MTC device and communication method for the MTC device

Abstract

An MTC (Machine Type Communication) device and a communication method therefor are provided that can improve the stability of communication quality in machine communication. [Solution] An MTC device 10 performs wireless communication with a core network CN via a base station BS, and includes a communication module 12 that can transition between an attached state in which communication with the core network CN is possible and a detached state in which communication with the core network CN is impossible, and a control module 15 that controls the communication module 12, where the control module 15 acquires a communication status that can determine the attached state or detached state of the communication module 12, and controls the communication module 12 to attach to the core network CN when the control module 15 determines that the communication module 12 is in the detached state based on the communication status.

Description

[Technical Field]

[0001] The present invention relates to an MTC device and a communication method for the MTC device, and more particularly to an MTC device that communicates with a core network via a base station and a communication method for the MTC device. [Background technology]

[0002] In recent years, with the spread of IoT, machine-to-machine communication systems equipped with MTC (Machine Type Communication) devices that communicate between devices have become widespread. In particular, machine-to-machine communication systems that use cellular communication lines with wide communication areas have attracted attention. Cellular communication lines divide the communication area into certain sections (cells), and a base station is located in each cell. In other words, MTC devices can perform wide-area communication by communicating with a core network (the core part of the network) via base stations distributed across the cells.

[0003] Here, an upper limit is set for the number of communication terminals that can communicate with one base station. Therefore, if the number of communication terminals located within a cell does not exceed the upper limit, the communication terminals are maintained in an attached state (online state) that allows communication with the core network. On the other hand, if the number of communication terminals present within a cell exceeds the upper limit, some of the communication terminals are controlled to a detached state. The detached state is an offline state in which the communication terminal cannot communicate with the base station or the core network. Patent Document 1 describes a service capability server that can forcibly control an MTC device to a detached state when a predetermined event occurs in the MTC device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2016-506694 Summary of the Invention [Problem to be solved by the invention]

[0005] As mentioned above, machine-to-machine communication systems using cellular communication lines can realize communication between devices over a wide communication area. However, it has been pointed out that the communication environment within the cell covered by a base station can sometimes cause MTC devices to be controlled into a detached state, which can result in the loss of communication opportunities for the MTC device and make it difficult to ensure stable communication quality.

[0006] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an MTC device that can improve the stability of communication quality in machine-to-machine communication, and a communication method for the MTC device. [Means for solving the problem]

[0007] The above problem is solved by the MTC device of the present invention, which is an MTC (Machine Type Communication) device that performs wireless communication with a core network via a base station, and includes a communication module that can transition between an attached state in which communication with the core network is possible and a detached state in which communication with the core network is impossible, and a control processor that controls the communication module, wherein the control processor acquires a communication status that can determine the attached state and detached state of the communication module, and when it is determined that the communication module is in a detached state based on the communication status, controls the communication module to attach to the core network.

[0008] According to the above configuration, the MTC device includes a communication module that communicates with a core network via a base station and a control processor that controls the communication module. The control processor acquires a communication status that can determine whether the communication module is attached or detached, and controls the communication module to attach to the core network when the control processor determines that the communication module is in a detached state. Therefore, when the communication module is controlled to a detached state due to the influence of the communication environment within the cell, the control processor can control the communication module to attach to the core network. This can prevent the MTC device from losing communication opportunities and can improve the stability of communication quality in machine-to-machine communication.

[0010] In addition, the communication module and the control processor are communicatively connected to each other via a plurality of communication ports, and the control processor may obtain the communication status from the communication module via a dedicated communication port among the plurality of communication ports. According to the above configuration, the control processor obtains the communication status via a dedicated communication port, making it possible to monitor the attached and detached states of the communication module without affecting the communication between the control processor and the communication module.

[0011] The dedicated communication port may be a communication port compatible with a GPIO (General Purpose Input / Output) interface. According to the above configuration, the control processor communicates with the communication module via a communication port corresponding to the GPIO interface, thereby suppressing the increase in power consumption associated with communication and reducing the cost of the MTC device.

