JP2017041712A - Radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication system which can reduce the power consumption of a transmitter.SOLUTION: The radio communication system includes a receiver which receives a radio signal transmitted from a plurality of transmitters and a transmitter which transmits a radio signal. The radio signal includes: information data Da, Db, Dc transmitted in a predetermined pattern which repeats a transmission period Ton and a non-transmission period Toff; a data start signal ST transmitted by a carrier wave having a frequency F1 preset to each transmitter, with the provision of an immediately prior non-transmission period Tof1 which is set immediately before the information data Da; and a data completion signal SO transmitted with the provision of an immediately posterior non-transmission period Tof2 which is set immediately after the information data DC. The receiver, after receiving the data start signal ST of the frequency F1, receives the information data Da, Db, DC, which are received before the reception of the data completion signal SO, synchronously with a predetermined pattern preserved in advance, so as to output as reception information.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a wireless communication system that transmits wireless signals from a plurality of transmitters to a receiver.

  2. Description of the Related Art In recent years, wireless communication systems that monitor the status of various devices installed at remote locations and transmit measurement data from measurement devices to receivers as wireless signals from transmitters have become widespread. In this type of radio communication system, a single receiver is often configured to receive radio signals from a plurality of transmitters, and the received radio signal is a radio signal from which transmitter of its own system. Is transmitted and received (for example, Patent Document 1).

  FIG. 5 is a block diagram showing a configuration of the wireless communication system 100 described in Patent Document 1. As shown in FIG. FIG. 6 is a schematic diagram showing a format of a radio signal in the conventional radio communication system 100. The wireless communication system 100 includes a plurality of transmitters 120 that selectively select a plurality of wireless channels and transmit wireless signals, and a receiver 110 that receives wireless signals.

  Each transmitter 120 includes a transmission unit 121 made of, for example, a specific low-power radio station, and transmits a radio signal including information according to the type of each transmitter 120 and the type of the system to which the transmitter 120 belongs to the receiver 110. doing. The receiver 110 includes, for example, a control unit 111 including a microcomputer, a reception unit 112 including a specific low-power radio station, a storage unit 113 including a nonvolatile semiconductor memory, and an operation input unit including a liquid crystal panel and a switch. 114. The reception unit 112 operates in accordance with the control of the control unit 111. When the measured signal strength is higher than a predetermined threshold, the reception unit 112 receives a radio signal flowing through the radio channel and outputs the radio signal to the control unit 111.

  The radio signal transmitted from the transmitter 120 to the receiver 110 adopts a format as shown in FIG. 6, and includes a preamble PA, a unique word UW, data DA, and an error detection code CR. For example, the preamble PA is a bit string composed of a bit synchronization pattern that alternately repeats “0” and “1”, the first bit is set to “0”, the last bit is set to “1”, and this bit string is continuous for 64 bits or more. Only in some cases, the bit string can be regarded as a preamble PA. The unique word UW is composed of bits different from the preamble PA and is set to a length of 32 bits. The data DA is a bit string including the identification address of the transmitter 120 that has transmitted and the transmission information that the transmitter 120 transmits, and the bit length can be made variable according to the content of the transmission information that is transmitted. . The error detection code CR is a bit string composed of CRC, and is set so that an abnormality such as bit inversion can be detected in at least the bit string constituting the data DA at the time of transmission / reception. The receiver 110 scans each wireless channel in a time division manner at a predetermined scanning period, and receives subsequent data when a preamble PA including a bit synchronization pattern is detected.

JP 2011-0666530 A

  However, the conventional wireless communication system has a problem that the transmission time of the preamble or the like becomes longer than the transmission address of the transmitter identification address and the transmission information to be transmitted. For example, when a transmitter of a device installed at a remote location uses a small-capacity battery or an environmental power generation device as a power source, it is required that the power consumption be as low as possible. Since the wireless transmission power occupies most of the power consumption in the transmitter, the wireless communication system having a long transmission time has a problem that the power consumption of the transmitter increases.

  The present invention solves the above-described problems, and an object thereof is to provide a wireless communication system that can reduce power consumption of a transmitter.

