Receiver, communication system, and communication method

Abstract

The receiver (20) receives packets transmitted by wireless communication from a plurality of transmitters. The receiver (20) includes a communication unit (43) that receives radio waves transmitting partial data constituting a packet from one of the plurality of transmitters at a time interval from other radio waves transmitting other partial data constituting the packet by being consecutive to the partial data, a storage unit (45) that stores a correspondence between each transmitter and a frequency expression of the radio waves received from the transmitter, and an identification unit (44) that identifies the transmitter that transmitted the radio waves based on the correspondence from the frequency expression of the radio waves received by the communication unit (43). The receiver (20) contributes to monitoring by wireless communication.

Description

[Technical field]

[0001] The present disclosure relates to a receiver , connoisseur The present invention relates to a communication system and a communication method. [Background technology]

[0002] At FA (Factory Automation) sites, a number of sensors are installed to monitor the ongoing process, the equipment in operation, the environment, and other conditions. If the sensor transmits the sensing results by wireless communication, the sensing results can be collected without the need for wiring communication lines. In addition, such wireless communication usually requires power, so a transmitter having a sensor is often connected to a power line or driven by a battery. In contrast, if the transmitter operates using power generated by energy harvesting, which has been attracting attention in recent years, it is possible to omit the wiring of power lines and the cumbersome work of managing and replacing batteries that deteriorate over time.

[0003] When wireless communication is performed using energy harvesting, it is necessary to reduce the size of transmitted packets. If the radio waves transmitted from the transmitter are identified using a technology that identifies a slave station by its unique frequency, it becomes unnecessary to insert a sender ID (identifier) ​​into the packet, and it becomes possible to reduce the packet size (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-327000 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when wireless communication is performed by energy harvesting, it takes a certain amount of time for the power required for packet transmission to accumulate in a capacitor. For example, in Bluetooth (registered trademark), a typical standard for low-power wireless communication, the minimum packet size is 8 bits, and transmission and reception are performed in packet units. For this reason, the transmitter must accumulate the power required to transmit at least 8 bits of data before starting transmission. Furthermore, when the packet size is large, it takes a long time to transmit the packet.

[0006] If it takes a long time to start transmitting packets, the operating status of the transmitter is unknown until the receiver receives the packets, and there is a risk of delaying measures to deal with the transmitter's communication failure. In addition, although the receiver may be able to perform processing using only a portion of the information to be transmitted by the packets, such processing must wait until all information is received before it can be performed. Therefore, there is room for improving the convenience of wireless communication using energy harvesting.

[0007] The present disclosure has been made in light of the above-mentioned circumstances, and aims to improve convenience when performing wireless communication via energy harvesting. [Means for solving the problem]

[0008] In order to achieve the above object, the receiver of the present disclosure is a receiver that receives packets transmitted by wireless communication from a plurality of transmitters, and includes a receiving means that receives a partial radio wave that transmits partial data constituting a packet from one of the plurality of transmitters at a time interval from other partial radio waves that transmit other partial data that are consecutive to the partial data and thereby constitute a packet, a storage means that stores a correspondence between each transmitter and a frequency representation of the radio wave received from the transmitter, and an identifying means that identifies the transmitter that transmitted the partial radio wave based on the correspondence from the frequency representation of the partial radio wave received by the receiving means. a registering means for registering a frequency representation of the received radio waves in a storage means when each transmitter sequentially transmits radio waves; and an instruction means for instructing a first transmitter to change the frequency of the radio waves to be transmitted when the frequency representation of the radio waves received from a first transmitter among the plurality of transmitters is equal to the frequency representation of the radio waves received from a second transmitter; Equipped with The registering means registers in the storage means a frequency representation of the radio wave received from the first transmitter after the instruction means instructs the frequency change. . Effect of the Invention

[0009] According to the present disclosure, it is possible to improve the convenience of wireless communication through energy harvesting. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 shows a configuration of a communication system according to a first embodiment. [Diagram 2] FIG. 1 is a diagram for explaining transmission of radio waves according to the first embodiment; [Diagram 3] FIG. 1 is a diagram showing a functional configuration of a receiver according to a first embodiment; [Figure 4] FIG. 1 is a diagram for explaining a registration phase according to the first embodiment. [Diagram 5] FIG. 1 is a diagram for explaining an operation phase according to the first embodiment. [Figure 6] FIG. 1 is a diagram for explaining the addition of time according to the first embodiment; [Figure 7] Flowchart showing communication processing according to the first embodiment [Figure 8] Flowchart showing registration processing according to the first embodiment [Figure 9] FIG. 11 is a diagram showing a first example of the reception timing of a radio wave according to the second embodiment; [Figure 10] Flowchart showing communication processing according to the second embodiment [Figure 11] FIG. 11 is a diagram showing a second example of the timing of receiving radio waves according to the embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, a communication system according to an embodiment of the present disclosure will be described in detail with reference to the drawings.

[0012] Embodiment 1 The communication system 1000 according to the present embodiment is a system that transmits sensing results obtained by a plurality of sensors via wireless communication using power obtained by energy harvesting in a facility such as a factory or a plant, and collects the sensing results. Packets indicating the sensing results are not transmitted on a packet-by-packet basis, but are divided into partial data constituting the packet and then transmitted. In particular, each time power for transmitting partial data of 1 bit size is accumulated, the partial data is transmitted.