[0012] Furthermore, the above problem is solved by a communication method of the present invention, which is a communication method for an MTC (Machine Type Communication) device that performs wireless communication with a core network via a base station, by acquiring, without going through the base station, a communication status that can determine the attached state and detached state of a communication module that can transition between an attached state in which communication with the core network is possible and a detached state in which communication with the core network is impossible, and controlling, without going through the base station, the communication module so as to attach to the core network when it is determined that the communication module is in a detached state based on the communication status.

[0013] According to the above configuration, the communication method of the MTC device acquires a communication status capable of determining the attached state or detached state of a communication module that communicates with a core network via a base station without going through the base station, and controls the communication module to attach to the core network when the detached state is determined. Therefore, when the communication module is controlled to the detached state due to the influence of the communication environment in the cell, the communication module can be controlled to attach to the core network. This makes it possible to prevent the MTC device from losing communication opportunities and to achieve improved stability of communication quality in the MTC device. [Effects of the Invention]

[0015] According to the MTC device and the communication method of the MTC device of the present invention, it is possible to improve the stability of communication quality in machine communication. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram for explaining an overview of a machine communication system. [Figure 2] FIG. 1 is a diagram illustrating a functional configuration of an MTC device. [Figure 3] FIG. 10 is a diagram for explaining the transition of the operating state of an MTC device. [Figure 4] FIG. 10 is a diagram showing the flow of a communication method for an MTC device. DETAILED DESCRIPTION OF THE INVENTION

[0017] An MTC device 10 and a communication method for the MTC device 10 according to one embodiment of the present invention (hereinafter referred to as the present embodiment) will be described below with reference to Figures 1 to 4. However, the embodiment described below is merely an example to facilitate understanding of the present invention and does not limit the present invention. In other words, the present invention may be modified or improved without departing from the spirit thereof, and of course, the present invention also includes equivalents thereof.

[0018] <<Overview of Machine Communication System 1>> 1 is a diagram illustrating an overview of a machine-to-machine communication system 1. The machine-to-machine communication system 1 includes an MTC device 10 that can communicate with a core network CN via a base station BS, and an MTC server 20 that collects data acquired by the MTC device 10 and visualizes and outputs the collected data. The MTC device 10 and the MTC server 20 are connected via a publicly available cellular communication line CC. Alternatively, the MTC device 10 and the MTC server 20 may be connected via the cellular communication line CC and an Internet line (not shown). This enables the MTC device 10 and the MTC server 20 to perform wide-area communication.

[0019] The MTC device 10 is a communication device that complies with LTE-M (Long Term Evolution for Machines), a communication standard specialized for machine communication. The MTC device 10 may be attached to various devices and facilities to acquire and transmit / receive information about the devices and facilities, or may be attached to a moving object such as an automobile to acquire and transmit / receive information about the moving object. As will be described later, the MTC device 10 has a sensor module 11 and a communication module 12 (see FIG. 2), and wirelessly transmits data detected by the sensor module 11 to the MTC server 20 via the communication module 12 (uplink communication). Details of the MTC device 10 will be described later. The MTC device 10 corresponds to the MTC apparatus of the present invention.

[0020] The MTC server 20 is a server device that has the function of collecting and storing data transmitted by the MTC device 10. The MTC server 20 is composed of one or more information processing devices. The MTC server 20 may also be an information processing device implemented as a cloud system. The MTC server 20 has a function of analyzing the data collected and stored from the MTC device 10, and after performing evaluation processing, visualizing the data and providing it to other information communication terminals.

[0021] The cellular communication line CC is a communication line conforming to LTE-M, and includes a base station BS and a core network CN. Base stations BS, also known as "eNodeB" or "eNB," are relay devices installed in each of the many cells that divide a communication area. Base stations BS are installed on steel towers erected in locations with good visibility, on the rooftops of buildings and apartment buildings, or on utility poles. Base stations BS ensure a communication area that covers each cell by effectively combining an omnidirectional antenna and multiple directional antennas.

[0022] Although three base stations BS are shown in FIG. 1, they are representative of a plurality of base stations BS, and it goes without saying that many more base stations BS are connected to the core network CN. Also, in Figure 1, one MTC device 10 is connected to one base station BS, but this one MTC device 10 is shown as a representative of multiple MTC devices 10, and it goes without saying that multiple MTC devices may be connected within a cell.

[0023] The core network CN forms the core of the cellular communication line CC, and includes a mobility management device CN1, a serving gateway CN2, and a packet data network gateway CN3.

