JP4504149B2 - Wireless communication system, wireless transmitter, wireless communication method, and wireless transmission method - Google Patents

Description

The present invention relates to a radio communication system for transmitting and receiving digital signals by an electromagnetic wave, a radio transmitter, relates radio communications method and a radio transmission method, and more particularly those suitable for use in weak wireless communication short distance.

  In wireless communication, it is difficult to transmit a direct current signal or a signal having a low frequency as it is. For this reason, usually, a signal is transmitted by performing information modulation on a high-frequency carrier wave. Specifically, on the transmission side, modulation is performed with a signal wave to be transmitted to a carrier wave, and a modulated wave is transmitted. On the other hand, the receiving side demodulates the received modulated wave to extract a signal wave from the carrier wave and obtain transmission data (for example, see Non-Patent Document 1).

  FIG. 17 shows an example of the configuration of a conventional wireless communication system. In FIG. 17, on the transmitting side, a voltage controlled oscillator (VCO: Voltage Controlled Oscillators) 1001 generates a carrier wave. This carrier wave is modulated by a multiplier 1002 by being multiplied by a baseband signal IN to be transmitted. The obtained modulated wave is amplified by the power amplifier 1005 and transmitted from the transmission antenna 1006. On the receiving side, the modulated wave received by the receiving antenna 1011 is amplified by a low noise amplifier (LNA) 1012 and an image component is removed by an image removal filter 1013. The modulated wave from which the image component has been removed is downconverted by the multiplier 1017 by being multiplied by the carrier wave generated by the VCO 1016, passes through the channel selection filter 1018, and is then transmitted to the baseband signal transmitted by the detector 1019. Is converted to FIG. 17 shows an example in which wireless communication is performed by phase modulation / demodulation. However, in other wireless communication systems, it is general to generate a carrier wave and modulate / demodulate the carrier wave to perform wireless communication.

  On the other hand, a wireless communication system using an ultra wideband (UWB) technology has been proposed as a system for performing communication without using a carrier wave (see, for example, Patent Document 1 and Patent Document 2). A UWB transmitter sends out a very short time axis pulse of over 1 billion times per second over a very wide frequency band of several GHz, and a receiver receives a sequence of pulses sent from the transmitter. To convert the pulse into data.

The applicant has not yet found prior art documents related to the present invention by the time of filing other than the prior art documents specified by the prior art document information described in this specification.
Special table 2003-529273 gazette Special Table 2003-535552 Hideo Ohba, Hideki Sakazaka, "Wireless Communication Equipment", Nippon Science and Technology Press, p. 120-121, p. 178-181, ISBN 4-89019-136-4

  As described above, in the conventional radio communication system shown in FIG. 17, a carrier wave is generated at the time of transmission and reception, and radio communication is performed by modulating / demodulating the carrier wave. For this reason, a circuit for generating a carrier wave and a circuit for modulating / demodulating the carrier wave are required, the wireless communication system becomes complicated, the scale and the amount of hardware of the transceiver constituting the wireless communication system increase, and the cost of the wireless communication system increases. There was a problem that power consumption increased.

  Also, in a radio communication system using UWB, a circuit for generating a band-limited Gaussian monopulse with a short pulse width is required, and the configuration of this pulse generation circuit is complicated. There has been a problem that the cost and power consumption of the wireless communication system increase due to an increase in scale and hardware amount.

The present invention solves such a conventional problem, and its purpose is to simplify the system, reduce the cost, and reduce the power consumption by eliminating the need for a circuit for generating or modulating / demodulating a carrier wave. wireless communication system capable of achieving reduction, wireless transmitter is to provide a radio communications method and a radio transmission method.

The radio communication system of the present invention includes a radio transmitter and a radio receiver, and the radio transmitter converts a data signal to be transmitted into a signal that changes state according to a logical value of the data signal. A radio wave receiver, comprising: a converting means; a rectangular wave signal generating means for generating a rectangular wave signal synchronized with a state transition of the signal output from the signal converting means; and a transmitting antenna for transmitting the rectangular wave signal. Has a receiving antenna for receiving the transmitted signal, a detector for detecting the signal received by the receiving antenna, and a restoring means for restoring the data signal based on the output signal of the detector. , the pulse width of the rectangular wave signal when the T, the central frequency of the transmission antenna matches the odd multiple of a frequency of one cycle of 2T, rectangular wave signal generating means of the radio transmitter, the pulse A first rectangular wave signal generating circuit for generating a first rectangular wave signal having a first pulse of T, and a second pulse having a second pulse and a third pulse having a pulse width of T. A second rectangular wave signal generating circuit for generating a rectangular wave signal; and a fourth pulse and a fifth pulse having a pulse width of T and a pulse interval different from that of the second rectangular wave signal. A third rectangular wave signal generating circuit that generates a third rectangular wave signal; a first switch disposed between an output terminal of the first rectangular wave signal generating circuit and the transmitting antenna; A second switch disposed between the output terminal of the second rectangular wave signal generation circuit and the transmission antenna; and a second switch disposed between the output terminal of the third rectangular wave signal generation circuit and the transmission antenna. A third switch, and the first switch and the second switch in response to the data signal And it is characterized in that comprising a switch and the third switch control circuit for controlling the opening and closing of the switch.

Also , in one configuration example of the wireless communication system of the present invention, the delay time of the third pulse with respect to the second pulse of the second rectangular wave signal is 2 mT (m is a positive integer), and the third The delay time of the fifth pulse with respect to the fourth pulse of the rectangular wave signal is (2n + 1) T (n is a positive integer different from or different from m).
In one configuration example of the wireless communication system of the present invention, the detector of the wireless receiver includes an envelope detector that detects an envelope of a signal received by the receiving antenna, and a signal received by the receiving antenna. A delay detector for delay-detecting the signal, wherein the restoration means of the radio receiver determines the state of the signal received by the receiving antenna based on a combination of the output results of the envelope detector and the delay detector. A signal discriminator that discriminates and restores the data signal is provided.

