JP2005123753A - Radio communication system and radio communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a UWB radio communication system adopting the frequency hopping system provided with an antenna capable of efficiently receiving a very weak radio wave and / or efficiently transmitting a transmission radio wave. <P>SOLUTION: The radio communication system is provided with: a broadband antenna 29; a demodulation circuit 35 for demodulating a signal from the broadband antenna 29; a plurality of narrow band antennas 32a to 32h; a selection circuit 30 for selecting a narrow band antenna for receiving a carrier frequency at that point of time according to a hopping pattern; a demodulation circuit 36 for demodulating the signal from the narrow band antenna selected by the selection circuit 30; and selection circuits 27, 38 for comparing a reception state of the broadband antenna 29 with a reception state of the selected narrow band antenna, and selecting the signal demodulated from the signal received by the antenna whose reception state is more preferable. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a wireless communication system and a wireless communication method suitable for UWB communication in which wireless communication is performed using broadband radio waves.

  The UWB (Ultra Wide Band) communication technology that uses a wider castle than in the past has attracted attention.

  FIG. 9 shows an example of a signal form of wireless communication by a frequency hopping method which is one form of UWB communication. In this example, the signal to be transmitted is modulated while hopping the modulation frequency on the time axis, and communication is performed using pulsed radio of several nsec. The frequency of the modulation signal (carrier wave) constituting the signal changes sequentially. FIG. 10 shows an example of the spectrum. In this example, 3.1 GHz to 10.6 GHz is divided into subbands every 500 MHz.

  FIG. 11 shows an example of a transmission / reception circuit corresponding to this method. The control circuit 111 sequentially switches the frequency of a signal to be transmitted / received as time progresses and instructs a local oscillator (LO) 112. The local oscillator LO112 supplies a signal (carrier signal) having a designated frequency (f in FIG. 9) to the mixers MX11 and MX13 and the π / 2 phase shifter 113. The π / 2 phase shifter 113 shifts the phase of the carrier signal from the LO 112 by π / 2 radians and outputs it to the mixers MX12 and MX14.

  At the time of transmission, transmission data is supplied to the modulator 114. The modulator 114 generates an in-phase component I (t) and a quadrature component Q (t) of transmission data, and outputs the in-phase component I (t) to the mixer MX11 and the quadrature component Q (t) to the mixer MX12.

  The mixer MX11 mixes and outputs the in-phase component I (t) and the carrier signal from the LO 112, and the mixer MX12 outputs the quadrature component Q (t) and the phase-shifted carrier signal from the π / 2 phase shifter 113. Are mixed and output.

  The adder 115 adds the signals from the mixers MX11 and MX12 to generate a pulsed modulation signal having a frequency specified by the control circuit 111, and supplies the pulsed modulation signal to the pulse amplifier (PA) 116. . The pulse amplifier 116 amplifies and outputs this pulsed modulation signal. The selection circuit (transmission / reception switching circuit) 117 is supplied with a transmission / reception switching signal from the control circuit 111, and guides the output signal of the pulse amplifier 116 to the antenna 119 via the noise filter 118 during transmission. Thereby, the transmission signal from the pulse amplifier 116 is emitted into the air via the antenna 119.

  On the other hand, at the time of reception, the selection circuit 117 connects the antenna 119 to a low noise amplifier (LNA) 120 by a transmission / reception switching signal. As a result, a weak signal generated by receiving a radio signal by the antenna 119 is supplied to the low noise amplifier circuit 120 via the noise filter 118, amplified, and output to the mixers MX13 and MX14.

  The mixer MX13 mixes the output signal of the low noise amplifier circuit 120 and the carrier signal from the LO 112, reproduces the in-phase component I (t) of the demodulated signal, and supplies it to the demodulator 121. The mixer MX14 mixes the output signal of the low-noise amplifier circuit 120 and the phase-shifted carrier signal from the π / 2 phase shifter 113, and reproduces the quadrature component Q (t) of the demodulated signal. To supply.

  The demodulator 121 reproduces and outputs a received signal from the in-phase component I (t) from the mixer MX13 and the quadrature component Q (t) from the mixer MX14 by performing a demodulation operation such as phase determination.