  The wireless communication system of the present invention is a wireless communication system comprising a plurality of transmitters that transmit wireless signals and a receiver that receives the wireless signals transmitted from the transmitters. And data data transmitted in a predetermined pattern that repeats a non-transmission period, and a data start signal transmitted by a carrier wave having a frequency set in advance for each transmitter by providing a previous non-transmission period immediately before the information data A data end signal transmitted immediately after the information data with a non-transmission period, and the receiver synchronizes with the predetermined pattern stored in advance after receiving the data start signal of the frequency The information data received until the data end signal is received is output as reception information.

  According to this configuration, a data start signal transmitted by a carrier wave having a frequency set in advance for each transmitter is received, and the data start signal is followed by a predetermined pattern and frequency stored in advance by the transmitter and the receiver. Since the information data transmitted in a predetermined pattern is received synchronously by the receiver, the transmitter can receive the data without malfunction by simply transmitting the shortest data start signal and information data. Electric power can be reduced.

  In the wireless communication system of the present invention, the data start signal is set to a 1-bit signal having a different frequency for each transmitter.

  According to this configuration, since the frequency of the data start signal is different in each transmitter, communication preparations for receiving information data transmitted in a predetermined pattern from the transmitter can be made only by receiving the data start signal by the receiver.

  In the wireless communication system of the present invention, the information data of the wireless signal transmitted from the transmitter is transmitted for each transmission period by a carrier wave having a frequency different from the frequency of the data start signal transmitted from the transmitter. It is characterized by hopping.

  According to this configuration, since the frequency is hopped and transmitted / received, it can be made resistant to jamming radio waves.

  Further, in the wireless communication system of the present invention, the wireless signal includes the data start signal transmitted by a carrier wave of the frequency, the information data transmitted in the predetermined pattern by providing the immediately preceding non-transmission period, The data end signal is transmitted immediately after the information data with the non-transmission period immediately after the information data, and is transmitted repeatedly a plurality of times.

  According to this configuration, since the wireless signal is transmitted a plurality of times, the probability that the receiver can receive the signal can be improved. In particular, since a short wireless signal can be transmitted, the number of repetitions can be increased even when the power of the transmitter is low.

  In the radio communication system of the present invention, the radio signal is a 1-bit communication signal by turning on / off a carrier wave.

  According to this configuration, transmission can be performed with low power by using 1-bit communication in which the carrier wave is 1 during a predetermined transmission period and 0 when the carrier wave is off.

  In the radio communication system of the present invention, the power source of the transmitter is an induced electromotive force due to electromagnetic induction.

  According to this configuration, since the power of the transmitter is supplied by the induced electromotive force, it is not necessary to connect a battery or a power receiving wiring to the transmitter. For this reason, it can be made small and light and can be installed freely.

  According to the present invention, a data start signal transmitted by a carrier wave having a frequency set in advance for each transmitter is received, and the data start signal is followed by a predetermined pattern and frequency stored in advance by the transmitter and the receiver. The information data transmitted in a predetermined pattern is received synchronously by the receiver. For this reason, the transmitter can receive the signal without malfunction by simply transmitting the shortest data start signal and information data, and the power consumption of the transmitter can be reduced. Therefore, it is possible to provide a wireless communication system that can reduce the power consumption of the transmitter.

It is a block diagram which shows the radio | wireless communications system of embodiment of this invention. It is a block diagram which shows the structure of a transmitter. FIG. 3A is a time chart illustrating a radio signal transmitted from a transmitter, FIG. 3A is a time chart of transmission power, and FIG. 3B is a time chart of carrier frequency. It is a time chart explaining the received signal strength of a receiver. It is a block diagram which shows the structure of the conventional radio | wireless communications system. It is the schematic which shows the format of the radio signal of the conventional radio | wireless communications system.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. For easy understanding, the dimensions of the drawings are appropriately changed.