Further, the wireless transmitter of the present invention includes a signal conversion unit that converts a data signal to be transmitted into a signal that changes state according to a logical value of the data signal, and a state of a signal output from the signal conversion unit A rectangular wave signal generating means for generating a rectangular wave signal synchronized with the transition; and a transmitting antenna for transmitting the rectangular wave signal, and the center of the transmitting antenna is defined as T when the pulse width of the rectangular wave signal is T The rectangular wave signal generating means has a first rectangular wave signal that generates a first rectangular wave signal having a first pulse with a pulse width of T, the frequency of which coincides with an odd multiple of a frequency of 2T as one cycle. A wave signal generation circuit, a second rectangular wave signal generation circuit that generates a second rectangular wave signal having a second pulse and a third pulse having a pulse width of T, and the pulse width is T. And the interval between the second rectangular wave signal and the pulse A third rectangular wave signal generating circuit for generating a third rectangular wave signal having different fourth and fifth pulses, an output terminal of the first rectangular wave signal generating circuit, and the transmitting antenna. A first switch disposed between the output terminal of the second rectangular wave signal generation circuit and the transmission antenna; and the third rectangular wave signal generation. A third switch disposed between an output terminal of the circuit and the transmitting antenna; and switch control for controlling opening and closing of the first switch, the second switch, and the third switch according to the data signal It is characterized by comprising a circuit.

The wireless communication method of the present invention also includes a signal conversion procedure for converting a data signal to be transmitted into a signal that changes state according to the logical value of the data signal, and the state of the signal converted by the signal conversion procedure. A rectangular wave signal generating procedure for generating a rectangular wave signal synchronized with the transition, a transmitting procedure for transmitting the rectangular wave signal from a transmitting antenna, a receiving procedure for receiving the transmitted signal at a receiving antenna, and the received A detection procedure for detecting a signal, and a restoration procedure for restoring the data signal based on an output signal obtained by the detection procedure, where T is a pulse width of the rectangular wave signal. Is equal to an odd multiple of a frequency having 2T as one period, and the rectangular wave signal generation procedure generates a first rectangular wave signal including a first pulse having a pulse width of T. Square wave Signal generating procedure, a second rectangular wave signal generating procedure for generating a second rectangular wave signal having the second pulse and the third pulse having the pulse width T, the pulse width is T, and A third rectangular wave signal generating procedure for generating a third rectangular wave signal having a fourth pulse and a fifth pulse having a pulse interval different from that of the second rectangular wave signal, and according to the data signal The output to the transmitting antenna is selected from a state in which no signal is output or a state in which any one of the first rectangular wave signal, the second rectangular wave signal, and the third rectangular wave signal is output. And a selection procedure to be performed .
The radio transmission method of the present invention also includes a signal conversion procedure for converting a data signal to be transmitted into a signal that changes state according to the logical value of the data signal, and the state of the signal converted by the signal conversion procedure. A rectangular wave signal generation procedure for generating a rectangular wave signal synchronized with the transition, and a transmission procedure for transmitting the rectangular wave signal from a transmission antenna, and when the pulse width of the rectangular wave signal is T, the transmission The center frequency of the antenna coincides with an odd multiple of a frequency having 2T as one period, and the rectangular wave signal generation procedure generates a first rectangular wave signal including a first pulse having the pulse width T. A rectangular wave signal generation procedure of 1, a second rectangular wave signal generation procedure of generating a second rectangular wave signal having a second pulse and a third pulse having a pulse width of T, and the pulse width is T and the second rectangular wave signal and A third rectangular wave signal generating procedure for generating a third rectangular wave signal having a fourth pulse and a fifth pulse having different intervals of the pulse, and an output to the transmitting antenna in accordance with the data signal, And a selection procedure for selecting from a state in which no signal is output or a state in which any one of the first rectangular wave signal, the second rectangular wave signal, and the third rectangular wave signal is output. It is a feature.

  According to the present invention, by converting the data signal to be transmitted into a rectangular wave signal having a pulse width T, the main lobe of the power spectrum of the transmission signal is converted into a high-frequency AC component, thereby enabling pulse transmission communication. Wireless communication without using a carrier wave eliminates the need for analog high-frequency circuits such as voltage-controlled oscillators necessary for generating carrier waves and multipliers necessary for up-conversion and down-conversion. In addition, the hardware amount of the radio receiver can be greatly reduced, and the system can be simplified, the cost can be reduced, and the power consumption can be reduced. In particular, since digital signal processing is mainly used for wireless transmitters, analog circuits can be greatly reduced, and drastic cost reduction and low power consumption can be achieved. Further, if the center frequency of the transmitting antenna is set to a frequency such as 3 times or 5 times the frequency of 2T as one period, a higher order harmonic component such as a third order harmonic component or a fifth order harmonic component of the rectangular wave signal. In this case, since the operation speed required for each configuration of the wireless transmitter can be reduced, a circuit that operates at high speed becomes unnecessary.

  In addition, since the rectangular wave signal generating means includes the first to third rectangular wave signal generating circuits, the first to third switches, and the switch control circuit, four-value information can be transmitted. The bit rate at which communication is possible can be improved by a factor of two. If the data rate is the same as when binary information is transmitted, the bandwidth of the communication path can be halved.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a radio transmitter of the radio communication system according to the first embodiment of the present invention, and FIG. 2 is a diagram showing an example of signal waveforms of each part of the radio transmitter.
The radio transmitter shown in FIG. 1 includes a signal converter 1 that converts a digital signal in which data is encoded (hereinafter referred to as a data signal) into a signal S1 that changes state according to a logical value “1” of the data signal. Excited by the rectangular wave signal generator 2 that generates the rectangular wave signal S2 in synchronization with the state transition of the signal S1 input from the signal converter 1, and the rectangular wave signal S2 supplied from the rectangular wave signal generator 2 And the transmitting antenna 3.

  The signal converter 1 includes an AND circuit 11 that calculates a logical sum of a data signal and a clock signal synchronized with the data signal, and a D flip-flop circuit (DFF) in which an output signal of the AND circuit 11 is input to a clock terminal clk. 12 and an inverter circuit 13 having an input terminal connected to the output terminal out of the DFF 12 and an output terminal connected to the input terminal in of the DFF 12.