In UWB wireless communication, a wide frequency band is used, but what matters is an antenna for supporting a wide band. In other words, due to the width of the frequency band, overlapping with other wireless standards is inevitable, so strict output regulation is provided, and very weak radio waves are demodulated on the receiving side, and high reception sensitivity is required. It is done. Under the condition that the ratio of the used bandwidth to the center frequency is approximately 1, it is difficult to increase the sensitivity with a single antenna.
Similarly, transmitting a wide frequency band signal with a single antenna is not easy, if not as much as reception.

  In order to solve such a problem, Patent Document 1 discloses a wireless communication system in which a wide communication band is divided into a plurality of narrow bands and a plurality of antennas for each narrow band are arranged.

However, this wireless communication system only receives radio waves with a plurality of antennas, and selects an antenna to be used for reception from the state of the received radio waves. In other words, for a plurality of antennas whose reception conditions fluctuate due to external factors, only the antenna in the optimal reception state is selected and used for reception, and the frequency at which transmission and reception are performed while sequentially switching the carrier frequency It cannot be applied to hopping wireless communication.
Japanese Patent Laying-Open No. 2003-169017 (for example, FIG. 6 to FIG. 8)

The present invention has been made in view of the above circumstances, and an object thereof is to appropriately perform wireless communication such as frequency hopping UWB communication.
Another object of the present invention is to provide a wireless communication system including an antenna capable of efficiently receiving weak radio waves and / or efficiently transmitting transmission radio waves in a frequency hopping UWB communication system and the like, and Another object is to provide a wireless communication method.

In order to achieve the above object, a wireless communication system according to a first aspect of the present invention includes:
A frequency hopping wireless communication system,
A plurality of antennas having different communication bands;
Control means for sequentially instructing switching of the carrier frequency;
Demodulation means for demodulating the signal from the antenna;
Based on an instruction from the control means, an antenna selection means for selecting any of the plurality of antennas and connecting to the demodulation means;
It is characterized by providing.

For example, the plurality of antennas includes a first antenna having a first communication band and a plurality of second antennas included in the first communication band and having second communication bands different from each other. ,
The demodulation means includes first demodulation means for demodulating a signal from the first antenna;
Second demodulation means,
The antenna selection means selects any one of the plurality of second antennas, and supplies the signal to the second demodulation means,
Demodulated signal selecting means for selecting one of the demodulated signal from the first demodulating means and the demodulated signal from the second demodulating means is further provided.

  Here, for example, the demodulated signal selection means compares the reception state of the first antenna with the reception state of the antenna selected by the antenna selection means, and based on the comparison result, the first and first One of the signals from the two demodulation means is selected.

  For example, the plurality of antennas are composed of a plurality of antennas having different communication frequencies and having mutually overlapping communication bands, the demodulation means includes first and second demodulation means, and the antenna selection means includes the antenna selection means Two antennas including a carrier wave having a frequency instructed by the control means are selected, a signal from one of the two selected antennas is sent to the first demodulation means, and a signal from the other one is sent Each is supplied to the second demodulation means.

  Demodulated signal selection means for comparing the reception state of the first antenna and the reception state of the second antenna and selecting one output of the first and second demodulation means based on the determination result is disposed May be.

The plurality of antennas include, for example, a plurality of antennas having different center frequencies and communication bandwidths, and each antenna is configured such that the communication band becomes wider as the center frequency becomes higher.
For example, at least one of the plurality of antennas is configured to include a plurality of carrier frequencies in a communication band.

  Transmission signal generation means for generating a transmission signal having a carrier frequency designated by the control means and transmitting the transmission signal to the common antenna, and antennas common to a plurality of carrier frequencies may be further arranged.

  Transmission signal generating means for generating a transmission signal of a carrier frequency specified by the control means, and information for identifying an antenna that has been in a predetermined good reception state when receiving a signal of a carrier frequency specified by the control means And a means for supplying the transmission signal generated by the transmission signal generation means to the antenna specified by the information stored in the storage means.

