JP2003318999A - Modulation circuit, demodulation circuit and radio device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To flexibly cope with a plurality of modulation/demodulation schemes. <P>SOLUTION: A modulation circuit 100 is provided with a QPSK modulation circuit 102, an 8PSK modulation circuit 103, a 64QAM modulation circuit 104, a diffusion modulation circuit 107, a first OFDM modulation circuit 110, a second OFDM modulation circuit 111, switches 101, 105, 106, 108, 109 and 112 for switching a connection relationship for each modulation circuit, and a modulation control circuit 115 for flexibly coping with a plurality of modulation schemes by switching a modulation route by controlling the respective switches. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a modulation circuit for performing digital modulation, a demodulation circuit for performing digital demodulation, and a radio apparatus including both.

[0002]

2. Description of the Related Art In recent years, with the development of information communication technology, it has become possible to exchange a large amount of data as well as voice. Among them, in mobile communication systems that make full use of wireless communication technology, mobile phones are becoming smaller and lighter,
Since it is possible to easily talk with anyone anytime, anywhere, and data communication such as e-mail or Internet, the number of users is increasing year by year and various services are being provided.

In mobile communication systems utilizing such wireless communication techniques, various digital modulation / demodulation techniques are used in order to efficiently transmit information in limited radio wave resources. Taking the mobile phone system, which is widely used at present, as an example, the carrier wave is 800 MHz band,
Quasi-microwave bands such as 1.5 GHz band, 1.9 GHz band and 2.1 GHz band are used. In addition, as a modulation method, QPSK (Quadrature Phase Shift Keying),
QAM (Quadrature Amplitude Modulation), GMS
Digital modulation techniques such as K (Gaussian filtered Minimum Shift Keying) have been put to practical use. Furthermore, as an access method, FDMA (Frequency Division Multipl
e Access), TDMA (Time Division Multiple Acces)
s), CDMA (Code Division Multiple Access), O
FDM (Orthogonal Frequency Division Multiplex)
Each method such as has been put to practical use.

Recently, a commercial service of a third-generation mobile communication system adopting a CDMA system applying a spread spectrum technology is started, and an information transmission rate of 384 kbps is realized in a mobile communication environment by using a frequency band of 5 MHz. Has been done. Hereinafter, a conventional radio apparatus based on the CDMA system to which the spread spectrum technique is applied will be described with reference to the drawings.

FIG. 5 is a block diagram showing a configuration example of a conventional radio apparatus. Note that, in FIG. 5, a configuration example of a wireless device based on a general direct spread method (DS-CDMA) is shown separately for a transmitter (1) and a receiver (2). However,
Multiplexing circuits, synchronizing circuits, various filters, etc. are omitted.

The transmitter shown in FIG. 5A has a QPSK modulating circuit 501, a spreading circuit 502, and a D / A converter 503.
A low pass filter (LPF) 504, a quadrature modulator 505, an up converter 506, a local oscillator 507, a power amplifier 508, and a transmission antenna 509.
It has and.

In the transmitter configured as described above, transmission data is mapped on the IQ plane by the QPSK modulation circuit 501. The data mapped on the IQ plane is spread and modulated by the spreading code in the spreading circuit 502. The signal spread-modulated by the spreading circuit 502 is converted into an analog signal by the D / A converter 503, and band-limited by the LPF 504.

A baseband signal composed of an I signal (in-phase component signal) and a Q signal (quadrature component signal) whose band is limited by the LPF 504 is subjected to quadrature modulation processing by a quadrature modulator 505, and an intermediate frequency signal (IF signal). ) Is converted to. The IF signal converted by the quadrature modulator 505 is frequency-converted by the up converter 506 into a transmission frequency based on the local signal from the local oscillator 507. The transmission signal frequency-converted to the transmission frequency is the power amplifier 508.
The power is amplified at and transmitted from the transmission antenna 509 to the free space.

The receiver shown in FIG. 5B has a receiving antenna 510, a low noise amplifier 511, a down converter 512, a local oscillator 513, a quadrature demodulator 514, and a low pass filter (LPF) 515. , A /
The D converter 516, the despreading circuit 517, and the QPSK demodulation circuit 518 are provided.

In the receiver configured as above, the received signal received by the receiving antenna 510 is amplified to a predetermined level by the low noise amplifier 511, and the down converter 512 outputs the local signal from the local oscillator 513. The frequency is converted into an IF signal based on.