  The clock signal is synchronized with the data signal as shown in FIGS. 2 (A) and 2 (B). The output signal of the AND circuit 11 is “1” when the logical value of the data signal is “1” and the clock signal is “1” as shown in FIG. Since the signal S1 output from the output terminal out of the DFF 12 is inverted by the inverter circuit 13 and input to the input terminal in of the DFF 12, the output signal of the AND circuit 11 input to the clock terminal clk is “1”. ”To“ 0 ”, the signal S1 changes from“ 0 ”to“ 1 ”or from“ 1 ”to“ 0 ”. Therefore, as shown in FIG. 2D, the signal S1 makes a state transition corresponding to the logical value “1” of the data signal. More specifically, the signal S1 undergoes a state transition at a position of 50% duty (center) of the data signal, and the rising and falling edges of the signal S1 correspond to the logical value “1” of the data signal.

  The signal conversion unit 1 is not limited to the configuration shown in FIG. 1, and any signal conversion unit 1 may be used as long as it has an equivalent function. Anything is acceptable. Alternatively, a signal S1 that changes state corresponding to the logical value “0” of the data signal may be output.

The rectangular wave signal generation unit 2 performs an exclusive OR operation (XOR: Exclusive OR) between the delay circuit 21 that outputs the signal S1 after being delayed by an arbitrary time T, and the signal S1 and the output signal of the delay circuit 21. And a logical OR circuit 22.
As shown in FIG. 2 (E), a rectangular wave signal S2 having a pulse width T is generated in synchronization with the rise and fall of the signal S1 by an exclusive OR operation between the signal S1 and the signal obtained by delaying the signal S1. Is done. The pulse width T of the rectangular wave signal S2 is determined by the delay amount of the delay circuit 21.

  When the rectangular wave signal S2 generated by the rectangular wave signal generation unit 2 is supplied to the transmission antenna 3, a high-frequency pulse signal (RF that matches the rectangular wave signal S2 as shown in FIG. Pulse signal) is output. Therefore, an RF pulse signal is output from the wireless transmitter corresponding to the logical value “1” of the data signal.

  As means for realizing the delay circuit 21 of the present embodiment, there is a flip-flop. When a flip-flop is used as the delay circuit 21, the delay time T of the delay circuit 21 is determined by a clock signal supplied to the flip-flop. That is, the pulse width T of the rectangular wave signal S2 can be dynamically changed by changing the frequency of the clock signal supplied to the flip-flop.

  Further, the delay circuit 21 can be realized by connecting a plurality of inverters in series without using a flip-flop. If there is no need to dynamically control the pulse width T of the rectangular wave signal S2, the delay circuit 21 may be realized by connecting a required number of inverters in series so as to have a predetermined delay time. In this case, it is not necessary to supply a clock, and a delay line can be easily realized. The delay circuit 21 may be realized using a resistor and a capacitor. In this case, the delay amount can be controlled by the RC time constant of the resistor R and the capacitor C. In any case, the configuration of the delay circuit 21 is not limited in the present embodiment.

  Hereinafter, the principle that an RF pulse signal is output from the transmission antenna 3 by supplying the rectangular wave signal S2 to the transmission antenna 3 will be described. Here, a case will be described as an example where the rectangular wave signal generation unit 2 includes a delay circuit 21 and an exclusive OR circuit 22.

  FIG. 3 is a waveform diagram showing harmonic signal components included in the rectangular wave signal S2 and the rectangular wave signal S2. As shown in FIG. 3, the rectangular wave signal S2 is a sine wave signal component (fundamental wave, first harmonic) having the same frequency as the rectangular wave signal S2, and a sine wave signal component (third harmonic) having a triple frequency. It consists of odd-order harmonic signal components such as a sinusoidal signal component (fifth-order harmonic) having a frequency five times higher. Therefore, a pulse signal having a pulse width T such as the rectangular wave signal S2 includes a sine wave signal having 2T as one cycle and its higher-order harmonic signal. Specifically, if the pulse width T of the rectangular wave signal S2 is 5 nsec, the frequency of the fundamental wave component of the rectangular wave signal S2 is 100 MHz (one cycle is 10 nsec), and the frequencies of the higher harmonic components are 300 MHz, 500 MHz,.・ ・

  In order to transmit the fundamental wave component or higher-order harmonic component of the rectangular wave signal S2 as described above from the transmission antenna 3, the center frequency of the transmission antenna 3 is set to an odd multiple of the frequency with 2T as one cycle. do it. That is, when the pulse width T of the rectangular wave signal S2 is 5 nsec, it is possible to transmit an RF pulse signal from the transmission antenna 3 by using the transmission antenna 3 whose center frequency is 100 MHz, 300 MHz, or 500 MHz.

  Note that the signal amplitude of the 2k + 1 (k = 0, 1, 2, 3,...) Order harmonic signal is 1 / (2k + 1) compared to the signal amplitude of the rectangular wave signal S2 as shown in FIG. Become. For example, when the amplitude of the rectangular wave signal S2 is 1, the amplitude of the 3rd harmonic is 1/3, and the amplitude of the 5th harmonic is 1/5. Therefore, the transmission signal power decreases as the higher-order harmonic components are transmitted.

  FIG. 4 is a conceptual diagram showing a signal waveform when the third harmonic component of the rectangular wave signal S2 is transmitted. As shown in FIG. 4A, when the pulse width T of the rectangular wave signal S2 is 5 nsec, the signal frequency of the third harmonic component of the rectangular wave signal S2 shown in FIG. 4B is 300 MHz. Therefore, when the rectangular wave signal S2 is supplied to the transmission antenna 3 having a center frequency of 300 MHz, the transmission antenna 3 outputs an RF pulse signal as shown in FIG. 4C that vibrates at a frequency of 300 MHz. The pulse width of this RF pulse signal is determined by the impulse response of the transmission antenna 3 and the antenna band. When the antenna band is wide, the pulse width is short, and conversely, when the antenna band is narrow, the pulse width is long.

  In general short-distance weak wireless communication, the transmission signal power is regulated to a considerably small value by regulations such as the Radio Law. For this reason, when it is going to transmit the fundamental wave component of rectangular wave signal S2, transmission signal power is large and may exceed a regulation value. In this case, the signal power may be weakened with an attenuator for transmission. Further, a rectangular wave signal S2 including a high-order harmonic component corresponding to the signal frequency band to be transmitted is generated, and signal components such as the third harmonic and the fifth harmonic of the rectangular wave signal S2 are transmitted. Good. In this case, the higher the higher harmonic, the smaller the signal amplitude and the lower the transmission signal power. Therefore, it is sufficient to select and use the higher harmonic component of the signal power that conforms to the regulation value. When transmitting higher-order harmonic components, the following effects can be obtained as compared with the case of transmitting fundamental wave components.