[0024] The mobility management device CN1 is also called "MME" and serves as a gateway for control signals. The mobility management device CN1 receives an attach request from the communication module 12 of the MTC device 10 via the base station BS, and transmits an attach response to the MTC device 10. This causes the MTC device 10 to transition to an attached state (online state) in which it can communicate with the core network CN. The mobility management device CN1 also transmits a detach request to the MTC device 10 depending on the communication environment within the cell. This causes the MTC device 10 to transition to a detached state (offline state) in which it cannot communicate with the core network CN.

[0025] The serving gateway CN2, also called "SGW," serves as a gateway for data packets transmitted and received by the MTC device 10. More specifically, the serving gateway CN2 relays data packets between the base station BS and a packet data network gateway CN3, which will be described later. The packet data network gateway CN3 is also called "PGW" and serves as a gateway that relays between the cellular communication line CC and an external communication line. As a specific example, the packet data network gateway CN3 can relay communication packets between the cellular communication line CC and an Internet line (not shown).

[0026] In the machine-to-machine communication system 1 configured as described above, the MTC device 10 communicates wirelessly with the core network CN via the base station BS of the cellular communication line CC. An upper limit is set on the number of MTC devices 10 that can communicate with the base station BS, and any MTC devices 10 exceeding the upper limit cannot communicate wirelessly with the base station BS. Therefore, due to the influence of the communication environment within the cell, the MTC device 10 may be controlled to a detached state in which it cannot communicate with the core network CN. The MTC device 10 in this embodiment monitors whether it has been controlled to a detached state and can return to an attached state based on the monitoring results. This prevents the MTC device 10 from losing communication opportunities in the detached state, thereby improving the stability of communication quality in machine-to-machine communication.

[0027] <<MTCデバイス10> > Next, the MTC device 10 will be described in detail. Fig. 2 is a diagram showing the functional configuration of the MTC device 10. As shown in Fig. 2, the MTC device 10 mainly includes a sensor module 11, a communication module 12, a communication antenna 13, a power supply module 14, and a control module 15.

[0028] The sensor module 11 serves to detect physical quantities at the installation location of the MTC device 10. More specifically, the sensor module 11 has a flow rate sensor 111 and a pressure sensor 112, and can detect the flow rate and pressure of a fluid. As a specific example, when the MTC device 10 is attached to a water supply pump, the flow rate sensor 111 detects the water supply rate of the water supply pump, and the pressure sensor 112 detects the water supply pressure of the water supply pump. This makes it possible to remotely monitor whether the motor of the water supply pump is operating properly. However, the physical quantities detected by the sensor module 11 are not limited to flow rate and pressure. The sensor module 11 may also detect vibrations using an acceleration sensor. The sensor module 11 may also detect temperature using a temperature sensor.

[0029] The communication module 12 is a communication circuit compliant with LTE-M. More specifically, the communication module 12 is a wireless communication circuit that transmits data detected by the sensor module 11 to the MTC server 20 via the base station BS and the core network CN. The communication module 12 may receive control data via the base station BS and the core network CN. The communication module 12 mainly includes an RF circuit 121 and a communication control circuit 122.

[0030] The RF circuit 121 has a transmitting unit including a frequency conversion circuit, a filter circuit, and an amplifier circuit, and generates a high-frequency signal that can be transmitted via the communication antenna 13. However, without being limited to this, the RF circuit 121 may further have a receiving unit and obtain a baseband signal from the high-frequency signal received via the communication antenna 13.

[0031] The communication control circuit 122 controls the communication module 12 and manages the communication state. More specifically, the communication control circuit 122 stores a communication status that can determine whether the communication module 12 is in at least an attached state or a detached state. The communication control circuit 122 is communicatively connected to the control module 15 (described later) via multiple communication ports (a first communication port 156 and a second communication port 157). More specifically, the communication control circuit 122 can acquire a control signal from the control module 15 via the first communication port 156 and control the RF circuit 121 to transmit a high-frequency signal. The communication control circuit 122 can output a communication status to the control module 15 via the second communication port 157.