The received signal frequency-converted into an IF signal is
The quadrature demodulator 514 receives the quadrature demodulation process, converts it into a baseband signal composed of an I signal (in-phase component signal) and a Q signal (quadrature component signal), receives a band limiting process in the LPF 515, and then an A / D converter At 516, it is converted into a digital signal. The digital baseband signal composed of the I signal and the Q signal output from the A / D converter 516 is a despreading circuit 517.
Despreading is performed by the spreading code at QPSK
The demodulation circuit 518 demodulates the original data and outputs it as received data.

By the way, as a result of the operation of a wide variety of wireless communication systems, there is an increasing demand for a plurality of wireless communication systems to be handled by a single terminal. In a familiar example, if it is now possible to handle mobile phone systems with different systems in different countries with a single terminal, it will be possible to use mobile phones around the world without having to prepare a mobile phone terminal according to the system. It becomes extremely convenient.

Furthermore, if a portable radio terminal with a high flexibility that can switch the modulation method according to the radio wave reception state in which the terminal is placed is put into practical use, the user only has to carry one terminal. You will be able to receive a wide variety of services seamlessly. As described above, there is an increasing expectation for realizing a flexible wireless terminal capable of supporting a plurality of frequency bands, modulation methods, and communication methods.

[0014]

However, the conventional radio apparatus is designed so that transmission / reception is performed by a specific modulation / demodulation method, and the modulation / demodulation method cannot be easily changed. For example, in the transmitter shown in FIG. 5, in the transmitter, a modulation circuit for mapping data on the IQ plane such as the QPSK modulator 501 and a spreading circuit 502 for spreading and modulating the modulated data by a spreading code are serialized. It is connected. Similarly, in the receiver, the despreading circuit 517 and the QPSK demodulation circuit 518 are serially connected. The pass band width (frequency characteristics) and phase characteristics of these processing circuits and filters are usually designed as dedicated fixed circuits. As described above, the wireless device shown in FIG. 5 has a configuration that does not have a modulation / demodulation function other than the DS-CDMA system, and that the modulation / demodulation system cannot be changed.

As described above, since the conventional wireless device is designed only for a specific wireless communication system, a plurality of wireless communication systems cannot be used by one wireless device. When configuring a wireless device compatible with a plurality of wireless communication systems, the commonly usable parts are extremely limited, and even if implemented, it is very complicated and the number of parts is large. Therefore, it consumes a large amount of power, is large, heavy, and expensive, and is not practical.

The present invention has been made in view of the above points, and an object of the present invention is to provide a modulation circuit, a demodulation circuit, and a radio apparatus including both of them, which can flexibly support a plurality of modulation / demodulation systems with a simple structure. To do.

[0017]

A modulation circuit according to the present invention is a modulation circuit for performing digital modulation, in which any one or a combination of phases, amplitudes and frequencies of a carrier wave is changed by digital information. One or more modulating means are arranged in the input stage of the data signal to be modulated, and one or more spreading means for subjecting the digital information to the spread modulation by the spreading code are arranged in the intermediate stage to convert the digital information into a plurality of low speed data signals. One or more OFDM modulating means for dividing and modulating are arranged in the output stage of the modulated data signal, and the data signal to be modulated passes through the input stage, the intermediate stage and the output stage in this order. A configuration is provided that includes a path switching unit that selects and switches the modulation processing path when receiving the modulation processing.

According to this structure, one or more modulation means and one
By selecting and switching a plurality of modulation processing paths passing through the above spreading means and one or more OFDM modulating means,
It is possible to easily carry out a series of modulation processing including a combination of various modulation means on the data signal to be modulated.

In the modulation circuit according to the present invention, in the above-mentioned invention, the path switching means selects a path which is not subjected to modulation processing in one or both of the intermediate stage and the output stage.

With this configuration, it is possible to support a communication system that does not employ a spreading means or an OFDM modulating means.

The modulation circuit according to the present invention comprises, in the above-mentioned invention, a D / A conversion means for converting a data signal output from the output stage and subjected to a predetermined modulation processing into an analog signal, and switching the path. The means adopts a configuration in which the sampling frequency of the D / A conversion means is variably controlled.

With this configuration, the sampling frequency of the D / A conversion means can be adjusted to the modulation system.