  When the fundamental wave component of the rectangular wave signal S2 is transmitted, the delay amount that must be realized by the delay circuit 21 is shorter than that when the high-order harmonic component is transmitted, and the delay circuit 21 is difficult to realize. . Specifically, when transmitting a 500 MHz band RF pulse signal, if the fundamental wave component of the rectangular wave signal S2 is used, the delay time of the delay circuit 21 needs to be 1 nsec, whereas the rectangular wave signal S2 If the fifth-order harmonic component is used, the delay time may be set to 5 nsec. When the delay circuit 21 is realized using a flip-flop, a 1 GHz clock signal is required to realize a delay time of 1 nsec, whereas a 200 MHz clock signal is required to realize a delay time of 5 nsec. The clock generation is easier when the higher-order harmonic component is used.

  Furthermore, as the delay time of the delay circuit 21 is shorter, the exclusive OR circuit 22 that outputs the rectangular wave signal S2 needs to operate at a higher speed. When the delay time of the delay circuit 21 is long, the operation speed required for the exclusive OR circuit 22 is reduced. In addition, by using a higher-order harmonic component corresponding to the regulation value of the transmission signal power, there is an effect that it is not necessary to use an attenuator that is necessary when the fundamental wave component is used.

  As described above, the wireless transmitter according to the present embodiment transmits a transmission signal without using a carrier wave, particularly an analog high-frequency carrier. For this reason, the wireless transmitter does not have a VCO for generating a carrier wave, a multiplier for multiplying the carrier wave by a data signal, or the like necessary for the use of the carrier wave.

  Next, the receiving side will be described. FIG. 5 is a block diagram showing a configuration example of a radio receiver of the radio communication system according to the present embodiment. Since the RF pulse signal is turned on and off in correspondence with data signals “1” and “0” from the wireless transmitter in FIG. 1, the wireless receiver may detect this on / off signal. The radio receiver shown in FIG. 5 includes a receiving antenna 4, a low noise amplifier (LNA) 5, a diode 6 serving as a detector, and an AD converter 7 serving as restoring means. A signal transmitted from the wireless transmitter of FIG. 1 is received by the receiving antenna 4, amplified by the LNA 5, and supplied to the diode 6. Then, the signal output from the LNA 5 is subjected to envelope detection by the diode 6, and the signal detected by the envelope detection is converted into a digital signal by the AD converter 7, thereby restoring the data signal.

  FIG. 6 is a block diagram illustrating another configuration example of the wireless receiver. The radio receiver shown in FIG. 6 includes a reception antenna 4, an LNA 5, an AD converter 7, and a multiplier 8 that is a detector. This wireless receiver performs envelope detection using square detection instead of diode detection. That is, the signal output from the LNA 5 is envelope-detected by the multiplier 8, and the signal detected by the envelope detection is converted to a digital signal by the AD converter 7, thereby restoring the data signal.

  As described above, the wireless receiver receives a signal transmitted without using a carrier wave, particularly an analog high-frequency carrier. For this reason, the radio receiver does not include a VCO for generating a carrier wave, a multiplier for multiplying the received signal by the carrier wave, and the like necessary for the use of the carrier wave.

The AD conversion by the AD converter 7 in FIGS. 5 and 6 determines the presence / absence of a pulse of the envelope-detected signal, so the presence / absence of a pulse is determined using a comparator instead of the AD converter 7. You may make it do.
In FIGS. 5 and 6, the envelope detection is performed on the RF signal as it is. However, the envelope detection may be performed after the RF signal is down-converted to an appropriate intermediate frequency. In this case, a circuit that performs down-conversion is required, but it is easier to realize envelope detection than when RF signals are directly detected.

  Hereinafter, the reason why wireless communication can be performed without using a carrier wave as in this embodiment will be described. Only an AC component can be transmitted by wireless communication, and no DC component is transmitted. For this reason, it is difficult to transmit a data signal (baseband signal) having a power spectrum peak near the DC component. On the other hand, if the main lobe of the power spectrum is an AC component, communication is possible if the AC signal component serving as the main lobe is transmitted / received even if the signal component near the DC is not transmitted / received. Therefore, the radio transmitter according to the present embodiment operates so that the main lobe of the power spectrum becomes an AC component by converting the data signal to be transmitted into a high-frequency rectangular wave signal S2. As a result, in this embodiment, wireless communication without using a carrier wave is possible.

  As described above, according to the present embodiment, by making the main lobe of the power spectrum of the transmission signal into a high-frequency AC component, pulse transmission communication is enabled and wireless communication is performed without using a carrier wave. The VCO required for carrier generation and the multiplier required for up-conversion and down-conversion are no longer required, greatly reducing the amount of hardware of the radio transmitter and radio receiver that make up the system, simplifying the system, Cost reduction and power consumption can be reduced. In particular, almost all wireless transmitters can be constituted by digital circuits, and digital signal processing is the main. For this reason, the number of analog circuits can be greatly reduced, and a significant reduction in cost and power consumption can be achieved.

  In this embodiment, the transmitting antenna is driven by a digital rectangular wave signal without a pulse generator for generating a Gaussian monopulse. This method also has a feature that the frequency band used for communication can be selected by the band of the antenna that uses the frequency band. If an antenna with a center frequency of several hundred MHz is used, communication is performed by transmitting and receiving radio waves in that frequency band. If an antenna having a center frequency of several GHz is used, communication is performed by transmitting and receiving radio waves in that frequency band. Is possible. The antenna used in any of these cases may be adjusted so that the main lobe of the data signal to be transmitted is included in the frequency band of the antenna used. Specifically, the pulse width T of the rectangular wave signal S2 shown in FIG. If the pulse width T is reduced, the frequency component contained in the signal spreads to the higher frequency side. The pulse width T is determined by the frequency of the clock signal supplied to the signal converter 1, and the frequency of the clock signal can be controlled by a frequency synthesizer.

