JP2016019200A - Sensor node communication terminal, host communication terminal, and radio sensor network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor node communication terminal, host communication terminal, and radio sensor network system capable of improving probability of receiving measurement data and saving the whole power.SOLUTION: A control unit 10 performs control so as to: transmit, on the basis of synchronization time information generated by a clock unit (RTC module 13), a request signal for requesting information on transmission reference time and reception window allocation information, from a transmission unit (radio transceiver 11) to a host communication terminal H1 at predetermined timing; receive, by a reception unit (radio transceiver 11), the information on transmission reference time and the reception window allocation information transmitted from the host communication terminal in response to the request signal, to store the received information in a storage unit 15; and transmit, on the basis of the information on the transmission reference time and the reception window allocation information, measurement data to the host communication terminal through the transmission unit.SELECTED DRAWING: Figure 1

Description

  The present embodiment relates to a sensor node communication terminal, a host communication terminal, and a wireless sensor network system.

  In recent years, a small sensor terminal with a wireless function (sensor node communication terminal) incorporating a power source has been developed.

  Such sensor node communication terminals are installed over a plurality of indoor and outdoor buildings (bridges, roads, railways, buildings, etc.), for example, and measure environmental information consisting of various physical quantities such as temperature, humidity, and strain. It is used for analysis.

  A wireless sensor network system that receives and stores measurement data transmitted from a plurality of sensor node communication terminals by a host communication terminal, and automatically measures and monitors the state of a building or the like based on the measurement data. Various proposals have been made.

JP2013-34210A

  By the way, in the wireless sensor network system according to the prior art, wireless standard IEEE802.15.4 (radio frequency is 2.4 [GHz]) is used for transmission and reception of signals and data between the sensor node communication terminal and the host communication terminal. Often used.

  This wireless standard IEEE802.15.4 has a feature of low cost and low power consumption, although the data transfer rate is relatively low at a maximum of 250 kbps.

  However, since the wireless standard IEEE802.15.4 is basically an asynchronous method, the time stamp (the mutual reference time) at the time of transmission / reception differs between the sensor node communication terminal and the host communication terminal. For this reason, the sensor node communication terminal unilaterally transmits measurement data to the host communication terminal, and it is unclear whether the measurement data is received on the host communication terminal side.

  Therefore, in order to reliably perform transmission and reception in the prior art, a transmission request (RTS: Request To Send) and a transmission permission (CTS: Clear To Send) are exchanged between the sensor node communication terminal and the host communication terminal. It was necessary to perform transmission / reception processing (transmission / reception operation) of various signals and data.

  However, when the frequency of reception processing in the sensor node communication terminal is increased, there is a problem that power consumption is relatively increased and it is difficult to perform continuous operation using a self-supporting power source configured with a photovoltaic element or the like. In particular, in order to improve the transmission / reception probability, the sensor node communication terminal may be controlled to transmit the same measurement data multiple times, but in this case, the total transmission processing time becomes long, and the sensor node communication There is a disadvantage that the power consumption on the terminal side is further increased.

  The present embodiment provides a sensor node communication terminal, a host communication terminal, and a wireless sensor network system that can improve the reception probability of measurement data and can achieve overall power saving.

  According to one aspect of the present embodiment, a sensor unit that measures a physical quantity, a transmission unit that transmits the physical quantity measured by the sensor unit as measurement data to a host communication terminal, and a transmission from the host communication terminal. A receiving unit that receives predetermined data, a clock unit that generates synchronization time information, transmission reference time information that defines a timing for transmitting the measurement data from the transmission unit, and the measurement on the host communication terminal side A storage unit that stores data reception window allocation information, a control unit that controls operations of the sensor unit, the transmission unit, the reception unit, the clock unit, and the storage unit, the sensor unit, and the transmission unit A power supply unit that supplies power to the reception unit, the clock unit, the storage unit, and the control unit, the control unit based on synchronization time information generated by the clock unit, A request signal for requesting the transmission reference time information and the receiving window allocation information is transmitted from the transmission unit to the host communication terminal at the timing, and from the host communication terminal according to the request signal The transmission reference time information transmitted and the reception window allocation information are received by the reception unit, stored in the storage unit, via the transmission unit, the transmission reference time information and the transmission window A sensor node communication terminal is provided that controls to periodically transmit the measurement data to the host communication terminal based on reception window allocation information.

  According to another aspect of the present embodiment, a reception unit that receives request signals and measurement data transmitted from two or more sensor node communication terminals, and information on a transmission reference time according to the request signal, A transmission unit that transmits reception window allocation information to the sensor node communication terminal, a clock unit that generates synchronization time information, and a transmission reference time that defines the timing at which the measurement data is transmitted from the sensor node communication terminal A storage unit that stores information of the reception window and allocation information of a reception window that receives the measurement data, a control unit that controls operations of the transmission unit, the reception unit, the clock unit, and the storage unit, and the transmission unit A power supply unit that supplies power to the reception unit, the clock unit, the storage unit, and the control unit, and the control unit is transmitted from the sensor node communication terminal at the reception unit. When the request signal is received, the transmission reference time information and the reception window are allocated to the sensor node communication terminal at a predetermined timing based on the synchronization time information generated by the clock unit. Information from the transmission unit, and based on the transmission reference time information and the reception window allocation information, the reception of the measurement data periodically transmitted from the sensor node communication terminal at a predetermined timing A host communication terminal that controls to store the measurement data in the storage unit in correspondence with the assigned reception window when the reception unit receives the measurement data.