  FIG. 1 is a block diagram showing a wireless communication system 1 according to an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of the transmitter 20. 3 is a time chart for explaining a radio signal transmitted from the transmitter 20, FIG. 3 (a) is a time chart of transmission power, and FIG. 3 (b) is a time chart of frequency of a carrier wave. FIG. 4 is a time chart for explaining the received signal strength of the receiver.

  As illustrated in FIG. 1, the wireless communication system 1 according to the present embodiment includes a plurality of transmitters 20 that transmit wireless signals and a receiver 10 that receives wireless signals transmitted from the transmitter 20. . The receiver 10 includes a receiving unit 10a capable of receiving a radio signal transmitted from the transmitter 20, and obtains information data from the radio signal received by the receiving unit 10a and outputs the information data as reception information. The reception system 50 includes a plurality of receivers 10 and an information processing unit 40, and processes reception information according to the purpose of the wireless communication system 1.

  As shown in FIG. 2, the transmitter 20 includes a transmission unit 20a, a control unit 20b, and a power supply unit 20c. The transmission unit 20a includes an electronic circuit having a function of transmitting a radio signal and an antenna. The control unit 20b is an electronic circuit having a function of preparing a radio signal including information data, and includes an arithmetic processing unit and a storage unit (not shown). The power supply unit 20c has a function of supplying necessary power to the transmission unit 20a and the control unit 20b, and includes a power generation unit 20d and a power supply circuit unit 20e in the present embodiment. The power generation unit 20d is an environmental power generation device that generates an induced electromotive force due to electromagnetic induction. The power supply circuit unit 20e is an electronic circuit that adjusts the power generated by the power generation unit 20d to a desired state.

  The power generation unit 20d used in the wireless communication system 1 of the present embodiment is one in which the permanent magnet moves relative to the coil due to the movement of the drive shaft, and generates a current in the coil. The power generation unit 20d is not limited to an electromagnetic induction type environmental power generation device, and may be, for example, a piezoelectric type. In these cases, the generated power is not constant, and is supplied after being rectified to a desired DC voltage by the power supply circuit unit 20e. In addition, when using an energy harvesting apparatus in which the generated power is relatively constant, the power supply circuit unit 20e becomes simpler, and may be a so-called constant voltage circuit, for example. In the present embodiment, the power supply unit 20c having the power generation unit 20d is provided. However, the radio signals described below are the same even when the power supply unit including the battery is provided.

  In the radio communication system 1 of the present embodiment, the radio signal shown in FIG. 3 is transmitted from the transmission unit 20a of the transmitter 20. The radio signal includes a data start signal ST, information data Da, Db, Dc, and a data end signal SO.

  As shown in FIG. 3A, the radio signal is transmitted in a predetermined pattern Ta that repeats a transmission period Ton and a non-transmission period Toff. In the case shown in FIG. 3A, the data start signal ST is transmitted in the first transmission period Ton. After the elapse of the immediately preceding non-transmission period Tof1, the information data Da, Db, Dc are transmitted in a predetermined pattern Ta that repeats the transmission period Ton and the non-transmission period Toff, respectively. Immediately after that, in the transmission period Ton following the non-transmission period Tof2, the data end signal SO is transmitted. At this time, as shown in FIG. 3B, in the first transmission period Ton, the frequency of the carrier wave is a preset frequency F1, and in the subsequent transmission period Ton, the frequencies of F1a, F1b, F1c, and F1d are sequentially set. Let it hop. Note that in the information data Db in FIG. 3A, the transmission power is zero, and the carrier wave of the frequency F1b in FIG. 3B is a virtual one that is not transmitted.

  The radio signal is a 1-bit communication signal by turning on / off a carrier wave. That is, 1 when the carrier wave is on during the predetermined transmission period Ton and 0 when it is off. Information data Da, Db, Dc means 3-bit digital information. In the case of FIG. 3A, (101) is represented. The amount of information can be increased by repeating the predetermined pattern Ta. For example, 8-bit digital information can be transmitted. However, the conventional radio signal has a problem that the transmission time of a preamble or the like becomes long even when digital information having a relatively small amount of information of 3 bits to 8 bits is transmitted.

