JP2003158556A - Transmitter, receiver and transmission method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmitter with a simple configuration that modulates transmission data by using a plurality of modulation systems with a different modulation multi-value number, transmitting the modulated transmission data, and enhance a symbol transmission speed while controlling the modulated signal to be within a specified frequency occupancy bandwidth. SOLUTION: Properly selecting a roll-off coefficient of Nyquist filters 104 to 106 so as to select a symbol transmission speed to have a desired value without changing a frequency bandwidth of a symbol after the modulation processing, can enhance the symbol transmission speed with a simple configuration while controlling the modulation signal to be within a specified frequency occupancy bandwidth.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmitting device, a receiving device and a transmitting method, and more particularly to a transmitting device and a receiving device used in a communication system for digitally modulating a transmission signal by a plurality of modulation methods having different multi-value numbers. And is suitable for application to the transmission method.

[0002]

2. Description of the Related Art Conventionally, as a system in which a plurality of modulation methods coexist in a wireless communication method, for example, a technology described in IEICE Technical Report RCS94-66 (1994-09) is known. . This is generally called an adaptive modulation method, and the data symbol modulation method is changed to, for example, QPSK modulation, 16QAM, 6 according to the state of the propagation path.
This is a method of switching between 4QAM and 256QAM.

In this type of wireless communication system, a transmitter / receiver receives an SIR (Signal to Inte
The current propagation path state is determined based on the (Rference Ratio), etc., and the modulation method is switched according to the state.

In practice, when the propagation path condition is good, the information symbols are digitally modulated by using a multi-level modulation method such as 256QAM or 64QAM which has a large amount of information transmission per symbol. On the other hand, when the state of the propagation path is poor, for example, 16Q
Digital modulation is performed using a modulation method such as AM or QPSK modulation method in which the amount of information transmission per symbol is small.

FIG. 7 shows an example of a concrete transmission frame structure. In the frame configuration of FIG. 7, a preamble, a data symbol, a pilot symbol, a data symbol, a pilot symbol, a unique word, a data symbol, a pilot symbol, and a data symbol are sequentially arranged from the beginning. Among these, the preamble, pilot symbol, and unique word are It is used when a data symbol is detected in the receiving device. As the data symbol, as described above, QPSK modulation, 16QAM,
Symbols modulated by one of the 64QAM and 256QAM modulation schemes will be transmitted.

Further, in wireless communication, usable frequency bandwidths are regulated, and it is obliged to store signals of respective channels within the prescribed bandwidths for transmission. For this reason, the transmission device is provided with a band limiting filter so that the modulated signal is transmitted within a predetermined bandwidth.

[0007]

By the way, when the above-mentioned adaptive modulation method is applied, the state of the propagation path is good and 64Q.
When the AM system or the 256QAM system can be used, the amount of information per symbol is large, so that the actual data transmission rate can be increased, but the propagation path condition is poor and the QPSK modulation system or the 16QAM system must be used. When not obtained, the amount of information per symbol is small, so that the actual data transmission rate becomes low.

As one method for solving this, QPS
The symbol transmission rate of a symbol modulated by a modulation scheme with a small number of modulation levels such as a K modulation scheme or a 16QAM scheme is changed to a symbol transmission rate by a modulation scheme with a large number of modulation levels such as a 256QAM scheme or a 64QAM scheme. By making the speed higher than the speed, it is possible to increase the substantial data transmission speed of the signal modulated by the modulation method having a small number of modulation levels.

However, since the frequency occupied bandwidth of each signal is defined in the wireless communication as described above, if the symbol rate of the modulation symbol is unnecessarily increased,
There is an inconvenience that the transmission signal does not fit within the specified frequency occupied bandwidth.

The present invention has been made in view of the above points, and when transmitting data is modulated by using a plurality of modulation schemes having different modulation multi-value numbers and transmitted, a simple configuration is adopted.
With the modulated signal within the specified frequency occupied bandwidth,
A transmitter capable of improving the symbol transmission rate,
An object is to provide a receiving device and a transmitting method.