  Therefore, in the system of the present embodiment, the transmission antenna and the frequency synthesizer on the transmitter side may be controlled in accordance with the frequency band to be used. Since the frequency synthesizer can be controlled by software, the antenna is the only component that needs to be changed in hardware when the frequency band used is changed. As described above, the present embodiment has a feature that the frequency band to be used can be changed only by switching the antenna without changing the components on the other transmitter side in hardware.

  On the other hand, a conventional radio communication system using UWB requires a pulse generator for generating a Gaussian monopulse. This pulse generator is tuned and mounted so that a frequency component of a Gaussian monopulse is included in a predetermined frequency band. Since this pulse generator is composed of a high-frequency analog circuit, it is difficult to design, and it is further difficult to design the pulse generator so that the frequency component of the Gaussian monopulse is variable. In other words, in a conventional wireless communication system using UWB, it is necessary to tune to a frequency band used for communication and to implement a pulse generator. Therefore, even if the antenna to be used is switched, the configuration on the transmitter side in hardware It is difficult to change the element pulse generator, and the frequency band used for communication cannot be changed.

[Second Embodiment]
In the first embodiment, binary information is transmitted by turning on and off the RF pulse signal, but in this embodiment, the information that can be transmitted by the RF signal in the first embodiment is multi-valued into four values. In addition to the characteristics of the first embodiment, the bit rate that can be transmitted can be improved by a factor of two. Details will be described below.

  FIG. 7 is a block diagram showing a configuration of a radio transmitter of the radio communication system according to the second embodiment of the present invention, and the same components as those in FIG. 1 are denoted by the same reference numerals. The radio transmitter shown in FIG. 7 includes a signal conversion unit 1, a rectangular wave signal generation unit 20, and a transmission antenna 3. The rectangular wave signal generation unit 20 includes three rectangular wave signal generation circuits 2a to 2c, switches 23a to 23c, and a switch control circuit 24. The first rectangular wave signal generation circuit 2a is a first delay circuit. 21a and a first exclusive OR circuit 22a, and the second rectangular wave signal generation circuit 2b is composed of a second delay circuit 21b and a second exclusive OR circuit 22b. The rectangular wave signal generation circuit 2c includes a third delay circuit 21c and a third exclusive OR circuit 22c.

  In the wireless transmitter according to the present embodiment, the first switch 23a is disposed between the output terminal of the first rectangular wave signal generation circuit 2a and the transmission antenna 3, and the second rectangular wave signal generation circuit 2b A second switch 23b is disposed between the output terminal and the transmission antenna 3, and a third switch 23c is disposed between the output terminal of the third rectangular wave signal generation circuit 2c and the transmission antenna 3. Yes. The switch control circuit 24 selectively controls the opening and closing of the switches 23a to 23c, and supplies any one of the rectangular wave signals S2 to S4 output from the rectangular wave signal generation circuits 2a to 2c to the transmitting antenna 3. Thus, the present embodiment is configured to handle quaternary information.

  FIG. 8 shows typical signal waveform examples of the signal S1 output from the signal converter 1 and the rectangular wave signals S2 to S4 output from the rectangular wave signal generation circuits 2a to 2c. Since the operation until the first rectangular wave signal S2 is output from the rectangular wave signal generation circuit 2a is the same as that of the first embodiment, the description thereof is omitted. The first rectangular wave signal S2 is input to the switch 23a, delay circuits 21b and 21c, and exclusive OR circuits 22b and 22c.

  The second delay circuit 21b delays the rectangular wave signal S2 by a time that is an even multiple of the delay time T of the first delay circuit 21a, that is, a time of 2mT (m is a positive integer). It outputs to the sum circuit 22b. By the exclusive OR operation of the signal S2 and the signal obtained by delaying the signal S2, the second rectangular wave signal S3 output from the second exclusive OR circuit 22b becomes as shown in FIG. The third delay circuit 21c delays the rectangular wave signal S2 by a time that is an odd multiple of the delay time T of the first delay circuit 21a, that is, a time of (2n + 1) T (n is a positive integer that is the same as or different from m). And output to the third exclusive OR circuit 22c. By the exclusive OR operation of the signal S2 and the signal obtained by delaying the signal S2, the third rectangular wave signal S4 output from the third exclusive OR circuit 22c becomes as shown in FIG.

  Next, an RF pulse signal when the rectangular wave signal S2 is transmitted from the transmission antenna 3 is shown in FIG. 9A, and an RF pulse signal when the rectangular wave signal S3 is transmitted from the transmission antenna 3 is shown in FIG. The RF pulse signal when the rectangular wave signal S4 is transmitted from the transmitting antenna 3 is shown in FIG. The two RF pulse signals in FIG. 9B are continuous in phase, and the two RF pulse signals in FIG. 9C are inverted in phase.

  The relationship of the phase of the RF pulse signal when the rectangular wave signals S3 and S4 are transmitted from the transmission antenna 3 will be described with reference to FIGS. FIG. 10A shows a rectangular wave signal S3, and FIG. 10B shows its third harmonic component. In FIG. 10B, the broken line portion indicates the third harmonic component corresponding to the first pulse (second pulse) of the rectangular wave signal S3, and the solid line portion indicates the second pulse (third pulse). ) Corresponding to the third harmonic component. FIG. 10B shows that the third harmonic component of the rectangular wave signal S3 has a continuous phase. In the case of the rectangular wave signal S3, phase discontinuity does not occur in not only the third-order harmonic component but also the odd-order higher-order harmonic component.

  On the other hand, FIG. 10C shows the rectangular wave signal S4, and FIG. 10D shows the third-order harmonic component. Similarly to FIG. 10B, the broken line portion in FIG. 10D is the third harmonic component corresponding to the first pulse (fourth pulse) of the rectangular wave signal S4, and the solid line portion is two. It is a third harmonic component corresponding to the eye pulse (fifth pulse). As shown in FIG. 10D, the third harmonic component of the first pulse of the rectangular wave signal S4 and the third harmonic component of the second pulse have a phase difference of 180 degrees. In the case of the rectangular wave signal S4, phase discontinuities occur not only in the third-order harmonic component but also in the odd-order higher-order harmonic component.