[0032] The communication antenna 13 is an antenna that transmits the high-frequency signal output by the communication module 12. The communication antenna 13 is a chip antenna that can be miniaturized, but is not limited to this. The communication antenna 13 may be a patch antenna or a whip antenna as long as it has antenna gain and directivity that enable communication with the base station BS.

[0033] The power supply module 14 supplies electrical energy to the sensor module 11, the communication module 12, and the control module 15. The power supply module 14 includes, but is not limited to, a chargeable and dischargeable secondary battery and a constant voltage output circuit (DC-DC converter). The power supply module 14 may also include a primary battery. The power supply module 14 may also include a power receiving terminal capable of receiving electrical energy from an external source.

[0034] The control module 15 is a control circuit including a control processor 15a, a volatile memory, and a non-volatile memory, and is responsible for controlling the MTC device 10. The control module 15 functions as a detection data acquisition unit 151, a communication status acquisition unit 152, an attachment control unit 153, a status control unit 154, and a timer unit 155 by the control processor 15a loading a program stored in the non-volatile memory into the volatile memory and executing it.

[0035] The detection data acquiring unit 151 acquires detection data (flow rate data and pressure data) detected by the flow rate sensor 111 and the pressure sensor 112. The detection data acquiring unit 151 may have an A / D converter and a filter circuit. The detection data acquiring unit 151 may also have an arithmetic circuit for acquiring statistical values ​​(average value, maximum value, minimum value) of the detection data.

[0036] The communication status acquisition unit 152 communicates with the communication module 12 and acquires the communication status. The communication status is information that can determine whether the communication module 12 is attached or detached, but is not limited to this. The communication status may include the communication volume and communication time of the communication module 12. The communication status may also include more detailed information regarding the communication status of the communication module 12. As described above, the control module 15 and the communication module 12 are communicatively connected to each other via the first communication port 156 and the second communication port 157. The first communication port 156 is used to transmit control data for communication control of the communication module 12 to the communication module 12. The first communication port 156 may also be used to transmit detection data acquired by the detection data acquisition unit 151 to the communication module 12.

[0037] The second communication port 157 is a dedicated communication port used to acquire the communication status of the communication module 12. The communication status acquisition unit 152 acquires the communication status using the second communication port 157, thereby making it possible to acquire the communication status of the communication module 12 regardless of the communication status of the first communication port 156. Furthermore, by using the second communication port 157, the communication status acquisition unit 152 can acquire the communication status without affecting the communication of the first communication port 156.

[0038] The second communication port 157 is preferably a communication port compatible with a GPIO (General Purpose Input / Output) interface, which can suppress an increase in power consumption due to the communication status acquisition by the communication status acquisition unit 152, and can also suppress an increase in the cost of the MTC device 10.

[0039] The attach control unit 153 determines whether the communication module 12 is in a detached state based on the communication status, and controls the communication module 12 to attach to the core network CN if it is determined to be in the detached state. More specifically, the attach control unit 153 causes the communication module 12 to transmit an attach request signal to the core network CN via the base station BS. After that, when the communication module 12 receives an attach response signal transmitted from the core network CN, the communication module 12 transitions from the detached state to the attached state. This allows the communication module 12 to return to the attached state even if the communication module 12 has entered the detached state. Therefore, it is possible to prevent the communication module 12 from losing communication opportunities for the MTC device 10 due to the communication module 12 being controlled to the detached state, and it is possible to achieve improved stability of communication quality.

[0040] The state control unit 154 controls the MTC device 10 so that it transitions between a normal operating state and a sleep state at a predetermined timing. 3 is a diagram illustrating transitions in the operating state of the MTC device 10. As shown in FIG. 3, the state control unit 154 controls the MTC device 10 to transition to a normal operating state in which it operates at a first power consumption P1 between time T1 and time T2 and between time T3 and time T4. In the normal operating state, the flow sensor 111 of the sensor module 11 acquires flow data, and the pressure sensor 112 acquires pressure data. In addition, in the normal operating state, the communication module 12 converts the flow data and pressure data acquired by the sensor module 11 into high-frequency signals and transmits them via the communication antenna 13. The normal operating state corresponds to the first operating state of the present invention, and the first power consumption P1 corresponds to first electric energy.