[0011]

In order to solve such a problem, a transmitting apparatus of the present invention corresponds to a plurality of modulation means for modulating transmission data by a plurality of modulation methods each having a different modulation multi-value number, and each modulation means. And a plurality of Nyquist filters that have a roll-off coefficient selected according to each modulation method and that store the modulation signal modulated by each modulation unit within a predetermined frequency bandwidth, and a filtering process. A configuration including a transmission unit that transmits a subsequent signal is adopted.

According to this structure, since the symbol time of the modulation symbol can be changed according to the change of the roll-off coefficient, the symbol transmission of the modulation symbol can be performed while the modulation symbol is contained in the specified frequency bandwidth. You can change the speed. As a result, the transmission rate of each modulation symbol can be easily selected to a desired value simply by changing the roll-off coefficient.

Further, in the transmitting apparatus of the present invention, the Nyquist filter has a configuration in which the roll-off coefficient is selected to be a smaller value for a filter corresponding to the modulating means having a smaller modulation multi-value number.

According to this structure, considering that the smaller the roll-off coefficient is, the higher the symbol transmission speed can be,
1 after modulation such as QPSK modulation system or 16QAM system
Since the roll-off coefficient of the Nyquist filter corresponding to the modulation system with a small amount of information transmission of the symbol is set to a smaller value, the substantial symbol transmission rate of the QPSK modulation system or 16QAM system is set to 64QAM system or 256QAM system.
It can be higher than the symbol transmission rate of the system. At this time, for a modulated signal with a small modulation multi-level number, even if the roll-off coefficient is reduced, the increase in the bit error rate in the carrier power-to-noise power ratio is small in an environment where there is a synchronization error. It is possible to achieve both suppression of bit error rate.

Further, the transmitting apparatus of the present invention has a configuration in which the roll-off coefficient is corrected according to the propagation path environment.

With this configuration, it is possible to achieve both high symbol transmission speed and suppression of an increase in bit error rate in an environment where there is a synchronization shift.

Further, the transmitting apparatus of the present invention further comprises a propagation state detecting means for detecting the state of the propagation path with the communication partner, and the better the propagation path state detected by the propagation state detecting means is, the more modulated the modulation is. A configuration is adopted in which the modulated signal obtained by the modulation means having a large number of multivalues is transmitted.

According to this structure, when the propagation path condition is good, a modulated signal modulated by a modulation system having a large number of modulation levels such as 256QAM system or 64QAM system is transmitted, so that high speed data transmission is possible. . When the channel condition is bad, for example, QPSK modulation system or 16Q
A modulation signal modulated by a modulation method with a small number of modulation levels such as the AM method is transmitted. At this time, by appropriately selecting the roll-off coefficient, it is possible to shorten one symbol time and increase the symbol transmission rate. Therefore, the data transmission speed can be substantially increased. As a result,
When the propagation path condition is bad, the substantial data transmission rate can be improved without increasing the transmission bit error in an environment where there is a synchronization shift. Therefore, the data quality can be maintained and the transmission rate can be increased as a whole. It is possible to realize a transmitter that can achieve both of the above.

Further, the receiving apparatus of the present invention is provided with a plurality of modulation means for modulating transmission data by a plurality of modulation methods each having a different modulation multi-value number, and provided corresponding to each modulation means, and for each modulation method. A plurality of Nyquist filters having correspondingly selected roll-off coefficients and containing the modulated signals modulated by each modulating means within a predetermined frequency bandwidth, and transmitting means for transmitting the filtered signals A receiving device for receiving and demodulating a signal transmitted by a transmitting device, a receiving means for receiving a transmission signal, and a plurality of Nyquist filters having filter characteristics similar to a plurality of Nyquist filters provided in the transmitting device, , Demodulation processing corresponding to a plurality of modulation means provided in the transmission device for the signals after the filtering processing by the plurality of Nyquist filters, respectively. It adopts a configuration comprising a plurality of demodulating means for performing.