  According to another aspect of the present embodiment, a wireless sensor network system including two or more sensor node communication terminals according to the present embodiment and a host communication terminal is provided.

  According to the present embodiment, it is possible to provide a sensor node communication terminal, a host communication terminal, and a wireless sensor network system that can improve the reception probability of measurement data and can achieve overall power saving.

1 is a configuration block diagram showing a schematic configuration of a sensor node communication terminal, a host communication terminal, and a wireless sensor network system according to an embodiment. The block diagram which shows the structural example of the sensor part with which the sensor node communication terminal which concerns on embodiment is provided. The block diagram which shows the structural example of the power supply part with which the sensor node communication terminal which concerns on embodiment is provided. The typical block diagram which shows the structural example of the wireless sensor network system which concerns on embodiment. The sequence diagram which shows the procedure of transmission / reception of the signal and data of the sensor node communication terminal and host communication terminal in the wireless sensor network system which concerns on embodiment. The sequence diagram which shows the other procedure of signal transmission / reception of the sensor node communication terminal and host communication terminal in the wireless sensor network system which concerns on embodiment. 6 is a timing chart showing a procedure for transmitting and receiving signals and data between the sensor node communication terminal and the host communication terminal in the wireless sensor network system according to the embodiment. 8 is a timing chart showing the continuation of FIG.

  Next, embodiments will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  Further, the embodiment described below exemplifies an apparatus and a method for embodying the technical idea, and in this embodiment, the material, shape, structure, arrangement, etc. of the component parts are described below. It is not something specific. This embodiment can be modified in various ways within the scope of the claims.

(Schematic configuration of wireless sensor network system)
With reference to FIG. 1, a schematic configuration of a wireless sensor network system 1 according to the present embodiment will be described.

  FIG. 1 is a configuration block diagram showing a schematic configuration of sensor node communication terminals N1, N2, a host communication terminal H1, and a wireless sensor network system 1 according to the embodiment.

  First, the wireless sensor network system 1 according to the present embodiment includes a plurality of sensor node communication terminals N (N1, N2,...) And one host communication terminal H1, and each sensor node communication terminal N1. , N2... And the host communication terminal H1 transmit and receive signals and data via radio (radio waves in a predetermined frequency band).

  For convenience of explanation, only two sensor node communication terminals N1 and N2 are shown in FIG. 1, but in the actually operating wireless sensor network system 1, three or more sensor node communication terminals N are provided. Is possible. More specifically, the total number of sensor node communication terminals N installed is, for example, several tens to several hundreds or thousands, although it depends on the type, size, and scale of the building or the like as the monitoring target or measurement target. In some cases, the unit becomes a unit.

  In addition, when there are a large number of sensor node communication terminals N, in consideration of reception efficiency, two or more host communication terminals H1 are provided, and data received by each host communication terminal H1 is transmitted via a predetermined network. May be integrated.

[Schematic configuration of sensor node communication terminal]
With reference to FIG. 1, a schematic configuration of sensor node communication terminal N1 (N2) according to the embodiment will be described. In the present embodiment, the sensor node communication terminals N1, N2,... Have the same configuration.

  The sensor node communication terminal N1 (N2) transmits from the sensor unit 20 that measures various physical quantities, a transmission unit that transmits the physical quantities measured by the sensor unit 20 to the host communication terminal H1 as measurement data, and the host communication terminal H1. And a wireless transmission / reception device (RFLSI or the like) 11 that constitutes a receiving unit that receives predetermined data.

  Also, an RTC (Real Time Clock) module 13 that constitutes a clock unit that generates synchronization time information, transmission reference time information that defines the timing at which measurement data is transmitted from the wireless transmission / reception device 11, and the host communication terminal H1 side A storage unit 15 composed of a non-volatile memory, a hard disk device or the like for storing the reception information of the measurement data reception window, and a micro that controls the operation of the sensor unit 20, the wireless transmission / reception device 11, the RTC module 13, and the storage unit 15. The control part 10 comprised with a computer etc. and the power supply part 12 which supplies electric power to the sensor part 20, the radio | wireless transmission / reception apparatus 11, the RTC module 13, the storage part 15, and the control part 10 are provided. An antenna 16 is connected to the wireless transmission / reception device 11. A configuration example of the sensor unit 20 and the power supply unit 12 will be described later.

  Based on the synchronization time information generated by the RTC module 13, the control unit 10 requests the host communication terminal H1 for the transmission reference time information and the reception window allocation information at a predetermined timing. A signal is transmitted from the wireless transmission / reception device 11 that constitutes the transmission unit, and information on the transmission reference time transmitted from the host communication terminal H1 in response to the request signal and the allocation information of the reception window are wireless signals that constitute the reception unit. The data is received by the transmission / reception device 11, stored in the storage unit 15, and the measurement data is periodically transmitted to the host communication terminal H 1 via the wireless transmission / reception device 11 based on the transmission reference time information and the reception window allocation information. It is supposed to be controlled to send to. Specific transmission / reception procedures will be described later.

