JP2004048217A - Receiver, communication apparatus and integrated circuit used therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a receiver, a communication apparatus and an integrated circuit used therefor which are suited for such a communication terminal that takes a modulation system explicitly designated by a base station at the start of communication and continues the communication in the designated modulation system. <P>SOLUTION: A received signal is inputted to a modulation system determining means to determine a modulation system used for following communications. The receiving level detected by a receiving level detecting means is corrected and outputted in accordance with the determined modulation system. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a communication system using a plurality of modulation schemes, and in particular, in a short-range communication such as road-to-vehicle communication, discriminates a modulation scheme specified from a plurality of modulation schemes in a communicable area, and determines the communication scheme. The present invention relates to a receiving device, a communication device, and an integrated circuit used for the communication device.
[0002]
[Prior art]
For example, the on-vehicle device described in Japanese Patent Application Laid-Open No. 2001-307162 has a reception sensitivity switching circuit, and can switch the reception sensitivity and the modulator according to each application.
[0003]
[Problems to be solved by the invention]
In a road-to-vehicle communication system using narrow-area communication, it is necessary to switch the transmission speed by changing the modulation method even in the same application. Further, even in the same application, it is necessary to switch the minimum reception level depending on the modulation method.
According to the above prior art, it is necessary to switch the receiving sensitivity and the modulator according to the application, and it is necessary to specify the application in advance on the communication terminal side. For example, in a narrow-band communication system specified by ARIB STD-T75, a signal that has been subjected to ASK modulation is received and demodulated at the start of communication. In the demodulated data, a modulation method to be used thereafter is explicitly specified. Therefore, only the communication terminal corresponding to the designated modulation scheme can continue the communication.
An object of the present invention is to provide a receiving device, a communication device, and an integrated circuit used for a communication terminal that explicitly specify a modulation method from a base station at the start of communication and continue communication with the specified modulation method. It is in.
[0004]
[Means for Solving the Problems]
According to the first aspect of the present invention, the receiving modulation scheme determining means demodulates the received signal and determines the designated modulation scheme. The reception level detection means detects a reception level of the reception signal and outputs a signal corresponding to the reception level. The reception level correction means corrects and outputs the reception level detected by the reception level detection means according to the modulation scheme determined by the reception modulation scheme determination means. Therefore, when signals of different modulation schemes can be received and the reception level detection output differs according to the specified modulation scheme, correction is performed, and communication starts and ends according to the reception level regardless of the modulation scheme. And other communication controls.
[0005]
According to the second aspect of the present invention, the receiving modulation scheme determining means demodulates the received signal and determines the designated modulation scheme. The transmission level varying means can vary the transmission level of the transmission signal according to the control signal. The transmission level correction means controls the transmission level by controlling the transmission level varying means according to the modulation scheme determined by the reception modulation scheme determination means. Therefore, when communication using different modulation schemes is possible and the transmission level needs to be changed according to the specified modulation scheme, the transmission level can be corrected according to the modulation scheme to be used.
[0006]
According to the third aspect of the present invention, the receiving modulation scheme determining means demodulates the received signal and determines the designated modulation scheme. The plurality of modulation units can receive the transmission data, perform modulation according to each modulation scheme, and output a modulation signal. The modulation scheme switching means selects from the plurality of modulation means according to the determination of the reception modulation scheme determination means. Therefore, when communication using different modulation schemes is possible and it is necessary to change the modulation scheme of the transmission signal according to the specified modulation scheme, it is possible to select a modulation unit according to the modulation scheme to be used.
[0007]
According to the fourth aspect of the present invention, the receiving modulation scheme determining means demodulates the received signal and determines the designated modulation scheme. The base signal generation means receives the transmission data as input, and generates and outputs a base signal according to the modulation scheme determined by the reception modulation scheme determination means. The quadrature modulation unit receives the base signal generated by the base signal generation unit as input, performs quadrature modulation, and outputs a transmission signal. Therefore, when it is necessary to change the modulation scheme of the transmission signal according to the specified modulation scheme because communication using different modulation schemes is possible, generate a base signal according to the modulation scheme to be used, perform quadrature modulation, and perform transmission. The modulation scheme of the signal can be adapted.