In order to achieve the above object, a wireless communication method according to a second aspect of the present invention includes:
A communication method for performing communication while switching the frequency of a carrier wave,
Prepare multiple antennas with different communication bands,
In response to switching of the carrier frequency, at least one of the plurality of antennas is selected, and communication using the carrier frequency is performed using the antenna.
It is characterized by that.

  According to the present invention, appropriate UWB communication can be performed.

(First embodiment)
FIG. 1 shows a configuration of a UWB communication system 1 according to a first embodiment of the present invention. As shown in the figure, the UWB communication system 1 includes at least two communication devices 11. The communication device 11 performs UWB wireless communication using a frequency hopping method.

  As shown in FIG. 2, each communication device 11 includes a control circuit 21, a local oscillator (LO) 22, a π / 2 phase shifter 23, a modulator 24, an adder 25, and a pulse amplifier (PA). 26, a first selection circuit 27, a broadband noise filter 28, a broadband antenna tenant 29, a second selection circuit 30, first to eighth narrowband noise filters 31a to 31h, and first to eighth narrowbands. Band antennas 32a to 32h, a first low noise amplifier (LNA) 33, a second low noise amplifier circuit 34, a first demodulator 35, a second demodulator 36, and an intensity determiner 37 And a third selection circuit 38 and mixers MX1 to MX6.

  The control circuit 21 stores a hopping pattern (frequency variation pattern) of the carrier frequency in an internal memory or the like, and instructs a local oscillator (LO: Local Oscillator) 22 to transmit a frequency according to the hopping pattern. Further, the control circuit 21 outputs a transmission / reception switching signal to the first selection circuit 27, and further outputs an antenna selection signal to the second selection circuit 30 at the time of reception.

  The local oscillator (LO) 22 outputs a carrier wave signal having a frequency designated by the control circuit 21 to the mixers MX1 to MX3 and the π / 2 phase shifter 23. The π / 2 phase shifter 23 shifts the carrier signal from the LO 22 by π / 2 radians and outputs it to the mixers MX4 to MX6.

  The modulator 24 is composed of, for example, a serial-parallel converter, converts transmission data into a baseband signal, generates an in-phase component I (t) and a quadrature component Q (t), and generates an in-phase component I ( t) is output to the mixer MX1, and the orthogonal component Q (t) is output to the mixer MX4.

  The mixer MX1 mixes and outputs the in-phase component I (t) and the carrier signal from the LO 22, and the mixer MX4 outputs the quadrature component Q (t) and the phase-shifted carrier signal from the π / 2 phase shifter 23. Are mixed and output.

  The adder 25 adds the signals from the mixers MX1 and MX4 to generate a pulsed modulation signal having a carrier frequency specified by the hopping pattern, and this pulsed modulation signal is supplied to a pulse amplifier (PA) 26. Supply.

  The pulse amplifier 26 amplifies and outputs this pulsed modulation signal.

The first selection circuit 27 connects the output terminal of the pulse amplifier 26 and the wideband noise filter 28 at the time of transmission according to the transmission / reception switching signal from the control circuit 21, and at the time of reception, the wideband noise filter 28 and the low noise amplifier (LNA1). 33 input terminals are connected.
The wideband noise filter 28 is composed of a bandpass filter having a passband that is substantially the entire carrier frequency used in the UWB communication system 1, and cuts a noise component included in the transmission / reception signal.

  The wideband antenna 29 is an antenna whose transmission / reception band is almost the entire carrier frequency used in the UWB communication system 1.

  The second selection circuit 30 connects any one of the narrowband noise filters 31 a to 31 h and the input terminal of the second low noise amplifier (LNA2) 34 according to the antenna selection signal from the control circuit 21.

  The narrow band noise filters 31a to 31h are each composed of a band pass filter having a relatively narrow pass band whose pass band is the reception band of the narrow band antennas 32a to 32h, and cuts noise components included in the received signal.

  The narrowband antennas 32a to 32h are antennas having each narrowband as a reception band when almost all the carrier frequency bands used in the UWB communication system 1 are divided into eight narrowbands.

  The first low noise amplifier circuit (LNA1) 33 amplifies a weak signal generated by receiving a radio signal with the wideband antenna 29 and outputs the amplified signal to the mixers MX2 and MX5.