  In addition, the control unit 10 further includes a random number generation unit 14 that generates a random number, and a request signal transmitted from the wireless transmission / reception device 11 constituting the transmission unit is transmitted from another sensor node communication terminal N2 or the host communication terminal H1. When an interference or collision (collision) occurs with another signal or information that has been sent, the request signal is retransmitted to the host communication terminal H1 at a timing based on the random number generated by the random number generation unit 14 instead of a predetermined timing. To be controlled.

  The request signal may include sensor node communication terminals N1, N2,..., Own address information (for example, a MAC address). This makes it possible to identify the sensor node communication terminals N1, N2,... On the host communication terminal H1 side, and to specify the position where the trouble occurs in the measurement data transmission source, the building, or the like. it can.

  In addition, the control unit 10 can control the wireless transmission / reception device 11 constituting the transmission unit and the reception unit to shift to the power saving state when the transmission operation and the reception operation are not performed. Thereby, the power consumption in each sensor node communication terminal N1, N2,.

[Configuration example of sensor unit]
Here, with reference to FIG. 2, the example of a structure of the sensor part 20 with which each sensor node communication terminal N1, N2 ... shown in FIG. 1 is provided is demonstrated.

In the sensor unit 20, a temperature sensor SN1 configured by a thermistor or the like that measures the temperature of an outer wall of a building or the like, a humidity sensor SN2 that measures the humidity of a building or the like, and the concentration of a gas such as CO ₂ are detected. Gas sensor SN3, strain sensor SN4 composed of a strain gauge or the like for detecting strain on a wall of a building, etc., and vibration sensor SN5 for detecting vibration of a building or the like.

  In addition, the kind of sensor provided in the sensor part 20 is not limited to the said example, According to the installation purpose of sensor node communication terminal N1, N2, ..., etc., it can select suitably. For example, physical quantities other than the above as sensing targets include light quantity, air volume, inclination amount, pressure, radiation dose, and the like.

  Further, the sensor units 20 of the sensor node communication terminals N1, N2,... May all be provided with the same sensor, or the types of sensors mounted on the sensor node communication terminals N1, N2,. May be changed.

  Thus, appropriate sensors are mounted on each sensor unit 20 according to the type and environment of the building such as a bridge, road, railway, building where the sensor node communication terminals N1, N2,. It is possible to acquire various physical quantities necessary for measurement as measurement data.

[Example of power supply configuration]
Next, a configuration example of the power supply unit 12 included in each sensor node communication terminal N1, N2,... Shown in FIG.

  The power supply unit 12 includes, for example, a photovoltaic power generation device 301 configured by a solar cell panel and the like, and a power storage device 302 configured by a secondary battery or an electric double layer capacitor that stores electricity generated by the photovoltaic power generation device 301. Can be prepared.

  Furthermore, the power storage device 302 can be configured to further include a power storage amount detector 303 that detects a power storage amount of the power storage device 302. Then, the control unit 10 shown in FIG. 1 causes the power storage amount detector 303 to cause the power storage amount of the power storage device 302 to exceed a predetermined threshold (for example, a voltage that can activate the wireless transmission / reception device 11 such as the sensor node communication terminal N1). When it is determined that the wireless transmission / reception apparatus 11 is active, the wireless transmission / reception apparatus 11 can be activated to transmit the request signal. As a result, it is possible to effectively use the electricity generated by the photovoltaic power generation apparatus 301, to save power, and to transmit each of the sensor node communication terminals N1, N2,.・ By starting, measurement data can be acquired stably over a long period of time.

  Instead of the photovoltaic power generation device 301, various power generation devices to which energy harvesting technology that converts various energy existing in the environment into electric power in various forms such as thermal (temperature difference) energy, vibration energy, and radio wave energy are applied. You may make it mount.

  Thus, driving power can be acquired from the photovoltaic power generation apparatus 301 or the like without supplying power to the sensor node communication terminals N1, N2,... Via the power line or the like, and the sensor node communication terminals N1, N2 can be obtained. Can be operated independently.

[Schematic configuration of host communication terminal]
A schematic configuration of the host communication terminal H1 according to the embodiment will be described with reference to FIG.

  The host communication terminal H1 receives a request signal and measurement data transmitted from the sensor node communication terminals N1, N2,..., Transmission reference time information, and reception window allocation according to the request signal. A wireless transmission / reception device (RFLSI or the like) 32 that constitutes a transmission unit that transmits information to the sensor node communication terminals N1, N2,.

  Also, an RTC (Real Time Clock) module 33 that constitutes a clock unit that generates synchronization time information, and transmission reference time information that defines the timing at which measurement data is transmitted from the sensor node communication terminals N1, N2,. A storage unit 35 including a non-volatile memory, a hard disk device, and the like for storing reception window allocation information for receiving measurement data, a microcomputer for controlling operations of the wireless transmission / reception device 31, the RTC module 33, and the storage unit 15 And a power transmitting / receiving device 31, an RTC module 33, a storage unit 35, and a power supply unit 32 that supplies power to the control unit 30. An antenna 36 is connected to the wireless transmission / reception device 31.