[0013] As shown in FIG. 1, the communication system 1000 has a plurality of transmitters 10 that transmit radio waves, a receiver 20 that receives radio waves from the plurality of transmitters 10, and a display 30 that displays information received by the receiver 20.

[0014] The transmitter 10 is, for example, a flat tag having a size of 1 cm square and a thickness of 1 mm. The transmitter 10 has a power generation unit 11 that generates power by energy harvesting and stores the generated power, a sensor 12 that measures the environmental state of the transmitter 10, a sensor data storage unit 13 that stores the results of the measurement by the sensor 12, a control unit 14 that controls the components of the transmitter 10, a memory 15 that temporarily stores data to be transmitted to the receiver 20, and a communication unit 16 that causes an antenna 17 to transmit radio waves that transmit the data.

[0015] The power generation unit 11 has a power generation element that generates power from light, heat, vibration, or electromagnetic waves in the environment of the transmitter 10, and a capacitor that accumulates the power generated by the power generation element. The power generation element may generate power from sunlight or lighting. The transmitter 10 may be attached to a heat-generating device, and the power generation element may generate power from heat generated by the device. The transmitter 10 may be attached to a vibrating machine, and the power generation element may generate power from the vibration of the machine. The power generation element may generate power from vibrations caused by sound waves propagating in the installation environment of the transmitter 10. The power generation element may generate power from electromagnetic waves propagating in the installation environment of the transmitter 10. The power generation efficiency of the power generation element is, for example, 100 microwatts, 1 milliwatt, or 10 milliwatts. The power generated by the power generation unit 11 is provided to each component of the transmitter 10. In detail, the power generated and accumulated by the power generation unit 11 is consumed to transmit partial data every time the power exceeds a predetermined threshold, as shown in the graph at the top of FIG. 2. The power generation unit 11 corresponds to an example of a power generation means that generates power from light, heat, vibration, or electromagnetic waves in the environment.

[0016] The sensor 12 measures the physical state of the environment of the transmitter 10. For example, the sensor 12 may measure pressure, flow velocity, temperature, illuminance, humidity, acceleration, current, voltage, magnetism, or the concentration of a specific component in a fluid, or may measure other conditions. The sensor 12 outputs the measurement result to the control unit 14. Note that, although FIG. 1 shows that the sensor 12 receives power from the power generation unit 11, the sensor 12 may operate without consuming power.

[0017] The sensor data storage unit 13 includes, for example, a Ferroelectric Random Access Memory (FeRAM). The sensor data storage unit 13 acquires the results of measurement by the sensor 12 from the control unit 14, stores them, and provides the stored measurement results to the control unit 14 in response to a request from the control unit 14. The sensor data storage unit 13 may accumulate a plurality of measurement results, or may store only the latest measurement result.

[0018] The control unit 14 includes a processor as a processing circuit. The control unit 14 stores the measurement results obtained from the sensor 12 in the sensor data storage unit 13. The control unit 14 also generates a packet including the measurement results to be transmitted to the receiver 20, and stores the generated packet in the memory 15. When the amount of power stored in the power generation unit 11 exceeds a threshold value required for transmitting partial data constituting a packet, the control unit 14 causes the communication unit 16 to transmit the partial data. As shown at the top of Fig. 2, a packet is a series of bit values, and partial data is 1-bit data.

[0019] The memory 15 includes, for example, FeRAM. The memory 15 may be the same storage element as the sensor data storage unit 13, or may be a different storage element. The memory 15 is a FIFO (First Input First Output) memory. The control unit 14 stores bit values ​​constituting a packet in order from the top in the memory 15, and the communication unit 16 reads out each bit.

[0020] The communication unit 16 is a processing circuit integrally formed with a flat antenna 17. The communication unit 16 reads out 1-bit partial data from the memory 15 at a timing instructed by the control unit 14, and transmits radio waves for transmitting the partial data from the antenna 17 by modulating a carrier wave with the partial data. The frequency band of the radio waves is, for example, 900 MHz or 2.4 GHz. Since the power generation efficiency of the power generation unit 11 is lower than the power consumed for continuously and steadily emitting radio waves, the communication unit 16 transmits radio waves intermittently. In detail, a time interval occurs between the transmission of radio waves by the communication unit 16 for transmitting one piece of partial data and the transmission of radio waves corresponding to the partial data before and after the transmission, as shown in FIG. 2.

[0021] The length of this time interval is determined by the power generation efficiency of power generation unit 11, the designed radio wave strength, and the calculation processing by control unit 14. However, the length of the time interval is at least longer than the transmission time of radio waves that transmit one bit of data. Therefore, when a device receiving the radio waves performs reception processing assuming that a series of bit values ​​equivalent to one packet has been transmitted by continuous radio waves, the data will be treated as having one or more bits missing.

[0022] The radio waves transmitted from the transmitter 10 are received by the receiver 20 at time intervals, as shown in Fig. 2. However, due to environmental factors including diffraction of the radio waves in the environment in which the communication system 1000 is constructed, movement of at least one of the transmitter 10 and the receiver 20, and reflection by other moving objects, the radio waves received by the receiver 20 vary from the radio waves transmitted by the transmitter 10. Based on such variations in frequency characteristics, the receiver 20 identifies the transmitter 10 that transmitted the radio waves, as will be described later.