[0041] Furthermore, the state control unit 154 controls the MTC device 10 to transition to a sleep state in which it operates at a second power consumption P2 that is lower than the first power consumption P1 between time T2 and time T3. In the sleep state, the flow sensor 111 and the pressure sensor 112 of the sensor module 11 do not acquire flow data or pressure data. In addition, in the sleep state, the communication module 12 does not transmit high-frequency signals. Therefore, the MTC device 10 can transmit flow data and pressure data to the MTC server 20 in the normal operating state, while suppressing unnecessary power consumption in the sleep state. The sleep state corresponds to the second operating state of the present invention, and the second power consumption P2 corresponds to the second power energy.

[0042] The above-mentioned communication status acquisition unit 152 acquires the communication status of the communication module 12 at time Ta in the sleep state. Then, when the attachment control unit 153 determines that the communication module 12 is in a detached state based on the communication status, it controls the communication module 12 to attach to the core network CN. The predetermined time Ta is a time a predetermined time before time T3 at which the MTC device 10 transitions from the sleep state to the normal operation state, and enables the MTC device 10 to obtain an opportunity to communicate with the core network CN at time T3.

[0043] The timer 155 includes a clock oscillator and a counter that counts the output of the clock oscillator. The clock oscillator is, but is not limited to, a crystal oscillator. The clock oscillator may also be a ceramic oscillator. The timing unit 155 outputs a timing signal when the time has come for the communication status acquisition unit 152 to acquire the communication status. Specifically, when time Ta shown in Fig. 3 has arrived, the timing unit 155 outputs a timing signal to the communication status acquisition unit 152. The timing unit 155 also outputs a timing signal when the time has come to transition from the sleep state to the normal operation state. Specifically, when time T1 and time T3 shown in Fig. 3 have arrived, the timing unit 155 outputs a timing signal to the state control unit 154.

[0044] <<Communication Processing of MTC Device 10>> Next, the communication processing of the MTC device 10 will be described. FIG. 4 shows the flow of communication processing executed by the control module 15 of the MTC device 10 at a predetermined timing (for example, a cycle of 100 msec). As shown in FIG. 4, the control module 15 first determines whether the state transition timing has arrived (step S10). More specifically, the control module 15 determines whether the timing unit 155 has output a timing signal indicating the arrival of the timing for transitioning from the sleep state to the normal operation state (the timings at time T1 and time T3 in FIG. 3).

[0045] When it is determined that the state transition timing has arrived (step S10: Yes), the control module 15 transitions the MTC device 10 to the normal operation state (step S11). More specifically, the state control unit 154 causes the power energy output by the power module 14 to be supplied to the sensor module 11, the communication module 12, and the control module 15, thereby transitioning each module to an operable state.

[0046] Next, the control module 15 acquires detection data (step S12). More specifically, the flow rate sensor 111 of the sensor module 11 acquires flow rate data, and the pressure sensor 112 acquires pressure data. The flow rate data and the pressure data are acquired by the detection data acquisition unit 151 of the control module 15.

[0047] The detection data acquisition unit 151 may acquire statistical values of the flow rate data and the pressure data. More specifically, the detection data acquisition unit 151 may acquire the average value, the maximum value, and the minimum value of the data detected by the flow rate sensor 111 or the pressure sensor 112. Further, the detection data acquisition unit 151 may acquire the frequency parameters of the flow rate data and the pressure data. More specifically, the detection data acquisition unit 151 may acquire the peak frequency of the data detected by the flow rate sensor 111 or the pressure sensor 112. Furthermore, the detection data acquiring unit 151 may determine whether or not there is an abnormality based on the flow rate data and the pressure data, and acquire the determination result. More specifically, the detection data acquiring unit 151 may determine whether or not there is an abnormality by comparing the data detected by the flow rate sensor 111 or the pressure sensor 112 with a predetermined threshold value for determining abnormality, and acquire the determination result.

[0048] Next, the control module 15 transmits the detection data (step S13). More specifically, the control module 15 outputs the detection data acquired by the detection data acquisition unit 151 to the communication module 12, converts it into a high-frequency signal, and transmits it to the MTC server 20 via the communication antenna 13.

[0049] Next, the control module 15 transitions the MTC device 10 to a sleep state (step S14). More specifically, the state control unit 154 stops the supply of power energy to the sensor module 11. The state control unit 154 also stops the supply of power energy to the RF circuit 121. The state control unit 154 may also partially limit the supply of power energy to the control module 15.