The mixer MX2 mixes the output signal of the first low noise amplifier circuit 33 and the carrier signal from the LO 22 to reproduce the in-phase component I1 (t) of the demodulated signal and supplies it to the first demodulator 35.
The mixer MX5 mixes the output signal of the first low noise amplifier circuit 33 and the phase-shifted carrier signal from the π / 2 phase shifter 23 to reproduce the quadrature component Q1 (t) of the demodulated signal. 1 is supplied to the demodulator 35.

  The first demodulator 35 performs a demodulation operation such as phase determination, so that a signal received by the broadband antenna 29 is obtained from the in-phase component I1 (t) from the mixer MX2 and the quadrature component Q1 (t) from the mixer MX5. Play and output.

  The second low noise amplification circuit 34 amplifies a weak signal generated by receiving a radio signal by the narrowband antenna 32 (32a to 32h) selected by the second selection circuit 30, and mixes the mixers MX3 and MX6. Output to.

  The mixer MX3 mixes the output signal of the second low noise amplifier circuit 34 and the carrier signal from the LO 22 to reproduce the in-phase component I2 (t) of the demodulated signal and supplies it to the second demodulator 36.

  The mixer MX6 mixes the output signal of the second low noise amplifier circuit 34 and the phase-shifted carrier signal from the π / 2 phase shifter 23 to reproduce the quadrature component Q2 (t) of the demodulated signal. The signal is supplied to the demodulator 36.

  The second demodulator 36 performs a demodulation operation such as phase determination, so that the narrowband antenna 32 (selected from the in-phase component I2 (t) from the mixer MX3 and the quadrature component Q2 (t) from the mixer MX6 is selected. 32a to 32h) reproduce and output the signal received.

  The intensity determiner 37 determines the signal intensity of I1 (t), I2 (t), Q1 (t), and Q2 (t), and should select one of the output signals of the first and second demodulators 35 and 36. To the third selection circuit 38.

  The third selection circuit 38 selects and outputs one of the output signals from the first demodulator 35 and the second demodulator 36 in accordance with the selection signal from the intensity determiner 35.

Next, the relationship between the wideband antenna 29 and the narrowband antennas 32a to 32h will be described.
As shown in FIG. 3, the broadband antenna 29 uses the entire frequency band used for communication in the UWB communication system 1 as a transmission / reception band.
On the other hand, the narrowband antennas 32a to 32h have a relatively narrow band centered around the center frequencies f1 to f8 actually used for communication among the entire frequency bands used for communication in the UWB communication system 1 as reception bands. Since the band is narrowed, the gain is about several dB higher than the broadband antenna 29.

  The control circuit 21 controls the oscillation frequency of the LO 22 so that signals can be transmitted and received at the frequencies f1 to f8. The circuit configuration of FIG. 2 has one stage of mixer for both transmission and reception, so the oscillation frequency of LO 22 is, for example, f1 to f8. However, this is appropriately selected and set according to the number of stages of frequency conversion, circuit configuration, and the like.

Next, the operation of the communication apparatus 11 having the above configuration will be described.
First, the control circuit 21 has, for example, a frequency hopping pattern as illustrated in FIG. 4 in a memory or the like provided therein, and this hopping pattern is used during reception / transmission. In the hopping pattern of FIG. 4, for example, at the time of reception / transmission, the reception / transmission frequency is set to f1, f2,. . f8 and then f8, f7. . It is assumed that the change of decreasing to f1 is repeated. In consideration of the stability of the circuit and the margin for the time synchronization deviation of devices communicating with each other, pulses are not transmitted and received in a certain time zone before and after the frequency transition. FIG. 5 shows this state, where the pulse length is 6 ns and the non-transmission / reception times before and after are 2 ns.

  The communication device 11 on the transmission side modulates the transmission data in a pulse shape by 6 ns at the carrier frequency (f1, f2,... F8) specified by the hopping pattern and wirelessly transmits the modulated data at an interval of 4 ns. And the operation of transmitting the next pulse-shaped modulation signal is repeated, and the radio signal having the pattern shown in FIG. 5 is transmitted. On the other hand, the communication device 11 on the receiving side receives and demodulates the signal transmitted as shown in FIG. 5 according to the same frequency hopping pattern, and reproduces the transmission data.