[0023] Returning to Fig. 1, the receiver 20 may be a device dedicated to communication, an industrial PC (Personal Computer), or other devices. While the transmitter 10 operates on power obtained by energy harvesting, the receiver 20 may operate on power supplied from an external source or on battery power. The receiver 20 corresponds to an example of a receiver that receives packets transmitted by wireless communication from each of the multiple transmitters 10.

[0024] The receiver 20 has a communication unit 22 that receives radio waves from the transmitter 10 via the antenna 21, a control unit 23 that controls the components of the receiver 20, a memory unit 24 that stores information, and an I / F (Interface) unit 25 for communicating with an external display 30.

[0025] The communication unit 22 is a processing circuit that is configured integrally with the antenna 21. The communication unit 22 outputs the waveform of the radio wave received by the antenna 21 to the control unit 23.

[0026] The control unit 23 includes a processor as a processing circuit. The control unit 23 executes arithmetic processing on the waveform of the radio wave received by the communication unit 22, and stores the calculation result in the storage unit 24. The control unit 23 also executes arithmetic processing on the data stored in the storage unit 24, and outputs information indicating the calculation result to the I / F unit 25.

[0027] The storage unit 24 includes at least one of a volatile memory such as a RAM and a non-volatile memory such as an EEPROM (Electrically Erasable Programmable Read-Only Memory). The storage unit 24 stores information provided by the control unit 23, and provides the stored information to the control unit 23 in response to a request from the control unit 23.

[0028] The I / F unit 25 includes a network interface circuit for communicating via the network NW. The I / F unit 25 transmits information output from the control unit 23 to the display 30 via the network NW.

[0029] The display 30 is a user interface terminal such as an industrial PC. The display 30 receives information from the receiver 20 via the network NW and presents the received information to a user of the display 30.

[0030] Fig. 3 shows the functional configuration of the receiver 20. As shown in Fig. 3, the receiver 20 has, as its functions, a registration unit 41 that registers the frequency expression of the radio wave received when each bit value is transmitted from each transmitter 10, an instruction unit 42 that instructs the transmitter 10 to change the frequency to be used, a communication unit 43 that receives the radio wave from the transmitter 10, an identification unit 44 that identifies the transmitter 10 that transmitted the radio wave and the bit value transmitted by the radio wave, a storage unit 45 that stores various information, a restoration unit 46 that restores a packet from the identified bit value, and a time assignment unit 47.

[0031] The registration unit 41 is mainly realized by the control unit 23. The registration unit 41 registers, in the correspondence relationship table 451 of the storage unit 45, frequency representations at the time of receiving radio waves transmitted from each transmitter 10 through mutually different transmission characteristics due to the environment of the communication system 1000. In detail, as shown in FIG. 4, in the registration phase, the first transmitter and the second transmitter, which are examples of the transmitter 10, transmit radio waves transmitting a registration packet in sequence, and the communication unit 43 receives the radio waves. The registration packet includes a source ID for identifying the transmitter 10 and includes predetermined initialization data having at least one or more bit values ​​that are zero and one. This initialization data is common to the transmitter 10 and the receiver 20, and is information known to the registration unit 41. The registration unit 41 extracts waveforms corresponding to each bit value constituting the initialization data from the waveform of the received radio waves, and obtains a frequency representation for each bit by fast Fourier transform. Then, the registration unit 41 registers, for each transmitter 10, the frequency representation at the time of receiving the radio wave transmitting each bit value in the correspondence relationship table 451. The correspondence relationship table 451 is used, when a radio wave corresponding to one bit is received in the operation phase, to identify the transmitter 10 that is the transmission source of the radio wave and the bit value transmitted by the radio wave.

[0032] The frequency expressions registered in the correspondence table 451 are the frequencies and intensities of multiple frequency components that constitute radio waves. When each transmitter 10 transmits radio waves with different peak frequencies and each transmitter 10 can still be identified by the transmission characteristics up to the receiver 20, the transmitter 10 may be identified by determining the peak frequency. However, when the number of transmitters 10 increases, the work of assigning different peak frequencies to each transmitter 10 and setting the transmitters 10 to transmit radio waves of the assigned frequencies becomes complicated. For this reason, even if the frequencies of radio waves transmitted from two or more transmitters 10 are the same, it is preferable to identify the transmitter 10 by using characteristics other than the peak frequency among the information indicated by the frequency spectrum at the time of reception that has become different due to the transmission characteristics.

[0033] Note that, although the following description focuses on an example in which the frequencies and intensities of a plurality of frequency components are treated as frequency representations to be registered in the correspondence table 451, the frequency representations are not limited to this. For example, a frequency representation including a phase may be registered in the correspondence table 451, or an envelope of the distribution of intensities may be registered.

[0034] 4 may be realized by an operator operating each transmitter 10 to transmit a registration packet, or may be started by receiving a start instruction from the receiver 20 via wireless communication. When the operation of the transmitter 10 is started by a start instruction, each transmitter 10 may transmit a registration packet at a timing based on a unique serial number that the transmitter 10 itself stores in advance. The registration unit 41 corresponds to an example of a registration means that registers the frequency expression of the received radio waves in a storage means when each transmitter 10 sequentially transmits radio waves.