In the modulation circuit according to the present invention, in the above invention, a digital filter for subjecting the data signal outputted from the output stage to the predetermined modulation processing to band limitation processing, and an output data signal of the digital filter are provided. D / A conversion means for converting into an analog signal, wherein the path switching means has a pass characteristic of the digital filter and the D / A conversion means.
The configuration is such that the sampling frequency of the A conversion means is variably controlled together.

With this configuration, the sampling frequency and pass band characteristic of the D / A conversion means can be matched with the modulation method.

In the above-mentioned invention, the modulation circuit according to the present invention is on the selected modulation processing path among the power supplies supplied to the modulation means arranged in each of the input stage, the intermediate stage and the output stage. The power supply control means for stopping the power supply to the modulation means not located at is adopted.

According to this structure, low power consumption can be achieved.

The demodulation circuit according to the present invention is a demodulation circuit for performing digital demodulation, and is one or more OFDs for demodulating a plurality of modulated low speed data signals to obtain original high speed data signals.
The M demodulation means is arranged at the input stage of the data signal to be demodulated,
Modulation in which one or more despreading means for performing despreading demodulation on a digital information by a spreading code is arranged in an intermediate stage, and one or some combination of carrier wave phase, amplitude, and frequency is changed by digital information. One or more demodulation means for demodulating the signal into the original data signal are arranged at the output stage of the demodulated data signal, and the data signal to be demodulated passes through the input stage, the intermediate stage and the output stage in this order. Then, a structure is provided which includes a path switching means for selecting and switching a demodulation processing path when receiving the demodulation processing.

According to this structure, one or more demodulation means and one
By selecting and switching a plurality of demodulation processing paths passing through the above spreading means and one or more OFDM demodulating means,
It is possible to easily carry out a series of demodulation processing including a combination of various demodulation means on the data signal to be demodulated.

In the demodulation circuit according to the present invention, in the above invention, the path switching means selects a path that is not demodulated in one or both of the input stage and the intermediate stage.

According to this configuration, despreading means and OFDM
It is possible to support a communication system that does not employ a demodulation means.

The demodulation circuit according to the present invention comprises, in the above-mentioned invention, an A / D conversion means for converting the received analog signal into a digital signal and generating the data signal to be demodulated, and the path switching means. , A configuration for variably controlling the sampling frequency of the A / D conversion means is adopted.

With this configuration, the sampling frequency of the D / A conversion means can be adjusted to the demodulation method.

In the demodulation circuit according to the present invention, in the above invention, A / D conversion means for converting the received analog signal into a digital signal and band limiting processing for the digital signal output by the A / D conversion means. And a digital filter for generating the data signal to be demodulated, and the path switching means variably controls both the sampling frequency of the A / D conversion means and the pass characteristic of the digital filter.

According to this structure, the sampling frequency and pass band characteristic of the D / A conversion means can be matched with the demodulation method.

In the demodulation circuit according to the present invention, in the above invention, on the demodulation processing path selected among the power supplies supplied to the demodulation means arranged in each of the input stage, the intermediate stage and the output stage. The power supply control means for stopping the power supply to the demodulation means not located at is adopted.

According to this structure, low power consumption can be achieved.

A radio apparatus according to the present invention has a configuration including at least one circuit of any one of the modulation circuits according to the above invention and one of the demodulation circuits according to the above invention.

According to this structure, a very large number of combinations of modulation / demodulation systems can be realized with a simple structure, so that a plurality of modulation / demodulation systems can be flexibly accommodated, and low power consumption, small size and light weight can be achieved. A wireless device can be obtained.

[0039]

BEST MODE FOR CARRYING OUT THE INVENTION The essence of the present invention is to enable a single wireless device to flexibly support a plurality of modulation / demodulation systems.

Embodiments of the present invention will be described in detail below with reference to the drawings.

(Embodiment 1) FIG.1 is a block diagram showing a configuration of a transmitter as a radio apparatus according to Embodiment 1 of the present invention.

The transmitter shown in FIG. 1 has QPSK modulation, 8P.
SK modulation, 64QAM modulation, spread modulation, 2 types of OFD
A modulation circuit 100 that realizes a total of 18 types of modulation functions that combine M modulation, and an I signal and a Q output by the modulation circuit 100.
A low-pass filter (LPF) 117 that limits the band of a baseband signal composed of a signal, a quadrature modulator 118 that converts the baseband signal that is band-limited by the LPF 117 into an IF signal, and a quadrature modulator 118 that converts the baseband signal. I
Up converter 1 for frequency-converting an F signal into a transmission frequency based on a local signal from a local oscillator 120
19, a power amplifier 121 for power-amplifying a transmission signal frequency-converted to a transmission frequency, and a transmission antenna 122 for transmitting the transmission signal output by the power amplifier 121 to a free space.
It has and.

