JP2016096568A - Data transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data transmitter capable of reducing costs of introducing a system that uses an RFID technology under a radio network environment.SOLUTION: A data transmitter 3 of the present invention includes a modulation circuit 32 that modulates a first electric wave used in a radio network according to transmission data as a transmission target so as to generate a second electric wave that causes a disturbance to the first electric wave. The modulation circuit 32, which includes an amplifier 35 that amplifies a first signal corresponding to the first electric wave according to the transmission data so as to generate a second signal, outputs the second signal as a second electric wave.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a wireless communication system and a wireless communication method, and more particularly, to a wireless communication system and a wireless communication method capable of introducing a system using RFID (Radio Frequency IDentification) technology in a wireless network environment.

  In recent years, a system using RFID attracts attention and has begun to be applied to various uses. The basic configuration of a system using an RFID includes an RFID reader / writer that performs data communication with an RFID wireless tag via radio, and a computer terminal that controls the RFID reader / writer. An RFID reader / writer can read or write data stored in a wireless tag (see Non-Patent Document 1).

  The RFID wireless tag does not include a battery because it generates a power supply voltage using wireless radio waves when transmitting / receiving data to / from the RFID reader / writer. Such a wireless tag is generally called a “passive type”. Specifically, an RFID wireless tag rectifies radio waves (part of a carrier wave) supplied from an RFID reader / writer from alternating current to direct current using a full-wave rectifier. Then, after stepping up and down to a voltage suitable as a circuit power source using an internal voltage control circuit and a booster circuit, this power is supplied as a power source for internal circuits such as a current mode demodulator and logic. In this case, the conversion efficiency from alternating current to direct current in the RFID wireless tag is determined by optimizing the element size of the PMOS / NMOS rectifier diode included in the full-wave rectifier, the parasitic capacitance before being input to the rectifier diode, etc. This can be increased by suppressing loss due to mismatch and loss due to mismatch between the antenna and the rectification input section.

  Patent Document 1 discloses a technique related to a room intruder detection device. The indoor intruder detection device disclosed in Patent Literature 1 includes a transmission device, a reception device, and an alarm device. The transmitter transmits an unmodulated wave signal having a predetermined carrier frequency. The reception device receives a signal output from the transmission device, a detection unit that detects the received signal, and outputs a detection signal when the level of the signal obtained by the detection exceeds a predetermined range. A level fluctuation detector. The alarm device issues an alarm based on the detection signal output from the level fluctuation detection unit of the receiving device. The indoor intruder detection device disclosed in Patent Literature 1 detects an intruder in the room from the variation in the received electric field of the radio wave output from the transmission device and the variation in the code error rate of the demodulated signal.

Japanese Patent Laid-Open No. 7-141577

International Solid Circuit Conference 2006 Proceedings No. 17.2

  As described in the background art, a dedicated RFID reader / writer is required to read data held by an RFID wireless tag (hereinafter also referred to as a data transmitter). Therefore, for example, in order to read data held by an RFID wireless tag in a wireless network (WLAN) environment, a dedicated RFID reader / writer connected to the wireless network by wire or wireless is required. For this reason, there is a problem that it is expensive to introduce a system using RFID technology in a wireless network environment.

  The wireless communication system according to the present invention modulates the first radio wave according to the first radio device that transmits the first data using the first radio wave and the second data to be transmitted. A data transmitter for outputting the second radio wave generated in step (b), and receiving the first radio wave and the second radio wave and transmitting from the first wireless device included in the received radio wave. And a second wireless device including a separation demodulation circuit that separates and demodulates the first data and the second data transmitted from the data transmitter. The data transmitter includes an amplifier that amplifies a first signal corresponding to the first radio wave according to the second data to generate a second signal, and converts the second signal to the second signal. Output as a radio wave.

  A wireless communication method according to the present invention uses a data transmitter in a wireless network including a first wireless device that transmits first data and a second wireless device that receives the first data. A wireless communication method for transmitting data, wherein the first data is transmitted from a first wireless device using a first radio wave, and the data transmitter transmits the first data according to the second data. A second radio wave is generated by modulating a radio wave, the second radio wave is output, the first radio wave and the second radio wave are received by the second wireless device, and the received radio wave The first data transmitted from the first wireless device and the second data transmitted from the data transmitter are separated and demodulated. Then, when generating and outputting the second radio wave in the data transmitter, a first signal corresponding to the first radio wave is amplified according to the second data to generate a second signal. The second signal is output as the second radio wave.

  In the wireless communication system and the wireless communication method according to the present invention, the data transmitter modulates the first radio wave according to the second data to be transmitted and outputs it as the second radio wave. Here, the modulated second radio wave acts as a disturbance to the first radio wave. Then, in the second wireless device, the first data transmitted from the first wireless device is separated from the second data transmitted from the data transmitter using the presence or absence of disturbance to the first radio wave, and the second data The first and second data are demodulated. This eliminates the need to provide a dedicated RFID reader / writer for reading data held by the data transmitter, thereby reducing the cost of introducing a system using RFID technology in a wireless network environment. it can. In addition, since the second radio wave output from the data transmitter is a radio wave obtained by amplifying the first radio wave, data transmission is possible even when the distance between the data transmitter and the second wireless device is long. The second data can be transmitted from the device to the second wireless device.

  In addition, the data transmitter according to the present invention modulates the first radio wave used in the wireless network according to the transmission data to be transmitted, thereby generating a second radio wave that causes disturbance to the first radio wave. A modulation circuit is provided. The modulation circuit includes an amplifier that amplifies a first signal corresponding to the first radio wave according to the transmission data to generate a second signal, and uses the second signal as the second radio wave Output.

  According to the present invention, it is possible to provide a wireless communication system and a wireless communication method capable of reducing the cost when introducing a system using RFID technology in a wireless network environment.

1 is a block diagram showing a wireless communication system according to a first exemplary embodiment; 1 is a block diagram illustrating a data transmitter used in a wireless communication system according to a first embodiment. It is a figure for demonstrating operation | movement of the data transmitter shown in FIG. It is a figure for demonstrating operation | movement of the data transmitter shown in FIG. It is a circuit diagram which shows the specific example of the data transmitter shown in FIG. FIG. 6 is a block diagram showing another example of a data transmitter used in the wireless communication system according to the first exemplary embodiment. FIG. 6 is a block diagram showing another example of a data transmitter used in the wireless communication system according to the first exemplary embodiment. FIG. 6 is a diagram for explaining a bit error rate of radio waves received by the second wireless device according to the first embodiment; FIG. 3 is a block diagram showing another example of the wireless communication system according to the first exemplary embodiment. 6 is a block diagram illustrating another example of the second wireless device included in the wireless communication system according to the first embodiment; FIG. FIG. 6 is a block diagram showing a data transmitter used in a wireless communication system according to a second exemplary embodiment. It is a figure for demonstrating operation | movement of the data transmitter shown in FIG. It is a figure for demonstrating operation | movement of the data transmitter shown in FIG. FIG. 6 is a block diagram illustrating a data transmitter used in a wireless communication system according to a third embodiment. It is a circuit diagram which shows the specific example of the data transmitter shown in FIG. FIG. 6 is a circuit diagram illustrating a data transmitter used in a wireless communication system according to a fourth embodiment. It is a figure for demonstrating the effect of the invention concerning Embodiment 4. FIG. FIG. 9 is a circuit diagram illustrating a data transmitter used in a wireless communication system according to a fifth embodiment; It is a figure for demonstrating the effect of the invention concerning Embodiment 5. FIG. FIG. 10 is a block diagram illustrating a wireless communication system according to a sixth embodiment. FIG. 10 is a block diagram illustrating a data transmitter used in a wireless communication system according to a sixth embodiment. It is a figure for demonstrating operation | movement of the data transmitter shown in FIG. It is a figure for demonstrating operation | movement of the data transmitter shown in FIG. FIG. 20 is a circuit diagram showing a specific example of the data transmitter shown in FIG. 19. FIG. 20 is a diagram for describing an arrangement of reception antennas and transmission antennas of the data transmitter illustrated in FIG. 19. FIG. 10 is a block diagram showing a wireless communication system according to a seventh exemplary embodiment. FIG. 10 is a block diagram illustrating a second wireless device used in the wireless communication system according to the seventh embodiment. 10 is a flowchart for explaining an operation of the wireless communication system according to the seventh exemplary embodiment; It is a figure for demonstrating the noise removal by a finite impulse response filter. It is a figure which shows the relationship between the carrier frequency of a radio | wireless communications system, and a data rate. 10 is a flowchart for explaining an operation of the radio communication system according to the eighth exemplary embodiment. FIG. 10 is a block diagram showing a wireless communication system according to a ninth exemplary embodiment. It is a figure which shows an example of the disturbance which each of a some data transmitter gives to a 1st electromagnetic wave. It is a figure which shows the S / N ratio at the time of using an M series PN code. It is a figure for demonstrating the example which applied this invention to the network in a vehicle. It is a figure for demonstrating the case where a data transmitter is attached to the adhesion member. It is sectional drawing for demonstrating the case where a data transmitter is attached to an adhesive member.

<Embodiment 1>
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram of the wireless communication system according to the first embodiment. As shown in FIG. 1, the wireless communication system according to the present embodiment includes a first wireless device 1, a second wireless device 2, and a data transmitter (corresponding to a wireless tag for RFID) 3. Prepare. The first wireless device 1 transmits the first data using the first radio waves 12 and 13. The data transmitter 3 modulates the first radio wave 13 according to the second data to be transmitted and generates and outputs a second radio wave 14. The second wireless device 2 receives the first radio wave 12 and the second radio wave 14 and transmits the first data and data transmitted from the first radio device 1 included in the received radio wave. A separation / demodulation circuit 24 for separating and demodulating the second data transmitted from the machine 3 is provided. A feature of the wireless communication system according to the present embodiment is that disturbance from the data transmitter 3 such as RFID, which has been removed as noise in the prior art, is separated by the separation / demodulation circuit 24 of the second wireless device 2, and data It can be taken out as Hereinafter, each element which comprises the radio | wireless communications system concerning this Embodiment is demonstrated in detail.

  The first wireless device 1 includes an internal circuit (not shown) and an antenna 11 for realizing wireless communication with the second wireless device 2, and uses the first radio waves 12 and 13 for the first data. To send. Here, the first radio wave 12 is a direct wave transmitted directly to the second wireless device 2. The first radio wave 13 is a radio wave received by the data transmitter 3.

  The second wireless device 2 includes an internal circuit (not shown) and an antenna 23 for realizing wireless communication with the first wireless device 1. The separation / demodulation circuit 24 included in the second wireless device 2 includes the first data transmitted from the first wireless device 1 and the data transmitter 3 included in the received first and second radio waves. Separated from the transmitted second data. Further, the separation / demodulation circuit 24 demodulates the first data transmitted from the first wireless device 1 and the second data transmitted from the data transmitter 3, respectively.

  Here, the first wireless device 1 and the second wireless device 2 form a wireless network (WLAN). For example, the first wireless device 1 is a WLAN base station (WLAN master), and the second The wireless device 2 can be a WLAN receiver (WLAN slave). Further, for example, the first wireless device 1 and the second wireless device 2 are configured to be able to perform bidirectional communication. In the present embodiment, normal data communication between the first wireless device 1 and the second wireless device 2 uses internal circuits provided in the first wireless device 1 and the second wireless device 2, respectively. Implemented. Since normal data communication between the first wireless device 1 and the second wireless device 2 is the same as the conventional technology, detailed description thereof is omitted.