  In the wireless communication system 1 of the present embodiment, the data start signal ST is transmitted with the immediately preceding non-transmission period Tof1 provided immediately before the information data Da. The data start signal ST is transmitted using a carrier wave having a frequency F1. In the case of FIG. 3A, the data start signal ST is set to a 1-bit signal. However, the transmittable data start signal ST is a 1-bit signal having a digital value “1”, and is not a 1-bit signal having a digital value “0”.

  Further, immediately after the information data Dc, a data end signal SO is transmitted with a non-transmission period Tof2 immediately after. In the case of FIG. 3A, the data end signal SO is set to a 1-bit signal. However, the transmittable data end signal SO is a 1-bit signal having a digital value “1”, and is not a 1-bit signal having a digital value “0”.

  The immediately preceding non-transmission period Tof1 and the immediately following non-transmission period Tof2 are equal to the non-transmission period Toff. The above radio signal has the shortest transmission time for recognizing the start and end of data transmission, and thus the transmission time required for transmitting digital information with a small amount of information is greatly reduced.

  Furthermore, the carrier waves of the information data Da, Db, and Dc are changed from the frequency F1 of the carrier wave of the data start signal ST to the frequencies F1a, F1b, and F1c hopped as shown in FIG. Further, the data end signal SO is hopped to a frequency F1d different from the frequency F1.

  In the wireless communication system 1 according to the present embodiment, the wireless signal is transmitted in a predetermined pattern Ta that repeats the transmission period Ton and the non-transmission period Toff shown in FIG. 3A, and subsequently, spaced from the non-transmission period Toff. Then, the data is repeatedly transmitted with the repetitive pattern Tb shown in FIG. This radio signal can be repeated as long as necessary power is supplied to the transmission unit 20a by the power generated by the power generation unit 20d, but it is preferable to set the number of repetitions in advance.

  In the wireless communication system 1 of the present embodiment, the frequency F1 of the carrier wave of the data start signal ST shown in FIG. 3 is set in advance for each transmitter 20 shown in FIG. The receivers 10 corresponding to the number of transmitters 20 are prepared corresponding to the transmitters 20 having different first frequencies F1 of the carrier waves.

  Each receiver 10 is preset in a state where it can receive a different frequency F1 and waits for a data start signal ST from the corresponding transmitter 20.

  When the received signal strength (RSSI) of the frequency F1 exceeds the detection threshold, the receiver 10 is synchronized so that a radio signal can be received with a predetermined pattern Ta. FIG. 4 is a time chart showing the received signal strength (RSSI) of the receiver 10 when the radio signal shown in FIG.

  Since the radio signal from the transmitter 20 is repeated with the predetermined pattern Ta shown in FIG. 3, the received signal strength (RSSI) of the receiver 10 is also detected in the period corresponding to the transmission period Ton. Further, since the carrier frequency of the data start signal ST changes from the frequency F1 to the hopped frequencies F1a, F1b, and F1c, the received signal strength (RSSI) is detected by changing the reception frequency of the receiver 10 correspondingly. . If the received signal of frequency F1 is a jamming radio wave that is not a radio signal from the transmitter 20, then it is impossible to receive repetition and frequency hopping with a predetermined pattern Ta stored in advance. Therefore, as shown in FIG. 4, when the received signal strength (RSSI) is received in synchronization with the predetermined pattern Ta stored in advance, it is clear that the signal is a radio signal from the transmitter 20. Therefore, the information data Da, Db, Dc transmitted following the data start signal ST is output as reception information of 3-bit digital information.

  In the wireless communication system 1 of the present embodiment, the wireless signal is repeatedly transmitted with the repetition pattern Tb after an interval from the non-transmission period Toff. Since the radio signal is transmitted a plurality of times, the probability that the receiver 10 can receive the signal can be improved. In particular, since a short wireless signal can be transmitted, the number of repetitions can be increased even when the power of the transmitter 20 is low. Then, after receiving the repeat pattern Tb, the receiver 10 repeatedly outputs the repeated radio signal as reception information. In the information processing unit 40 shown in FIG. 1, repeated radio signals can be temporarily stored and compared, and correct information can be selected.