The modulation circuit 100 is provided with a switch 101 for switching the input transmission data to three routes and outputting it, and a Q provided corresponding to the three switching output terminals of the switch 101.
PSK modulation circuit 102, 8 PSK modulation circuit 103 and 6
A switch 105 having a 4QAM modulation circuit 104 and three switching input terminals corresponding to the output terminals of the three modulation circuits.
A switch 106 for switching and outputting the output of the switch 105 in two ways; a spreading modulation circuit 107 for receiving a signal from one switching output end of the switch 106; a switching of the output of the spreading modulation circuit 107 and the other of the switches 106; A switch 108 for receiving a signal from the output terminal is provided.

Further, the modulation circuit 100 includes a switch 10
Switch 109 for switching the output of 8 to the three-way output
And the first OFDM modulation circuit 1 provided corresponding to two switching output terminals of the three switching output terminals of the switch 109.
10 and the second OFDM modulation circuit 111, and the two O
A switch 112 for receiving each output of the FDM modulation circuit and a signal from the remaining switching output terminal of the switch 109, a D / A converter 113 for receiving an output of the switch 112 and outputting an analog baseband signal to the LPF 117, Power supply control circuit 1 for controlling power supply to the five modulation circuits
14 and a modulation control circuit 115 that implements 18 types of modulation functions by controlling the switching of the six switches.

The QPSK modulation circuit 102, the 8PSK modulation circuit 103 and the 64QAM modulation circuit 104 respectively map the transmission data on the IQ plane. The spread modulation circuit 107 directly spreads using a spread code. The first OFDM modulation circuit 110 and the second OFDM modulation circuit 111 have different numbers of subcarriers and different frequency intervals, divide a high-speed data signal into a plurality of low-speed data signals, and modulate each of them to form a narrowband signal. .

Next, the modulation operation realized by the transmitter having the above configuration will be described with reference to the flow chart shown in FIG.

When the transmission data is input (step S2
01), the modulation control circuit 115 interlocks with the switch 101 and the switch 105 to select the modulation method to be applied (step S202). As a result, the transmitted data is
QPSK modulation circuit 102, 8 PSK modulation circuit 103, 6
Input to any of the 4QAM modulation circuits 104, and QPSK
Modulation (step S203), 8PSK modulation (step S203)
204) or 64QAM modulation (step S205). The complex data mapped on the IQ plane is output from the switch 105 to the switch 106.

Next, the modulation control circuit 115 interlocks with the switch 106 and the switch 108 to make the switch 1
It is selected whether or not spread modulation is applied to the 01 output data signal (step S206). When performing spread modulation, the output data signal of the switch 105 is input to the spread modulation circuit 107, directly spread modulated, and output from the switch 108 to the switch 109 (step S207). When the spread modulation is not performed, the output data signal of the switch 105 is directly transmitted from the switch 106 to the switch 108 and output from the switch 108 to the switch 109.

Next, the modulation control circuit 115 interlocks with the switch 109 and the switch 112 to make the switch 1
It is selected whether or not OFDM modulation is applied to the 08 output data signal (step S208). When performing OFDM modulation, the output data signal of the switch 108 is converted into the first OFDM signal.
It is given to either the modulation circuit 110 or the second OFDM modulation circuit 111. Accordingly, the first OFDM modulation circuit 110
The modulation process (step S209) by the second OFDM modulation circuit 111 or the modulation process (step S210) by the second OFDM modulation circuit 111 is performed, and the switch 112 switches the D / A converter 113.
Is output to. When the OFDM modulation is not applied, the output data signal of the switch 108 is the switch 109.
Is directly transmitted to the switch 112, and is output from the switch 112 to the D / A converter 113.