[0008]
According to the fifth aspect of the present invention, the basis signal generating means of the fourth aspect comprises a serial / parallel conversion means and a filtering means. The serial / parallel means performs serial / parallel conversion of transmission data according to a rule according to the modulation scheme determined by the reception modulation scheme determination means, and separates the transmission data into in-phase signal data and quadrature signal data. The filtering unit filters each of the separated in-phase signal data and quadrature signal data with characteristics according to the modulation scheme determined by the reception modulation scheme determining unit. Therefore, when it is necessary to change the base signal used for quadrature modulation according to the specified modulation scheme, which allows communication using different modulation schemes, the base signal can be adapted according to the modulation scheme used.
[0009]
According to the sixth aspect of the present invention, in the receiving device, the communication device, and the integrated circuit according to the first to fifth aspects, an amplitude modulation method and an angle modulation method are used as the plurality of modulation methods. Therefore, the correction of the reception level and the correction of the transmission level are effective due to the features of the amplitude modulation method in which the amplitude greatly varies and the angle modulation method in which the amplitude does not vary much.
[0010]
According to the seventh aspect of the present invention, in the receiving apparatus, the communication apparatus, and the integrated circuit according to the first to fifth aspects, an ASK (Amplitude Shift Keying) modulation scheme and a π / 4 shift QPSK (Quadrature Phase Shift Keying) are used as a plurality of modulation schemes. A modulation method is used. Therefore, the correction of the reception level and the correction of the transmission level are effective due to the features of the ASK modulation method in which the amplitude fluctuates greatly and the π / 4 shift QPSK modulation method in which the amplitude does not change much.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to FIGS.
FIG. 1 is a diagram illustrating an example of a configuration of a receiving device according to an embodiment of the present invention.
In FIG. 1, 100 is a receiving antenna, 110 is frequency conversion means, 120 is intermediate frequency amplification means, 130 is π / 4 shift QPSK demodulation means, 140 is modulation scheme determination means, 141 is ASK demodulation means, 142 is ASK data analysis Means, 150 is a reception level detection means, and 160 is a reception level correction means.
[0012]
As the receiving antenna 100, an antenna of a type suitable for a frequency band to be used, such as a horn type or a patch type, is used. The receiving antenna 100 receives a radio signal transmitted from another communication device such as a base station, converts the radio signal into an electric signal, and outputs the electric signal. It is for.
The frequency conversion unit 110 is configured by an LNA (Low Noise Amplifier), a mixer, a high-frequency oscillator, and the like, and converts an input received signal into an intermediate frequency and outputs it.
The intermediate frequency amplifier 120 amplifies the received signal converted to the intermediate frequency by the frequency converter 110 to a level that can be demodulated by the subsequent demodulator and outputs the amplified signal.
The π / 4 shift QPSK demodulation means 130 includes a quadrature detector, an oscillator, a filter, a comparator, a clock recovery circuit, and the like, and demodulates the received π / 4 shift QPSK modulated intermediate frequency signal to demodulate the received signal. This is for outputting received data.
[0013]
The modulation method determining means 140 includes an ASK demodulating means 141 and an ASK data analyzing means 142.
The ASK demodulation means 141 includes an envelope detection circuit, a comparator, a clock recovery circuit, and the like, and is for demodulating the received intermediate-frequency ASK-modulated reception signal and outputting received data.
The ASK data analysis means 142 is constituted by a data processing circuit, analyzes received data output from the ASK demodulation means, and determines a modulation method to be used. It is also for outputting received data.
The reception level detection means 150 is for performing, for example, logarithmic detection using a part of the signal of the intermediate frequency amplification means 120 and outputting a detection signal corresponding to the reception level.
The reception level correcting means 160 corrects and outputs the output of the reception level detecting means 150 according to the modulation method determined by the ASK data analyzing means 142.
[0014]
FIG. 4 is a diagram showing an example of the characteristic of the detection voltage with respect to the reception level of the reception level detection means 150 according to one embodiment of the present invention.
According to ARIB STD-T75, the reception level of the ASK modulation signal is specified by the peak power, and the reception level of the π / 4 shift QPSK modulation signal is specified by the average power. Therefore, even at the same reception level, the ASK modulation signal differs from the π / 4 shift QPSK modulation signal as shown in FIG. Therefore, when the reception level Rx is input, the detection output of the reception level detection means 150 is a1 if the signal is an ASK modulation signal, and is a2 if the reception level Rx is a π / 4 shift QPSK modulation signal.
Therefore, it is possible to eliminate the difference between a1 and a2 by controlling the reception level correcting means 160 according to the modulation method determined by the modulation method determining means 140.
