality of wireless sensor tags, each wireless sensor tag is assigned a unique identifier. Thereby, when the communication circuit 315 receives the identifier information of the wireless sensor tag 31 from the data collection device, the control circuit 313 can recognize that the wireless sensor tag 31 has been selected. Further, when the communication circuit 315 transmits the identifier information of the wireless sensor tag 31 to the data collection device, the data collection device can identify the wireless sensor tag 31.

  Referring again to FIG. 1, the plurality of data collection devices 11, 12,... Use any one of the antennas 21, 22, 23, 24,. , 34,..., 34,..., Receive measurement information and identifier information transmitted from the wireless sensor tag, and process measurement data and time data.

  FIG. 3 is a block diagram illustrating a configuration example of the data collection device illustrated in FIG. 1. In FIG. 3, the structural example of the data collection device 11 used as a master is shown. The data collection device 11 includes communication circuits 111 and 112, a control unit 113, a storage unit 114, an operation unit 115, and a display unit 116.

  The communication circuits 111 and 112 are connected to the antennas 21 and 22, respectively, and communicate with the wireless sensor tag. For example, the communication circuits 111 and 112 transmit various commands to the wireless sensor tag together with the identifier information. The communication circuits 111 and 112 receive measurement information and identifier information transmitted from the wireless sensor tag.

  The control unit 113 includes a node integration adjustment unit 113a, a node control unit 113b, and a tag access control unit 113c. The node integration adjustment unit 113a adjusts the operation of the entire communication system in accordance with the operation of the operator using the operation unit 115, and integrates information obtained by a plurality of data collection devices. The node control unit 113b controls transmission / reception of commands, data, and the like with other data collection devices connected to the network. The tag access control unit 113c controls the communication circuits 111 and 112 so as to access the selected wireless sensor tag.

  Further, the control unit 113 processes the measurement data and time data received by the communication circuits 111 and 112, generates data representing the measurement result, and stores the generated data in association with the identifier information of the wireless sensor tag. Stored in the unit 114. The control unit 113 may be configured by a CPU (central processing unit) and software (control program), or may be configured by a digital circuit. The control program is stored in the storage unit 114 configured by a hard disk or a memory. The display unit 116 displays an image representing the measurement result based on the data representing the measurement result.

  In FIG. 3, the configuration example of the data collection device 11 used as the master is shown, but the configuration of the data collection device 12 serving as the slave is the same as that except that the node integration adjustment unit 113a is not necessary. Good.

  Next, the operation of the communication system according to the present embodiment will be described with reference to FIGS. FIG. 4 is a flowchart for explaining the operation of the communication system according to the embodiment of the present invention. Hereinafter, in order to simplify the description, a case where the data collection devices 11 and 12 are respectively arranged in the two nodes N1 and N2 will be described.

  The wireless sensor tags 31, 32, 33, 34,... Shown in FIG. 1 are arranged at respective measurement points determined for measurement reasons in order to measure physical phenomena such as water level and temperature. The measurement may be performed according to a measurement command transmitted from the data collection device, or may be performed when a specific event occurs, for example, when a tilt sensor measures vibration. Alternatively, the measurement may be performed periodically, or the measurement may be performed at a time set by the data collection device.

  In order to perform wireless communication between the wireless sensor tag and the data collection device, antennas 21, 22, 23, 24,. Since the signal used for the wireless communication between the wireless sensor tag and the data collection device is weak, the antennas 21, 22, 23, 24,... Are, for example, within 3 m to 4 m from the wireless sensor tag of the communication partner And is connected to any data collection device via a wire of several tens of meters.

  Here, when a single data collection device is used, an antenna that maximizes the intensity of a received signal obtained from a wireless sensor tag may be selected as an antenna used for wireless communication with the wireless sensor tag. However, many data collection devices are also used to cover a very wide antenna location. Even in that case, the same communication frequency band (carrier frequency) is used for wireless communication between all wireless sensor tags and all data collection devices, so that good communication quality is ensured. Which wireless sensor tag and which antenna to communicate with becomes a problem.

  Therefore, when the communication system is activated, the master data collection device 11 investigates a combination of an antenna and a wireless sensor tag that enables wireless communication between each data collection device and each wireless sensor tag. Further, it is investigated whether or not the wireless communication can be performed at the same time for those combinations, and one antenna and a minimum communication time slot are assigned to each of the plurality of wireless sensor tags based on the result of the investigation.

  First, the master data collection device 11 investigates whether or not wireless communication is possible between each data collection device and each wireless sensor tag (communication investigation). For example, the data collection device sequentially transmits to each wireless sensor tag using a plurality of connected antennas, and the intensity of the received signal obtained from the wireless sensor tag in response is equal to or higher than a predetermined value. If there is, it is determined that wireless communication is possible with the wireless sensor tag.