  In addition, the wireless communication system according to the present embodiment is not limited to WLAN, and can be widely applied to devices of existing wireless standards such as Bluetooth (registered trademark) and mobile phones in addition to WLAN. it can.

  The data transmitter 3 includes an antenna 31, a modulation circuit 32, and a sensor 33. The data transmitter 3 receives the first radio wave 13 output from the first wireless device 1 by the antenna 31 and uses the modulation circuit 32 to change the first radio wave 13 according to the second data to be transmitted. To generate and output a second radio wave 14. Here, the second data transmitted by the data transmitter 3 is data collected using the sensor 33, for example. The sensor 33 is, for example, a temperature sensor that measures a human body temperature, a pressure sensor that measures a human blood pressure, or the like. For example, the temperature of the measurement target can be sequentially checked by attaching a data transmitter with a built-in temperature sensor to the measurement target, wirelessly transmitting temperature information of the measurement target, and receiving the information on a wireless network.

  The sensor 33 is not limited to a temperature sensor and a pressure sensor, and any sensor can be used as long as it can acquire predetermined data.

  The modulation circuit 32 generates the second radio wave 14 by modulating the first radio wave 13 according to the second data to be transmitted. Here, the modulation circuit 32 can generate the second radio wave 14 by load-modulating the first radio wave 13 according to, for example, second data to be transmitted. That is, the modulation circuit 32 connected to the antenna 31 of the data transmitter 3 is configured by a load modulation circuit, and the matching with respect to the first radio wave 13 received by the antenna 31 is changed, so that the second wireless device 2 is changed. Can send data.

  For example, in the impedance on the output side of the antenna 31 and the input side of the modulation circuit 32, the impedance is set in the modulation circuit 32 so that the real part matches and the absolute value matches while the sign of the imaginary part is inverted. To do. Then, the power transmission efficiency from the antenna 31 to the inside of the data transmitter 3 is maximized, and the radio wave received by the antenna 31 is ideally not re-reflected. That is, the second radio wave is not output from the antenna 31.

  On the other hand, if the impedance is not set as described above in the impedances on the output side of the antenna 31 and the input side of the modulation circuit 32, the first radio wave 13 input from the antenna 31 is reflected by an impedance mismatch. . This reflected wave is radiated from the antenna 31 as the second radio wave 14.

  Since this reflected wave (second radio wave 14) acts as a disturbance to the first radio wave 12, the second wireless device 22 detects the presence or absence of this disturbance, and the second wireless device 22 detects the presence of this disturbance. Binary data can be transmitted to the device 2.

  However, the load modulation as described above is performed without the data transmitter 3 being supplied with power from the outside. Therefore, the second modulation having a strength greater than the strength of the first radio wave 13 received by the antenna 31. The radio wave 14 cannot be transmitted from the antenna 31. In other words, the reflected wave (second radio wave 14) reflected by the impedance mismatch is weaker than the intensity of the first radio wave 13 received by the antenna 31. For this reason, when a load modulation circuit is used as the modulation circuit 32, the power consumption can be kept low, but the communication distance between the data transmitter 3 and the second wireless device 2 is limited to a short one. There is a problem.

  Therefore, in the wireless communication system according to the present embodiment, the data transmitter 3 shown in FIG. 2 can be used as the data transmitter 3 in order to solve such a problem. The data transmitter 3 illustrated in FIG. 2 includes an antenna 31, a modulation circuit 32, and a sensor 33. The modulation circuit 32 includes an amplifier (variable gain amplifier) 35 and a separation element 37. The modulation circuit 32 generates the second radio wave 14 by modulating the first radio wave 13 according to the second data to be transmitted.

  At this time, the amplifier 35 included in the modulation circuit 32 generates the second signal 16 by amplifying the first signal 15 corresponding to the first radio wave 13 received by the antenna 31 according to the second data. The generated second signal 16 is radiated from the antenna 31 as the second radio wave 14. The amplifier 35 can change the amplification factor according to the gain control signal 36. Here, the value of the gain control signal 36 corresponds to the second data to be transmitted.

  In addition, the separation element 37 includes a path 17 (see FIG. 3A) for inputting the first signal 15 corresponding to the first radio wave 13 received by the antenna 31 to the amplifier 35, and the second signal amplified by the amplifier 35. 16 from the amplifier 35 to the antenna 31 (see FIG. 3A). As the separation element 37, for example, a directional coupler can be used. That is, the separation element 37 is configured to transmit power from the antenna 31 to the input of the amplifier 35 and to transmit power from the output of the amplifier 35 to the antenna 31. In other words, the separation element 37 transmits power from the output of the amplifier 35 to the input of the amplifier 35, transmits power from the input of the amplifier 35 to the output of the amplifier 35, and transmits power from the input of the amplifier 35 to the antenna 31. , And the transmission of power from the antenna 31 to the output of the amplifier 35.

  For example, as illustrated in FIG. 3A, when the second data to be transmitted is “1” (that is, when the gain control signal 36 is “1” (active state)), the amplifier 35 includes the antenna 31. The first signal 15 corresponding to the first radio wave 13 received at is amplified to generate a second signal 16 having a large amplitude. The generated second signal 16 is radiated from the antenna 31 as the second radio wave 14 and acts as a disturbance to the first radio wave 12. At this time, a stronger second radio wave 14 can be output from the antenna 31 by increasing the amplification factor in the amplifier 35. In this way, data “1” is transmitted from the data transmitter 3 to the second wireless device 2.

  On the other hand, as shown in FIG. 3B, when the second data to be transmitted is “0” (that is, when the gain control signal 36 is “0” (inactive state)), the amplifier 35 The amplitude of the first signal 15 corresponding to the first radio wave 13 received at 31 is set to a sufficiently small value. Therefore, in this case, since the amplitude of the second signal 16 output from the amplifier 35 is sufficiently small, the second radio wave 14 radiated from the antenna 31 does not act as a disturbance to the first radio wave 12. In this way, data “0” is transmitted from the data transmitter 3 to the second wireless device 2. When the gain control signal 36 is “0”, the amplifier 35 may set the amplitude of the first signal 15 corresponding to the first radio wave 13 received by the antenna 31 to zero. At this time, since the second signal 16 is not output from the amplifier 35, the second radio wave 14 is not output from the antenna 31.

  FIG. 4 is a circuit diagram showing a specific example of the data transmitter 3 shown in FIG. Note that the data transmitter 3 shown in FIG. 4 is an example, and in the present embodiment, the data transmitter is limited to the data transmitter shown in FIG. 4 as long as it can realize the operation described above. There is nothing.

  As shown in FIG. 4, the amplifier (single-ended amplifier) 35 includes N-type transistors Tr1 and Tr2, capacitors C1 and C2, and resistors R1, R2, and R3. The first signal 15 corresponding to the first radio wave 13 received by the antenna 31 is supplied to one end of the capacitor C1, and the other end is connected to one end of the resistor R1 and the gate of the N-type transistor Tr2. A bias voltage bias_1 is supplied to the other end of the resistor R1. The drain of the N-type transistor Tr2 is connected to the source of the N-type transistor Tr1, and the source is grounded.

  A gain control signal 36 is supplied to the gate of the N-type transistor Tr1, and the drain is connected to one end of the resistor R2 and one end of the capacitor C2. The other end of the resistor R2 is connected to the power supply VDD. The other end of the capacitor C2 is connected to one end of the resistor R3. A bias voltage bias_2 is supplied to the other end of the resistor R3. The second signal 16 amplified by the amplifier 35 is output from a node node_1 to which the other end of the capacitor C2 and one end of the resistor R3 are connected.

  In the amplifier 35 shown in FIG. 4, when the gain control signal 36 is “0”, the N-type transistor Tr1 is turned off, so that the amplified signal is not output from the node node_1. On the other hand, when the gain control signal 36 is “1”, the N-type transistor Tr1 is turned on. At this time, a signal obtained by increasing the first signal 15 by the bias voltage bias_1 is supplied to the gate of the N-type transistor Tr2. As a result, the N-type transistor Tr2 operates in response to the first signal 15, so that the second signal 16 obtained by amplifying the first signal 15 is output from the node node_1. The amplified signal is supplied to the antenna 31 via the separation element 37 and is radiated from the antenna 31 as the second radio wave 14.

  By using the data transmitter 3 including the amplifier 35 described above, even if the distance between the data transmitter 3 and the second wireless device 2 is long, the second wireless device is connected to the second wireless device 2 from the data transmitter 3. The second data can be transmitted to the device 2. For example, the gain of the amplifier 35 is 10 dB, the communication distance between the data transmitter 3 and the second wireless device 2 when the amplifier 35 is not used is r, and the data transmitter 3 and the second transmitter when the amplifier 35 is used. The communication distance with the wireless device 2 is r ′. Assuming that the difference in attenuation between the communication distances r and r ′ is 10 dB and that the distance attenuation follows the Friis propagation formula, the following equation can be derived.

  20 log (4πr ′ / λ) −20 log (4πr / λ) = 10 Equation 1

  Therefore, r ′ = 3.2r from Equation 1 above, and when the amplifier 35 is used in the modulation circuit 32, the communication distance between the data transmitter 3 and the second wireless device 2 is improved by a factor of 3.2. Can do.

  The second data transmitted by the data transmitter 3 may be data included in the data transmitter 3 in advance. In this case, as shown in FIG. 5, the data transmitter 3 does not need to include a sensor, and can be configured to include a data storage unit 38 that stores data. The second data transmitted by the data transmitter 3 may be data acquired by the data transmitter 3 from the outside. In this case, as shown in FIG. 6, the data transmitter 3 includes an input terminal 39, and the data transmitter 3 can acquire the external data 40 via the input terminal 39. Here, the acquired value of the external data 40 corresponds to the gain control signal 36.

  The data transmitter 3 may include a power generation circuit 34 as in another example of the wireless communication system according to the present embodiment illustrated in FIG. That is, the power generation circuit 34 included in the data transmitter 30 shown in FIG. 8 receives the first radio wave (environmental radio wave) 13 using the antenna 31 and converts the first radio wave (environmental radio wave) 13 into a full-wave rectifier. To rectify from AC to DC. Then, after the voltage is stepped up and down to a voltage suitable as a circuit power source using an internal voltage control circuit and a booster circuit, this power can be supplied to the modulation circuit 32, the sensor 33, and the like. In this case, the data transmitter 30 does not need to be equipped with a battery, and constitutes a so-called passive data transmitter. On the other hand, the data transmitter 3 may include a battery, and in this case, a so-called active data transmitter is configured. In the case of the active type, the remaining amount of the battery may be included as the second data transmitted by the data transmitter 3. Also in this case, the communication distance between the data transmitter 3 and the second radio equipment 2 can be further extended by providing the amplifier 35 in the modulation circuit 32.

Next, the operation of the wireless communication system according to the present embodiment will be described.
The first wireless device 1 and the second wireless device 2 shown in FIG. 1 constitute a wireless network (WLAN). At this time, the first wireless device 1 and the second wireless device 2 are configured to be able to communicate using the first radio wave 12 having a modulation element compliant with the standard.

  FIG. 7 is a diagram for explaining the bit error rate of radio waves (first radio wave 12 and second radio wave 14) received by the second wireless device 2. When there is no data transmission from the data transmitter 3, the first radio wave 12 is not affected by the second radio wave 14 transmitted from the data transmitter 3. That is, in this case, since the second radio wave 14 transmitted from the data transmitter 3 does not act as a disturbance to the first radio wave 12, the bit error rate does not increase as indicated by reference numeral 71 in FIG. Therefore, the first wireless device 1 and the second wireless device 2 can communicate at a low bit error rate (symbol 71) shown in FIG. Then, the second wireless device 2 receives the first radio wave 12 by the antenna 23, and the separation / demodulation circuit 24 demodulates the first data transmitted from the first wireless device 1.