  Therefore, when the rectangular wave signals S3 and S4 shown in FIGS. 8C and 8D are output to the transmission antenna 3, the RF pulse signals output from the transmission antenna 3 are those shown in FIGS. (C), the phase is continuous in the RF pulse signal based on the rectangular wave signal S3, and the phase is inverted in the RF pulse signal based on the rectangular wave signal S4.

  In the present embodiment, the delay times of the delay circuits 21b and 21c need to be determined in consideration of the antenna band. As described with reference to FIG. 4C, the pulse width of the RF pulse signal corresponding to one rectangular wave signal is determined by the antenna band. If the delay times of the delay circuits 21b and 21c are too short, the RF pulse signal based on the first pulse of the rectangular wave signal overlaps with the RF pulse signal based on the second pulse of the rectangular wave signal. The two RF pulse signals cannot be distinguished. Therefore, it is necessary to set the delay times of the delay circuits 21b and 21c so that the two RF pulse signals can be distinguished in consideration of the antenna band.

  As described above, in the wireless transmitter according to the present embodiment, there are four signal states (no signal state, one RF pulse signal state, and two RF pulse signal phases being continuous, The quaternary information can be transmitted by handling the state in which the phases of the two RF pulse signals are inverted. Hereinafter, “0” indicates no signal, “1” indicates one RF pulse signal, “2” indicates that two RF pulse signals are in continuous phase, and two RF pulse signals are inverted in phase. The state that is in progress is assumed to be “3”.

  As shown in FIGS. 11A and 11B, for example, when the two bits of the data signal are “00”, the state “0” is set, and when the two bits of the data signal are “01”, the state “1” is set. The state “2” is when the two bits of the data signal are “10”, and the state “3” is when the two bits of the data signal are “11”. These four signal states can be selected by controlling the switches 23 a to 23 c by the switch control circuit 24.

  For example, when the 2 bits of the data signal are “00”, the switch control circuit 24 turns off all the switches 23a to 23c, and turns on the switch 23a when the 2 bits of the data signal is “01”. When the 2 bits of the data signal are "10", the switch 23b is turned on and the other switches are turned off. When the 2 bits of the data signal are "11", the switch 23c is turned on and the other Turn off the switch. Thus, in this embodiment, quaternary information can be transmitted.

  FIG. 12 is a block diagram showing a configuration of a radio receiver of the radio communication system according to the present embodiment. The radio receiver of FIG. 12 includes a reception antenna 31, an LNA 32, an oscillator 33, a mixer 34, an envelope detector 35, a delay detector 36, and a signal discriminator 37. A signal transmitted from the wireless transmitter in FIG. 7 is received by the receiving antenna 31, amplified by the LNA 32, and supplied to the mixer 34. The reception signal amplified by the LNA 32 and the local signal supplied from the oscillator 33 are multiplied by the mixer 34. As a result, the received signal is down-converted to an appropriate intermediate frequency band.

  The envelope detector 35 performs envelope detection on the received signal input from the mixer 34, the delay detector 36 performs delay detection on the received signal, and the signal discriminator 37 includes the envelope detector 35 and the delay detector 36. Based on the output signal, a four-value signal is discriminated, and 2 bits of the data signal are restored. FIG. 13 (A) shows the output signal of the envelope detector 35 when the RF pulse signal of FIG. 9 (A) is received, and FIG. 13 (B) shows the case of receiving the RF pulse signal of FIG. 9 (B). The output signal of the envelope detector 35 is shown, and FIG. 13C shows the output signal of the envelope detector 35 when the RF pulse signal of FIG. 9C is received. As can be seen from FIGS. 13A to 13C, the envelope of the RF pulse signal is detected. The configuration of the envelope detector 35 can be realized by using diode detection or square detection as shown in FIGS.

FIG. 14A shows an output signal of the delay detector 36 when the RF pulse signal of FIG. 9A is received, and FIG. 14B shows when the RF pulse signal of FIG. 9B is received. The output signal of the delay detector 36 is shown, and FIG. 14C shows the output signal of the delay detector 36 when the RF pulse signal of FIG. 9C is received.
FIG. 15 shows a configuration example of the delay detector 36. The delay detector 36 includes a delay circuit 361 and a multiplier 362. The multiplier 362 multiplies the input signal from the mixer 34 and the input signal delayed by the delay circuit 361 for a predetermined time. , Delay detection. The delay time of the delay circuit 361 is an average value of the delay times 2mT and (2n + 1) T set by the delay circuits 21b and 21c on the transmission side.

  As apparent from FIG. 14 (A), when the RF pulse signal of FIG. 9 (A) based on the rectangular wave signal S2 is subjected to delay detection, nothing is output from the delay detector 36, whereas the rectangular wave signal S3. When the RF pulse signal shown in FIG. 9B based on the delay detection is delayed, an output signal having a positive polarity is obtained from the delay detector 36 as shown in FIG. 14B. The reason why a positive output signal is obtained is that the phases of two RF pulse signals based on the rectangular wave signal S3 are continuous. On the other hand, when the RF pulse signal of FIG. 9C based on the rectangular wave signal S4 is delay-detected, an output signal having a negative polarity is obtained from the delay detector 36 as shown in FIG. 14C. The reason why a negative output signal is obtained is that the phases of the two RF pulse signals based on the rectangular wave signal S4 are inverted.

  Therefore, it can be seen that the four transmitted signal states can be discriminated from the combination of the output signals of the envelope detector 35 and the delay detector 36. That is, the four signal states are a state in which there is no output from the envelope detector 35, a state in which there is an output from the envelope detector 35 and no output from the delay detector 36, and an envelope detector 35 and a delay detector. The detector 36 has an output, the output of the delay detector 36 is in a positive state, the envelope detector 35 and the delay detector 36 have both outputs, and the output of the delay detector 36 is in a negative / positive state. Either. By discriminating the combination of the output signals of the envelope detector 35 and the delay detector 36 by the signal discriminator 37, the quaternary information (2 bits of the data signal) can be restored.

  As described above, since the four-value information can be handled in this embodiment, in addition to the effect of the first embodiment, there is an effect that the bit rate at which communication is possible can be improved by a factor of two. Have. Further, when the data rate is the same as that of the first embodiment, the bandwidth of the communication path may be half that of the first embodiment.