  Note that the power supply unit 32 may be configured to receive power supply from a power line, or may be configured to include the photovoltaic device 301 and the power storage device 302 as illustrated in FIG. 3 depending on the installation environment.

  The host communication terminal H1 is connected to a data management unit 40 composed of a personal computer, a database server, a cloud server, and the like, and integrates and manages measurement data received by the host communication terminal H1.

  And the control part 30 is based on the synchronous time information produced | generated by the RTC module 33, when the wireless transmission / reception apparatus 31 receives the request signal transmitted from sensor node communication terminal N1, N2, ... The transmission reference time information and the reception window assignment information are transmitted from the wireless transmission / reception apparatus 31 to the sensor node communication terminals N1, N2,... At a predetermined timing, and the transmission reference time information and the reception window assignment are transmitted. Based on the information, when the wireless transmission / reception apparatus 31 receives measurement data periodically transmitted from the sensor node communication terminals N1, N2,... At a predetermined timing, the measurement data is sent to the assigned reception window. Control is performed so that the data are stored in the storage unit 35 in correspondence with each other.

  It is desirable that the number of reception windows allocated be equal to or greater than the number of sensor node communication terminals N1, N2,. Thereby, the measurement data transmitted from each sensor node communication terminal N1, N2,... Can be received and stored more reliably.

  In addition, when the wireless transmitter / receiver 31 does not receive the measurement data from a predetermined sensor node communication terminal (any one of the sensor node communication terminals N1, N2,...) For a predetermined time, the control unit 30 Control can be performed so that the reception window assigned to the sensor node communication terminal is assigned to another sensor node communication terminal. Thereby, a finite receiving window can be used effectively. That is, for a sensor node communication terminal that has not received measurement data for a predetermined time, it is assumed that some failure has occurred, and other sensor node communication terminals that have been suspended or a sensor node communication terminal that has been prepared as a spare device are activated. In response to a request signal from the sensor node communication terminal, the reception window assigned to the faulty device can be reassigned and used.

[Configuration example of wireless sensor network system]
The schematic block diagram of FIG. 4 shows a configuration example of the wireless sensor network system 1 according to the embodiment.

  In the configuration example shown in FIG. 4, a plurality of sensor node communication terminals N (N1, N2,... Ni, Ni + 1, Nn) and measurement data wirelessly transmitted from these sensor node communication terminals N are transmitted at the transmission reference time. And a host communication terminal H1 that receives information on the basis of information and reception window assignment information.

  Each of the sensor node communication terminals N1, N2,... Is installed in a building such as a bridge, a road, a railway, or a building. In addition, as mentioned above, when the photovoltaic device 301 and the electrical storage apparatus 302 are provided as the power supply part 12 of each sensor node communication terminal N1, N2, ..., it is obtained with the photovoltaic device 301 by irradiation of sunlight. Each sensor node communication terminal N1, N2,... Can be driven independently by electric power.

  For example, the host communication terminal H1 is installed on a column or tower having a predetermined height. Thus, signals and data can be reliably transmitted and received between the sensor node communication terminals N1, N2,.

  Further, when there are a large number of sensor node communication terminals N, two or more host communication terminals H1 are considered in consideration of the reception efficiency with the sensor node communication terminal N installed at a position that is shaded by radio waves. The data management unit 40 may integrate the data received by each host communication terminal H1 via a predetermined network.

[Signal and data transmission / reception procedures]
With reference to the sequence diagrams shown in FIG. 5 and FIG. 6, procedures for transmitting and receiving signals and data between sensor node communication terminal N1 (N2...) And host communication terminal H1 in wireless sensor network system 1 according to the embodiment. Will be described.

  First, as shown in FIG. 5, the sensor node communication terminal N1 (N2...) In the wireless sensor network system 1 according to the embodiment starts up (starts up) the wireless transmission / reception apparatus 11 constituting the transmission unit in step S10. To do).

  As shown in FIG. 3 described above, when the storage amount detector 303 is provided, the storage amount detector 303 sets the storage amount of the storage device 302 to a predetermined threshold (for example, a wireless communication such as the sensor node communication terminal N1). When it is determined that the voltage that can activate the transmission / reception device 11 is exceeded, the wireless transmission / reception device 11 can be controlled to be activated.

  The activated wireless transmission / reception device 11 controls the control unit 10 to transmit the reference transmission time information and the reception window to the host communication terminal H1 at a predetermined timing based on the synchronization time information generated by the RTC module 13. A request signal for requesting allocation information is wirelessly transmitted (steps S11 and S12).

  The host communication terminal H1 receives and stores the request signal transmitted from the sensor node communication terminal N1 (N2...) And the identification information (MAC address etc.) of the sensor node communication terminal N1 (N2...). The data is stored in the unit 35 (step S13).

  Next, in response to the request signal, the host communication terminal H1 wirelessly transmits the transmission reference time information and the reception window allocation information to the sensor node communication terminal N1 (N2...) (Steps S14 and S15). ).

  The sensor node communication terminal N1 (N2...) Receives the transmission reference time information and the reception window allocation information, and stores them in the storage unit 15 (step S16).

  Next, the sensor node communication terminal N1 (N2...) Wirelessly transmits measurement data (sensor data) to the host communication terminal H1 based on the transmission reference time information and the reception window allocation information (step S17a). , S18a).