Thus, in the modulation circuit 100, (1) Q
PSK modulation / spreading modulation / first OFDM modulation modulation processing path, (2) 8PSK modulation / spreading modulation / first OFDM modulation processing path, and (3) 64QAM modulation / spreading modulation / first OFDM modulation processing path , (4) QPSK
A modulation / spreading / second OFDM modulation processing path,
(5) Modulation processing path of 8PSK modulation / spreading modulation / second OFDM modulation, and (6) 64QAM modulation / spreading modulation / second
Modulation processing path for OFDM modulation and (7) QPSK modulation
Modulation processing path for the first OFDM modulation, (8) 8PSK modulation / modulation processing path for the first OFDM modulation, and (9) 64Q
A modulation processing path of AM modulation / first OFDM modulation, and (1
0) QPSK modulation / second OFDM modulation modulation processing path, (11) 8PSK modulation / second OFDM modulation modulation processing path, (12) 64QAM modulation / second OFDM modulation modulation processing path, (13) QPSK modulation Spreading modulation processing path, (14) 8PSK modulation / spreading modulation processing path, (15) 64QAM modulation / spreading modulation / first OFDM modulation processing path, and (16) QPSK modulation only processing path Then, a baseband signal composed of an I signal and a Q signal is generated in any one of (17) 8PSK modulation processing path and (18) 64QAM modulation only modulation processing path.

The generated baseband signal is converted into an analog signal by the D / A converter 113 (step S2).
11), after being band-limited by the LPF 117, it is quadrature-modulated by the quadrature modulation circuit 118 (step S212) and becomes a transmission signal by the up converter 119 (step S213).

Thus, according to the first embodiment,
It can support 18 types of modulation methods. For example,
Of the 18 types of modulation processing paths described above, (13)
In the modulation processing path of QPSK modulation / spreading modulation, digital modulation compatible with the third generation mobile communication is possible. Also, (9) 64QAM modulation / first OFDM modulation processing path, or (12) 64QAM modulation / second OFD.
A wireless LAN (IEEE 8
The digital modulation corresponding to 02.11) is possible.

(17) In the modulation processing path of only the 8PSK modulation circuit, the PH using π / 4 shift QPSK is used.
Digital modulation corresponding to digital cordless communication corresponding to S and digital cellular communication corresponding to PDC becomes possible.

By adopting such a structure,
Since the power supply of the unused modulation circuit can be cut off by using the power supply control circuit 114, the power consumption of the modulation circuit can be significantly reduced.

Further, the modulation control circuit 115 causes D /
It is also possible to change the sampling frequency of the A converter 113 according to the modulation method.

Further, in FIG. 1, quadrature modulation is performed through a low-pass filter after D / A conversion, but D / A conversion may be performed after performing digital filter or digital quadrature modulation.

Although the QPSK modulation circuit, the 8PSK modulation circuit, the 64QAM modulation circuit, the spread modulation circuit, and the first and second OFDM modulation circuits are combined as the modulation circuit in the first embodiment, other modulation methods are also possible. It goes without saying that they can be used in combination in the same manner.

Although two OFDM modulation circuits are shown in FIG. 1, the number of subcarriers, frequency intervals, or I
A plurality of OFDM modulation circuits having different FFT sizes may be switched.

As described above, the modulation circuit according to the first embodiment has a plurality of modulation functions, and various switches can be arbitrarily combined by operating the switch for switching and connecting the modulation functions. Since the above modulation method can be obtained, it is possible to realize a wireless device having a very simple configuration and being compatible with different modulation methods and having extremely high flexibility. As a result, it becomes possible to select the optimum modulation method according to the communication situation and perform communication. For example, when moving at high speed, select a modulation method that has a relatively low data transmission rate that is resistant to fading and multipath failures,
When stationary, it is possible to select a modulation method having a wide band and a high data transmission rate. Alternatively, the cheapest communication system can be selected according to the user's request.

(Embodiment 2) FIG.3 is a block diagram showing the configuration of a receiver as a radio apparatus according to Embodiment 2 of the present invention.

The receiver shown in FIG. 3 has a receiving antenna 301.
A low noise amplifier 302 for amplifying a high frequency received signal output from the receiving antenna 301, and a down converter for frequency converting the high frequency signal amplified by the low noise amplifier 302 into an IF signal based on a local signal from a local oscillator 304. 303, a quadrature demodulator 305 that converts an IF signal into a baseband signal composed of an I signal and a Q signal,
Low-pass filter (LPF) 306 for limiting the band of the baseband signal, QPSK demodulation, 8PSK demodulation, 6
A demodulation circuit 300 that realizes a total of 18 types of demodulation functions by combining 4QAM demodulation, despreading, and 2 types of OFDM demodulation.