[0015]
According to the present embodiment, the reception modulation scheme determination unit 140 demodulates the received signal by the ASK demodulation unit 141 and determines the modulation scheme specified by the ASK data analysis unit 142. The reception level detection means 150 detects a reception level of a reception signal and outputs a signal corresponding to the reception level. The reception level correction means 160 corrects the reception level detected by the reception level detection means 150 according to the modulation scheme determined by the reception modulation scheme determination means 140 and outputs the result. Therefore, it is possible to receive the signal of the ASK modulation method and the signal of the π / 4 shift QPSK modulation method, and the reception level detection output is different due to the influence of the signal bandwidth and the filter depending on the specified modulation method. In such a case, the correction can be performed, and the communication control such as the communication start and the communication end can be accurately performed according to the reception level irrespective of the difference in the modulation method.
[0016]
Next, an embodiment of the present invention will be described with reference to FIG.
FIG. 2 is a diagram illustrating an example of a configuration of a communication device according to an embodiment of the present invention.
2, reference numeral 200 denotes a transmission antenna, 210 denotes a transmission level correction unit, 220 denotes a transmission level variable unit, 230 denotes a modulation scheme switching unit, 240 denotes an ASK modulation unit, and 250 denotes a π / 4 shift QPSK modulation unit.
1 have the same functions.
ASK modulating means 240 receives transmission data as input, filters unnecessary high frequency signals, performs amplitude modulation, and outputs the result.
The π / 4 shift QPSK modulator 250 receives transmission data as input, filters unnecessary high frequency signals, performs π / 4 shift QPSK modulation, and outputs the result.
The modulation scheme switching section 230 receives the modulation signal output from the ASK modulation section 240 and the modulation signal output from the π / 4 shift QPSK modulation section 250 as inputs, and outputs the modulation signal from the modulation section determined by the modulation scheme determination section 140. Select and output modulation output.
[0017]
The transmission level correction unit 210 controls the transmission level of the transmission level variable unit 220 according to the modulation scheme determined by the modulation scheme determination unit 140.
The transmission level varying means 220 receives the signal from the modulation scheme switching means 230 as input, varies the transmission level according to the control signal of the transmission level correction means 210, and outputs the result.
The transmission antenna 200 receives the transmission signal from the transmission level varying unit 220 and outputs the transmission signal.
[0018]
According to the present embodiment, the receiving modulation scheme determining unit 140 demodulates the received signal and determines the designated modulation scheme. The transmission level varying means 220 can vary the transmission level of the transmission signal according to the control signal. The transmission level correction unit 210 controls the transmission level by controlling the transmission level varying unit 220 in accordance with the modulation scheme determined by the reception modulation scheme determination unit 140. Therefore, when communication using different modulation schemes is possible and the transmission level needs to be changed according to the specified modulation scheme, the transmission level can be corrected according to the modulation scheme to be used.
Further, the ASK modulating means 240 and the π / 4 shift QPSK modulating means 250 can receive the transmission data, perform modulation according to each modulation scheme, and output a modulated signal. The modulation scheme switching means 230 performs selection from the plurality of modulation means according to the determination of the reception modulation scheme determination means 140. Therefore, when communication using different modulation schemes is possible and it is necessary to change the modulation scheme of the transmission signal according to the specified modulation scheme, it is possible to select a modulation unit according to the modulation scheme to be used.
[0019]
Next, an embodiment of the present invention will be described with reference to FIG.
FIG. 3 is a diagram illustrating an example of a configuration of a communication device according to an embodiment of the present invention.
In FIG. 3, reference numeral 260 denotes an orthogonal modulation unit, 270 denotes a base signal generation unit, 271 denotes a filtering unit, and 272 denotes an orthogonal / parallel conversion unit.
1 and 2 have the same functions.
The base signal generation unit 270 includes a serial / parallel conversion unit 272 and a filtering unit 271.
The serial / parallel converter 272 includes a digital circuit, a delay circuit, and the like, and performs serial / parallel conversion using transmission data as input to create in-phase signal data and quadrature signal data required for quadrature modulation.
[0020]
The filtering means 271 includes a digital signal processing circuit, a digital-to-analog conversion circuit, and the like, filters the in-phase signal data and the quadrature signal data, and outputs the in-phase signal and the quadrature signal necessary for quadrature modulation.
The quadrature modulation means 260 is composed of a quadrature modulator, an oscillator and a phase shifter, multiplies the input in-phase signal and quadrature signal by the oscillator output shifted by the phase shifter, and adds the multiplied signals to transmit as a transmission modulation signal. Output to antenna 200.