[0035] Returning to Fig. 3, the instruction unit 42 is mainly realized by the control unit 23. When the frequency representations to be registered in the correspondence table 451 by the registration unit 41 are equivalent for the two transmitters 10, the instruction unit 42 instructs at least one of these two transmitters 10 to change the frequency of the radio waves to be transmitted by wireless communication. Here, the fact that the frequency representations are equivalent means that it is not possible to determine which transmitter 10 is the source of transmission, or that the probability of erroneous determination is higher than a predetermined threshold, or that the similarity indicating the degree to which the frequency representations are similar is higher than a predetermined threshold.

[0036] The instruction unit 42 may simply instruct to change the frequency, or may specify the changed frequency. The changed frequency is preferably a frequency at which a new frequency representation different from the frequency representations already registered in the correspondence table 451 is expected to be received. For example, the instruction unit 42 may specify, as the changed frequency, a frequency that is not included in any of the frequency representations already registered in the correspondence table 451, or a frequency that is different from a peak in any of the frequency representations. The instruction unit 42 corresponds to an example of an instruction means for instructing the first transmitter to change the frequency of the radio waves to be transmitted when the frequency representation of the radio waves received from a first transmitter among the multiple transmitters is equal to the frequency representation of the radio waves received from the second transmitter. The registration unit 41 corresponds to an example of a registration means for registering the frequency representation of the radio waves received from the first transmitter in the storage means after the instruction means instructs to change the frequency.

[0037] The communication unit 43 is mainly realized by the antenna 21 and the communication unit 22. In the registration phase, the communication unit 43 outputs the waveform of the received radio wave to the registration unit 41, and transmits the frequency change instruction from the instruction unit 42 to each transmitter 10. In the operation phase, the communication unit 43 intermittently receives radio waves corresponding to 1-bit partial data, and outputs the waveform of the received radio wave to the identification unit 44. The communication unit 43 corresponds to an example of a receiving means that receives a partial radio wave transmitting partial data constituting a packet from any one of a plurality of transmitters, at a time interval from other partial radio waves transmitting other partial data constituting a packet together with the partial data by being continuous with the partial data.

[0038] The identification unit 44 is mainly realized by the control unit 23. As shown in Fig. 5, the identification unit 44 converts the waveform of the radio wave corresponding to one bit from each transmitter 10 into a frequency representation. The identification unit 44 also identifies the transmitter 10 that transmitted the radio wave and the bit value transmitted by the radio wave by comparing the frequency representation obtained by the conversion with the frequency representation registered in the correspondence table 451. The identification unit 44 then writes information indicating the identified transmitter 10 and bit value into the storage unit 45. The identification unit 44 corresponds to an example of an identification means that identifies the transmitter that transmitted the partial radio wave based on the correspondence from the frequency representation of the partial radio wave received by the receiving means.

[0039] The storage unit 45 is realized mainly by the storage unit 24. The storage unit 45 corresponds to an example of a storage means that stores the correspondence between each transmitter 10 and the frequency expression of the radio wave received from that transmitter.

[0040] The restoration unit 46 is mainly realized by the control unit 23. The restoration unit 46 refers to the source transmitter 10 and the bit value identified by the identification unit 44 and stored in the storage unit 45, and restores a packet, which is a series of the bit values, from the bit values ​​transmitted continuously at time intervals from the same transmitter 10, as shown in the bottom part of Fig. 5. Then, the restoration unit 46 outputs the measurement result of the sensor 12 indicated by the restored packet to the time assignment unit 47. The restoration unit 46 corresponds to an example of a restoration means that restores a packet from partial data transmitted by partial radio waves that are partial radio waves received multiple times by the receiving means and that are identified continuously by the identification means as having been transmitted from the same transmitter.

[0041] The time setting unit 47 is realized mainly by cooperation between the control unit 23 and the I / F unit 25. The time setting unit 47 sets a time corresponding to the measurement to measurement result data indicating the result of the measurement by the sensor 12, which is included in the packet restored by the restoration unit 46, as shown in Fig. 6. Then, the time setting unit 47 notifies the display unit 30 of the measurement result with the time set, thereby transmitting time series data of the measurement result to the display unit 30. The time setting unit 47 corresponds to an example of a time setting means that sets a time to information indicated by a packet restored by the restoration means and outputs the information.

[0042] The time given by the time giving unit 47 may be a value included in the packet. For example, when the transmitter 10 inserts a timestamp value indicating the timing of measurement into the packet together with the measurement result, the value may be given as the time by the time giving unit 47. The given time may also be a result of a predetermined calculation process performed on the value included in the packet. For example, when the above-mentioned timestamp indicates UNIX (registered trademark) time, the time giving unit 47 may convert the UNIX (registered trademark) time into a value indicating date and time and then give it to the measurement result. The time giving unit 47 may also give the measurement result the time when the first bit value constituting the packet is received by the communication unit 43. The reception time given to the measurement result may be the time when any of the predetermined bit values ​​constituting the packet is received.