[0050] Next, the control module 15 resets the time counting by the timer 155 (step S15) and ends the communication process. More specifically, the timer 155 resets the count value of the counter that counts the output of the clock oscillator.

[0051] On the other hand, if it is not determined in step S10 that the state transition timing has arrived (step S10: No), the control module 15 determines whether or not the communication status acquisition timing has arrived (step S16). More specifically, the control module 15 determines whether or not the timer unit 155 has output a timing signal indicating the arrival of the timing to acquire the communication status (the timing of time Ta in FIG. 3). If it is not determined that the timing to obtain the communication status has arrived (step S16: No), the control module 15 ends the communication process.

[0052] On the other hand, if it is determined that the communication status acquisition timing has arrived (step S16: Yes), the control module 15 acquires the communication status (step S17). More specifically, the communication status acquisition unit 152 communicates with the communication control circuit 122 of the communication module 12 via the second communication port 157, which is a dedicated communication port, and acquires the communication status that can determine the attached state or detached state of the communication module 12.

[0053] Next, the control module 15 determines whether the communication module 12 is in a detached state (step S18). More specifically, the attachment control unit 153 determines whether the communication module 12 is in a detached state based on the communication status acquired by the communication status acquisition unit 152. If it is not determined that the communication module 12 is in the detached state (step S18: No), the control module 15 ends the communication process.

[0054] On the other hand, if it is determined that the communication module 12 is in a detached state (step S18: Yes), the control module 15 executes an attach process (step S19). More specifically, the attach control unit 153 controls the communication module 12 to transmit an attach request signal to the core network CN, thereby causing the detached communication module 12 to attach to the core network CN. Here, the attach control unit 153 causes the power supply module 14 to supply power energy to the RF circuit 121, thereby causing the RF circuit 121 to transition to an operable state, and then causes the RF circuit 121 to transmit the attach request signal. When the communication module 12 receives an attach response signal from the core network CN, the attach process ends, and the control module 15 ends the communication process.

[0055] The above describes the flow of communication processing executed by the control module 15 of the MTC device 10. The MTC device 10 includes a communication module 12 that communicates with the core network CN, and a control module 15 that controls the communication module 12. The control module 15 acquires a communication status that can determine whether the communication module 12 is in an attached state or a detached state, and controls the communication module 12 to attach to the core network CN when the communication module 12 is determined to be in a detached state based on the communication status. In addition, the communication method of the MTC device 10 executes the following steps: acquiring a communication status capable of determining the attached state and detached state of the communication module 12, which can transition between the attached state and the detached state, without going through the base station BS; and controlling the communication module 12, without going through the base station BS, to attach to the core network CN when the communication module 12 is determined to be in the detached state based on the communication status. This makes it possible to prevent the MTC device 10 from losing communication opportunities, and improve the stability of the communication quality of machine communication performed by the MTC device 10.

[0056] Although the MTC device 10 and the communication method for the MTC device according to one embodiment of the present invention have been described, the above-described embodiment is merely an example for facilitating understanding of the present invention and is not intended to limit the present invention. In other words, the present invention may be modified or improved without departing from the spirit thereof, and the present invention naturally includes equivalents thereof.

[0057] In the above-described embodiment, the communication status acquisition unit 152 has been described as acquiring the communication status at a predetermined timing in the sleep state (the timing indicated by time Ta in FIG. 3), but the timing of acquiring the communication status is not limited to this. The communication status acquisition unit 152 may also acquire the communication status at periodic timing in the sleep state. This makes it possible to quickly return the communication module 12 to the attached state when the communication module 12 enters the detached state. Furthermore, the communication status acquisition unit 152 may also acquire the communication status immediately after the MTC device 10 transitions to the normal operating state.

[0058] In the above-described embodiment, the attach control unit 153 is described as causing the RF circuit 121 to transition to an operable state and then transmitting an attach request signal when it is determined that the communication module 12 is in a detached state, but this is not limiting. When it is determined that the communication module 12 is in a detached state, the attach control unit 153 may wait until the MTC device 10 transitions from a sleep state to a normal operation state, and transmit an attach request signal after transitioning to the normal operation state. This makes it possible to reduce power consumption of the MTC device 10.