[0021]
According to this embodiment, the base signal generation unit 270 receives transmission data as input, and generates and outputs a base signal according to the modulation scheme determined by the reception modulation scheme determination unit 140. The orthogonal modulator 260 receives the base signal generated by the base signal generator 270 as input, performs orthogonal modulation, and outputs a transmission signal. Therefore, when communication using different modulation schemes is possible and it is necessary to change the modulation scheme of the transmission signal according to the specified modulation scheme, a base signal corresponding to the modulation scheme to be used is generated, and orthogonal modulation is performed to perform transmission. The modulation scheme of the signal can be adapted.
[0022]
Further, the base signal generation unit 270 is configured by a serial / parallel conversion unit 272 and a filtering unit 271. The serial / parallel unit 272 performs serial / parallel conversion of transmission data according to a rule according to the modulation scheme determined by the reception modulation scheme determination unit 140, and creates in-phase signal data and quadrature signal data. The filtering means 271 filters the separated in-phase signal data and quadrature signal data with characteristics according to the modulation scheme determined by the reception modulation scheme determining means 140. Therefore, when it is necessary to change the base signal used for quadrature modulation according to the specified modulation scheme, which allows communication using different modulation schemes, the base signal can be adapted according to the modulation scheme used. Further, by forming the base signal generation means 270 as an integrated circuit, a small and inexpensive device can be produced.
[0023]
As the filtering means 271, a method of using analog signal processing by discrete components, a method of performing digital signal processing by data processing, and outputting an analog signal by a digital-to-analog converter can be applied. In the case of performing by digital signal processing, it is easy to change the characteristic according to the modulation method by changing the algorithm of digital signal processing. Further, since discrete components are not used, it is suitable for integration into an integrated circuit.
[0024]
In the present invention, the receiving modulation scheme determining means demodulates the received signal and determines the designated modulation scheme. The reception level detection means detects a reception level of the reception signal and outputs a signal corresponding to the reception level. The reception level correction means corrects and outputs the reception level detected by the reception level detection means according to the modulation scheme determined by the reception modulation scheme determination means. Therefore, when signals of different modulation schemes can be received and the reception level detection output differs according to the specified modulation scheme, correction is performed, and communication starts and ends according to the reception level regardless of the modulation scheme. And other communication controls.
Further, the transmission level varying means can vary the transmission level of the transmission signal according to the control signal. The transmission level correction means controls the transmission level by controlling the transmission level varying means according to the modulation scheme determined by the reception modulation scheme determination means. Therefore, when communication using different modulation schemes is possible and the transmission level needs to be changed according to the specified modulation scheme, the transmission level can be corrected according to the modulation scheme to be used.
[0025]
Further, the plurality of modulating units can receive the transmission data, perform modulation according to each modulation scheme, and output a modulated signal. The modulation scheme switching means selects from the plurality of modulation means according to the determination of the reception modulation scheme determination means. Therefore, when communication using different modulation schemes is possible and it is necessary to change the modulation scheme of the transmission signal according to the specified modulation scheme, it is possible to select a modulation unit according to the modulation scheme to be used.
The base signal generation means receives the transmission data as input, and generates and outputs a base signal according to the modulation scheme determined by the reception modulation scheme determination means. The quadrature modulation unit receives the base signal generated by the base signal generation unit as input, performs quadrature modulation, and outputs a transmission signal. Therefore, when it is necessary to change the modulation scheme of the transmission signal according to the specified modulation scheme because communication using different modulation schemes is possible, generate a base signal according to the modulation scheme to be used, perform quadrature modulation, and perform transmission. The modulation scheme of the signal can be adapted.
[0026]
On the other hand, the base signal generating means includes a serial / parallel conversion means and a filtering means. The serial / parallel means performs serial / parallel conversion of transmission data according to a rule according to the modulation scheme determined by the reception modulation scheme determination means, and separates the transmission data into in-phase signal data and quadrature signal data. The filtering unit filters each of the separated in-phase signal data and quadrature signal data with characteristics according to the modulation scheme determined by the reception modulation scheme determining unit. Therefore, when it is necessary to change the base signal used for the quadrature modulation according to the designated modulation scheme, which allows communication using different modulation schemes, the base signal can be adapted according to the modulation scheme to be used.
By using the amplitude modulation method and the angle modulation method as the plurality of modulation methods, the correction of the reception level and the correction of the transmission level are effective due to the characteristics of the amplitude modulation method in which the amplitude fluctuates greatly and the angle modulation method in which the amplitude does not fluctuate much. It is.