  Next, the case where the data transmitter 3 transmits data will be described. In this case, first, the data transmitter 3 receives the first radio wave 13 output from the first wireless device 1. Further, the sensor 33 outputs the data acquired by the sensor 33 to the modulation circuit 32. The modulation circuit 32 modulates the received first radio wave 13 according to the data acquired by the sensor 33 (second data to be transmitted), and outputs the modulated radio wave as the second radio wave 14. .

  When the data transmitter 3 transmits data, the first radio wave 12 is affected by the second radio wave 14 transmitted from the data transmitter 3 as shown in FIG. Therefore, in this case, since the second radio wave 14 transmitted from the data transmitter 3 works as a disturbance to the first radio wave 12, the bit error rate increases as indicated by reference numeral 72 in FIG.

  That is, the second radio wave generated by being modulated in the data transmitter 3 disturbs the first radio wave 12 transmitted from the first wireless device 1 and lowers the reception SN ratio. Increase the rate. That is, if on / off keying modulation is applied in the data transmitter 3, the second data can be transmitted using the temporal variation of the bit error rate as shown in FIG. Then, the second data transmitted from the data transmitter 3 can be demodulated by detecting the time variation of the bit error rate in the second receiving device 2.

  Note that the bit error rate 72 at this time is in a range lower than the wireless standard value of the bit error rate so as not to adversely affect the communication between the first wireless device 1 and the second wireless device 2. That is, both the bit error rate 71 and the bit error rate 72 are within a range lower than the wireless standard value of the bit error rate. In general, since the communication environment constantly changes and various disturbances are mixed, a wireless standard is formulated so as to ensure the robustness of communication against such disturbances.

  The second wireless device 2 receives the first radio wave 12 and the second radio wave 14 with the antenna 23. The separation / demodulation circuit 24 separates the first data transmitted from the first wireless device 1 included in these received radio waves and the second data transmitted from the data transmitter 3, and These data are demodulated to generate demodulated data 25 from the first wireless device 1 and demodulated data 26 from the data transmitter 3.

  Here, the first data transmitted by the first wireless device 1 includes the first radio wave 12 having a modulation element conforming to the standards of the first wireless device 1 and the second wireless device 2 (that is, in accordance with the standard). Radio waves having a compliant carrier frequency). On the other hand, the second data transmitted by the data transmitter 3 uses a change in the bit error rate (that is, the level of the bit error rate) in the radio waves (first and second radio waves) received by the second wireless device 2. Is transmitted.

At this time, the period of change in the bit error rate of the radio wave received by the second wireless device 2 (that is, the modulation period of the bit error rate) is greater than the modulation period of the first radio wave 12 having a carrier frequency compliant with the standard. slow. For this reason, it is possible to separate the first data transmitted from the first wireless device 1 and the second data transmitted from the data transmitter 3 by using the separation / demodulation circuit 24.
For example, the separation / demodulation circuit 24 includes a low-pass filter (LPF), and by using the low-pass filter (LPF), it is possible to separate the second data having a low bit error rate modulation period. Further, for example, the separation / demodulation circuit 24 may include a band pass filter (BPF), and in this case as well, the second data having a low bit error rate modulation period is separated by using the band pass filter (BPF). be able to. Here, the band pass filter (BPF) can be configured by combining a low pass filter (LPF) and a high pass filter (HPF). At this time, by using a high-pass filter (HPF), the fluctuation component of the environmental radio wave whose modulation period is slower than the fluctuation period of the second data can be removed from the second data.
The separation / demodulation circuit 24 may be a filter circuit for analog signals, or may be a filter circuit for digital signals after A / D conversion.

  FIG. 8 is a block diagram showing another example of the wireless communication system according to the present embodiment. As shown in FIG. 8, the first radio wave 12 and the second radio wave 14 received by the antenna 23 of the second wireless device 2 may be amplified by an amplifier 27. As shown in FIG. 8, a baseband filter 28 may be used as the separation / demodulation circuit 24. Further, a filter may be added as appropriate in accordance with the surrounding radio wave conditions, and the filter process may be performed in a strong frequency band of the second radio wave 14. The signal amplitude can be increased by the amplifier 27 and the filter processing to such an extent that the separation / demodulation circuit 24 (baseband filter 28) in the subsequent stage can perform the separation / demodulation processing.

  Further, the separation / demodulation circuit 24 included in the second wireless device 2 shown in FIG. 1 can also be configured as follows. FIG. 9 is a diagram illustrating a configuration of the second wireless device 22 of the wireless communication system according to the present embodiment. The second wireless device 22 shown in FIG. 9 includes an antenna 23, a receiving circuit 81, and a protocol processing unit 82, and this configuration is the same as that of an existing wireless device. Then, software processing is applied to the protocol processing unit 82 so that the protocol processing unit 82 of the second wireless device 22 operates as the separation / demodulation circuit 24. In this way, by performing software processing on the protocol processing unit 82, the second wireless device 2 shown in FIG. 1 can be configured using an existing wireless device. In the present embodiment, a part of the protocol processing unit shown in FIG. 9 may be configured by hardware. In this case, the software processing is applied to the second part by performing software processing in addition to the part configured by the hardware of the protocol processing unit. Wireless device 2 can be configured.

  That is, the first data transmitted by the first wireless device 1 includes the first radio wave 12 having a modulation element compliant with the standards of the first wireless device 1 and the second wireless device 2 (that is, compliant with the standard). Transmitted using a radio wave having a carrier frequency. On the other hand, the second data transmitted by the data transmitter 3 uses a change in the bit error rate (that is, the level of the bit error rate) in the radio waves (first and second radio waves) received by the second wireless device 2. Is transmitted. Then, the first data transmitted by the first wireless device 1 (that is, data transmitted at a carrier frequency compliant with the standard) and the second data transmitted by the data transmitter 3 are transmitted to the protocol processing unit 82. (Ie, data transmitted using a bit error rate modulated at a predetermined modulation frequency) is subjected to software processing so as to be separated and demodulated, whereby demodulated data 25 and data from the first wireless device 1 are processed. Demodulated data 26 from the transmitter 3 can be obtained. Such processing in the protocol processing unit 82 is performed in the baseband domain.

  Conventionally, in order to read data held by an RFID wireless tag (data transmitter) in a wireless network environment, a dedicated RFID reader / writer connected to the wireless network in a wired or wireless manner has been required. . For this reason, there is a problem that it is expensive to introduce a system using RFID technology in a wireless network environment.

  However, in the wireless communication system according to the present embodiment, the data transmitter 3 is the second transmission target in the wireless network environment configured by the first wireless device 1 and the second wireless device 2. A second radio wave 14 is generated and output by modulating the first radio wave 13 according to the data. Here, the modulated second radio wave 14 acts as a disturbance to the first radio wave 12. Then, in the separation / demodulation circuit 24 of the second wireless device 2, the first data transmitted from the first wireless device 1 and the data transmitter 3 are transmitted using the presence / absence of disturbance to the first radio wave 12. The second data is separated and the first and second data are demodulated.

  In the wireless communication system according to the present embodiment having such a configuration, it is not necessary to provide a dedicated RFID reader / writer in order to read data held by the RFID wireless tag (data transmitter 3). Therefore, the invention according to this embodiment can provide a wireless communication system capable of reducing the cost when introducing a system using RFID technology in a wireless network environment.

  Further, in the wireless communication system according to the present embodiment, the separation / demodulation circuit 24 shown in FIG. 1 is used for the protocol processing unit 82 of the second wireless device 22 having the existing hardware configuration shown in FIG. By performing software processing so as to operate, the second wireless device can be configured. Therefore, since the second wireless device according to the present embodiment can be configured simply by introducing software into an existing hardware configuration, the cost of introducing a system using RFID technology in a wireless network environment Can be reduced.

  In the radio communication system according to the present embodiment, as shown in FIG. 2, an amplifier 35 is provided in the modulation circuit 32 of the data transmitter 3. In this manner, by providing the amplifier 35 in the modulation circuit 32, the output of the generated second radio wave 14 can be increased. Therefore, even if the distance between the data transmitter 3 and the second wireless device 2 is long, the second data can be transmitted from the data transmitter 3 to the second wireless device 2. .

  Further, in the passive type data transmitter 3 that generates a power supply voltage using a radio wave, when power is supplied to the data transmitter 3 from a dedicated RFID reader / writer, there is a radio wave that does not go to the data transmitter 3. It was. That is, when the antenna of the RFID reader / writer has no directivity, there is wasted power without going to the data transmitter 3. Further, even if the antenna of the RFID reader / writer is given directivity to improve power transmission efficiency, there is power that is wasted in space rather than transmitting power by radio waves.

  On the other hand, in the radio communication system according to the present embodiment shown in FIG. 8, a data transmitter is used by using radio waves (environmental radio waves) used for communication between the first radio equipment 1 and the second radio equipment 2. Thirty power generation circuits 34 generate power. Therefore, it is not necessary to newly introduce an RFID reader / writer and output power supply radio waves, so that power consumption of the wireless communication system can be reduced.

The technique disclosed in Patent Document 1 only detects the presence or absence of a disturbance, distinguishes a temporally varying disturbance from data, and determines an undesired disturbance generation source as a desired disturbance. I couldn't. That is, in such a wireless communication system, various disturbances are mixed due to changes in the communication environment, and the bit error rate also changes accordingly. The technique disclosed in Patent Document 1 merely detects the presence or absence of a change in disturbance based on the bit error rate, and does not extract the desired disturbance as meaningful data.
On the other hand, in the wireless communication system according to the present embodiment, the second data (data transmitted from the data transmitter) having a low bit error rate modulation period is separated using a separation / demodulation circuit. 2 data is demodulated.
Therefore, acquisition of communication data from a desired disturbance, noise removal essential for establishment of wireless data communication, and communication partner in one-to-multiple communication, which was impossible with the technique disclosed in Patent Document 1, Sorting (see Embodiment 9 for details) is possible.

  Further, the wireless communication method according to the present embodiment includes a data transmitter in a wireless network including a first wireless device 1 that transmits first data and a second wireless device 2 that receives the first data. 3 is a wireless communication method for transmitting second data using 3, and includes the following steps. (1) A step of transmitting first data from the first wireless device 1 using the first radio waves 12 and 13. (2) A step of modulating the first radio wave 13 according to the second data in the data transmitter 3 to generate the second radio wave 14 and outputting the second radio wave 14. (3) The second radio equipment 2 receives the first radio wave 12 and the second radio wave 14, and the first data transmitted from the first radio equipment 1 included in the received radio wave Separating and demodulating the second data transmitted from the data transmitter 3; When the data transmitter 3 generates and outputs the second radio wave 14, the first signal 15 corresponding to the first radio wave 13 is amplified according to the second data to generate the second signal 16. Then, the second signal 16 is radiated as the second radio wave 14. Here, when the first radio wave 13 is amplified according to the second data, for example, an amplifier 35 shown in FIG. 2 can be used.

  By the present invention according to this embodiment described above, it is possible to provide a wireless communication system and a wireless communication method capable of reducing the cost when introducing a system using RFID technology in a wireless network environment. it can. Furthermore, in the invention according to the present embodiment, since the amplifier 35 is provided in the modulation circuit 32 of the data transmitter 3, the distance between the data transmitter 3 and the second wireless device 2 is long. In addition, the second data can be transmitted from the data transmitter 3 to the second wireless device 2.