(Transmission operation)
The control circuit 21 switches the first selection circuit 27 by the transmission / reception switching signal to connect the pulse amplifier 26 and the broadband noise filter 28, and switches the second selection circuit 30 by the antenna selection signal to change the second selection circuit 30. The low noise amplifier 34 and the narrow band noise filters 31a to 31h are electromagnetically separated.

  The control circuit 21 instructs the local oscillator 22 to oscillate in order to transmit data at the carrier frequency specified by the hopping pattern (instruct the carrier frequency) according to the time of an internal timer or the like. The local oscillator (LO) 22 supplies a signal having a predetermined frequency to the mixers MX1 to MX3 and the π / 2 phase shifter 23 in accordance with the instruction. The π / 2 phase shifter 23 shifts the carrier wave from the LO 22 by π / 2 radians and outputs the phase to the mixers MX4 to MX6.

  The modulator 24 converts the sequentially transmitted transmission data into a baseband signal, further generates an in-phase component I (t) and a quadrature component Q (t), and converts the in-phase component I (t) to the mixer MX1. Then, the orthogonal component Q (t) is output to the mixer MX4.

  The mixer MX1 mixes and outputs the in-phase component I (t) and the carrier wave signal from the local oscillator 22, and the mixer MX2 is phase-shifted from the quadrature component Q (t) and the π / 2 phase shifter 23. A carrier signal is mixed and output.

  The adder 25 adds the signals from the mixers MX1 and MX4 to generate a pulsed modulation signal having a carrier frequency designated by the control circuit 21, and supplies the pulsed modulation signal to the pulse amplifier (PA) 26. To do. The pulse amplifier 26 amplifies and outputs this pulsed modulation signal. The first selection circuit 27 guides the output signal of the pulse amplifier 26 to the broadband antenna 29 through the broadband noise filter 28 in accordance with the transmission / reception switching signal. As a result, the transmission signal from the pulse amplifier 26 is emitted into the air via the broadband antenna 29.

  The control circuit 21 sequentially switches the oscillation frequency of the local oscillator 22 according to the hopping pattern. Thereby, the transmission data as shown in FIG. 5 is modulated in the form of pulses with different carrier frequencies and transmitted.

(Reception operation)
In response to the transmission / reception switching signal, the control circuit 21 switches the first selection circuit 27 to connect the broadband noise filter 28 and the first low noise amplifier 33, and switches the second selection circuit 30 to receive at that time. The noise filter 31 and the second low noise amplifier 34 connected to the antenna 32 whose reception band is the frequency to be received (any one of f1 to f8) are connected. For example, if the carrier frequency of the hopping pattern is f2 at this time, the control signal 21 is sent to the second selection circuit 30 by the narrowband noise filter 31b and the second low noise amplifier 34 having f2 as the center frequency of the reception band. And connect.

  A weak signal generated by receiving a radio signal having a center frequency f2 by the broadband antenna 29 is supplied to the first low-noise amplifier circuit 33 via the broadband noise filter 28 and amplified to the mixers MX2 and MX5. Is output. The mixer MX2 mixes the output signal of the first low noise amplifier circuit 33 and the carrier signal from the LO 22 to reproduce the in-phase component I1 (t) of the demodulated signal and supplies it to the first demodulator 35. The mixer MX5 mixes the output signal of the first low-noise amplifier circuit 33 and the phase-shifted carrier signal from the π / 2 phase shifter 23 to reproduce the quadrature component Q1 (t) of the demodulated signal, 1 is supplied to the demodulator 35.

  The first demodulator 35 reproduces the received signal from the in-phase component I1 (t) from the mixer MX2 and the quadrature component Q1 (t) from the mixer MX5 by performing a demodulation operation such as phase determination, and outputs it. To do.