[0043] The display device 30 displays the progress of the measurement results to the user of the display device 30 as shown in the lower part of Fig. 6. In the example of Fig. 6, the progress from the measurement result assigned with time T1 to the measurement result assigned with time T2 is displayed in a graph format.

[0044] Next, a communication process executed in the communication system 1000 will be described with reference to Figures 7 to 8. This communication process corresponds to an example of a communication method executed in the communication system 1000.

[0045] In the communication process, the receiver 20 executes a registration process (step S1). In the registration process, as shown in Fig. 8, the communication unit 43 of the receiver 20 receives radio waves from any one of the transmitters 10 (step S11). This radio wave carries a registration packet. Next, the registration unit 41 divides the radio waves received in step S11 into segments with time widths corresponding to 1-bit partial data, and converts the radio waves of each segment into a frequency representation (step S12).

[0046] The registration unit 41 judges whether or not the frequency representation obtained in step S12 is equal to any of the frequency representations already registered in the correspondence table 451 for the transmitter 10 different from the transmitter 10 that transmitted the radio wave received in step S11 (step S13). If it is judged that the frequency representations are equal (step S13; Yes), the instruction unit 42 instructs the transmitter 10 that transmitted the radio wave received in step S11 to change the frequency, and the communication unit 43 receives the radio wave with the changed frequency from the transmitter 10 again (step S14). Thereafter, the processes from step S12 onwards are repeated. As a result, a frequency representation that allows the transmitter 10 to be distinguished from other transmitters 10 as a transmission source is registered in the correspondence table 451.

[0047] If it is determined in step S13 that the frequencies are not equal (step S13; No), the registration unit 41 registers the frequency representation of the separated radio waves in the correspondence table 451 in association with the transmitter 10 that transmitted the radio waves received in step S11 and the value of the 1-bit partial data corresponding to the radio waves separated in step S12 (step S15). Specifically, the registration unit 41 registers the frequencies and intensities of the multiple frequency components of the radio waves corresponding to the bit value in association with the source ID included in the registration packet and the bit value constituting the initialization data of the registration packet in the correspondence table 451.

[0048] Next, the registration unit 41 judges whether or not the registration has been completed for all the transmitters 10 (step S16). The registration unit 41 may make a positive judgment in step S16 when the frequency expressions have been registered for the number of transmitters 10 designated in advance by the user of the receiver 20. The registration unit 41 may also make a positive judgment in step S16 when the length of time during which radio waves are not received from any of the transmitters 10 exceeds a predetermined threshold.

[0049] If it is determined that registration has not been completed for all transmitters 10 (step S16; No), the processes from step S11 onwards are repeated. As a result, the frequency representation of radio waves is registered for transmitters 10 whose frequency representation has not yet been registered. On the other hand, if it is determined that registration has been completed for all transmitters 10 (step S16; Yes), the process by the receiver 20 returns from the registration process in Fig. 8 to the communication process in Fig. 7. This ends the registration phase and starts the operation phase.

[0050] 7, the communication unit 43 of the receiver 20 receives radio waves corresponding to 1-bit partial data transmitted from any of the transmitters 10 (step S2). Next, the identification unit 44 converts the radio waves received in step S2 into a frequency representation (step S3). Then, the identification unit 44 collates the frequency representation obtained by the conversion with the frequency representations registered in the correspondence table 451 to identify the transmitter 10 that transmitted the radio waves and the partial data transmitted by the radio waves (step S4). The identified transmitter 10 and the partial data are stored in the storage unit 45 in a mutually associated manner.

[0051] Next, the restoration unit 46 judges whether or not the packet can be restored using the partial data received from the same transmitter 10 and stored (step S5). For example, if the packet is of a fixed length, it is judged whether or not partial data corresponding to the fixed-length packet has been stored by repeatedly executing step S4. Also, if the packet is of a variable length, it may be judged whether or not the packet can be restored by combining the stored partial data and attempting to restore the packet.

[0052] If it is determined that the packets cannot be restored (step S5; No), the processes from step S2 onwards are repeated, whereby the partial data intermittently transmitted from each transmitter 10 continues to be received.

[0053] If it is determined that the packet can be restored (step S5; Yes), the restoration unit 46 restores the packet (step S6), and the time stamping unit 47 stamps the measurement result indicated by the restored packet with a time and outputs it to the display 30 (step S7). The display 30 then displays a graph of the time series data of the measurement result as shown in FIG. 6 (step S8). Thereafter, the processes from step S2 onwards are repeated. This makes it easy to collect and utilize sensing results through wireless communication using energy harvesting.

[0054] As described above, the communication unit 43 receives radio waves transmitting partial data from any of the transmitters 10 at a time interval from other radio waves transmitting other partial data that are successive to the partial data to form a packet, and the identification unit 44 identifies the transmitter 10 that transmitted the radio waves based on the correspondence table 451 from the frequency expression of the radio waves. Therefore, it is possible to receive partial data transmitted from the transmitter 10 without waiting for the accumulation of power in the transmitter 10 for transmitting the entire packet at once. This makes it possible to improve the convenience of wireless communication by energy harvesting.