[0059] In the above-described embodiment, the communication module 12 has been described as transitioning between an attached state in which communication with the core network CN is possible and a detached state in which communication with the core network CN is impossible, but the communication state of the communication module 12 is not limited to this. The communication module 12 may have communication states other than the attached state and the detached state and transition between these states.

[0060] In the above-described embodiment, the communication module 12 and the control module 15 are described as being communicatively connected to each other via a dedicated port corresponding to a GPIO interface, but this is not limiting. The communication module 12 and the control module 15 only need to be connected so as to monitor the attached and detached states of the communication module 12 and be able to controllably change the communication module 12 to the attached state when it is in the detached state.

[0061] Furthermore, in the above-described embodiment, the MTC device 10 has been described as a communication device conforming to LTE-M, but is not limited thereto. The MTC device 10 may also be a communication device conforming to NB-IoT (Narrow Band-IoT) or mMTC (Massive Machine Type Communication). Even in such a case, the control module 15 can monitor the attached state and detached state of the communication module 12 and perform control so as to attach to the core network CN when in the detached state, thereby achieving the same effects as those of the above-described embodiment.

[0062] In the above-described embodiment, the MTC device 10 includes the communication module 12 and the control module 15, and the control module 15 monitors the attached and detached states of the communication module 12. However, this is not limiting. A control device separate from the MTC device 10 and capable of sending control signals to the communication module 12 may acquire the communication status of the communication module 12 without going through a base station BS (e.g., via a control cable, etc.). If the communication module 12 is determined to be in a detached state based on the communication status, the control device may control the communication module 12 to attach to the core network CN without going through a base station BS. Even in this case, the same effects as those of the above-described embodiment can be achieved. In this case, the control device controls the operation state so that the MTC device 10 transitions between a normal operation state in which the MTC device 10 operates with a first power consumption P1 and a sleep state in which the MTC device 10 operates with a second power consumption P2 that is lower than the first power consumption P1. The control device also causes the communication module 12 to communicate with the core network CN in the normal operation state and acquires the communication status in the sleep state.

[0063] In the above-described embodiment, the control module 15 is configured separately from the communication module 12, but this is not limiting. The control module 15 and the communication module 12 may be realized as a single integrated semiconductor integrated circuit, or the communication module 12 may incorporate the functional configuration of the control module 15. Even in such a case, the same effects as those of the above-described embodiment can be achieved. [Explanation of symbols]

[0064] 1 Machine Communication System 10 MTC Device 11 Sensor Module 111 Flow sensor 112 Pressure Sensor 12 Communication Module 121 RF circuit 122 communication control circuit 13 Communication Antenna 14 Power Supply Modules 15 Control Module 15a Control Processor 151 Detection data acquisition unit 152 Communication status acquisition unit 153 Attachment control section 154 State control section 155 Timing section 156 First communication port 157 Second communication port 20 MTC Server CC Cellular communication line BS base station CN Core Network CN1 Mobility Management Device CN2 Serving Gateway CN3 Packet Data Network Gateway

Claims

1. An MTC (Machine Type Communication) device that performs wireless communication with a core network via a base station, a communication module capable of transitioning between an attached state in which communication with the core network is possible and a detached state in which communication with the core network is impossible; a control processor that controls the communication module; The control processor acquiring a communication status that can determine an attached state or a detached state of the communication module; The MTC device is characterized in that, when it is determined that the communication module is in a detached state based on the communication status, the MTC device controls the communication module to attach to the core network.

2. the communication module and the control processor are communicatively connected to each other via a plurality of communication ports; The MTC device according to claim 1 , wherein the control processor acquires the communication status from the communication module via a dedicated communication port among the plurality of communication ports.

3. The MTC device according to claim 2, wherein the dedicated communication port is a communication port compatible with a GPIO (General Purpose Input / Output) interface.

4. A communication method for an MTC (Machine Type Communication) device that performs wireless communication with a core network via a base station, comprising: Acquiring a communication status capable of determining an attached state and a detached state of a communication module that can transition between an attached state in which communication with the core network is possible and a detached state in which communication with the core network is impossible, without going through the base station; and when it is determined that the communication module is in a detached state based on the communication status, controlling the communication module so as to attach to the core network without going through the base station.

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