  On the other hand, the weak signal generated by receiving the radio signal by the narrowband antenna 32b is supplied to the second low noise amplifier circuit 34 via the narrowband noise filter 31b and the second selection circuit 30, and is amplified and mixed. It is output to MX3 and MX6. The mixer MX3 mixes the output signal of the second low noise amplifier circuit 34 and the carrier wave signal from the local oscillator 22 to reproduce the in-phase component I2 (t) of the demodulated signal and supplies it to the second demodulator 36. The mixer MX6 mixes the output signal of the second low-noise amplifier circuit 34 and the phase-shifted carrier signal from the π / 2 phase shifter 23 to reproduce the quadrature component Q2 (t) of the received signal. 2 is supplied to the demodulator 36.

  The second demodulator 36 reproduces the received signal from the in-phase component I2 (t) from the mixer MX3 and the quadrature component Q2 (t) from the mixer MX6 by performing a demodulation operation such as phase determination, and outputs it. To do.

  The strength determiner 37 compares the intensities of I1 (t) to Q2 (t), thereby obtaining a demodulated signal of the signal received by the wideband antenna 29 and a demodulated signal of the signal received by the narrowband antenna 31b. Either one having the higher signal level is discriminated and a selection signal is output.

  The third selection circuit 38 selects and outputs one of the demodulated signals of the first and second demodulators 35 and 36 according to the determination of the intensity determiner 37.

  Thereafter, the same operation is repeated while sequentially switching the reception frequency according to the hopping pattern.

  In such a configuration, since the gain of the narrowband antenna 32 (32a to 32h) is high, the strength determiner 37 normally selects the output signal of the second demodulator 36 to the third selection circuit 38. Instruct. However, in wireless communication, interference or the like occurs due to changes in the surrounding situation, and the reception state at the wideband antenna 29 may exceed the reception state at the narrowband antenna 32. In such a case, the signal intensities of I1 (t) and Q1 (t) become stronger than the signal intensities of I2 (t) and Q2 (t). The selection circuit 38 is instructed to select the output signal of the first demodulator 35, whereby a better received signal can be obtained.

(Application example of the first embodiment)
In FIG. 3, the transmission / reception frequency bands of the narrow band antenna 32 (32a to 32h) are set so as not to overlap each other. However, the present invention is not limited to this, and as shown in FIG. 6, the transmission / reception frequency bands of the narrowband antenna 32 may be set so as to partially overlap each other.

  In addition, the number of antennas may be reduced by setting the reception band of the narrowband antenna 32 without difficulty and setting so that one antenna can transmit and receive carrier waves of a plurality of frequencies. For example, as shown in FIG. 6, the reception band of the antenna 32e is set so as to include the carrier frequencies f5 and f6, the reception band of the antenna 32f is set so as to include the carrier frequencies f7 and f8, and the carrier frequency f9 is set. If the reception band of the antenna 32g is set to include f10 and f10, and the reception band of the antenna 32h is set to include the carrier frequencies f11, f12, and f13, 13 carrier frequencies are transmitted by eight antennas.・ Receivable.

  Similarly, for example, the reception band of the antenna 32a is set so as to include the carrier frequencies f1 and f2, the reception band of the antenna 32b is set so as to include the carrier frequencies f3 and f4, and the carrier frequencies f5 and f6 are set. If the reception band of the antenna 32c is set so as to include, and the reception band of the antenna 32d is set so as to include the carrier frequencies f7 and f8, eight carrier frequencies can be transmitted and received by the four antennas.

  Further, as shown in FIG. 6, the number of antennas can be reduced without degrading the antenna characteristics by expanding the band to be covered as the center frequency of the communication band of each antenna increases (for example, in proportion). It is possible to process a plurality of carrier frequencies with a small number of antennas.

  In addition, the selection of the reception data output from the first and second demodulators 35 and 36 is performed by determining the signal strength, but other methods can also be used. For example, when a certain number of bits are continuously contained in a carrier wave of one frequency and an error determination of the received data can be performed, the received data may be selected based on the error rate. In this case, in place of the strength determiner 37, the third selection circuit is to check the accuracy of the output data of the first and second demodulators 35 and 36 and select the output with the smaller error rate. A check circuit instructing to 38 is arranged.