<Embodiment 2>
Next, a second embodiment of the present invention will be described. FIG. 10 is a block diagram of the data transmitter 503 included in the wireless communication system according to the second embodiment. In the radio communication system according to the present embodiment, the modulation circuit 532 of the data transmitter 503 includes two amplifiers 534 and 535 and a switch 536. The radio communication system according to the first embodiment (in particular, FIG. 2). Since other than this is the same as that of the radio | wireless communications system concerning Embodiment 1, the same code | symbol is attached | subjected to the same component and the overlapping description is abbreviate | omitted.

  A data transmitter 503 illustrated in FIG. 10 includes an antenna 31, a modulation circuit 532, and a sensor 33. The modulation circuit 532 includes two amplifiers (variable gain amplifiers) 534 and 535, a switch 536, and a separation element 538. The separation element 538 is basically the same as the separation element 37 described in the first embodiment. That is, the separation element 538 includes a path 517 (see FIG. 11A) for inputting the first signal 515 corresponding to the first radio wave 13 received by the antenna 31 to the amplifier 534, and the amplified second signal 516 as an amplifier. 535 has a function of separating the path 518 (see FIG. 11A) that is output from the antenna 535 to the antenna 31. As the separation element 538, for example, a directional coupler can be used.

  A switch 536 is provided between the amplifier 534 and the amplifier 535. The switch 536 switches the connection between the amplifier 534 and the amplifier 535 according to the control signal 537 corresponding to the second data to be transmitted.

  For example, as shown in FIG. 11A, when the second data to be transmitted is “1” (that is, when the control signal 537 is “1”), the switch 536 is in a conductive state, and the amplifier 534 and the amplifier 535 are connected. Are connected to each other via a switch 536. At this time, the amplifier 534 and the amplifier circuit 535 amplify the first signal 515 corresponding to the first radio wave 13 received by the antenna 31 to generate the second signal 516. The generated second signal 516 is radiated from the antenna 31 as the second radio wave 14, and acts as a disturbance to the first radio wave 12. At this time, it is possible to output a stronger second radio wave 14 from the antenna 31 by amplifying the amplitude of the first radio wave 13 using the amplifier 534 and the amplifier circuit 535. In this way, data “1” is transmitted from the data transmitter 503 to the second wireless device 2.

  On the other hand, as shown in FIG. 11B, when the second data to be transmitted is “0” (that is, when the control signal 537 is “0”), the switch 536 becomes non-conductive and the amplifier 534 and the amplifier 535 is not connected. Therefore, since the signal amplified by the amplifier 534 is not supplied to the amplifier 535, the second signal 516 is not output from the amplifier 535. Therefore, the second radio wave 14 is not radiated from the antenna 31. In this way, data “0” is transmitted from the data transmitter 503 to the second wireless device 2.

  At this time, the amplifier 534 immediately after the antenna 31 is configured with a low noise amplifier, and the amplifier 535 that outputs the second signal 516 to the antenna 31 is configured with a high gain amplifier matched with the antenna 31. The S / N ratio in the signal can be minimized, and the communication distance between the data transmitter 503 and the second wireless device 2 can be extended.

  As described above, in the wireless communication system according to the present embodiment, as shown in FIG. 10, the amplifiers 534 and 535 are provided in the modulation circuit 532 of the data transmitter 503. Thus, by providing the modulation circuit 532 with the amplifiers 534 and 535, the output of the generated second radio wave 14 can be increased. Therefore, even when the distance between the data transmitter 503 and the second wireless device 2 is long, the second data can be transmitted from the data transmitter 503 to the second wireless device 2. .

<Embodiment 3>
Next, a third embodiment of the present invention will be described. In the data transmitter 3 shown in FIG. 2, the separation element 37 is used to prevent the second signal 16 from being fed back to the amplifier 35. However, if the function of the separation element 37 is insufficient, a part of the second signal 16 may be fed back to the amplifier 35. In this case, depending on the setting of circuit design parameters (such as amplification factor and phase margin), oscillation may occur in the modulation circuit.

  In the wireless communication system according to the third embodiment, a data transmitter that can suppress oscillation in the modulation circuit will be described. In addition, since it is the same as that of the radio | wireless communications system concerning Embodiment 1 except this, the same code | symbol is attached | subjected to the same component and the overlapping description is abbreviate | omitted.

  FIG. 12 is a block diagram showing a data transmitter used in the wireless communication system according to the present embodiment. A data transmitter 603 illustrated in FIG. 12 includes a modulation circuit 632 and a sensor 33. The modulation circuit 632 includes a separation element 633, an amplifier 634, an attenuator 635, signal strength detectors 638 and 639, and an operational amplifier AMP11.

  The separation element 633 is basically the same as the separation element 37 described in the first embodiment. That is, the separation element 633 outputs the first signal 611 corresponding to the first radio wave 13 received by the antenna 31 to the amplifier 634 and outputs the amplified second signal 613 from the amplifier 634 to the antenna 31. It has a function of separating the path to be performed. As the separation element 633, for example, a directional coupler can be used.

  As the amplifier 634, for example, a two-input variable gain amplifier can be used. The amplifier 634 receives the first signal 611 corresponding to the first radio wave 13 received by the antenna 31 and the signal (third signal) 612 output from the attenuator 635, and responds to the gain control signal 637. The amplified second signal 613 is generated. The generated second signal 613 is supplied to the antenna 31 via the separation element 633 and radiated from the antenna 31 as the second radio wave 14.

  For example, when the gain control signal 637 is “1”, the amplifier 634 receives the first signal 611 corresponding to the first radio wave 13 received by the antenna 31 and the signal 612 output from the attenuator 635. Then, an amplified second signal 613 is generated. The generated second signal 613 is radiated from the antenna 31 as the second radio wave 14 and acts as a disturbance to the first radio wave 12. In this way, data “1” is transmitted from the data transmitter 603 to the second wireless device.

  On the other hand, when the gain control signal 637 is “0”, the amplifier 634 receives the first signal 611 corresponding to the first radio wave 13 received by the antenna 31 and the signal 612 output from the attenuator 635. Then, the second signal 613 having a small amplitude is generated. In this case, since the second signal 613 output from the amplifier 634 is a signal having a sufficiently small amplitude, it does not act as a disturbance to the first radio wave 12. In this way, data “0” is transmitted from the data transmitter 603 to the second wireless device. When the gain control signal 637 is “0”, the amplifier 3634 may set the amplitude of the first signal 611 corresponding to the first radio wave 13 received by the antenna 31 to zero. At this time, since the second signal 613 is not output from the amplifier 634, the second radio wave 14 is not radiated from the antenna 31.

  The attenuator 635 attenuates the second signal 613 output from the amplifier 634 so as to have the same strength as the first signal 611, and outputs the attenuated signal 612 to the amplifier 634. That is, the second signal 613 output from the amplifier 634 is fed back to the amplifier 634 via the attenuator 635.

  The signal strength detector 638 detects the strength of the signal 612 output from the attenuator 635, and outputs a signal corresponding to the detected signal strength to the inverting input terminal of the operational amplifier AMP11. The signal strength detector 639 detects the strength of the first signal 611 corresponding to the first radio wave 13 received by the antenna 31, and outputs a signal corresponding to the detected signal strength to the non-inverting input terminal of the operational amplifier AMP11. . The signal strength detectors 638 and 639 are circuits that can convert, for example, the amplitude levels of the signals 611 and 612 into a DC voltage.

  The operational amplifier AMP11 adjusts the attenuation amount of the attenuator 635 so that the intensity of the first signal 611 detected by the signal intensity detector 639 is equal to the intensity of the signal 612 detected by the signal intensity detector 638.

  That is, in the modulation circuit 632 illustrated in FIG. 12, the second signal 613 output from the amplifier 634 is attenuated to have the same intensity as the first signal 611, and the attenuated signal 612 is supplied to the amplifier 634. I am returning. Then, the output value of the amplifier 634 is subtracted using the signal 612. Thereby, the feedback loop in the amplifier 634 can be stabilized, and oscillation of the modulation circuit 632 can be suppressed. At this time, the signal strength detectors 638 and 639 are set so that the strength of the first signal 611 corresponding to the first radio wave 13 received by the antenna 31 is equal to the strength of the signal 612 output from the attenuator 635. The operational amplifier AMP11 and the attenuator 635 constitute a feedback loop.

  FIG. 13 is a circuit diagram showing a specific example of the data transmitter 603 shown in FIG. Note that the data transmitter 603 illustrated in FIG. 13 is an example, and the present embodiment is limited to the data transmitter illustrated in FIG. 13 as long as the data transmitter can realize the operation described above. There is nothing.

  As shown in FIG. 13, the amplifier 634 includes P-type transistors Tr11 and Tr12 and N-type transistors Tr13 to Tr15. The source of the P-type transistor Tr11 is connected to the power supply VDD, and the gate and drain are connected to the gate of the P-type transistor Tr12. The source of the P-type transistor Tr12 is connected to the power supply VDD, the gate is connected to the gate and drain of the P-type transistor Tr11, and the drain is connected to the drain of the N-type transistor Tr14.

  The drain of the N-type transistor Tr13 is connected to the gate and drain of the P-type transistor Tr11 and the gate of the P-type transistor Tr12. The first signal 611 is supplied to the gate of the N-type transistor Tr13. The drain of the N-type transistor Tr14 is connected to the drain of the P-type transistor Tr12. A signal 612 is supplied to the gate of the N-type transistor Tr14. The sources of the N-type transistor Tr13 and the N-type transistor Tr14 are connected to the drain of the N-type transistor Tr15. The source of the N-type transistor Tr15 is grounded, and the gain control signal 637 is supplied to the gate. A second signal 613 is output from a node where the drain of the P-type transistor Tr12 and the drain of the N-type transistor Tr14 are connected. That is, the amplifier 634 constitutes a differential amplifier.

  The signal intensity detector 638 includes a diode D11 that performs half-wave rectification and a capacitor C11. A signal 612 is supplied to the anode of the diode D11, and the cathode is connected to one end of the capacitor C11. The other end of the capacitor C11 is grounded.

  The signal strength detector 639 includes a diode D12 that performs half-wave rectification and a capacitor C12. The first signal 611 is supplied to the anode of the diode D12, and the cathode is connected to one end of the capacitor C12. The other end of the capacitor C12 is grounded.

  The attenuator 635 is composed of a variable resistor VR11. A second signal 613 is supplied to one end of the variable resistor VR11, and a signal 612 is output from the other end. The resistance value of the variable resistor VR11 is adjusted based on a signal output from the operational amplifier AMP11.

  In the data transmitter 603 shown in FIG. 13, when the gain control signal 637 is “0”, the N-type transistor Tr15 is turned off. In this case, the amplified second signal 613 is not output from the amplifier 634. On the other hand, when the gain control signal 637 is “1”, the N-type transistor Tr15 is turned on. In this case, the second signal 613 amplified according to the first signal 611 and the signal 612 is output from the amplifier 634. The amplified second signal 613 is supplied to the antenna 31 via the separation element 333 and radiated from the antenna 31 as the second radio wave 14.