  When the delay time 2mT set in the delay circuits 21b and 21c on the transmission side and (2n + 1) T are greatly different, the output signal described in FIGS. 14A to 14C is output from the delay detector 36. I can't get it. In such a case, it is sufficient to use two delay detectors as shown in FIG. Whether or not to use the configuration of FIG. 16 is determined based on whether or not the value of (m + n + 1/2) is away from 2m, 2n + 1. When the value of (m + n + 1/2) is away from 2m, 2n + 1, FIG. It is preferred to use 16 configurations.

  The configuration of the delay detectors 38 and 39 is as shown in FIG. The delay time of the delay circuit in the delay detector 38 is set to 2 mT, while the delay time of the delay circuit in the delay detector 39 is set to (2n + 1) T. Only when the RF pulse signal of FIG. 9B based on the rectangular wave signal S3 is delay-detected from the delay detector 38, an output signal having the same positive polarity as that of FIG. 14B is obtained. Nothing is output when the signal is delayed. Also, the delay detector 39 obtains an output signal having the same negative polarity as that of FIG. 14C only when the RF pulse signal of FIG. 9C based on the rectangular wave signal S4 is delay-detected. Nothing is output when the RF pulse signal is delayed. Therefore, the signal discriminator 37 can restore the quaternary information by discriminating the combination of the output signals of the envelope detector 35 and the delay detectors 38 and 39.

  In the first and second embodiments, the rectangular wave signal generation unit 2 and the rectangular wave signal generation circuits 2a to 2c are composed of delay circuits 21, 21a to 21c and exclusive OR circuits 22, 22a to 22c. However, the present invention is not limited to this. Instead of the delay circuits 21, 21a to 21c, for example, an inverting delay circuit composed of an odd number of inverter circuits is used, and instead of the exclusive OR circuits 22, 22a to 22c. Exclusive NOR (a circuit that outputs “1” when an even number of input signals among the plurality of input signals have the same logical value, and outputs “0” in other cases) may be used. .

  The present invention can be applied to wireless communication in which digital signals are transmitted and received by electromagnetic waves.

It is a block diagram which shows the structure of the radio | wireless transmitter of the radio | wireless communications system which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the signal waveform of each part of the radio | wireless transmitter shown in FIG. It is a signal waveform diagram which shows the harmonic signal component contained in a rectangular wave signal and a rectangular wave signal. It is a conceptual diagram which shows the signal waveform in the case of transmitting the 3rd harmonic component of the rectangular wave signal output from a rectangular wave signal generation part. It is a block diagram which shows one structural example of the radio receiver of the radio | wireless communications system which concerns on the 1st Embodiment of this invention. It is a block diagram which shows the other structural example of the radio | wireless receiver of the radio | wireless communications system which concerns on the 1st Embodiment of this invention. It is a block diagram which shows the structure of the radio | wireless transmitter of the radio | wireless communications system which concerns on the 2nd Embodiment of this invention. FIG. 8 is a signal waveform diagram of a signal output from a signal conversion unit of the wireless transmitter illustrated in FIG. 7 and a rectangular wave signal output from a rectangular wave signal generation circuit. It is a signal waveform diagram of an RF pulse signal when a rectangular wave signal is transmitted from a transmission antenna. It is a figure for demonstrating the relationship of the phase of RF pulse signal when a rectangular wave signal is transmitted from a transmission antenna. It is a figure which shows the relationship between a data signal and four signal states transmitted from a radio transmitter. It is a block diagram which shows the structure of the radio | wireless receiver of the radio | wireless communications system which concerns on the 2nd Embodiment of this invention. It is a signal waveform diagram of the output signal of the envelope detector of the wireless receiver shown in FIG. FIG. 13 is a signal waveform diagram of an output signal of a delay detector of the wireless receiver shown in FIG. 12. It is a block diagram which shows the structure of the delay detector of the radio | wireless receiver shown in FIG. It is a block diagram which shows the other structure of the radio | wireless receiver of the radio | wireless communications system which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows an example of a structure of the conventional radio | wireless communications system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Signal conversion part, 2, 20 ... Rectangular wave signal generation part, 2a-2c ... Rectangular wave signal generation circuit, 3 ... Transmission antenna, 4, 31 ... Reception antenna, 5, 32 ... Low noise amplifier, 6 ... Diode, 7 ... AD converter, 11 ... AND circuit, 12 ... D flip-flop circuit, 13 ... inverter circuit, 21, 21a-21c ... delay circuit, 22, 22a-22c ... exclusive OR circuit, 23a-23c ... switch, 24 ... Switch control circuit 33 ... oscillator 34 ... mixer 35 ... envelope detector 36, 38, 39 ... delay detector 37 ... signal discriminator S2-S4 ... rectangular wave signal.

Claims (10)