(Second Embodiment)
In the first embodiment, only the wideband antenna 29 is used for transmission, but a plurality of narrowband antennas may be used for transmission. FIG. 7 shows a circuit block of the communication apparatus 11 having such a configuration.

  In the configuration shown in FIG. 7, the same components as those shown in FIG.

  In the configuration of FIG. 7, a plurality of narrowband transmission antennas 29a to 29d and noise filters 28a to 28d are arranged. Further, a fourth selection circuit 41 is disposed between the first selection circuit 27 and the noise filters 28a to 28d.

The fourth selection circuit 41 connects the first selection circuit 27 and any one of the noise filters 28 a to 28 d according to the antenna selection signal from the control circuit 21. In addition, a storage circuit 40 that stores the determination result by the intensity determiner 37 and outputs a selection signal to the first selection circuit 27 is disposed.
The antenna 32 is composed of four antennas 32a to 32d, and the noise filter 31 is composed of four noise filters 31a to 31d.

  FIG. 8 schematically shows gains of the antennas 29a to 29d and 32a to 32d. The antenna 29a exhibits the maximum gain with respect to the carrier frequency f1, but has a gain that can be received with respect to the carrier frequency f2. The antenna 32a exhibits the maximum gain with respect to the carrier frequency f2, but has a gain that can be received with respect to the carrier frequencies f1 and f3. Similarly, the antennas 29b to 29d and 32b to 32d include a carrier frequency indicating the maximum gain and a carrier frequency indicating a receivable gain in the communication band.

  When receiving the carrier frequency f1, the fourth selection circuit 41 selects the antenna 29a and the second selection circuit 30 selects the antenna 32a according to a command from the control circuit 21. In addition, the antenna selection at the time of receiving each frequency is as shown in Table 1 below.

 In such a configuration, in a normal state, since the signal strength from the antenna having the maximum gain at the frequency is maximum, the demodulated signal from the first or second demodulator 35 or 36 connected to the antenna is In response to an instruction from the strength determiner 37, the third selection circuit 38 selects the first demodulator 35 at the carrier frequencies f1, f3, f5, and f7, and the second demodulator 36 at the carrier frequencies f2, f4, f6, and f8. ). However, in wireless communication, interference occurs due to changes in the surrounding conditions, and the signal strength of the antenna having the maximum gain at the adjacent frequency located slightly away from it is higher than the antenna having the maximum gain in frequency. It can happen. For example, when the carrier frequency is f1, the signal strength from the antenna 29a may exceed the signal strength from the antenna 32a. In such a case, since the signal strengths of I2 (t) and Q2 (t) are superior to those of I1 (t) and Q1 (t), the strength determiner 37 detects this and selects the third selection. A good received signal can be obtained by switching the circuit 38.

Information indicating which of the two groups of antennas is in good condition at each frequency f1 to f8 at the time of reception is recorded in the storage circuit 40. When the communication apparatus 11 performs transmission, it reads out from the storage circuit 40 which antenna belongs to the antenna group 29 or 32 in the transmission frequency, and switches the first selection circuit 27. The output signal of the pulse amplifier 26 is connected to a good antenna.
With such a configuration, an optimal antenna can be selected and transmitted when the communication environment or the like changes due to the external environment.

In addition, this invention is not limited to the said embodiment, A various deformation | transformation and application are possible.
For example, each communication device 11 starts communication when one operating each communication device inputs the same hopping pattern in advance to each communication device, or inputs it each time. For this, a method of inputting a common ID, one address number, etc., instead of inputting the hopping pattern itself, and generating a hopping pattern by mathematical calculation from now on is widely known. It may be taken.

  Further, the communication device 11 further includes an error correction circuit that encodes an information signal with an error correction code in the modulation / demodulation circuit, thereby enabling wireless communication by various wireless communication methods. In addition to the above-described strength determination unit 37 for selecting received data, this error correction circuit can improve the quality of large-capacity data communication such as images, and enables further high-quality communication in UWB communication. .