  The signal intensity detector 638 converts the amplitude of the signal 612 into an intensity signal (DC component) and outputs the intensity signal to the inverting input terminal of the operational amplifier AMP11. The signal intensity detector 639 converts the amplitude of the first signal 611 into an intensity signal (DC component) and outputs the intensity signal to the non-inverting input terminal of the operational amplifier AMP11. The operational amplifier AMP11 adjusts the resistance value of the attenuator 635 so that the intensity of the first signal 611 detected by the signal intensity detector 639 is equal to the intensity of the signal 612 detected by the signal intensity detector 638. The signals handled by the signal intensity detectors 638 and 639, the operational amplifier AMP11, and the variable resistor VR11 are assumed to be analog values, but may be changed to circuits that handle digital values.

  As described above, in the wireless communication system according to the present embodiment, the second signal 613 output from the amplifier 634 is attenuated so as to have the same strength as the first signal 611, and then attenuated. The signal 612 is fed back to the amplifier 634. Then, the output value of the amplifier 634 is subtracted using the signal 612. Thereby, the feedback loop in the amplifier 634 can be stabilized, and oscillation of the modulation circuit 632 can be suppressed.

  Further, in the wireless communication system according to the present embodiment, as shown in FIG. 12, an amplifier 634 is provided in the modulation circuit 632 of the data transmitter 603. Thus, by providing the modulation circuit 632 with the amplifier 634, the output of the generated second radio wave 14 can be increased. Therefore, even when the distance between the data transmitter 603 and the second wireless device 2 is long, the second data can be transmitted from the data transmitter 603 to the second wireless device 2. .

<Embodiment 4>
Next, a fourth embodiment of the present invention will be described. In the data transmitter 3 shown in FIG. 2, it is possible to transmit the second radio wave 14 having high intensity by using the amplifier 35 provided in the data transmitter 3. However, depending on the setting of the amplifier 35, the intensity of the second radio wave 14 output from the data transmitter 3 may become too high, affecting other electronic devices.

  In the radio communication system according to the present embodiment, a data transmitter that can suppress the intensity of the second radio wave output from the data transmitter to a predetermined intensity will be described. In addition, since it is the same as that of the radio | wireless communications system concerning Embodiment 1 except this, the same code | symbol is attached | subjected to the same component and the overlapping description is abbreviate | omitted.

  FIG. 14 is a circuit diagram showing a data transmitter 703 used in the wireless communication system according to the present embodiment. A data transmitter 703 shown in FIG. 14 includes a modulation circuit 732 and a sensor 33. The modulation circuit 732 includes amplifiers (single-ended amplifiers) 733 and 734, a step-down circuit 735, and a separation element 737. Here, the amplifiers (single-ended amplifiers) 733 and 734 and the step-down circuit 735 constitute a variable gain amplifier with an amplitude limiting function.

  The separation element 737 is basically the same as the separation element 37 described in the first embodiment. That is, the separation element 737 outputs the first signal 711 corresponding to the first radio wave 13 received by the antenna 31 to the amplifier 733 and outputs the amplified second signal 713 from the amplifier 734 to the antenna 31. It has a function of separating the path to be performed. As the separation element 737, for example, a directional coupler can be used.

  As shown in FIG. 14, the amplifier 733 includes N-type transistors Tr21 and Tr22, capacitors C21 and C22, and resistors R21, R22, and R23. A first signal 711 corresponding to the first radio wave 13 received by the antenna 31 is supplied to one end of the capacitor C21, and the other end is connected to one end of the resistor R21 and the gate of the N-type transistor Tr22. A bias voltage bias_21 is supplied to the other end of the resistor R21. The drain of the N-type transistor Tr22 is connected to the source of the N-type transistor Tr21, and the source is grounded.

  A gain control signal 736 is supplied to the gate of the N-type transistor Tr21, and the drain is connected to one end of the resistor R22 and one end of the capacitor C22. The other end of the resistor R22 is connected to the power supply VDD_1. The other end of the capacitor C22 is connected to one end of the resistor R23. A bias voltage bias_22 is supplied to the other end of the resistor R23. The signal 712 amplified by the amplifier 733 is output to the amplifier 734 from a node node_21 to which the other end of the capacitor C22 and one end of the resistor R23 are connected.

  The amplifier 734 includes N-type transistors Tr23 and Tr24, a capacitor C23, and resistors R24 and R25. The drain of the N-type transistor Tr24 is connected to the source of the N-type transistor Tr23, the signal 712 output from the amplifier 733 is supplied to the gate, and the source is grounded. A gain control signal 736 is supplied to the gate of the N-type transistor Tr23, and the drain is connected to one end of the resistor R24 and one end of the capacitor C23. The other end of the resistor R24 is connected to the power supply VDD_2. The other end of the capacitor C23 is connected to one end of the resistor R25. A bias voltage bias_23 is supplied to the other end of the resistor R25. The second signal 713 amplified by the amplifier 734 is output from the node node_22 to which the other end of the capacitor C23 and one end of the resistor R25 are connected.

  The step-down circuit 735 converts the power supply voltage VDD_1 into a power supply voltage VDD_2 that is lower than the power supply voltage VDD_1.

  In the amplifiers 733 and 734 shown in FIG. 14, when the gain control signal 736 is “0”, the N-type transistor Tr21 of the amplifier 733 and the N-type transistor Tr23 of the amplifier 734 are turned off. Signal 713 is not output from amplifier 734.

  On the other hand, when the gain control signal 736 is “1”, the N-type transistor Tr21 of the amplifier 733 is turned on. At this time, a signal obtained by increasing the first signal 711 by the bias voltage bias_21 is supplied to the gate of the N-type transistor Tr22. As a result, the N-type transistor Tr22 operates in response to the first signal 711, so that a signal 712 obtained by amplifying the first signal 711 is output from the node node_21.

  When the gain control signal 736 is “1”, the N-type transistor Tr23 of the amplifier 734 is turned on. At this time, since the signal 712 output from the amplifier 733 is supplied to the gate of the N-type transistor Tr24, the N-type transistor Tr24 operates according to the signal 712, and the second signal 713 obtained by amplifying the signal 712 is output. Output from the node node_22. At this time, since the power supply voltage VDD_2 is lower than the power supply voltage VDD_1, the amplitude value of the second signal 713 output from the node node_22 is smaller than the amplitude value of the signal 712 output from the amplifier 733. The amplified second signal 713 is supplied to the antenna 31 via the separation element 737 and is radiated from the antenna 31 as the second radio wave 14.

  That is, in the data transmitter 703 according to the present embodiment, the power supply voltage VDD_2 of the amplifier 734 is set to a voltage lower than the power supply voltage VDD_1 using the step-down circuit 735. Accordingly, the amplitude value of the second signal 713 amplified by the amplifier 734 can be set to a value lower than the power supply voltage VDD_2, so that the intensity of the second radio wave output from the data transmitter is set to a predetermined intensity. Can be suppressed.

  FIG. 15 is a diagram for explaining the effect of the invention according to the present embodiment. In the data transmitter 3 according to the first embodiment, depending on the setting of the amplifier 35, the intensity of the second radio wave 14 output from the data transmitter 3 may be larger than the standard value (see reference numeral 715). ). On the other hand, since the data transmitter 3 according to the present embodiment uses a variable gain amplifier with an amplitude limiting function, the intensity of the second radio wave 14 can be reduced to a standard value or less (see reference numeral 716). ). At this time, the intensity of the second radio wave output from the data transmitter can be adjusted by changing the value of the power supply voltage VDD_2 set by the step-down circuit 735.

  Note that the variable gain amplifier with an amplitude limiting function configured by the amplifiers 733 and 734 and the step-down circuit 735 described above is an example, and an amplifier that can suppress the intensity of the second radio wave to a predetermined intensity. Any amplifier can be used.

<Embodiment 5>
Next, a fifth embodiment of the present invention will be described. In the data transmitter 3 shown in FIG. 2, harmonic distortion may occur when the amplifier 35 provided in the data transmitter 3 is operated in a non-linear region. If the power intensity of the harmonic distortion is too large, other electronic devices may be affected.

  In the radio communication system according to the present embodiment, a data transmitter that can suppress the power intensity of the harmonic distortion below a standard value will be described. In addition, since it is the same as that of the radio | wireless communications system concerning Embodiment 1 except this, the same code | symbol is attached | subjected to the same component and the overlapping description is abbreviate | omitted.

  FIG. 16 is a circuit diagram showing a data transmitter 803 used in the wireless communication system according to the present embodiment. A data transmitter 803 shown in FIG. 16 includes a modulation circuit 832 and a sensor 33. The modulation circuit 832 includes an amplifier (single-ended amplifier) 833, a harmonic removal circuit (low-pass filter) 834, and a separation element 837. Here, the amplifier 833 and the harmonic elimination circuit 834 constitute a variable gain amplifier with a harmonic elimination function.

  The separation element 837 is basically the same as the separation element 37 described in the first embodiment. In other words, the separation element 837 has a path for inputting the first signal 811 corresponding to the first radio wave 13 received by the antenna 31 to the amplifier 833 and the amplified second signal 813 from the harmonic removal circuit 834 to the antenna. 31 has a function of separating the path output to 31. As the separation element 837, for example, a directional coupler can be used.

  As shown in FIG. 16, the amplifier 833 includes N-type transistors Tr31 and Tr32, capacitors C31 and C32, and resistors R31, R32, and R33. A first signal 811 corresponding to the first radio wave 13 received by the antenna 31 is supplied to one end of the capacitor C31, and the other end is connected to one end of the resistor R31 and the gate of the N-type transistor Tr32. A bias voltage bias_31 is supplied to the other end of the resistor R31. The drain of the N-type transistor Tr32 is connected to the source of the N-type transistor Tr31, and the source is grounded.

  A gain control signal 836 is supplied to the gate of the N-type transistor Tr31, and the drain is connected to one end of the resistor R32 and one end of the capacitor C32. The other end of the resistor R32 is connected to the power supply VDD. The other end of the capacitor C32 is connected to one end of the resistor R33. A bias voltage bias_32 is supplied to the other end of the resistor R33. The signal 812 amplified by the amplifier 833 is output to the harmonic removal circuit 834 from the node node_31 to which the other end of the capacitor C32 and one end of the resistor R33 are connected.

  The harmonic removal circuit 834 includes P-type transistors Tr33 and Tr34, N-type transistors Tr35 to Tr37, a capacitor C33, and a resistor R34. The source of the P-type transistor Tr33 is connected to the power supply VDD, and the gate and drain are connected to the gate of the P-type transistor Tr34. The source of the P-type transistor Tr34 is connected to the power supply VDD, the gate is connected to the gate and drain of the P-type transistor Tr33, and the drain is connected to the drain of the N-type transistor Tr36.

  The drain of the N-type transistor Tr35 is connected to the gate and drain of the P-type transistor Tr33 and the gate of the P-type transistor Tr34, and the gate is grounded. The drain of the N-type transistor Tr36 is connected to the drain of the P-type transistor Tr34. A signal 812 is supplied to the gate of the N-type transistor Tr36 via the resistor R34. The sources of the N-type transistor Tr35 and the N-type transistor Tr36 are connected to the drain of the N-type transistor Tr37. The source of the N-type transistor Tr37 is grounded, and the gate is connected to the power supply VDD. The capacitor C33 is connected between the gate and drain of the N-type transistor Tr36. A harmonic elimination circuit (low-pass filter) 834 shown in FIG. 16 is configured to have a frequency characteristic indicated by reference numeral 815 in FIG.

  In the amplifier 833 shown in FIG. 16, when the gain control signal 836 is “0”, the N-type transistor Tr31 is turned off, so that the amplified second signal 813 is not output.