[0055] Furthermore, the identification unit 44 identifies the transmitter 10 that transmitted the radio wave, based on the frequency and strength of multiple frequency components contained in the radio wave that transmits the partial data, based on the correspondence relationship table 451. The frequency and strength of these frequency components vary depending on the transmission characteristics of the radio wave from the transmitter 10 to the receiver 20. Therefore, compared to identifying a transmitting device by setting a unique peak frequency for each transmitting device, the task of setting the peak frequency can be simplified. Furthermore, identification of the transmitter 10 based on multiple frequency components is expected to be more robust against disturbances than identification based on the peak frequency.

[0056] Furthermore, when the frequency representations of the radio waves received from the two transmitters 10 are the same, the instruction unit 42 instructs at least one of the transmitters 10 to change the transmission frequency. If a transmitter changes its frequency, the frequency representations of the radio waves received from these two transmitters 10 will be different. Therefore, it is possible to reliably identify the transmitter 10 that is the source of the radio waves.

[0057] Furthermore, the restoration unit 46 restores packets from partial data consecutively received from the same transmitter 10. This eliminates the need to design a dedicated process for handling partial data.

[0058] Furthermore, the time setting unit 47 sets a time to the measurement result indicated by the packet. This allows an appropriate time to be set to the measurement result transmitted by a plurality of partial data obtained in a time-distributed manner. Furthermore, it is often difficult for the transmitter 10 that operates by energy harvesting to acquire time, and even in such a case, an appropriate time can be set to the measurement result. As a result, the monitoring of the sensing result can be efficiently performed.

[0059] Embodiment 2 Next, the second embodiment will be described, focusing on the differences from the first embodiment. The same or equivalent configurations as those in the first embodiment will be denoted by the same reference numerals. In the first embodiment, it was assumed that radio waves having a frequency expression equivalent to the frequency expression registered in the correspondence table 451 in the registration phase would also be received in the operation phase. However, if the environment of the communication system 1000 changes from the registration phase, the frequency expression of the radio waves received in the operation phase may also change. This makes it difficult to identify the transmitter 10 based on the frequency expression. Below, an example will be described in which information other than the frequency expression is further used to identify the transmitter 10 that transmitted the radio waves.

[0060] 9 shows an example in which a radio wave transmitting 1-bit partial data is received six times. Here, the sender of the first, third, and fifth received radio waves is identified as the first transmitter indicated by "ID:01," and the sender of the second and fourth received radio waves is identified as the second transmitter indicated by "ID:02."

[0061] However, for the sixth received radio wave, the transmitter 10 cannot be identified from its frequency representation, and it is indicated that the source is unknown. In detail, when the frequency representation of the sixth received radio wave is not equal to any of the frequency representations registered in the correspondence table 451, and when it is equal to two or more frequency representations registered in the correspondence table 451, the source transmitter 10 is unknown.

[0062] Here, as shown in Fig. 2, the amount of power generated by energy harvesting is usually constant. Therefore, as shown in Fig. 9, the timing of transmitting radio waves from each transmitter 10 is periodic. In detail, it is shown that the transmission period of radio waves from the first transmitter is period PR1, and the transmission period of radio waves from the second transmitter is period PR2. Therefore, by comparing the length of time that has passed from the timing of receiving the sixth radio wave with the transmission period of the radio waves from each transmitter 10, it is possible to identify the source of the sixth radio wave.

[0063] 9, the sixth reception timing is a timing when a time equal to the period PR2 has elapsed since the fourth reception of the radio wave from the second transmitter, and therefore the source of the transmission is identified as the second transmitter. If it is identified as the second transmitter, the 1-bit partial data transmitted by this radio wave can be estimated from the frequency representation associated with the second transmitter in the correspondence table 451.

[0064] Fig. 10 shows the flow of communication processing according to this embodiment. As shown in Fig. 10, in this communication processing, steps S1 to S4 similar to those in the first embodiment are executed. Next, the identification unit 44 judges whether or not the transmitter 10 and the bit value have been identified in step S4 (step S21). If they have been identified (step S21; Yes), the processing from step S5 onwards is executed.

[0065] On the other hand, if the transmitter cannot be identified (step S21; No), the identification unit 44 identifies the transmitter based on the timing of receiving the radio waves, and identifies the value of the partial data by referring to the correspondence table 451 (step S22). Specifically, the identification unit 44 predicts the next reception timing for each transmitter 10 from the periodic timing of past reception of radio waves from each transmitter 10, and identifies the transmitter 10 with the reception timing predicted to be closest to the reception timing of the radio waves whose transmission source could not be identified, as the transmission source. Then, the processing from step S5 onwards is executed.

[0066] As described above, the identification unit 44 identifies the transmitter 10 that transmitted the radio waves based on the correspondence table 451 and the timing of receiving the radio waves. In detail, when the frequency expression of the received radio waves is different from any of the frequency expressions registered in the correspondence table 451, or corresponds to two or more registered frequency expressions, the identification unit 44 identifies the transmitter that transmitted the radio waves based on the period in which the radio waves were previously received from each transmitter 10. This makes it possible to identify the transmission source even when it is not possible to identify the transmission source based only on the frequency expression of the waveform of the radio waves.

[0067] Although the example of identifying the sender based on the reception timing of the radio wave has been described only when the sender cannot be identified by comparing the frequency expressions alone, the present invention is not limited to this example. The identification unit 44 may identify the sender based on both the frequency expressions and the reception timing from the beginning.