According to this structure, since the Nyquist filter performs the same filtering process as the Nyquist filter of the transmitting device, only the modulated signal in the frequency band corresponding to each demodulation unit passes through the Nyquist filter and is sent to the corresponding demodulation unit. Since it is input, the demodulation means can satisfactorily restore only the target modulated signal.

Further, according to the transmission method of the present invention, the transmission data is modulated by a plurality of modulation systems having different modulation levels, and the frequency band of the modulated signal has a Nyquist having a roll-off coefficient according to the modulation level. The filter limits the signal within a predetermined width, and transmits the modulated signal after band limitation.

According to this method, if the roll-off coefficient is changed, the symbol time of the modulation symbol can be changed accordingly. Therefore, the symbol transmission of the modulation symbol can be performed while the modulation symbol is contained in the specified frequency bandwidth. You can change the speed. As a result, the transmission rate of each modulation symbol can be easily selected to a desired value simply by changing the roll-off coefficient.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The essence of the present invention is that the symbol transmission rate is selected to a desired value without changing the frequency bandwidth of the symbol after modulation processing by appropriately selecting the roll-off coefficient of the Nyquist filter. Is.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1) In FIG. 1, reference numeral 100 generally indicates the configuration of a transmitting apparatus according to Embodiment 1 of the present invention. The transmitter 100 transmits the transmission data D1 to QPSK (Q
uadrature Phase Shift Keying) Modulation method mapping unit 101, 16QAM (Quadrature Amplitude Modulatio)
n) Input to the scheme mapping unit 102 and the 64QAM scheme mapping unit 103.

The QPSK modulation method mapping section 101 performs QPSK modulation processing on the transmission data D1 and sends the in-phase component and the quadrature component of the QPSK modulation method quadrature baseband signal thus obtained to the QPSK modulation method root Nyquist filter 104. To do. The 16QAM system mapping unit 102 performs 16QAM processing on the transmission data D1, and sends the in-phase component and the quadrature component of the 16QAM system quadrature baseband signal thus obtained to the 16QAM system root Nyquist filter 105. The 64QAM scheme mapping unit 103 uses 64QA for the transmission data D1.
M processing is performed, and the in-phase component and the quadrature component of the 64QAM system quadrature baseband signal thus obtained are sent to the 16QAM system root Nyquist filter 106.

The root Nyquist filter 104 for the QPSK modulation method, the root Nyquist filter 105 for the 16QAM method, and the root Nyquist filter 106 for the 64QAM method are respectively included in the root Nyquist filter 104.
Control signal S1 for determining the roll-off factor of
Is entered.

In the case of this embodiment, it is assumed that different frequency bands as shown in FIG. 2 are assigned to signals modulated by each modulation method. That is, FIG. 2 shows the channel arrangement of the embodiment, where the horizontal axis is frequency and the vertical axis is power. At this time, the frequency channel interval (frequency bandwidth) is determined to be within fw.

A signal modulated by the QPSK modulation method is assigned as channel A, and 16QA is assigned as channel B.
The signal modulated by the M method is assigned, and the channel C is set to 6
A signal modulated by the 4QAM method is assigned.

Here, the frequency occupied band, the symbol transmission rate and the roll-off coefficient of the root Nyquist filter in the embodiment will be described. The root Nyquist filter is a filter represented by the following equation, where ω is an angular frequency, α is a roll-off coefficient, ω0 is a Nyquist angular frequency, and H (ω) is an amplitude characteristic of the root Nyquist filter.