  The host communication terminal H1 receives the measurement data transmitted from the sensor node communication terminal N1 (N2...) At a predetermined timing by the wireless transmission / reception device 31, and associates the measurement data with the assigned reception window. Store in the storage unit 35 (step S19a).

  Then, the sensor node communication terminal N1 (N2...) Performs the measurement data transmission process as described above at predetermined time intervals based on the transmission reference time information and the reception window allocation information (steps S17b, 18b). , 17c, 18c ...). As a result, the sensor node communication terminal N1 (N2...) Can shift to the power saving state (sleep state) without performing the reception mode in a state where transmission processing is not performed. Total power consumption required for transmission and reception can be reduced.

  In addition, the host communication terminal H1 side receives measurement data transmitted at time intervals based on the information of the transmission reference time in the reception window assigned to each sensor node communication terminal N1 (N2...). Therefore, it is sufficient to wait in the reception mode. Thereby, while being able to receive measurement data from each sensor node communication terminal N1 (N2 ...) reliably, power consumption can also be suppressed.

  Actually, until the measurement data can be stably received from each of the sensor node communication terminals N1 (N2...), A predetermined period of time is caused by the influence of signal and data interference and collision (collision). Will be required.

  Here, with reference to the sequence diagram of FIG. 6, a procedure when a signal or data interference or collision (collision) occurs will be described.

  In addition, about the same procedure, the same step code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  As shown in FIG. 6, the sensor node communication terminal N1 (N2,...) Related to the wireless sensor network system 1 starts the wireless transmission / reception apparatus 11 that configures the transmission unit in step S10, and starts the wireless transmission / reception apparatus. 11 wirelessly transmits a request signal for requesting transmission reference time information and reception window allocation information to the host communication terminal H1 at a predetermined timing based on the synchronization time information generated by the RTC module 13. (Steps S11 and S12).

  Here, in the transmission process of step S12, the signal is received by the host communication terminal H1 in the reception mode state due to interference with a request signal or measurement data transmitted from another sensor node communication terminal N or the influence of collision (collision) C. Assume a situation where an impossible situation occurs.

  In this case, even when the predetermined time has elapsed, the host communication terminal H1 does not transmit the transmission reference time information corresponding to the request signal and the reception window allocation information (step S103).

  This state is determined by the control unit 10, and the sensor node communication terminal N1 (N2...) Wirelessly transmits the request signal again after a predetermined time has elapsed (steps S104 and S105).

  In this case, as in step S11, the request signal may be transmitted again at a constant time interval based on the synchronization time information generated by the RTC module 13, but from other sensor node communication terminals N as well. If it is transmitted at the same time interval as before, there is a possibility that interference or collision (collision) may occur again. Therefore, the request signal transmitted from the wireless transmission / reception device 11 of the sensor node communication terminal N1 (N2...) Interferes with other signals and information transmitted from the other sensor node communication terminal N or the host communication terminal H1. When a collision occurs, it may be controlled to retransmit the request signal to the host communication terminal H1 at a timing based on a random number generated by the random number generation unit 14 instead of a predetermined timing.

  Then, the host communication terminal H1 receives the request signal retransmitted from the sensor node communication terminal N1 (N2...) And the identification information (MAC address etc.) of the sensor node communication terminal N1 (N2...). And stored in the storage unit 35 (step S106).

  Next, in response to the request signal, the host communication terminal H1 wirelessly transmits the transmission reference time information and the reception window allocation information to the sensor node communication terminal N1 (N2...) (Steps S107, S108). ).

  The sensor node communication terminal N1 (N2...) Receives the transmission reference time information and the reception window allocation information and stores them in the storage unit 15 (step S109).

  Next, the sensor node communication terminal N1 (N2...) Wirelessly transmits measurement data (sensor data) to the host communication terminal H1 based on the transmission reference time information and the reception window allocation information (step S110a). , S111a).

  The host communication terminal H1 receives the measurement data transmitted from the sensor node communication terminal N1 (N2...) At a predetermined timing by the wireless transmission / reception device 31, and associates the measurement data with the assigned reception window. Store in the storage unit 35 (step S112a).

  Then, the sensor node communication terminal N1 (N2...) Performs measurement data transmission processing as described above at predetermined time intervals based on the transmission reference time information and the reception window allocation information (steps S110b, 111b). ...).

  Due to such a procedure, a situation occurs in which the host communication terminal H1 in the reception mode state cannot receive due to the influence of the interference or collision (collision) with the request signal and measurement data transmitted from the other sensor node communication terminal N. Even in such a case, by retransmitting the request signal, the above situation can be avoided and the measurement data can be reliably received.

  Actually, in the case of being affected by interference or collision (collision) with a request signal or measurement data transmitted from another sensor node communication terminal N, the sensor node communication terminal N1 (N2...) A predetermined time is required until transmission / reception of a request signal and measurement data is stably established with the host communication terminal H1. A specific example will be described next with reference to FIGS.

[Specific examples of signal and data transmission / reception]
Based on the timing charts shown in FIGS. 7 and 8, a specific example of signal and data transmission / reception between the sensor node communication terminal N and the host communication terminal H1 in the wireless sensor network system 1 according to the embodiment will be described.