[0068] Also, although an example has been described in which the timing of transmitting radio waves by the transmitter 10 is periodic, the present invention is not limited to this. For example, as shown by the triangular marks in Fig. 11, radio waves may be transmitted at timings that are not periodic but have regularity. In the example of Fig. 11, a group including three timings appears periodically, so it is possible to predict future reception timings. In this way, if the reception timings are regular, it is possible to identify the source of transmission based on the timings.

[0069] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments.

[0070] For example, an example has been described in which measurement results by the sensor 12 are collected and displayed in a time series format. However, the information transmitted by the packets is not limited to the measurement results by the sensor 12 and may be other information. Furthermore, the processing performed on the information transmitted by the packets after the receiver 20 receives the information is not limited to graph display and may be other processing.

[0071] In addition, although an example has been described in which receiver 20 has memory unit 45, restoration unit 46, and time setting unit 47, the present invention is not limited to this. Identification unit 44 may store the results of identifying the source of the radio wave and the value of the partial data transmitted by the radio wave in an external storage device of receiver 20 instead of memory unit 45, and further the external device may perform functions equivalent to those of restoration unit 46 and time setting unit 47.

[0072] Also, although an example in which the size of partial data is 1 bit has been described, the size of partial data may be 2 bits or more. However, even when the size of partial data is 2 bits or more, the partial data does not need to include a source ID because the sender can be identified from the frequency expression of the radio waves. Similarly, a packet consisting of multiple partial data does not need to include a source ID.

[0073] Furthermore, it is not necessary for all transmitters 10 to transmit radio waves with unique frequency characteristics. Even if two or more transmitters 10 transmit radio waves with the same frequency characteristics, the frequency expressions of the radio waves when received will be different from each other due to the characteristics of the transmission path, so that each of these two or more transmitters 10 can be identified as the transmission source.

[0074] Various embodiments and modifications of the present disclosure are possible without departing from the broad spirit and scope of the present disclosure. The above-described embodiments are for explaining the present disclosure and do not limit the scope of the present disclosure. In other words, the scope of the present disclosure is indicated by the claims, not the embodiments. Various modifications made within the scope of the claims and within the scope of the disclosure equivalent thereto are considered to be within the scope of the present disclosure. [Industrial Applicability]

[0075] The present disclosure is suitable for low power consumption wireless communication. [Explanation of symbols]

[0076] 10 transmitter, 11 power generation unit, 12 sensor, 13 sensor data storage unit, 14, 23 control unit, 15 memory, 16, 22, 43 communication unit, 17, 21 antenna, 20 receiver, 24, 45 storage unit, 25 I / F unit, 30 display, 41 registration unit, 42 instruction unit, 44 identification unit, 46 restoration unit, 47 time assignment unit, 451 correspondence relationship table, 1000 communication system, PR1, PR2 period, NW network.

Claims

1. A receiver that receives packets transmitted wirelessly from multiple transmitters, A receiving means that receives a partial radio wave transmitting partial data constituting the packet from one of the plurality of transmitters, such that it is received in succession with the partial data and separated by a time interval from other partial radio waves transmitting other partial data constituting the packet; A storage means for storing the correspondence between each of the aforementioned transmitters and the frequency representation of the radio waves received from the transmitters, A means for identifying the transmitter that transmitted the partial radio wave based on the correspondence relationship, from the frequency representation of the partial radio wave received by the receiving means, When each of the aforementioned transmitters transmits radio waves sequentially, a registration means registers the frequency representation of the received radio waves in the storage means, An instruction means for instructing the first transmitter to change the frequency of the radio waves it transmits when the frequency representation of the radio waves received from the first transmitter among the plurality of transmitters is equal to the frequency representation of the radio waves received from the second transmitter, Equipped with, The registration means registers the frequency representation of the radio waves received from the first transmitter after the frequency change has been instructed by the instruction means into the storage means. Receiver.

2. The storage means stores the correspondence between each transmitter and the frequencies and intensities of multiple frequency components contained in the radio waves transmitted from the transmitter. The identifying means identifies the transmitter that transmitted the partial radio wave based on the correspondence relationship, using the frequencies and intensities of the multiple frequency components contained in the partial radio wave. The receiver according to claim 1.

3. A recovery means for recovering the packet from the partial data transmitted by the partial radio waves that have been received multiple times by the receiving means and which have been successively identified by the identifying means as having been transmitted from the same transmitter. The receiver according to claim 1, further comprising:

4. The system further comprises a time-adding means for adding a time to the information indicated by the packet restored by the restoration means and outputting it, The packet indicates the results of measurements by the sensor as the information, The time assignment means assigns to the measurement result the value indicated by the packet, the result of a predetermined calculation performed on the value, or the reception time at which any of the partial data constituting the packet was received, as the time. The receiver according to claim 3.

5. A receiver that receives packets transmitted wirelessly from each of a plurality of transmitters, A receiving means that receives a partial radio wave transmitting partial data constituting the packet from one of the plurality of transmitters, such that it is received in succession with the partial data and separated by a time interval from other partial radio waves transmitting other partial data constituting the packet; A storage means for storing the correspondence between each of the aforementioned transmitters and the frequency representation of the radio waves received from the transmitters, A means for identifying the transmitter that transmitted the partial radio wave based on the correspondence relationship, from the frequency representation of the partial radio wave received by the receiving means, Equipped with, The identifying means identifies the transmitter that transmitted the partial radio wave based on the correspondence and the timing of the reception of the partial radio wave. Receiver.