  Referring to FIG. 4, the data collection device 11 arranged in the node N1 investigates whether or not wireless communication is possible with the wireless sensor tag 31 in step S11, and in step S12, the wireless sensor tag 32 is checked. In step S13, it is investigated whether wireless communication is possible with the wireless sensor tag 33, and this is repeated thereafter.

  As a result, as shown in FIG. 5, the data collection device 11 creates a communicable tag table that represents wireless sensor tags that can wirelessly communicate with the node N1. According to this communicable tag table, the data collection device 11 can wirelessly communicate with the wireless sensor tag 31 using the antenna 21 and wirelessly communicate with the wireless sensor tags 32 and 33 using the antenna 22. It can be seen that communication is possible. Also, the strength of each received signal is stored.

  In step S <b> 14, the master data collection device 11 instructs the slave data collection device 12 to perform a similar communication investigation. The data collection device 12 arranged at the node N2 investigates whether or not wireless communication is possible with the wireless sensor tags 31 and 32, and then can wirelessly communicate with the wireless sensor tag 33 in step S21. In step S22, it is investigated whether wireless communication is possible with the wireless sensor tag 34, and this is repeated thereafter.

  In step S23, as shown in FIG. 6, the data collection device 12 creates a communicable tag table representing a wireless sensor tag capable of wireless communication with respect to the node N2, and reports a communicable investigation result to the data collection device 11. . According to this communicable tag table, the data collection device 12 can communicate wirelessly with the wireless sensor tags 33 and 34 using the antenna 23, and communicate with the wireless sensor tags 33 and 34 using the antenna 24. It can be seen that wireless communication is possible. Also, the strength of each received signal is stored.

  Next, the master data collection device 11 investigates whether or not mutual interference becomes a problem when a plurality of antennas communicate in the same communication time slot (antenna competition survey). For example, if a plurality of data collection devices can simultaneously transmit to a plurality of wireless sensor tags using a plurality of antennas connected to the respective data collection devices and confirm that the corresponding wireless sensor tags have responded, It is determined that there is no problem with interference between the antennas.

  In step S <b> 15, the master data collection device 11 instructs the slave data collection device 12 to perform an antenna competition investigation between the antenna 21 and the antenna 23 together. In step S16, the data collection device 11 in the node N1 performs wireless communication using the antenna 21. In step S24, the data collection device 12 in the node N2 performs wireless communication using the antenna 23. I do. Thereby, the antenna competition investigation between the antenna 21 and the antenna 23 is performed. In step S <b> 25, the slave data collection device 12 reports the result of the antenna contention investigation to the master data collection device 11.

  In this way, the data collection device 11 includes the communication between the data collection device 1 using the antenna 21 or 22 and one of the wireless sensor tags 31 to 33, and the data collection device using the antenna 23 or 24. 12 and whether or not communication between any of the wireless sensor tags 33 to 34 is possible at the same time.

  Such an antenna competition survey is performed for all combinations of antennas capable of wireless communication and wireless sensor tags. If trouble occurs in any antenna competition investigation between two antennas, it is determined that mutual interference between the antennas becomes a problem. When all the antenna competition surveys are completed, the master data collection apparatus 11 creates an antenna competition table representing the results of the antenna competition survey as shown in FIG. According to this antenna competition table, it can be seen that mutual interference between the antenna 22 and the antenna 23 becomes a problem. Note that a plurality of antennas connected to the same data collection device cannot be used simultaneously.

  In step S17, the master data collection device 11 determines the communication time slot used in the combination of the antenna and the wireless sensor tag and the wireless communication between them based on the results of the communication feasibility investigation and the antenna competition investigation. Is determined (allocation process).

  FIG. 8 is a flowchart for explaining the contents of the allocation process. In step S171, the data collection device 11 creates a communicable antenna table indicating antennas capable of wireless communication with respect to the wireless sensor tag, based on the communicable tag table related to the nodes N1 and N2, as shown in FIG. According to this communicable antenna table, the wireless sensor tag 31 can wirelessly communicate only through the antenna 21, the wireless sensor tag 32 can wirelessly communicate only through the antenna 22, and the wireless sensor tag 33 It can be seen that wireless communication is possible via the antennas 22 to 24, and the wireless sensor tag 34 is wirelessly communicable via the antennas 23 and 24.

  In step S172, the data collection device 11 lists wireless sensor tags that can communicate only through one antenna, and preferentially assigns antennas and communication time slots to these wireless sensor tags. In FIG. 9, the wireless sensor tag 31 that can communicate only through the antenna 21 and the wireless sensor tag 32 that can communicate only through the antenna 22 correspond to this.

  In step S173, the data collection device 11 lists all other combinations, and selects a combination that minimizes the number of communication time slots and can communicate with all wireless sensor tags. As a result, a combination list as shown in FIG. 10 is created.

  The rightmost column of the combination list shown in FIG. 10 shows the result of the antenna competition investigation in the antenna competition table shown in FIG. Therefore, among the combinations A to H extracted from the combination list shown in FIG. 10, only combinations C, D, G, and H do not cause a problem of competition between antennas.