  For convenience of explanation, FIGS. 7 and 8 describe an example of transmission / reception between three sensor node communication terminals N1 to N3 and one host communication terminal H1. However, the basic procedure is the same even when the number of sensor node communication terminals N is four or more or when two or more host communication terminals H1 are provided.

  In the timing charts shown in FIGS. 7 and 8, it is assumed that the host communication terminal H1 is always in a state (reception mode state) where signals and data can be received.

  The timing charts shown in FIGS. 7 and 8 basically proceed based on the synchronization time information generated by the RTC module 33 included in the host communication terminal H1.

  In the timing charts shown in FIGS. 7 and 8, a pulse waveform indicated by a broken line indicates a state where reception has failed, and a pulse waveform including a hatch line indicates a state where reception is successful.

  In the example shown here, it is assumed that five reception windows W1 to W5 every 12 seconds obtained by dividing the entire frame for one minute by 5 are set as reception windows. Note that the number of reception windows can be appropriately changed according to the number of sensor node communication terminals and the like.

  When the wireless sensor network system 1 operates, first, the sensor node communication terminal N2 is first activated at the timing TN2 (near the time t1 on the host communication terminal H1 side). Although not particularly limited, the activation timing of each of the sensor node communication terminals N1 to N3 is determined by the storage amount detector 303 when the photovoltaic device 301 is mounted on the power supply unit 12 as described above, for example. It can be set as the time when it is determined that the amount of stored electricity exceeds a predetermined threshold.

  Then, the request signal P1a is wirelessly transmitted at a random time within one minute from the timing TN2 (generated by the random number generation unit 14). The request signal P1a is a request signal for requesting transmission reference time information and reception window allocation information, and can include identification information (such as a MAC address) of the sensor node communication terminal N2.

  Next, the host communication terminal H1 receives the request signal P2a from the time t3 and stores it in the storage unit 35.

  The host communication terminal H1 wirelessly transmits the transmission reference time information and the reception window allocation information data P3a after a predetermined time from the reception of the request signal P2a.

  Then, the sensor node communication terminal N2 in the reception mode state receives the transmission reference time information and the reception window allocation information data P4a and stores them in the storage unit 15. In addition, since no signal is transmitted / received between the other sensor node communication terminals N1 and N3 and the host communication terminal H1 in the time period from the time t3 to the time t4, interference with other signals and data, No collision occurs, and the data P4a is received by the sensor node communication terminal N2 without any trouble.

  Here, for the sensor node communication terminal N2, the transmission reference time is “0 second” every minute (that is, the timing of time t5, t10, t15...) And the reception window W1 is assigned. To do.

  Next, the sensor node communication terminal N2 wirelessly transmits the measurement data D1a starting from time t5 based on the transmission reference time information and the reception window allocation information.

  On the other hand, the sensor node communication terminal N3 is activated at timing TN3 (near time t4 on the host communication terminal H1 side).

  Then, the request signal P1b is wirelessly transmitted at a random time (generated by the random number generator 14) within, for example, one minute from the timing TN3.

  Here, the transmission of the measurement data D1a from the sensor node communication terminal N2 and the transmission of the request signal P1b from the timing TN3 overlap in the time period from time t5 to t6. For this reason, interference or collision (collision) occurs in the radio signal between the measurement data D1a and the request signal P1b, and the measurement data D1a and the request signal P1b are not received by the host communication terminal H1.

  Therefore, it is necessary to retransmit the measurement data D1a and the request signal P1b according to the procedure described below.

  First, for the measurement data D1a, the sensor node communication terminal N2 retransmits the measurement data D1a from the time t10 based on the information on the transmission reference time and the allocation information on the reception window. In the time period from t10 to t11, since signals are not transmitted / received between the other sensor node communication terminals N1, N3 and the host communication terminal H1, interference or collision with other signals or data is not performed. The measurement data D1a is received by the reception window W1 of the host communication terminal H1 without any trouble.

  As for the request signal P1b, for example, after 1 minute has elapsed from the timing TN3, the request signal P1b is retransmitted in the vicinity of time t12, which is a random time within 1 minute (generated by the random number generation unit 14).

  On the other hand, the sensor node communication terminal N1 is activated at timing TN1 (near time t9 on the host communication terminal H1 side).

  Then, the request signal P5b is wirelessly transmitted at a random time within one minute from the timing TN1 (generated by the random number generator 14).

  Here, the transmission of the request signal P1b from the sensor node communication terminal N3 and the transmission of the request signal P5b from the sensor node communication terminal N1 overlap in the time period from time t12 to t13. For this reason, interference and collision (collision) occur in the radio signals of the request signal P1b and the request signal P5b, and the request signal P1b and the request signal P5b are not received by the host communication terminal H1.

  Therefore, the request signal P1b and the request signal P5b need to be retransmitted according to the following procedure.

  First, for the request signal P1b, after 2 minutes elapse from the timing TN3, for example, the request signal P1b is transmitted again in the vicinity of time t18 which is a random time within 1 minute (generated by the random number generation unit 14).

  The host communication terminal H1 wirelessly transmits the transmission reference time information and the reception window assignment information data P3b after a predetermined time from the reception of the request signal P2b.