The demodulation circuit 300 includes an A / D converter 307 for converting the output of the LPF 306 into a digital signal and an A / D converter.
A switch 308 that switches the output of the converter 307 to three routes and outputs the output, and a first OFDM provided corresponding to two of the three switch output ends of the switch 308.
A switch 311 that receives the demodulation circuit 309 and the second OFDM demodulation circuit 310, the outputs of the two OFDM demodulation circuits, and the signals from the remaining switching output terminals of the switch 308.
, A switch 312 for switching the output of the switch 311 to a two-way output, a despreading circuit 313 for receiving a signal from one switching output end of the switch 312, and a despreading circuit 3
The switch 314 receives the output of the switch 13 and the signal from the other switching output terminal of the switch 312.

Further, the demodulation circuit 300 includes a switch 31.
A switch 315 for switching the output of 4 to 3 routes and outputting
And a QPSK demodulation circuit 316, 8PSK modulation circuit 31 provided corresponding to the three switching output terminals of the switch 315.
7 and 64 QAM modulation circuit 318, and three switching input terminals corresponding to the output terminals of the three demodulation circuits are provided, and one of the outputs of the three demodulation circuits is received data (demodulation data).
A switch 319 that outputs a power supply, a power supply control circuit 320 that controls power supply to the five demodulation circuits, and
A demodulation control circuit 321 that controls the switching of one switch and realizes 18 types of demodulation functions is provided.

First OFDM demodulation circuit 309 and second OF
The DM demodulation circuit 310 varies the number of subcarriers and the frequency interval, and restores a plurality of low-speed data signals composed of narrowband signals to the original high-speed data signal. The despreading circuit 313 despreads with a spreading code. QP
SK demodulation circuit 316, 8PSK demodulation circuit 317 and 64
The QAM demodulation circuit 318 restores the transmission data, which is the data mapped on the IQ plane, into a data string.

Next, the demodulation operation realized by the receiver having the above configuration will be described with reference to the flow chart shown in FIG.

The received signal from the receiving antenna 301 (step S401) is amplified by the low noise amplifier 302,
After being converted into an IF signal by the down converter 303, the quadrature demodulator 305 converts it into an analog baseband signal composed of an I signal and a Q signal (step S40).
2). Next, after the band is limited by the LPF 306, A
The signal is converted into a digital baseband signal by the / D converter 307 (step S403) and input to the switch 308.

The demodulation control circuit 321 first detects the switch 3
08 and the switch 311 are interlocked with each other to select whether or not to perform OFDM demodulation on the output data signal of the A / D converter 307 (step S404). When performing OFDM modulation, the output data signal of the A / D converter 307 is converted into the first O
It is given to either the FDM demodulation circuit 309 or the second OFDM demodulation circuit 310. As a result, the demodulation process by the first OFDM demodulation circuit 309 (step S405) and the second OF
Demodulation processing by the DM demodulation circuit 310 (step S40
6) is performed, the switch 311 to the switch 3
12 is output. When the OFDM demodulation is not performed, the output data signal of the A / D converter 307 is directly transmitted from the switch 308 to the switch 311 and the switch 3
11 is output to the switch 312.

Next, the demodulation control circuit 321 interlocks with the switch 312 and the switch 314 to make the switch 3
It is selected whether or not despreading is applied to the output data signal 11 (step S407). When despreading is performed, the output data signal of the switch 311 is input to the despreading circuit 313, despreaded, and output from the switch 314 to the switch 315 (step S408). When despreading is not performed, the output data signal of the switch 311 is the switch 3
12 is directly transmitted to the switch 314, and the switch 31
4 to the switch 315.

Next, the demodulation control circuit 321 interlocks with the switch 315 and the switch 319 to select the demodulation method to be applied (step S409). As a result, the output data signal of the switch 314 is input to any of the QPSK demodulation circuit 316, the 8PSK demodulation circuit 317, and the 64QAM demodulation circuit 318, and the QPSK demodulation (step S410), 8PSK demodulation (step S411), 64.
It is demodulated by any method of QAM demodulation (step S412). The data mapped on the IQ plane is returned to the original data string and output from the switch 319 as received data (step S413).