  In addition, in order to be able to select a more correct signal, in addition to the information data Da, Db, Dc to be transmitted, a parity signal may be transmitted after that.

  In addition, although the receiving system 50 includes the plurality of receivers 10 and the information processing unit 40, the plurality of receivers 10 may each include an information processing unit. In addition, the reception system 50 including a plurality of receivers 10 has been described with reference to FIG. 1. However, the present invention is not limited to this. A wireless communication system may be configured with a receiver that can obtain the above.

  In the wireless communication system 1 according to the present embodiment, as shown in FIG. 3A, the transmission power is a time within the total time of the transmission period Ton. Therefore, compared to the time of the repetitive pattern Tb including the non-transmission period Toff. The power of the transmitter 20 can be reduced. Furthermore, since the data start signal ST and the data end signal SO are set to 1-bit signals, the transmission power required for them can be minimized. Further, since the frequency F1 of the carrier wave of the data start signal ST is changed for each transmitter 20, the information data Da transmitted from the transmitter 20 with the predetermined pattern Ta only by receiving the data start signal ST. , Db, Dc can be prepared for communication.

  Hereinafter, the effect by having set it as this embodiment is demonstrated.

  The wireless communication system 1 of this embodiment includes a plurality of transmitters 20 that transmit wireless signals and a receiver 10 that receives wireless signals transmitted from the transmitter 20. The radio signal is transmitted for each transmitter 20 by providing information data Da, Db, Dc transmitted in a predetermined pattern Ta that repeats the transmission period Ton and the non-transmission period Toff, and the immediately preceding non-transmission period Tof1 immediately before the information data Da. It includes a data start signal ST transmitted by a carrier wave having a preset frequency F1, and a data end signal SO transmitted immediately after the information data Dc with a non-transmission period Tof2. The receiver 10 receives the data data Da, Db, Dc received before receiving the data end signal SO after receiving the data start signal ST of the frequency F1 in synchronization with a predetermined pattern Ta stored in advance. Output as received information.

  According to this structure, the data start signal ST transmitted by the carrier wave of the frequency F1 preset for every transmitter 20 is received. Then, the receiver 10 synchronizes the information data Da, Db, Dc transmitted in the predetermined pattern Ta following the data start signal ST at the predetermined pattern Ta and frequency stored in advance in the transmitter 20 and the receiver 10. Receive. For this reason, the transmitter 20 can receive by the receiver 10 without malfunction only by transmitting the shortest data start signal ST and the information data Da, Db, Dc, and the power consumption of the transmitter 20 can be reduced.

  Further, in the wireless communication system 1 of the present embodiment, the data start signal ST is set to a 1-bit signal having a frequency F1 that is different for each transmitter 20.

  According to this configuration, since the frequency F1 of the data start signal ST is different in each transmitter 20, the receiver 10 simply transmits the data start signal ST that is a 1-bit signal and transmits the data start signal ST with the predetermined pattern Ta. Ready to receive the received information data Da, Db, Dc.

  Further, in the wireless communication system 1 of the present embodiment, the information data Da, Db, Dc of the wireless signal transmitted from the transmitter 20 has a frequency different from the frequency F1 of the data start signal ST transmitted from the transmitter 20. Hopping is performed for each transmission period Ton by a carrier wave.

  According to this configuration, since the frequency is hopped and transmitted / received, it can be made resistant to jamming radio waves.

  Further, in the wireless communication system 1 of the present embodiment, the wireless signal is a data start signal ST transmitted by a carrier wave having a frequency F1 and information data Da and Db transmitted by a predetermined pattern Ta with a previous non-transmission period Tof1. , Dc and the data end signal SO transmitted immediately after the information data Da, Db, Dc with a non-transmission period Tof2, and transmitted repeatedly a plurality of times.

  According to this configuration, since the radio signal is repeatedly transmitted a plurality of times, the probability that the receiver 10 can receive can be improved. In particular, since a short wireless signal can be transmitted, the number of repetitions can be increased even when the power of the transmitter 20 is low.