A wireless transmitter and a wireless receiver;
The radio transmitter is synchronized with a signal conversion unit that converts a data signal to be transmitted into a signal that changes state according to a logical value of the data signal, and a state transition of the signal output from the signal conversion unit. A rectangular wave signal generating means for generating a rectangular wave signal; and a transmission antenna for transmitting the rectangular wave signal;
The radio receiver includes a receiving antenna that receives the transmitted signal, a detector that detects a signal received by the receiving antenna, and a restoration unit that restores the data signal based on an output signal of the detector And
When the pulse width of the rectangular wave signal is T, the center frequency of the transmitting antenna coincides with an odd multiple of a frequency having 2T as one cycle ,
The rectangular wave signal generating means of the wireless transmitter is
A first rectangular wave signal generating circuit for generating a first rectangular wave signal having a first pulse with a pulse width of T;
A second rectangular wave signal generation circuit for generating a second rectangular wave signal having the second pulse and the third pulse having a pulse width of T;
A third rectangular wave signal generating circuit that generates a third rectangular wave signal having a pulse width T and a fourth pulse and a fifth pulse having a pulse interval different from that of the second rectangular wave signal. When,
A first switch disposed between an output terminal of the first rectangular wave signal generation circuit and the transmission antenna;
A second switch disposed between an output terminal of the second rectangular wave signal generation circuit and the transmission antenna;
A third switch disposed between an output terminal of the third rectangular wave signal generation circuit and the transmission antenna;
A wireless communication system comprising: a switch control circuit that controls opening and closing of the first switch, the second switch, and the third switch in accordance with the data signal . The wireless communication system according to claim 1, wherein
The delay time of the third pulse with respect to the second pulse of the second rectangular wave signal is 2 mT (m is a positive integer), and the fifth pulse with respect to the fourth pulse of the third rectangular wave signal is set. A radio communication system, wherein a delay time of a pulse is (2n + 1) T (n is a positive integer different from or different from m) . The wireless communication system according to claim 1 , wherein
The detector of the radio receiver comprises an envelope detector that detects an envelope of a signal received by the receiving antenna, and a delay detector that delay-detects a signal received by the receiving antenna,
The restoration unit of the radio receiver is configured to determine a state of a signal received by the reception antenna based on a combination of output results of the envelope detector and the delay detector, and to determine a signal that restores the data signal. wireless communication system comprising: a vessel. A signal conversion means for converting a data signal to be transmitted into a signal that changes state according to the logical value of the data signal;
A rectangular wave signal generating means for generating a rectangular wave signal synchronized with the state transition of the signal output from the signal converting means;
A transmission antenna for transmitting the rectangular wave signal;
When the pulse width of the rectangular wave signal is T, the center frequency of the transmitting antenna coincides with an odd multiple of a frequency having 2T as one cycle,
The rectangular wave signal generation means includes
A first rectangular wave signal generating circuit for generating a first rectangular wave signal having a first pulse with a pulse width of T;
A second rectangular wave signal generation circuit for generating a second rectangular wave signal having the second pulse and the third pulse having a pulse width of T;
A third rectangular wave signal generating circuit that generates a third rectangular wave signal having a pulse width T and a fourth pulse and a fifth pulse having a pulse interval different from that of the second rectangular wave signal. When,
A first switch disposed between an output terminal of the first rectangular wave signal generation circuit and the transmission antenna;
A second switch disposed between an output terminal of the second rectangular wave signal generation circuit and the transmission antenna;
A third switch disposed between an output terminal of the third rectangular wave signal generation circuit and the transmission antenna;
A radio transmitter comprising: a switch control circuit that controls opening and closing of the first switch, the second switch, and the third switch in accordance with the data signal . The wireless transmitter according to claim 4, wherein
The delay time of the third pulse with respect to the second pulse of the second rectangular wave signal is 2 mT (m is a positive integer), and the fifth pulse with respect to the fourth pulse of the third rectangular wave signal is set. A radio transmitter characterized in that a delay time of a pulse is (2n + 1) T (n is a positive integer different from or different from m) . A signal conversion procedure for converting a data signal to be transmitted into a signal that changes state according to the logical value of the data signal;
A rectangular wave signal generation procedure for generating a rectangular wave signal synchronized with the state transition of the signal converted by this signal conversion procedure,
A transmission procedure for transmitting the rectangular wave signal from a transmission antenna;
A receiving procedure for receiving the transmitted signal at a receiving antenna;
A detection procedure for detecting the received signal;
A restoration procedure for restoring the data signal based on the output signal obtained by the detection procedure,
When the pulse width of the rectangular wave signal is T, the center frequency of the transmitting antenna coincides with an odd multiple of a frequency having 2T as one cycle,
The rectangular wave signal generation procedure includes:
A first rectangular wave signal generation procedure for generating a first rectangular wave signal having a first pulse with a pulse width of T;
A second rectangular wave signal generating procedure for generating a second rectangular wave signal having the second pulse and the third pulse having the pulse width T;
A third rectangular wave signal generation procedure for generating a third rectangular wave signal having a fourth pulse and a fifth pulse having a pulse width T and a pulse interval different from that of the second rectangular wave signal. When,
According to the data signal, the output to the transmitting antenna is output in a state in which no signal is output, or any one of the first rectangular wave signal, the second rectangular wave signal, and the third rectangular wave signal. And a selection procedure for selecting from among the states to be performed . The wireless communication method according to claim 6, wherein
The delay time of the third pulse with respect to the second pulse of the second rectangular wave signal is 2 mT (m is a positive integer), and the fifth pulse with respect to the fourth pulse of the third rectangular wave signal is set. A radio communication method, wherein a delay time of a pulse is (2n + 1) T (n is a positive integer that is the same as or different from m). The wireless communication method according to claim 6, wherein
The detection procedure consists of an envelope detection procedure for detecting an envelope signal received by the reception antenna, and a delay detection procedure for delay detection of the signal received by the reception antenna,
The restoration procedure, a radio, characterized in that the envelope detection procedure on the basis of the combination of the delay detection procedure of an output result to restore the data signal to determine the state of signals received by the receiving antenna Communication method . A signal conversion procedure for converting a data signal to be transmitted into a signal that changes state according to the logical value of the data signal;
A rectangular wave signal generation procedure for generating a rectangular wave signal synchronized with the state transition of the signal converted by this signal conversion procedure,
A transmission procedure for transmitting the rectangular wave signal from a transmission antenna ;
When the pulse width of the rectangular wave signal is T, the center frequency of the transmitting antenna coincides with an odd multiple of a frequency having 2T as one cycle ,
The rectangular wave signal generation procedure includes:
A first rectangular wave signal generation procedure for generating a first rectangular wave signal having a first pulse with a pulse width of T;
A second rectangular wave signal generating procedure for generating a second rectangular wave signal having the second pulse and the third pulse having the pulse width T;
A third rectangular wave signal generation procedure for generating a third rectangular wave signal having a fourth pulse and a fifth pulse having a pulse width T and a pulse interval different from that of the second rectangular wave signal. When,
According to the data signal, the output to the transmitting antenna is output in a state in which no signal is output, or any one of the first rectangular wave signal, the second rectangular wave signal, and the third rectangular wave signal. wireless transmission method characterized by comprising a selection procedure for selecting from among the states. The wireless transmission method according to claim 9, wherein
The delay time of the third pulse with respect to the second pulse of the second rectangular wave signal is 2 mT (m is a positive integer), and the fifth pulse with respect to the fourth pulse of the third rectangular wave signal is set. A radio transmission method characterized in that a delay time of a pulse is (2n + 1) T (n is a positive integer different from or different from m).

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