Thus, in the demodulation circuit 300, (1) Q
Demodulation processing path of PSK demodulation / spreading demodulation / first OFDM demodulation, (2) Demodulation processing path of 8PSK demodulation / spreading demodulation / first OFDM demodulation, and (3) Demodulation processing path of 64QAM demodulation / spreading demodulation / first OFDM demodulation , (4) QPSK
A demodulation / spreading demodulation / second OFDM demodulation processing path,
(5) Demodulation processing path of 8PSK demodulation / spreading demodulation / second OFDM demodulation, and (6) 64QAM demodulation / spreading demodulation / second
Demodulation processing path for OFDM demodulation and (7) QPSK demodulation
Demodulation processing path for first OFDM demodulation, (8) 8PSK demodulation / demodulation processing path for first OFDM demodulation, (9) 64Q
A demodulation processing path of AM demodulation / first OFDM demodulation, and (1
0) QPSK demodulation / second OFDM demodulation processing path, (11) 8PSK demodulation / second OFDM demodulation processing path, (12) 64QAM demodulation / second OFDM demodulation processing path, and (13) QPSK demodulation processing Spreading demodulation processing path, (14) 8PSK demodulation / spreading demodulation processing path, (15) 64QAM demodulation / spreading demodulation / first OFDM demodulation processing path, and (16) QPSK demodulation only demodulation processing path Then, the received data (demodulated data) is generated by any one of the demodulation processing path for (17) 8PSK demodulation only and the demodulation processing path for (18) 64QAM demodulation only.

As described above, according to the second embodiment,
It can support 18 types of demodulation methods. For example,
Of the 18 types of demodulation processing paths described above, (13)
In the demodulation processing path of QPSK demodulation / spreading demodulation, digital demodulation compatible with the third generation mobile communication is possible. Also, (9) 64QAM demodulation / first OFDM demodulation demodulation processing path, or (12) 64QAM demodulation / second OFD.
A wireless LAN (IEEE 8
The digital demodulation corresponding to 02.11) is possible.

(17) In the demodulation processing path of only the 8PSK demodulation circuit, the PH using π / 4 shift QPSK is used.
Digital demodulation compatible with digital cordless communication compatible with S and digital cellular communication compatible with PDC becomes possible.

By adopting such a configuration,
The power supply of the demodulation circuit which is not used can be cut off by using the power supply control circuit, and the power consumption of the demodulation circuit can be significantly reduced.

Further, the demodulation control circuit 321 causes A /
It is also possible to change the sampling frequency of the D converter 307 according to the demodulation method.

Further, in FIG. 3, although the quadrature demodulation is performed and the A / D conversion is performed after passing the low pass filter, the digital quadrature demodulation or the digital filter may be performed after the A / D conversion.

In the second embodiment, the QPSK demodulation circuit, the 8PSK demodulation circuit, the 64QAM demodulation circuit, the despreading demodulation circuit, and the first and second OFDM demodulation circuits are combined as the demodulation circuit. It goes without saying that they can be used in combination in the same manner.

Although two OFDM demodulation circuits are shown in FIG. 3, the number of subcarriers, frequency intervals or I
A plurality of OFDM demodulation circuits having different FFT sizes may be switched.

As described above, the demodulation circuit according to the second embodiment has a plurality of demodulation functions, and various switches can be arbitrarily combined by operating the switches for switching and connecting the respective demodulation functions. Since it is possible to obtain the demodulation method of (1), it is possible to realize a wireless device having a very simple configuration, which is compatible with different demodulation methods, and which is extremely flexible. As a result, it becomes possible to select an optimal demodulation method according to the communication situation and perform communication. For example, when moving at high speed, select a demodulation method with relatively low data transmission speed that is resistant to fading and multipath failures,
When stationary, it becomes possible to select a demodulation method having a wide band and high data transmission rate. Alternatively, the cheapest communication system can be selected according to the user's request.

As described above, according to the present invention,
It is possible to obtain a modulation circuit, a demodulation circuit, and a wireless device configured by them that can flexibly support a plurality of modulation / demodulation methods.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a transmitter as a wireless device according to a first embodiment of the present invention.

FIG. 2 is a flowchart for explaining a modulation operation performed in the transmitter as the wireless device according to the first embodiment.

FIG. 3 is a block diagram showing a configuration of a receiver as a wireless device according to a second embodiment of the present invention.

FIG. 4 is a flowchart for explaining a demodulation operation performed in a receiver as a wireless device according to the second embodiment.

FIG. 5 is a block diagram showing a configuration example of a conventional wireless device.