  In the wireless communication system 1 of the present embodiment, the wireless signal is a 1-bit communication signal by turning on / off a carrier wave.

  According to this configuration, transmission can be performed with low power by performing 1-bit communication in which the carrier wave is 1 during the predetermined transmission period Ton and 0 when the carrier wave is off.

  In the wireless communication system 1 of the present embodiment, the power source of the transmitter 20 is an induced electromotive force due to electromagnetic induction.

  According to this configuration, since the power of the transmitter 20 is provided by the induced electromotive force, it is not necessary to connect a battery or a power receiving wiring to the transmitter 20. For this reason, it can be made small and light and can be installed freely.

  As described above, the wireless communication system 1 according to the embodiment of the present invention has been specifically described. However, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. It is possible. For example, the present invention can be modified as follows, and these also belong to the technical scope of the present invention.

  (1) In the present embodiment, it is assumed that the data start signal ST is set to a 1-bit signal having a different frequency F1 for each transmitter 20, but the time to be transmitted from the plurality of transmitters 20 is determined in advance. In some cases, the frequency F1 may be the same. Further, it may be configured not to be a 1-bit signal but to be a 2-bit or 3-bit signal and to perform frequency hopping by transmission of the data start signal ST so as to ensure the detection.

  (2) In the present embodiment, the information data Da, Db, and Dc are hopped for each transmission period Ton using a carrier having a frequency different from the frequency F1, but in an environment with less influence of jamming radio waves. The frequency hopping may not be performed. In this case, although it becomes difficult to detect at the timing when the jamming wave is present, the probability can be reduced by repeatedly transmitting.

  (3) In this embodiment, the radio signal is a 1-bit communication signal by turning on and off the carrier wave. However, when frequency hopping is not performed as described above, the carrier wave is continuous over the time of the repetitive pattern Tb. It may be transmitted. In this case, the data start signal ST, the information data Da, Db, Dc, and the data end signal SO are transmitted as modulation signals.

DESCRIPTION OF SYMBOLS 1 Wireless communication system 10 Receiver 10a Receiving part 20 Transmitter 20a Transmitting part 20b Control part 20c Power supply part 20d Power generation part 20e Power supply circuit part 40 Information processing part 50 Reception system Da Information data Db Information data Dc Information data F1 Frequency SO Data end Signal ST Data start signal Ta Predetermined pattern Tb Repeat pattern Toff Non-transmission period Tof1 Immediate non-transmission period Tof2 Immediate non-transmission period Ton transmission period

Claims (6)

A plurality of transmitters for transmitting radio signals;
In a wireless communication system comprising: a receiver that receives the wireless signal transmitted from the transmitter;
The radio signal includes information data transmitted in a predetermined pattern that repeats a transmission period and a non-transmission period, and a carrier wave having a frequency set in advance for each transmitter by providing a previous non-transmission period immediately before the information data. A data start signal to be transmitted, and a data end signal transmitted immediately after the information data with a non-transmission period,
The receiver receives the data start signal of the frequency in synchronization with the predetermined pattern stored in advance, and outputs the information data received until the data end signal is received as reception information. A wireless communication system.   The radio communication system according to claim 1, wherein the data start signal is set to a 1-bit signal having a different frequency for each transmitter.   The information data of the radio signal transmitted from the transmitter is hopped for each transmission period by a carrier wave having a frequency different from the frequency of the data start signal transmitted from the transmitter. The wireless communication system according to claim 1 or 2.   The wireless signal includes the data start signal transmitted by a carrier wave of the frequency, the information data transmitted in the predetermined pattern with the immediately preceding non-transmission period, and the immediately following non-transmission period immediately after the information data. 4. The wireless communication system according to claim 1, wherein the data end signal is transmitted by being provided a plurality of times, and is transmitted a plurality of times. 5.   The wireless communication system according to any one of claims 1 to 4, wherein the wireless signal is a 1-bit communication signal by turning on and off a carrier wave. The wireless communication system according to any one of claims 1 to 5, wherein a power source of the transmitter is an induced electromotive force by electromagnetic induction.