By using an ASK (Amplitude Shift Keying) modulation scheme and a π / 4 shift QPSK (Quadrature Phase Shift Keying) modulation scheme as the plurality of modulation schemes, an ASK modulation scheme in which the amplitude greatly fluctuates and a π / 4 in which the amplitude does not fluctuate much are used. Due to the characteristics of the shift QPSK modulation method, correction of the reception level and correction of the transmission level are effective.
[0027]
【The invention's effect】
In the present invention, when the reception level detection output is different according to the specified modulation scheme capable of receiving a signal of a different modulation scheme, correction is performed and communication is started according to the reception level, regardless of the difference between the modulation schemes, Communication control such as communication termination can be performed.
[0028]
Further, according to the present invention, when communication using different modulation schemes is possible and the transmission level needs to be changed according to the specified modulation scheme, the transmission level can be corrected according to the modulation scheme to be used.
[0029]
Further, according to the present invention, when it is necessary to change the modulation scheme of a transmission signal according to a specified modulation scheme, which allows communication using different modulation schemes, a modulation unit can be selected according to a modulation scheme to be used. .
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an example of a configuration of a receiving device according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating an example of a configuration of a communication device according to an embodiment of the present invention;
FIG. 3 is a diagram showing an example of a configuration of a communication device according to an embodiment of the present invention.
FIG. 4 is an example of a characteristic of a detection voltage with respect to a reception level of a reception level detection unit according to an embodiment of the present invention.
[Explanation of symbols]
100 receiving antenna 110 frequency converting means 120 intermediate frequency amplifying means 130 π / 4 shift QPSK demodulating means 140 modulation method determining means 141 ASK demodulating means 142 ASK data analyzing means 150 receiving level detecting means 160 receiving Level correction means 200 transmission antenna 210 transmission level correction means 220 transmission level variable means 230 modulation method switching means 240 ASK modulation means 250 π / 4 shift QPSK modulation means 260 orthogonal modulation means 270 base signal generation means 271… Filtering means 272… Serial / parallel conversion means

Claims (8)

In a receiving apparatus used in a communication system in which a modulation scheme to be used for subsequent communication is specified by data received first,
Demodulating the received signal, a receiving modulation scheme determining means for determining a designated modulation scheme,
A reception level detection unit that outputs a signal corresponding to a reception level of the reception signal,
A receiving apparatus comprising: a reception level correction unit that corrects an output of the reception level detection unit according to a modulation scheme determined by the reception modulation scheme determination unit. In a communication device used for a communication system in which a modulation method to be used for subsequent communication is specified by data received first,
Demodulating the received signal, a receiving modulation scheme determining means for determining a designated modulation scheme,
A transmission level varying unit that varies a transmission level of the transmission signal;
A communication apparatus, comprising: a transmission level correction unit that controls the transmission level variable unit to correct a transmission level according to a modulation scheme selected by the reception modulation scheme determination unit. In a communication device used for a communication system in which a modulation method to be used for subsequent communication is specified by data received first,
Demodulating the received signal, a receiving modulation scheme determining means for determining a designated modulation scheme,
A plurality of modulation means for inputting transmission data and outputting a modulated transmission signal,
A communication apparatus, comprising: a modulation unit switching unit that selects one of the plurality of modulation units and switches a transmission signal in accordance with a modulation system selected by the reception modulation system determination unit. In a communication device used for a communication system in which a modulation method to be used for subsequent communication is specified by data received first,
Demodulating the received signal, a receiving modulation scheme determining means for determining a designated modulation scheme,
Base signal generation means for generating a base signal required for quadrature modulation from transmission data according to the modulation scheme determined by the reception modulation scheme determination means,
A communication device comprising: a quadrature modulation unit that receives the base signal, performs quadrature modulation, and outputs a modulation signal. The base signal generation means according to claim 4 comprises at least serial / parallel conversion means for serial / parallel conversion of transmission data and filtering means for filtering a signal converted in parallel,
The conversion method of the serial / parallel conversion means, the filtering characteristic of the filtering means is controlled according to the modulation scheme determined by the reception modulation scheme determination means, and the base signal generation means, 5. The integrated circuit used in the communication device according to claim 4, further comprising a basis generation unit. 2. The receiving apparatus according to claim 1, wherein at least an amplitude modulation method and an angle modulation method are used as the plurality of modulation methods. 5. The communication device according to claim 2, wherein at least an amplitude modulation method and an angle modulation method are used as the plurality of modulation methods. 5. The communication device according to claim 2, wherein at least the ASK modulation method and the π / 4 shift QPSK modulation method are used as the plurality of modulation methods.

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