  The sensor node communication terminal N3 in the reception mode state receives the transmission reference time information and the reception window allocation information data P4b and stores them in the storage unit 15. In addition, since no signal is transmitted / received between the other sensor node communication terminals N1 and N2 and the host communication terminal H1 in the time period from time t18 to t19, interference with other signals and data, A collision does not occur and the data P4b is received by the sensor node communication terminal N3 without any trouble.

  Here, with respect to the sensor node communication terminal N3, it is assumed that the transmission reference time is “12 seconds” every minute (that is, the timing of time t21, t26...) And the reception window W2 is assigned.

  Then, the sensor node communication terminal N2 wirelessly transmits the measurement data D2a from the time t21 based on the transmission reference time information and the reception window allocation information.

  Since no signals are transmitted / received between the other sensor node communication terminals N1, N2 and the host communication terminal H1 in the time period from time t21 to t22, interference and collision with other signals and data occur. The measurement data D2a is received by the reception window W2 of the host communication terminal H1 without any trouble.

  Further, the request signal P5a from the sensor node communication terminal N1 is retransmitted in the vicinity of time t15, which is a random time within one minute (generated by the random number generator 14), for example, after one minute has elapsed from the timing TN1. .

  However, since the sensor node communication terminal N2 automatically and periodically transmits the measurement data D1b starting from the time t15, interference and collision with the request signal P5a occurs. For this reason, the measurement data D1b and the request signal P5a are not received on the host communication terminal H1 side.

  Therefore, the request signal P5a needs to be retransmitted. That is, the sensor node communication terminal N1 again transmits the request signal P5b again in the vicinity of time t22 which is a random time within 1 minute (generated by the random number generation unit 14) after 2 minutes elapse from the timing TN1.

  The host communication terminal H1 wirelessly transmits the transmission reference time information and the reception window allocation information data P4c after a predetermined time from the reception of the request signal P5a.

  The sensor node communication terminal N1 in the reception mode state receives the transmission reference time information and the reception window allocation information data P4c and stores them in the storage unit 15. In addition, since no signal is transmitted / received between the other sensor node communication terminals N2 and N3 and the host communication terminal H1 in the time period from time t22 to t23, interference with other signals and data, No collision occurs, and the data P4c is received by the sensor node communication terminal N1 without any trouble.

  Here, with respect to the sensor node communication terminal N1, it is assumed that the transmission reference time is “24 seconds” every minute (that is, timings at times t27, t32...) And the reception window W3 is assigned.

  Then, the sensor node communication terminal N1 wirelessly transmits the measurement data D3a from the time t27 based on the transmission reference time information and the reception window allocation information.

  Since no signals are transmitted / received between the other sensor node communication terminals N2 and N3 and the host communication terminal H1 in the time period from time t27 to t28, interference and collision with other signals and data occur. The measurement data D3a is received by the reception window W3 of the host communication terminal H1 without any trouble.

  When the sensor node communication terminals N1 to N3 succeed in receiving the transmission reference time information and the reception window allocation information data (P4a, P4b, P4c) from the host communication terminal H1 in this way, A state in which measurement data (D1e, D2c, D3b, etc.) is periodically transmitted is established based on the transmission reference time information and the reception window allocation information.

  Thereby, the sensor node communication terminals N1 to N3 do not need to shift to the reception mode after receiving the transmission reference time information and the reception window allocation information data (P4a, P4b, P4c). In addition, during periods other than when periodic transmission of measurement data is performed by the wireless transmission / reception device 11, it is possible to shift to a power saving state, so that the total power consumption required for transmission of measurement data can be efficiently suppressed. it can.

  Even when a situation occurs in which the host communication terminal H1 in the reception mode cannot receive due to interference or collision with a request signal or measurement data transmitted from another sensor node communication terminal. By retransmitting the request signal, the measurement data can be reliably received. Thereby, measurement data can be efficiently acquired from each sensor node communication terminal N1, N2, N3... And monitoring of a building or the like in which each sensor node communication terminal N1, N2, N3. Etc. can be performed reliably.

[Other embodiments]
As described above, the embodiments have been described. However, it should be understood that the descriptions and drawings forming a part of this disclosure are illustrative and do not limit the embodiments. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  As described above, this embodiment includes various embodiments not described here.

  For example, when a predetermined shift occurs in the synchronization time information generated by the RTC modules 13 and 33 constituting the clock unit included in each sensor node communication terminal N and the host communication terminal H1 due to long-term operation, The request signal may be retransmitted from the sensor node communication terminal N to reacquire the transmission reference time information and the reception window allocation information.

  Further, in the configuration in which the power supply unit 12 includes the photovoltaic power generation device, even when the sensor node communication terminal N that has been in a dormant state in which measurement data is not transmitted for a relatively long period of time due to the influence of sunshine hours or the like starts Similarly, the request signal may be retransmitted from the sensor node communication terminal N to reacquire the transmission reference time information and the reception window allocation information.

  The sensor node communication terminal, host communication terminal, and wireless sensor network system of the present embodiment can be applied to various buildings such as bridges, roads, railways, buildings, etc., and include temperature, humidity, gas concentration, strain, vibration, etc. Can be obtained by a sensor node communication terminal equipped with various sensors, and the measurement data can be applied to a system capable of transmitting wirelessly with low power consumption.