  As shown in FIG. 10, when there are a plurality of selectable combinations, in step S174, the data collection apparatus 11 refers to the communicable tag table shown in FIG. The combination with the larger minimum value of the received signal strength obtained by the plurality of antennas to be compared is selected.

  For example, referring to FIG. 6, in combination C, the strength of the received signal obtained from the wireless sensor tag 33 by the antenna 23 is 1500, and the strength of the received signal obtained from the wireless sensor tag 34 by the antenna 24 is 2000. The minimum value of the received signal strength is 1500.

  On the other hand, in the combination D, the strength of the received signal obtained from the wireless sensor tag 34 by the antenna 23 is 1000, and the strength of the received signal obtained from the wireless sensor tag 33 by the antenna 24 is 1000. The minimum value is 1000.

  In the combination G, the strength of the received signal obtained from the wireless sensor tag 33 by the antenna 24 is 1000, and the strength of the received signal obtained from the wireless sensor tag 34 by the antenna 24 is 2000. The minimum value is 1000. Even in the combination H, the minimum value of the strength of the received signal is 1000.

  Accordingly, the data collection device 11 selects the combination C having the larger received signal strength minimum value. Note that if there are a plurality of combinations having the same minimum value of the intensity of the received signal, the data collection device 11 may select any of them.

  Referring again to FIG. 4, in step S <b> 18, the master data collection device 11 instructs the slave data collection device 12 to share the data collection device 12 in the combination C. In step S <b> 26, the slave data collection device 12 makes a response to the master data collection device 11 that the sharing has been confirmed. In step S19, the master data collection device 11 reports the end of the assignment of the antenna and the communication time slot to the operator.

  In the above embodiment, the case where the wireless sensor tag that wirelessly transmits the measurement data and the data collection device that collects the measurement data from the wireless sensor tag has been described. However, the present invention is not limited to this embodiment. The present invention is not limited, and can be applied to a communication system including a general wireless tag and a communication device, and many modifications can be made within the technical idea of the present invention by a person having ordinary knowledge in the technical field. Is possible.

  DESCRIPTION OF SYMBOLS 11, 12, ... Data collection device, 21, 22, ... Antenna, 31, 32, ... Wireless sensor tag, 111, 112 ... Communication circuit, 113 ... Control part, 113a ... Node integration adjustment part, 113b ... node control unit 113c ... tag access control unit 114 ... storage unit 115 ... operation unit 116 ... display unit 310 ... sensor element 311 ... sensor circuit 312 ... timer circuit 313 ... control circuit 314 ... Memory circuit, 315 ... communication circuit

Claims (4)

A plurality of wireless tags that perform wireless communication using the same communication frequency band;
A plurality of communication devices each connected to a plurality of antennas;
One of the plurality of communication devices investigates a combination of an antenna and a wireless tag that enables wireless communication between the individual communication device and each wireless tag, and further, the combination of the antenna and the wireless tag is simultaneously performed. It investigated whether a wireless communication possible, on the basis of their findings, respectively assigned one antenna及beauty communication credit time slots to the plurality of wireless tags, when performing the allocation, one antenna A communication system that prioritizes a wireless tag that can be wirelessly communicated only via the Internet . A plurality of wireless tags that perform wireless communication using the same communication frequency band;
A plurality of communication devices each connected to a plurality of antennas;
One of the plurality of communication devices investigates a combination of an antenna and a wireless tag that enables wireless communication between the individual communication device and each wireless tag, and further, the combination of the antenna and the wireless tag is simultaneously performed. investigated whether a wireless communication possible, on the basis of their findings, respectively assigned one antenna及beauty communication credit time slots to the plurality of wireless tags, when performing the allocation, the plurality of radio When there are a plurality of combinations of antennas and radio tags that allow one antenna and a communication time slot to be assigned to each tag, the minimum value of the received signal strength obtained by the plurality of antennas to be compared is A communication system that selects the larger combination . A control method of a communication system including a plurality of wireless tags that perform wireless communication using the same communication frequency band, a plurality of antennas, and a communication device that communicates with the wireless tag via the antennas,
A communication system control method that preferentially assigns a radio tag capable of radio communication only through one antenna when assigning one of the plurality of antennas and a communication time slot to each of the plurality of radio tags. . A control method of a communication system including a plurality of wireless tags that perform wireless communication using the same communication frequency band, a plurality of antennas, and a communication device that communicates with the wireless tag via the antennas,
An antenna capable of allocating one antenna and a communication time slot to each of the plurality of wireless tags when allocating one antenna and a communication time slot among the plurality of antennas to each of the plurality of wireless tags; A communication system control method for selecting a combination having a larger minimum value of received signal strength obtained by a plurality of antennas to be compared when there are a plurality of combinations with wireless tags.

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