[0031]

[Equation 1]

If the symbol intervals of channels A, B and C are Ta, Tb and Tc, respectively, the symbol transmission rates of channels A, B and C are 1 / Ta, 1 / Tb and 1 /, respectively.
It becomes Tc. Here, channel A is a root Nyquist filter having roll-off coefficient αa (that is, root Nyquist filter 104 for QPSK modulation system), channel B is
Is band-limited by a root Nyquist filter having a roll-off coefficient αb (that is, a root Nyquist filter 105 for 16QAM system), and channel C is band-limited by a root Nyquist filter having a roll-off coefficient αc (that is, a root Nyquist filter 106 for 64QAM system).

As a result, the frequency frequency occupied bandwidth fa of channel A is fa = (1.0 + αa) / Ta, and the frequency frequency occupied bandwidth fb of channel B is fb = (1.0
+ Αb) / Tb, the frequency / frequency occupied bandwidth fc of channel C is fc = (1.0 + αc) / Tc.

Here, in the conventional wireless communication system, for example, the modulation method is QPSK modulation method, 16QAM method, 64
In any of the QAM systems, when the symbol rate is fixed to Tx and the roll-off coefficient is 0.5, the frequency occupied bandwidth fx is fx = (1.0 + 0.5) / T
x, so that fx can be contained within the frequency channel interval fw.

On the other hand, in the embodiment, it is considered that the signal transmission rate of each channel is changed while keeping the signal of each channel within the occupied frequency bandwidth fx. Therefore, in the embodiment, the root Nyquist filter 104 to
The roll-off coefficient of 106 is selected appropriately.

Specifically, the symbol transmission rate Tc of channel C is set to Tc = Tx and the roll-off coefficient αc =
Set to 0.5. At this time, the frequency occupied bandwidth of channel C is fc = fx. When the roll-off coefficient αb of channel B is 0.4 and the frequency occupied bandwidth fb of channel B is fb = fx, the symbol transmission rate of channel B is 1 / Tb> 1 / Tx. Further, when the roll-off coefficient αa of channel A is 0.2 and the frequency occupied bandwidth fa of channel A is fa = fx, the symbol transmission rate of channel A is 1 / Ta> 1 / Tb> 1 / Tc = Tx.

As described above, the roll-off coefficient of the root Nyquist filters 104 to 106 of the embodiment is set to 1 by selecting a roll-off coefficient having a smaller value for the root Nyquist filter corresponding to a modulation method having a smaller number of modulation levels. It is designed to increase the symbol transmission rate of a modulation method in which the amount of transmission information per symbol is small.

As a result, in any of the conventional QPSK modulation system, 16QAM system and 64QAM system, the symbol rate is kept constant at Tx, the roll-off coefficient is kept constant at 0.5, and the occupied frequency bandwidth fx is set at the frequency. The occupied frequency bandwidth fx is compared with the frequency channel interval f as compared with the wireless communication system within the channel interval fw.
By changing the roll-off coefficient according to the modulation method under the condition of within w, the symbol transmission rate of the QPSK modulation method and 16QAM method can be increased.

In practice, each root Nyquist filter 10
A control signal S1 representing the state of the propagation path is input to 4 to 106, and the roll-off coefficient is corrected to some extent according to the control signal S1. This makes it possible to suppress signal deterioration even when the roll-off coefficient is changed according to the modulation method.

For example, when the propagation path condition is bad and a modulation signal modulated by the QPSK modulation method is selected as the transmission signal, there is no problem when the propagation path condition is moderately bad, but when the roll-off coefficient is too low when it is very bad. QP
Intersymbol interference may occur in the SK modulated signal, and the signal may deteriorate. In consideration of this, in the present embodiment, the roll-off coefficient preset for each modulation method is corrected to some extent according to the state of the propagation path.

Each route Nyquist filter 104-10
The in-phase component signal and the quadrature component signal output from 6 are sent to the in-phase component switching unit 107 and the quadrature component switching unit 108, respectively. In-phase component switching section 107
The control signal S1 indicating the propagation path state is input to the quadrature component switching unit 108. In-phase component switching unit 107
The quadrature component switching unit 108 selects and outputs a signal according to the control signal S1.