  Further, the communication device 11 further includes a circuit for encrypting and decrypting the information signal in the modulation / demodulation circuit, and encrypting the information signal by various encryption methods and decrypting the information signal, thereby providing high confidentiality. It is also possible to perform high-quality information communication having

  Furthermore, it is a device connected to each communication device 11 via an arbitrary network, and transmits a frequency hopping pattern according to a request from each communication device 11, and / or a frequency hopping pattern to each communication device 11. The UWB communication system may be configured as a form including the instruction device by connecting an instruction device for instructing to the communication device.

It is a block diagram which shows an example of a structure of the radio | wireless communications system which concerns on the 1st Embodiment of this invention. It is a block diagram which shows an example of a structure of the communication apparatus concerning 1st Embodiment. It is a figure which shows the relationship between a frequency and the gain of each antenna. It is a figure which shows the example of the hopping pattern of frequency hopping. It is a frequency transition diagram in a communication apparatus. It is a figure which shows the other example of a relationship between a frequency and the gain of each antenna. It is a block diagram which shows an example of a structure of the communication apparatus concerning 2nd Embodiment. It is a figure which shows the further another example of a relationship between a frequency and the gain of each antenna. It is a figure for demonstrating UWB of a frequency hopping system. It is a graph which shows the example of the relationship between a frequency and power. It is a figure which shows the example of a structure of the communication apparatus of the conventional frequency hopping system.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... UWB communication system, 11 ... Communication apparatus, 29 ... Broadband antenna, 32 ... Narrowband antenna, 21 ... Control circuit

Claims (10)

A frequency hopping wireless communication system,
A plurality of antennas having different communication bands;
Control means for instructing switching of the carrier frequency;
Demodulation means for demodulating the signal from the antenna;
Based on an instruction from the control means, an antenna selection means for selecting any of the plurality of antennas and connecting to the demodulation means;
A wireless communication system comprising: The plurality of antennas include a first antenna having a first communication band and a plurality of second antennas included in the first communication band and having second communication bands different from each other,
The demodulating means includes first demodulating means for demodulating a signal from the first antenna;
Second demodulation means,
The antenna selection means selects any one of the plurality of second antennas and supplies the signal to the second demodulation means,
Demodulation signal selection means for selecting one of the demodulation signal from the first demodulation means and the demodulation signal from the second demodulation means,
The wireless communication system according to claim 1. The demodulated signal selection means compares the reception state of the first antenna with the reception state of the antenna selected by the antenna selection means, and based on the comparison result, from the first and second demodulation means Select one of the signals
The wireless communication system according to claim 2. The plurality of antennas are composed of a plurality of antennas having communication bands that have mutually different center frequencies and overlap each other.
The demodulating means includes first and second demodulating means,
The antenna selection unit selects two antennas including a carrier frequency instructed by the control unit in a communication band, and a signal from one of the two antennas is sent to the first demodulation unit and the other one Respectively, to the second demodulation means,
The wireless communication system according to claim 1.   Demodulating signal selecting means for comparing the receiving state of the first antenna and the receiving state of the second antenna and selecting one output of the first and second demodulating means based on the determination result; The wireless communication system according to claim 4, further comprising:   The plurality of antennas include a plurality of antennas having different center frequencies and communication bandwidths, and each antenna is configured such that a communication band becomes wider as the center frequency becomes higher. Item 6. The wireless communication system according to any one of Items 1 to 5.   The wireless communication system according to any one of claims 1 to 6, wherein at least one of the plurality of antennas is configured to include a plurality of carrier frequencies in a communication band. Transmission signal generation means for generating a transmission signal of a carrier frequency specified by the control means;
Antennas for multiple carrier frequencies;
The wireless communication system according to any one of claims 1 to 7, further comprising: Transmission signal generation means for generating a transmission signal of a carrier frequency specified by the control means;
Storage means for storing information for identifying an antenna that was in a predetermined good reception state when receiving a signal of a carrier frequency specified by the control means;
Means for supplying the transmission signal generated by the transmission signal generation means to the antenna specified by the information stored in the storage means;
The wireless communication system according to claim 1, further comprising: A communication method for performing communication while switching the frequency of a carrier wave,
Prepare multiple antennas with different communication bands,
In response to switching of the carrier frequency, at least one of the plurality of antennas is selected, and communication using the carrier frequency is performed using the antenna.
A wireless communication method.

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