6. The identifying means, when the frequency representation of the partial radio wave received by the receiving means is different from any of the frequency representations stored in the storage means, or when it corresponds to two or more frequency representations stored in the storage means, identifies the transmitter that transmitted the partial radio wave based on the period in which the partial radio wave was previously received from each of the transmitters. The receiver according to claim 5.

7. The aforementioned time interval is longer than the time required to transmit one bit of data that constitutes the packet. The receiver according to claim 1 or 5.

8. The size of the aforementioned partial data is 1 bit. The receiver according to claim 1 or 5.

9. A communication system comprising a plurality of transmitters that transmit packets by wireless communication and a receiver that receives the packets, The aforementioned receiver is A receiving means that receives a partial radio wave transmitting partial data constituting the packet from one of the plurality of transmitters, such that it is received in succession with the partial data and separated by a time interval from other partial radio waves transmitting other partial data constituting the packet; A storage means for storing the correspondence between each of the aforementioned transmitters and the frequency representation of the radio waves received from the transmitters, The system includes a means for identifying the transmitter that transmitted the partial radio wave based on the correspondence relationship, using the frequency representation of the partial radio wave received by the receiving means. Each of the aforementioned transmitters transmits the aforementioned partial radio waves at a time interval from the aforementioned other partial radio waves. The frequency components contained in the radio waves transmitted by the aforementioned plurality of transmitters are equal to each other. Communication system.

10. A communication system comprising a plurality of transmitters that transmit packets by wireless communication and a receiver that receives the packets, The aforementioned receiver is A receiving means that receives a partial radio wave transmitting partial data constituting the packet from one of the plurality of transmitters, such that it is received in succession with the partial data and separated by a time interval from other partial radio waves transmitting other partial data constituting the packet; A storage means for storing the correspondence between each of the aforementioned transmitters and the frequency representation of the radio waves received from the transmitters, A means for identifying the transmitter that transmitted the partial radio wave based on the correspondence relationship, from the frequency representation of the partial radio wave received by the receiving means, When each of the aforementioned transmitters transmits radio waves sequentially, a registration means registers the frequency representation of the received radio waves in the storage means, An instruction means for instructing the first transmitter to change the frequency of the radio waves it transmits when the frequency representation of the radio waves received from the first transmitter among the plurality of transmitters is equal to the frequency representation of the radio waves received from the second transmitter, Equipped with, The registration means of the receiver registers the frequency representation of the radio waves received from the first transmitter after the frequency change has been instructed by the instruction means into the storage means. Each of the transmitters transmits the partial radio wave at a time interval from the other partial radio waves, and when instructed to change the transmission frequency, transmits the partial radio wave with the frequency changed in accordance with the instruction. Communication system.

11. A communication method that transmits packets via wireless communication, Each of the multiple transmitters transmits a partial radio wave that transmits a partial data that constitutes the packet, while maintaining a time interval between this partial data and other partial radio waves that transmit other partial data that constitute the packet by being continuous with the aforementioned partial data. The receiving means of the receiver receives the partial radio wave, The receiver's identification means identifies the transmitter that transmitted the partial radio wave based on the frequency representation of the partial radio wave received by the receiving means, based on a predetermined correspondence between each transmitter and the frequency representation of the radio wave received from the transmitter. The receiver's registration means registers the frequency representation of the received radio waves in the storage means that stores the correspondence relationship when each of the transmitters transmits radio waves sequentially. The instruction means of the receiver instructs the first transmitter to change the frequency of the radio waves it transmits when the frequency representation of the radio waves received from the first transmitter among the plurality of transmitters is equal to the frequency representation of the radio waves received from the second transmitter. The registration means registers the frequency representation of the radio waves received from the first transmitter after the frequency change has been instructed by the instruction means into the storage means. A communication method that includes the following.

12. A communication method for transmitting packets by wireless communication, Each of the multiple transmitters transmits a partial radio wave that transmits a partial data that constitutes the packet, while maintaining a time interval between this partial data and other partial radio waves that transmit other partial data that constitute the packet by being continuous with the aforementioned partial data. The receiver receives the partial radio wave, The receiver identifies the transmitter that transmitted the partial radio wave based on the frequency representation of the received partial radio wave, the correspondence between each predetermined transmitter and the frequency representation of the radio wave received from the transmitter, and the timing at which the partial radio wave was received. Including, Communication method.

13. A communication method for transmitting packets by wireless communication, Each of the multiple transmitters transmits a partial radio wave that transmits a partial data that constitutes the packet, while maintaining a time interval between this partial data and other partial radio waves that transmit other partial data that constitute the packet by being continuous with the aforementioned partial data. The receiver receives the partial radio wave, The receiver identifies the transmitter that transmitted the partial radio wave based on the frequency representation of the received partial radio wave, based on a predetermined correspondence between each transmitter and the frequency representation of the radio wave received from that transmitter. This includes, The frequency components contained in the radio waves transmitted by the aforementioned plurality of transmitters are equal to each other. Communication method.

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