  On the other hand, when the gain control signal 836 is “1”, the N-type transistor Tr31 of the amplifier 833 is turned on. At this time, a signal obtained by increasing the first signal 811 by the bias voltage bias_31 is supplied to the gate of the N-type transistor Tr32. As a result, the N-type transistor Tr32 operates in response to the first signal 811. Therefore, a signal 812 obtained by amplifying the first signal 811 is output from the node node_31.

  The harmonic component of the signal 812 output from the amplifier 833 is removed by a harmonic removal circuit 834 having a frequency characteristic indicated by reference numeral 815 in FIG. Then, the second signal 813 amplified by the amplifier 833 and from which the harmonic component is removed by the harmonic removal circuit 834 is output from the node node_32. The second signal 813 is supplied to the antenna 31 via the separation element 837 and is radiated from the antenna 31 as the second radio wave 14.

  FIG. 17 is a diagram for explaining the effect of the invention according to the present embodiment. In the data transmitter 3 according to the first embodiment, harmonic distortion (indicated by reference numeral 816) may occur when the amplifier 35 provided in the data transmitter 3 is operated in a non-linear region. If the power intensity of the harmonic distortion is too large, other electronic devices may be affected. On the other hand, since the data transmitter 3 according to the present embodiment uses a variable gain amplifier with a harmonic removal function, the power intensity of harmonic distortion can be suppressed to a standard value or less. That is, as shown in FIG. 17, the power intensity of the second harmonic can be made lower than the standard value (see reference numeral 817), and the electric field intensity of the third harmonic can be made zero.

  Note that the variable gain amplifier with an amplitude limiting function configured by the amplifier 833 and the harmonic elimination circuit 834 described above is an example, and is an amplifier that can suppress the power intensity of harmonic distortion below a standard value. Any amplifier may be used as long as it is present.

<Embodiment 6>
Next, a sixth embodiment of the present invention will be described. FIG. 18 is a block diagram of a wireless communication system according to the sixth embodiment. FIG. 19 is a block diagram of a data transmitter 903 used in the wireless communication system according to the sixth embodiment. In the wireless communication system according to the present embodiment, the first radio wave 13 is received by the reception antenna 931_1 of the data transmitter 903, and the second radio wave 14 is transmitted from the transmission antenna 931_2. Different from the wireless communication system according to the first embodiment. Since other than this is the same as that of the radio | wireless communications system concerning Embodiment 1, the same code | symbol is attached | subjected to the same component and the overlapping description is abbreviate | omitted.

  A data transmitter 903 illustrated in FIG. 19 includes a reception antenna 931_1, a transmission antenna 931_2, a modulation circuit 932, and a sensor 33. The modulation circuit 932 includes an amplifier (variable gain amplifier) 935. The modulation circuit 932 generates the second radio wave 14 by modulating the first radio wave 13 according to the second data to be transmitted.

  At this time, the amplifier 935 included in the modulation circuit 932 generates the second signal 916 by amplifying the first signal 915 corresponding to the first radio wave 13 received by the receiving antenna 931_1 according to the second data. To do. The generated second signal 916 is radiated as the second radio wave 14 from the transmitting antenna 931_2. The amplifier 935 can change the amplification factor according to the gain control signal 936. Here, the value of the gain control signal 936 corresponds to the second data to be transmitted.

  For example, as illustrated in FIG. 20A, when the second data to be transmitted is “1” (that is, when the gain control signal 936 is “1”), the amplifier 935 receives the signal via the reception antenna 931_1. The first signal 915 corresponding to the first radio wave 13 is amplified to generate a second signal 916 having a large amplitude. The generated second signal 916 is radiated as the second radio wave 14 from the transmitting antenna 931_2, and acts as a disturbance to the first radio wave 12. At this time, by increasing the amplification factor in the amplifier 935, a stronger second radio wave 14 can be output from the transmitting antenna 931_2. In this way, data “1” is transmitted from the data transmitter 903 to the second wireless device 2.

  On the other hand, as shown in FIG. 20B, when the second data to be transmitted is “0” (that is, when the gain control signal 936 is “0”), the amplifier 935 receives the signal via the reception antenna 931_1. The amplitude of the first signal 915 corresponding to the first radio wave 13 is set to a sufficiently small value. Therefore, in this case, since the amplitude of the second signal 916 output from the amplifier 935 is sufficiently small, the second radio wave 14 output from the transmitting antenna 931_2 does not work as a disturbance to the first radio wave 12. . In this way, data “0” is transmitted from the data transmitter 903 to the second wireless device 2. When the gain control signal 936 is “0”, the amplifier 935 may set the amplitude of the first signal 915 corresponding to the first radio wave 13 received by the receiving antenna 931_1 to zero. At this time, since the second signal 916 is not output from the amplifier 935, the second radio wave 14 is not output from the transmitting antenna 931_2.

  FIG. 21 is a circuit diagram showing a specific example of the data transmitter 903 shown in FIG. Note that the data transmitter 903 illustrated in FIG. 21 is an example, and in the present embodiment, any data transmitter capable of realizing the operation described above is limited to the data transmitter illustrated in FIG. There is nothing.

  As shown in FIG. 21, the amplifier (single-ended amplifier) 935 includes N-type transistors Tr41 and Tr42, capacitors C41 and C42, and resistors R41, R42, and R43. The first signal 915 corresponding to the first radio wave 13 received by the receiving antenna 931_1 is supplied to one end of the capacitor C41, and the other end is connected to one end of the resistor R41 and the gate of the N-type transistor Tr42. A bias voltage bias_41 is supplied to the other end of the resistor R41. The drain of the N-type transistor Tr42 is connected to the source of the N-type transistor Tr41, and the source is grounded.

  A gain control signal 936 is supplied to the gate of the N-type transistor Tr41, and the drain is connected to one end of the resistor R42 and one end of the capacitor C42. The other end of the resistor R42 is connected to the power supply VDD. The other end of the capacitor C42 is connected to one end of the resistor R43. A bias voltage bias_42 is supplied to the other end of the resistor R43. The second signal 916 amplified by the amplifier 935 is output from the node node_41 to which the other end of the capacitor C42 and one end of the resistor R43 are connected to the transmitting antenna 931_2.

  In the amplifier 935 shown in FIG. 21, when the gain control signal 936 is “0”, the N-type transistor Tr41 is turned off, so that the amplified signal is not output from the node node_41. On the other hand, when the gain control signal 936 is “1”, the N-type transistor Tr41 is turned on. At this time, a signal obtained by increasing the first signal 915 by the bias voltage bias_41 is supplied to the gate of the N-type transistor Tr42. As a result, the N-type transistor Tr42 operates in response to the first signal 915, so that the second signal 916 obtained by amplifying the first signal 915 is output from the node node_41. The amplified signal is supplied to the transmitting antenna 931_2 and is radiated as the second radio wave 14 from the transmitting antenna 931_2.

  By using the data transmitter 903 including the amplifier 935 described above, even if the distance between the data transmitter 903 and the second wireless device 2 is long, the second wireless device is connected from the data transmitter 903. The second data can be transmitted to the device 2. Further, in the data transmitter 903 according to the present embodiment, since the receiving antenna 931_1 and the transmitting antenna 931_2 are provided, the separation element 37 used in the modulation circuit 32 of the first embodiment can be omitted. it can. In addition, oscillation in the amplifier 935 can be prevented.

  In this embodiment, the data transmitter 903 includes the reception antenna 931_1 and the transmission antenna 931_2, and therefore the second radio wave 14 radiated from the transmission antenna 931_2 is received again by the reception antenna 931_1. It is necessary not to be done. That is, when the second radio wave 14 radiated from the transmitting antenna 931_2 is received again by the receiving antenna 931_1, a loop is formed via the receiving antenna 931_1, the amplifier 935, and the transmitting antenna 931_2, and the modulation circuit 932 may oscillate.

  Therefore, in this embodiment, it is preferable to configure the reception antenna 931_1 and the transmission antenna 931_2 of the data transmitter 903 as illustrated in FIG. That is, the reception antenna 931_1 and the transmission antenna 931_2 are configured as loop antennas, and the reception antenna 931_1 and the transmission antenna 931_2 are respectively rotated by 90 degrees in the same plane. By arranging the receiving antenna 931_1 and the transmitting antenna 931_2 in this way, it is possible to avoid the second radio wave radiated from the transmitting antenna 931_2 from being received again by the receiving antenna 931_1. Note that reference numerals 951 and 952 shown in FIG. 22 indicate spatial radiation characteristics of the receiving antenna 931_1, and reference numerals 953 and 954 indicate spatial radiation characteristics of the transmitting antenna 931_2.

  The invention according to the present embodiment may be appropriately combined with the inventions according to the second to fifth embodiments described above.

<Embodiment 7>
Next, a seventh embodiment of the present invention will be described. FIG. 23 is a block diagram of a wireless communication system according to the seventh embodiment. In the wireless communication system according to the present embodiment, the second wireless device 21 includes the demodulation circuit 41 and the error rate evaluation circuit 42 as the separation demodulation circuit 24. The wireless communication according to the first embodiment described with reference to FIG. Different from the communication system. Since other than this is the same as in the case of the first embodiment, the same components are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 23, the second wireless device 21 of the wireless communication system according to the present embodiment includes an amplifier 27, a demodulation circuit 41, and an error rate evaluation circuit 42. The amplifier 27 can be omitted as long as the signal levels of the first radio wave 12 and the second radio wave 14 are high, that is, if the signal level can be processed by the separation / demodulation circuit 24 in the subsequent stage. .

  The demodulation circuit 41 demodulates the first data transmitted from the first wireless device 1 included in the received radio wave, and outputs the demodulated data as demodulated data 25 from the first wireless device 1. . The error rate evaluation circuit 42 demodulates the first data transmitted from the first wireless device 1 and then evaluates the bit error rate. Based on the time variation of the bit error rate, the data from the data transmitter 3 is evaluated. Is demodulated, and demodulated data 26 from the data transmitter 3 is generated. In the wireless communication system according to the present embodiment, the demodulation circuit is only the demodulation circuit 41 that demodulates the first data transmitted from the first wireless device 1, and the data transmitted from the data transmitter 3. Are demodulated in the subsequent baseband processing.

  For example, when a third-party interference wave further enters the wireless communication system having such a configuration, the first radio wave from the first radio device 1 is compared with the second radio wave 14 from the data transmitter 3. When the radio wave (direct wave) 12 is in a dominant positional relationship, the reception SN ratio of the second data from the data transmitter 3 decreases. In such a case, the reception S / N ratio of the second data from the data transmitter 3 can be increased by performing the majority process and the code spreading process, and the data transmitter 3 in the second wireless device 21 can be increased. The second data from can be received.

  For example, the distance between the first wireless device 1 and the second wireless device 21 and the distance between the first wireless device 1 and the data transmitter 3 are equal, and the distance between the second wireless device 21 and the data transmitter 3 is equal. They are arranged as isosceles triangles that are half of them, and the data transmitter 3 has an attenuation coefficient of about 0.5 when the radio wave from the first wireless device 1 is modulated and radiated as the second radio wave. (Here, in order to illustrate the case where the SN ratio of the signal transmitted from the data transmitter 3 decreases, the attenuation factor of the second radio wave is set low). In this case, compared to the distance directly entering the second wireless device 21 from the first wireless device 1, the distance indirectly entering the second wireless device 21 via the data transmitter is 1.5 times, Assuming that the reached power is proportional to the reciprocal of the square of distance, the indirect wave has a distance attenuation of 10 * log (1 / (1.5 * 1.5)) = − 4 dB compared to the direct wave. Furthermore, since the attenuation coefficient is 0.5, attenuation of 10 * log (0.5) = − 3 dB is added. As a result, the ratio between the power N at which radio waves from the first wireless device 1 directly enter the second wireless device 21 as noise and the power S that enters the second wireless device 21 as data via the data transmitter 3. Is a signal component attenuation amount = distance attenuation + modulation attenuation, and noise power is not increased or decreased, and S / N = −3 dB−4 dB = −7 dB, and is buried in noise.