[Explanation of symbols]

100 modulation circuit 101, 105, 106, 108, 109, 112 switch 102 QPSK modulation circuit 101 8PSK modulation circuit 104 64QAM modulation circuit 107 spreading modulation circuit 110 first OFDM modulation circuit 111 second OFDM modulation circuit 113 D / A converter 114 power control Circuit 115 Modulation control circuit 117 Low pass filter (LPF) 118 Quadrature modulator 119 Up converter 120 Local oscillator 121 Power amplifier 122 Transmit antenna 300 Demodulation circuit 301 Receive antenna 302 Low noise amplifier 303 Down converter 304 Local oscillator 305 Quadrature demodulator 306 Low pass filter 307 A / D converters 308, 311, 312, 314, 315, 319 Switch 309 First OFDM demodulation circuit 310 Second OFDM demodulation circuit 13 despreading circuit 316 QPSK demodulation circuit 317 8PSK demodulation circuit 318 64QAM demodulation circuit 320 the power supply control circuit 321 demodulation control circuit

Claims (11)

[Claims] 1. A modulation circuit for performing digital modulation, comprising:
One or more of the phase, amplitude, and frequency of the carrier wave or a combination of some of them is changed at the input stage of the data signal to be modulated by the digital information, and spread modulation is performed on the digital information by the spread code. One or more diffusion means for performing the modulation are arranged in the intermediate stage, and the digital information is divided into a plurality of low-speed data signals and modulated by one or more O's.
A modulation processing path for arranging the FDM modulation means at the output stage of the modulated data signal, and the data signal to be modulated passes through the input stage, the intermediate stage and the output stage in this order to undergo the modulation process. A modulation circuit comprising a path switching means for selecting and switching. 2. The modulation circuit according to claim 1, wherein the path switching means selects a path that is not subjected to modulation processing in one or both of the intermediate stage and the output stage. 3. A D / A for converting a data signal output from the output stage and subjected to a predetermined modulation processing into an analog signal.
3. The modulation circuit according to claim 1, further comprising a conversion unit, wherein the path switching unit variably controls the sampling frequency of the D / A conversion unit. 4. A digital filter for subjecting a data signal outputted from the output stage to a predetermined modulation processing to band limiting processing, and a D / A conversion means for converting an output data signal of the digital filter into an analog signal. 3. The modulation circuit according to claim 1, wherein the path switching means variably controls both the pass characteristic of the digital filter and the sampling frequency of the D / A conversion means. 5. The power supply to the modulation means not located on the selected modulation processing path among the power supplies to the modulation means arranged in each of the input stage, the intermediate stage and the output stage. 5. The modulation circuit according to any one of claims 1 to 4, further comprising a power supply control means for stopping the operation. 6. A demodulation circuit for performing digital demodulation, comprising:
One or more OFDM demodulation means for demodulating a plurality of modulated low-speed data signals to obtain an original high-speed data signal are arranged at an input stage of a data signal to be demodulated, and digital information is subjected to despreading demodulation by a spreading code. The above despreading means is arranged in the intermediate stage, and any one of the phase, amplitude and frequency of the carrier wave or some combination thereof is demodulated to the original data signal by the digital information 1
A demodulation process in which the above demodulation means is arranged in the output stage of the demodulated data signal, and the data signal to be demodulated passes through the input stage, the intermediate stage and the output stage in this order to undergo the demodulation process. A demodulation circuit comprising path switching means for selecting and switching a path. 7. The demodulation circuit according to claim 6, wherein the path switching means selects a path for which demodulation processing is not performed in one or both of the input stage and the intermediate stage. 8. A / D conversion means for converting a received analog signal into a digital signal and generating the data signal to be demodulated, wherein the path switching means changes the sampling frequency of the A / D conversion means. The demodulation circuit according to claim 6 or 7, which is variably controlled. 9. An A / D conversion means for converting a received analog signal into a digital signal, and a digital signal for subjecting the digital signal output by the A / D conversion means to band limiting processing to generate the data signal to be demodulated. Equipped with a filter,
8. The demodulation circuit according to claim 6, wherein the path switching unit variably controls both the sampling frequency of the A / D conversion unit and the pass characteristic of the digital filter. 10. The power supply to the demodulation means not located on the selected demodulation processing path among the power supplies supplied to the demodulation means arranged in each of the input stage, the intermediate stage and the output stage. The demodulation circuit according to any one of claims 6 to 9, further comprising a power supply control means for stopping the power supply. 11. A radio comprising at least one circuit of the modulation circuit according to any one of claims 1 to 5 or the demodulation circuit according to any one of claims 6 to 10. apparatus.