DESCRIPTION OF SYMBOLS 1 ... Wireless sensor network system H1 ... Host communication terminal N (N1, N2, N3 ...) ... Sensor node communication terminal 10, 30 ... Control part 11 ... Wireless transmitter / receiver 12 ... Power supply part 13, 33 ... RTC module 14 ... Random number generation unit 15, 35 ... storage unit 16, 36 ... antenna 20 ... sensor unit 31 ... wireless transmission / reception device 32 ... power supply unit 40 ... data management unit 301 ... photovoltaic power generation device 302 ... power storage device 303 ... storage amount detector D1a, D2b , D3a: Measurement data P1a, P1b, P2a, P2b, P5a, P5b ... Request signals P3a, P3b, P4a, P4b, P4c ... Transmission reference time information and reception window allocation information data W1-W5 ... Reception window

Claims (12)

A sensor unit for measuring physical quantities;
A transmission unit for transmitting the physical quantity measured by the sensor unit to the host communication terminal as measurement data;
A receiving unit for receiving predetermined data transmitted from the host communication terminal;
A clock unit for generating synchronization time information;
A storage unit that stores information on a transmission reference time that defines a timing at which the measurement data is transmitted from the transmission unit, and allocation information of a reception window of the measurement data on the host communication terminal side;
A control unit that controls operations of the sensor unit, the transmission unit, the reception unit, the clock unit, and the storage unit;
A power supply unit that supplies power to the sensor unit, the transmission unit, the reception unit, the clock unit, the storage unit, and the control unit;
The controller is
Based on the synchronization time information generated by the clock unit, a request signal for requesting the transmission reference time information and the reception window allocation information to the host communication terminal at a predetermined timing is transmitted to the transmission unit. Send from
The information on the transmission reference time transmitted from the host communication terminal in response to the request signal and the allocation information on the reception window are received by the reception unit, and stored in the storage unit,
A sensor for controlling to periodically transmit the measurement data to the host communication terminal based on the transmission reference time information and the reception window allocation information via the transmission unit. Node communication terminal. The control unit further includes a random number generation unit that generates a random number,
When the request signal transmitted from the transmitter interferes with or collides with another signal or information transmitted from another sensor node communication terminal or the host communication terminal, the predetermined timing is used instead of the predetermined timing. The sensor node communication terminal according to claim 1, wherein control is performed so that the request signal is retransmitted to the host communication terminal at a timing based on the random number generated by the random number generation unit.   The sensor node communication terminal according to claim 1, wherein the transmission unit and the reception unit are configured by a wireless transmission / reception device.   The sensor node communication terminal according to any one of claims 1 to 3, wherein the request signal includes address information of the sensor node communication terminal itself.   5. The control unit according to claim 1, wherein the control unit controls the transmission unit and the reception unit to shift to a power saving state when the transmission operation and the reception operation are not performed. The sensor node communication terminal according to claim 1.   The sensor node communication according to any one of claims 1 to 5, wherein the power supply unit includes a photovoltaic power generation device and a power storage device that stores electricity generated by the photovoltaic power generation device. Terminal. The power supply unit further includes a storage amount detector that detects a storage amount of the power storage device,
The control unit controls to activate the transmission unit and transmit the request signal when the storage amount detector determines that the storage amount of the power storage device exceeds a predetermined threshold value. The sensor node communication terminal according to claim 6.   The sensor node communication terminal according to any one of claims 1 to 7, wherein the sensor unit includes at least one of a temperature sensor, a humidity sensor, a gas sensor, a strain sensor, and a strain sensor. A receiving unit that receives request signals and measurement data transmitted from two or more sensor node communication terminals according to any one of claims 1 to 8,
In accordance with the request signal, a transmission unit that transmits information of a transmission reference time and reception window allocation information to the sensor node communication terminal;
A clock unit for generating synchronization time information;
A storage unit that stores transmission reference time information that defines a timing for transmitting the measurement data from the sensor node communication terminal, and reception window assignment information for receiving the measurement data;
A control unit that controls operations of the transmission unit, the reception unit, the clock unit, and the storage unit;
A power supply unit that supplies power to the transmission unit, the reception unit, the clock unit, the storage unit, and the control unit;
The controller is
When the receiving unit receives the request signal transmitted from the sensor node communication terminal, based on the synchronization time information generated by the clock unit, the sensor node communication terminal is transmitted at a predetermined timing. The transmission reference time information and the reception window allocation information are transmitted from the transmission unit,
Based on the information of the transmission reference time and the allocation information of the reception window, the measurement data is received when the reception unit receives the measurement data periodically transmitted from the sensor node communication terminal at a predetermined timing. The host communication terminal is controlled so as to be stored in the storage unit in association with the assigned reception window.   The host communication terminal according to claim 9, wherein the number of reception windows allocated is equal to or greater than the number of installed sensor node communication terminals.   When the receiving unit does not receive the measurement data from the predetermined sensor node communication terminal for a predetermined time, the control unit sets the reception window assigned to the sensor node communication terminal to another sensor. The host communication terminal according to claim 9 or 10, wherein control is performed so as to be assigned to a node communication terminal. Two or more sensor node communication terminals according to any one of claims 1 to 8,
A wireless sensor network system comprising: the host communication terminal according to claim 9.

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