However, for example, when the same data is transmitted 12 times from the data transmitter 3 and the majority process is performed in the second wireless device 2 to suppress random noise,
H (z ^-1 ) = 1 + z ^-1 + z ^-2 +… + z ^-11
As shown in FIG. 26, the 12-tap finite impulse response filter S / N defined by (1) is improved by 7.6 dB, so that data of S / N = −7 dB can be received.

  Here, as shown in FIG. 27, in the WLAN carrier frequency 2.4 GHz band, the data rate is at least 1 Mbps or more. Therefore, since the environmental radio waves do not have periodicity at a low frequency where the data rate is lower than 1 Mbps, it is considered that the white light is sufficiently diffused in the communication band of the data transmitter 3. Therefore, the S / N ratio can be improved by executing the majority process. Since the majority process and code spreading process require redundancy, the effective data communication speed decreases. In this case, the scale of data that can be handled is smaller than that of a conventional RFID system.

  Next, the second wireless device 21 used in the wireless communication system according to the present embodiment will be specifically described with reference to FIG. 24 includes a demodulator 51, a demapping processor 52, a soft decision deinterleave Viterbi demodulator 53, and a frame processor 54.

  The demapping output from the demapping processing unit 52 is output to the soft decision deinterleave Viterbi demodulation processing unit 53 and the error rate evaluation circuit 42. The soft decision / Viterbi output from the soft decision deinterleave Viterbi demodulation processing unit 53 is output to the frame processing unit 54 and the error rate evaluation circuit 42. The frame processing output from the frame processing unit 54 is output as demodulated data 25 from the first wireless device 1. The frame processing output from the frame processing unit 54 is also output to the error rate evaluation circuit 42.

  The error rate evaluation circuit 42 includes a storage unit 61. The error rate evaluation circuit 42 demodulates the second data from the data transmitter 3 based on at least one of the demapping output, the soft decision / Viterbi output, and the frame processing output. Demodulated data 26 is output.

FIG. 25 is a flowchart for explaining the operation of the second wireless device 21 shown in FIG.
First, the first data transmitted from the first wireless device 1 is demodulated by the demodulator 51. The demodulated data demodulated by the demodulator 51 is branched from each layer of the protocol processing and output from the demodulating circuit 41 such as a bit string after demapping processing, a bit string after soft decision / Viterbi processing, and a bit string after frame processing. The As protocol processing proceeds in the demapping processing unit 52, soft decision deinterleave Viterbi demodulation processing unit 53, and frame processing unit 54, the influence of disturbances such as interference waves is alleviated. For this reason, the influence of disturbance is greater in the bit string after the demapping process than in the bit string after the frame process.

  Next, the bit error rate at the frame processing output is sampled (step S1). At this time, the bit error rate is sampled at a speed equal to or higher than the symbol rate of the data transmitted from the data transmitter 3. Then, the obtained sampling results are held in the storage unit in an array (step S2).

Next, the code despreading process is performed on the arrays acquired in steps S1 and S2 to improve the SN ratio (step S3). At this time, a correlation between the spreading code held in advance in the second wireless device 21 and the held sampling result is taken and despreading processing is performed, and the bit string of the obtained result is further stored in the storage unit Hold on.
Further, since the same data is repeatedly transmitted from the data transmitter 3, a majority decision process is performed between them, and the result is stored in the storage unit (step S4).

  Next, it is determined whether or not there is a clear error such as a parity bit being inverted in the result obtained after the majority process (step S5). If it is determined in step S5 that there is no clear error, the obtained result is output as data (second data) transmitted from the data transmitter 3 (step S6). On the other hand, if it is determined in step S5 that there is a clear error, it can be said that the data from the data transmitter 3 is in a transmission environment that is easily buried in noise.

  In such a case, the bit error rate at the soft decision / Viterbi output having a greater influence of disturbance is sampled (step S7). Then, the same processing as the processing from step S2 to step S4 is performed on the sampling result of the bit error rate at the soft decision / Viterbi output (step S8). Further, it is determined whether or not there is a clear error in the result after the majority processing, such as the parity bit being inverted (step S9). If it is determined in step S9 that there is no clear error, the obtained result is output as data (second data) transmitted from the data transmitter 3 (step S6).

  On the other hand, if it is determined in step S9 that there is a clear error, the bit error rate at the demapping output that is more affected by disturbance is sampled (step S10). Then, the same processing as the processing from step S2 to step S4 is performed on the sampling result of the bit error rate at the demapping output (step S11). Then, the obtained result is output as data (second data) transmitted from the data transmitter 3 (step S6).

The sampling becomes more sensitive to noise as the bit error rate at the frame processing output, the bit error rate at the soft decision / Viterbi output, and the bit error rate at the demapping output. In this case, the influence of noise can be reduced by increasing the length of the above spreading code or increasing the number of samplings in the majority process.
In addition, when it is limited to use in an environment with little noise, for example, an environment where the distance between the data transmitter 3 and the second wireless device 2 is short, there is no need to adopt the complicated configuration as described above, and frame processing By tracing only the subsequent error rate, the second data transmitted from the data transmitter 3 can be demodulated.

  Also in the wireless communication system according to the present embodiment, it is possible to provide a wireless communication system capable of reducing the cost when introducing a system using RFID technology in a wireless network environment.

  Note that the second wireless device 21 in the wireless communication system according to the present embodiment can also be configured by performing software processing on an existing wireless device. That is, since the process after the demapping process in the second wireless device 21 shown in FIG. 24 is a protocol process, for example, by executing the software process in the protocol processing unit shown in FIG. 9, the second process shown in FIG. Wireless device 21 can be configured. In the present embodiment, a part of the protocol processing unit shown in FIG. 9 may be configured by hardware. In this case, the software processing is applied to the second part by performing software processing in addition to the part configured by the hardware of the protocol processing unit. Wireless device 21 can be configured.

<Eighth embodiment>
Next, an eighth embodiment of the present invention will be described. In the wireless communication system according to the present embodiment, the process in second wireless device 21 shown in FIG. 24 is different from the process in the seventh embodiment. Since other than this is the same as in the case of the seventh embodiment, the same components are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 28 is a flowchart for explaining processing of the second wireless device 21 according to the present embodiment. The difference between the flow shown in FIG. 25 described in Embodiment 7 and the flow shown in FIG. 28 is that the determination using the parity bits described in FIG. 25 (steps S5 and S9) is not required in the flow shown in FIG. It is a point.

  That is, in the flow shown in FIG. 28, first, the bit error rate at the frame processing output is sampled (step S21). Then, the obtained sampling results are held in the storage unit in an array (step S22).

  Next, the code despreading process is performed on the arrays acquired in steps S21 and S22 to improve the SN ratio (step S23). At this time, a correlation between the spreading code held in advance in the second wireless device 21 and the held sampling result is taken and despreading processing is performed, and the bit string of the obtained result is further stored in the storage unit Hold on. Then, majority processing is performed using the data transmitted repeatedly from the data transmitter 3, and the result (result 1) is held in the storage unit (step S24).

Further, the following processing is performed in parallel with the processing of steps S21 to S24.
First, the bit error rate at the demapping output is sampled (step S25). Then, the obtained sampling results are held in the storage unit in an array (step S26).

  Next, the code despreading process is performed on the arrays acquired in steps S25 and S26 to improve the SN ratio (step S27). At this time, a correlation between the spreading code held in advance in the second wireless device 21 and the held sampling result is taken and despreading processing is performed, and the bit string of the obtained result is further stored in the storage unit Hold on. Then, majority processing is performed using the data transmitted repeatedly from the data transmitter 3, and the result (result 2) is held in the storage unit (step S28).

  Finally, the difference between the majority processing result 1 and the majority processing result 2 is output as data (second data) transmitted from the data transmitter (step S29).

  In this way, by taking the difference between the frame processing output that is less affected by the disturbance than the demapping output and the demapping output, the data transmitted as disturbance from the data transmitter 3 can be extracted. Further, in the wireless communication system according to the present embodiment, the processing of the second wireless device 21 can be simplified as compared with the processing according to the seventh embodiment.

<Embodiment 9>
Next, a ninth embodiment of the present invention will be described. The wireless communication system according to the present embodiment is different from the wireless communication system described in Embodiments 1 to 8 in that a plurality of data transmitters 3_1 to 3_N are provided. Except this, since it is the same as in Embodiments 1 to 8, the same components are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 29A is a block diagram showing a radio communication system according to the present embodiment. As shown in FIG. 29A, in the wireless communication system according to the present embodiment, a plurality of data transmitters 3_1 to 3_N are included within a range in which the first radio wave output from the first wireless device 1 can be received. Have. The data transmitter 3_1 receives the first radio wave 13_1 output from the first wireless device 1, modulates the first radio wave 13_1 according to the second data to be transmitted, and the second radio wave 14_1. Is output. Similarly, the data transmitter 3_2 receives the first radio wave 13_2 output from the first wireless device 1, modulates the first radio wave 13_2 in accordance with the second data to be transmitted, The radio wave 14_2 is output. Similarly, the data transmitter 3_N receives the first radio wave 13_N output from the first wireless device 1, modulates the first radio wave 13_N according to the second data to be transmitted, The radio wave 14_N is output.

  FIG. 29B is a diagram illustrating an example of disturbance that each of the plurality of data transmitters 3_1 to 3_N gives to the first radio waves 13_1 to 13_N. As shown in FIG. 29B, each of the plurality of data transmitters 3_1 to 3_N adds identification information such as a spread code to the data to be transmitted as a header.

  The second wireless device 2 receives the first radio wave 12 and the second radio waves 14_1 to 14_N, and the first data transmitted from the first radio device 1 included in the received radio wave Each data transmitted from each of the data transmitters 3_1 to 3_N is separated and demodulated using the separation / demodulation circuit 24. Here, the separation / demodulation circuit 24 can distinguish each data transmitted from each data transmitter 3_1 to 3_N based on the identification information added as a header to the data to be transmitted. The data separated and demodulated by the separation / demodulation circuit 24 is output as demodulated data 25 from the first wireless device 1 and demodulated data 26_1 to 26_N from the data transmitters 3_1 to 3_N.

  In the above example, a spread code is used as the identification information. However, the identification information may be any information as long as it is information that can distinguish each data. For example, an M sequence can be used as the spreading code. However, the pseudo-random number having high autocorrelation is not particularly limited to the M sequence, and for example, a GOLD code can be used. In the seventh and eighth embodiments, the example in which the despreading process is performed has been described. In this case, the diffusion process for data identification is required prior to the despreading process.

For example, in the case of using a pseudo random number pattern that is a code sequence having a small autocorrelation as a spreading code, if it is PN4, there is one set of pseudo random number systems depending on the initial values allowed for the M sequence. On the other hand, if PN5 and PN7 are used, the number increases to 3 sets and 9 sets, respectively. As shown in FIG. 30, when the autocorrelation of PN4 and PN5 is taken, the difference between the peak value and the bottom value of the correlation strength is 16 and 32, respectively, which are 24 dB and 30 dB, respectively. As a result, it is possible to distinguish data having another spreading code with higher accuracy than the S / N ratio required for demodulation of on / off keying with a bit error rate> 10 ⁻² .

  If the desired data transmitter and the second wireless device 2 are synchronized by adopting PN5 as the header and applying a matched filter at the beginning of data reception, three sets in the second wireless device 2 Even if there is a wireless chip, only data from one desired data transmitter can be selectively received. When there are four or more sets of data transmitters, data from each data transmitter can be selectively received by using a spreading code of PN7 or higher.

  With such a wireless communication system, even when there are a plurality of data transmitters 3_1 to 3_N, it is possible to avoid reception of interference and distinguish and receive each data transmitted from each data transmitter.

<Embodiment 10>
Next, an embodiment 10 of the invention will be described. In the tenth embodiment, a case where the wireless communication system described in the first to ninth embodiments is applied to an in-vehicle network of an automobile will be described.

  In the present embodiment, as shown in FIG. 31, the in-vehicle network of the automobile 90 is constructed using the first wireless device 1 and the second wireless device 2 described in the first to ninth embodiments. The first wireless device 1 transmits the first data to the second wireless device 2 using the first radio wave 12. Here, the first radio wave 12 is a direct wave transmitted directly from the first wireless device 1 to the second wireless device 2.

  For example, the first wireless device 1 is connected to an engine control ECU, a transmission control ECU, an air conditioner control ECU, and the like, and these control information is transferred to the second wireless device 2 using the first wireless device 1. You may comprise so that it may transmit. Further, for example, the second wireless device 2 may be connected to the car navigation system, and the control information transmitted from the first wireless device 1 may be displayed on the screen of the car navigation system.

  The above example is merely an example, and any in-vehicle network may be constructed using the first wireless device 1 and the second wireless device 2 in the present embodiment.

  In the present embodiment, the data transmitter 3 can be installed at any location of the automobile. For example, the data transmitter A (3_1) may be installed on the tire 91 in order to monitor the air pressure of the tire 91 of the automobile. At this time, the data transmitter A (3_1) may be provided with a pressure sensor, and the air pressure information of the tire 91 acquired by the pressure sensor may be transmitted to the second wireless device 2.

  When transmitting air pressure information from the data transmitter A (3_1) to the second wireless device 2, the method described in the first to ninth embodiments can be used. That is, the data transmitter A (3_1) modulates the first radio wave 13_1 transmitted from the first wireless device 1 according to the information on the air pressure to be transmitted, and outputs it as the second radio wave 14_1. Here, the modulated second radio wave 14_1 acts as a disturbance to the first radio wave (direct wave) 12 transmitted from the first wireless device 1 to the second wireless device 2. Then, the second wireless device 2 determines whether or not there is a disturbance to the first radio wave 12, and the data transmitted from the first wireless device 1 and the air pressure information transmitted from the data transmitter A (3_1). And the data are demodulated.

  Further, for example, the data transmitter B (3_2) may be installed in the window 92 in order to monitor the open / closed state of the window 92 of the automobile. At this time, the data transmitter B (3_2) may be provided with a position sensor that detects the open / closed state of the window 92, and transmits information related to the open / closed state of the window 92 acquired by the position sensor to the second wireless device 2. You may make it do.

  When transmitting information on the open / closed state of the window 92 from the data transmitter B (3_2) to the second wireless device 2, the method described in the first to ninth embodiments can be used. That is, the data transmitter B (3_2) modulates the first radio wave 13_2 transmitted from the first wireless device 1 according to the information related to the open / closed state of the window 92 that is the transmission target, and the second radio wave 14_2. Output as. Here, the modulated second radio wave 14_2 acts as a disturbance to the first radio wave (direct wave) 12 transmitted from the first wireless device 1 to the second wireless device 2. Then, in the second wireless device 2, the presence or absence of disturbance to the first radio wave 12 is determined, and the data transmitted from the first wireless device 1 and the window 92 transmitted from the data transmitter B (3_2) are displayed. The information about the open / closed state is separated and these data are demodulated.

  Further, for example, the data transmitter C (3_3) may be installed at any location in the vehicle in order to monitor the temperature in the vehicle. At this time, the data transmitter C (3_3) may include a temperature sensor, and information related to the temperature inside the vehicle acquired by the temperature sensor may be transmitted to the second wireless device 2.

  When transmitting information related to the temperature inside the vehicle from the data transmitter C (3_3) to the second wireless device 2, the method described in the first to ninth embodiments can be used. That is, the data transmitter C (3_3) modulates the first radio wave 13_3 transmitted from the first wireless device 1 according to the information about the temperature inside the vehicle that is the transmission target, and outputs it as the second radio wave 14_3. To do. Here, the modulated second radio wave 14_3 acts as a disturbance to the first radio wave (direct wave) 12 transmitted from the first wireless device 1 to the second wireless device 2. Then, in the second wireless device 2, the presence or absence of disturbance to the first radio wave 12 is determined, and the data transmitted from the first wireless device 1 and the temperature inside the vehicle transmitted from the data transmitter C (3_3). And the data are demodulated.

  For example, when information indicating abnormality is transmitted from the data transmitters 3_1 to 3_3, the second wireless device 2 displays a warning on the car navigation system connected to the second wireless device 2, thereby driving the vehicle. The person can be notified of the abnormality.

  In addition, the place where the data transmitter 3 described above is installed is an example, and the data transmitter 3 can be installed at any other location. When a plurality of data transmitters 3 are installed, it is necessary to distinguish the data transmitted from the data transmitters 3_1 to 3_3. In this case, for example, as described in the ninth embodiment, transmission of data transmitted from a plurality of data transmitters 3_1 to 3_3 is performed by adding identification information such as a spread code to the data to be transmitted as a header. The origin can be distinguished.

  In the present embodiment, the data transmitter 3 can operate without receiving power supply from the outside. Therefore, the present invention is particularly effective when measuring the state of a place where wiring of a power source is difficult with a sensor, such as measurement of tire air pressure.

<Other embodiments>
Hereinafter, other embodiments will be described.
The data transmitter described in the above embodiment may be manufactured on a semiconductor chip. That is, each circuit (modulation circuit, sensor, etc.) constituting the data transmitter may be manufactured on a semiconductor chip. In this case, the antenna may be formed on the same chip as the semiconductor chip on which each circuit included in the data transmitter is formed. Further, an antenna may be formed separately from the semiconductor chip on which each circuit included in the data transmitter is formed.

  As shown in FIG. 32A, a data transmitter 591 manufactured using a semiconductor chip can be attached to an object to be measured using an adhesive member 594. As the adhesive member 594, for example, a bandage can be used. Here, the data transmitter 591 includes circuits 592 and an antenna 593 that constitute the data transmitter. For example, when the data transmitter 591 includes a temperature sensor, the temperature of the measurement target can be easily measured by attaching the chip-shaped data transmitter 591 to the adhesive member 594 and attaching the adhesive member 594 to the measurement target. can do.

  The adhesive member cannot be used after a predetermined time has passed since its adhesive strength decreases with time. In contrast, the product life of the data transmitter 591 is long. Therefore, the data transmitter 591 can be reused by configuring the adhesive member 594 so that the data transmitter 591 can be removed. For example, the data transmitter 591 can be removed by forming a pocket in the adhesive member 594.

  FIG. 32B is a cross-sectional view of the adhesive member. As shown in FIG. 32B, when the data transmitter 591 includes a temperature sensor, a material having a high thermal conductivity as the member 595 located between the data transmitter 591 attached to the adhesive member 594 and the measurement target. Is preferably used. Thus, the temperature of the object to be measured can be accurately measured by using a material having high thermal conductivity. Here, as a material having high thermal conductivity, a metal material such as copper, a resin material having high thermal conductivity, or the like can be used.

  The data transmitter may be provided in the thermometer. In this case, you may use the temperature sensor with which a thermometer is provided as a sensor of a data transmitter. By providing the data transmitter in the thermometer, the history of the temperature of the measurement target can be transmitted to the second wireless device 2.

  The present invention has been described with reference to the above embodiment, but is not limited to the configuration of the above embodiment, and can be made by those skilled in the art within the scope of the invention of the claims of the present application. It goes without saying that various modifications, corrections, and combinations are included.

1 First wireless device 2, 20, 21, 22 Second wireless device 3, 503, 603, 703, 803, 903 Data transmitter 11, 23, 31 Antenna 12 First radio wave (direct wave)
13 First radio wave 14 Second radio wave 15 First signal 16 Second signal 24 Separation / demodulation circuit 25 Demodulated data from first wireless device 26 Demodulated data from data transmitter 27 Amplifier 28 Baseband filter 32 Modulation Circuit 33 Sensor 34 Power generation circuit 35 Amplifier 36 Gain control signal 37 Separation element 38 Data storage unit 39 Input terminal 40 External data 41 Demodulation circuit 42 Error rate evaluation circuit 81 Reception circuit 82 Protocol processing unit 90 Automobile 91 Tire 92 Window

Claims (12)

A modulation circuit that generates a second radio wave that disturbs the first radio wave by modulating the first radio wave used in the wireless network in accordance with transmission data to be transmitted;
The modulation circuit includes an amplifier that amplifies a first signal corresponding to the first radio wave according to the transmission data to generate a second signal, and uses the second signal as the second radio wave Output,
Data transmitter. The data transmitter further comprises:
One antenna for receiving the first radio wave and transmitting the second radio wave;
A path for transmitting the first signal corresponding to the received first radio wave from the antenna to the input of the amplifier, and a second signal to be transmitted as the second radio wave from the output of the amplifier to the antenna A separation element that separates a path for transmission to
The data transmitter according to claim 1. The data transmitter further comprises:
A receiving antenna for receiving the first radio wave;
A transmission antenna for transmitting the second radio wave,
The data transmitter according to claim 1.   The data transmitter according to claim 3, wherein the reception antenna and the transmission antenna are configured as loop antennas and are respectively rotated by 90 degrees in the same plane. The amplifier is
A first amplifier for inputting and amplifying the first signal;
A second amplifier for further amplifying the amplified signal output from the first amplifier and outputting the second signal;
A switch provided between the first amplifier and the second amplifier,
Generating the second signal by switching a conduction state of the switch according to the transmission data;
The data transmitter according to any one of claims 1 to 4. The data transmitter is
An attenuator for attenuating the amplified second signal to generate a third signal;
An amplifier that inputs the first signal and the third signal and generates the second signal in accordance with the transmission data;
The amount of attenuation in the attenuator is determined based on the amplitude value of the first signal and the amplitude value of the third signal.
The data transmitter according to any one of claims 1 to 4. The amplifier includes a differential amplifier that inputs the first signal and the third signal,
The amount of attenuation in the attenuator is determined so that the amplitude value of the first signal is equal to the amplitude value of the third signal.
The data transmitter according to claim 6. The amplifier includes an amplitude limiting function that limits a power intensity of the generated second signal to a predetermined value or less.
The data transmitter according to any one of claims 1 to 7. The amplifier includes a harmonic removal circuit that removes harmonics generated when generating the second signal.
The data transmitter according to any one of claims 1 to 7.   The data transmitter according to any one of claims 1 to 9, wherein the data transmitter includes a sensor for acquiring the transmission data to be transmitted.   The data transmitter according to claim 1, further comprising a data storage unit for storing the transmission data to be transmitted.   The data transmitter according to any one of claims 1 to 9, wherein the data transmitter acquires the transmission data to be transmitted from the outside via an input terminal.