Specifically, when the control signal S1 indicating that the propagation path condition is good is input, the signal input from the Nyquist filter 106 for the 64QAM system is selectively output, and the propagation path condition is set to this. When the control signal S1 indicating that the signal is bad is input, the signal input from the Nyquist filter 104 for the QPSK modulation method is selectively output.

The radio section 109 is an in-phase component switching section 107.
And the in-phase component and the quadrature component of the modulation signal selected by the quadrature component switching unit 108 and the control signal S
Enter 1. As a result, the wireless unit 109 causes the control signal S1
A carrier wave having a center frequency fα, fβ or fγ according to is generated, and the input modulated signal is superimposed on the generated carrier wave.

That is, in this embodiment, as shown in FIG. 2, since the modulation signals corresponding to the carrier waves having the center frequencies fα, fβ or fγ which are different for each channel are superimposed, the control signal S1 is obtained. The carrier wave corresponding to the modulated signal selected by is generated by the radio unit 109,
The selected modulation signal is superimposed on the carrier wave. The transmission signal after the radio processing is amplified by the amplifier 110 and then transmitted via the antenna 111.

FIG. 3 shows the configuration of a receiving device 200 that receives and demodulates the signal transmitted by the transmitting device 100. The receiving device 200 receives the signal received by the antenna 201 from the wireless unit 2.
02 to the route Nyquist filter 203 for the QPSK modulation system, the route Nyquist filter 204 for the 16QAM system, and the route Nyquist filter 205 for the 64QAM system.

Each route Nyquist filter 203-20
5 has the same configuration as each of the root Nyquist filters 104 to 106 provided in the transmission device 100. Thereby, for example, when the received signal is a QPSK modulated signal contained in the frequency band of channel A shown in FIG.
An output can be obtained only from the root nyquist filter 203 for the QPSK modulation method. If the received signal is a 16QAM signal contained in the frequency band of channel B shown in FIG. 2, an output can be obtained only from the 16QAM system root Nyquist filter 204. Further, the received signal is contained in the frequency band of channel C shown in FIG.
When it is a QAM signal, an output is obtained only from the 64QAM system root Nyquist filter 205.

Each route Nyquist filter 203-20
The output of 5 is sent to the corresponding detection units 206 to 208,
A final received signal is obtained by performing detection processing using a unique word by the detection units 206 to 208.

Now, the relationship between the modulation method and the roll-off coefficient will be described. In FIG. 4, the horizontal axis represents time and the vertical axis represents 1
The waveform (eye pattern) when the in-phase component or the quadrature component of the 6QAM quadrature baseband signal is cut out at every symbol interval t1 period is shown.

FIG. 4A shows an eye pattern when the roll-off coefficient is 0.2, and FIG. 4B shows an eye pattern when the roll-off coefficient is 0.5. For example, when symbol synchronization is ideally performed in the 16QAM detection unit 207 of the receiving apparatus 200 in FIG. 3, the data symbols are not synchronized when the symbol synchronization is achieved as at times t2 and t3 in FIG. It is detected at the punching point.

However, in reality, it is punched out and detected in a state where a time offset occurs in the symbol synchronization as at times t4 and t5. At this time, as can be seen from FIG. 4, the smaller the roll-off coefficient, the larger the punching error due to the time offset of symbol synchronization. As a result, the bit error rate characteristic in the carrier power to noise power ratio of the receiver 200 is deteriorated.

On the other hand, the influence of the punching error caused by the time offset of the symbol synchronization on the deterioration of the bit error rate characteristic in the carrier power-to-noise power ratio of the receiving apparatus 200 is larger as the number of modulation levels of the modulation method is larger. .

Considering the above two points, when the modulation multi-value number is small, even if the roll-off coefficient is made small, in the carrier power to noise power ratio of the receiving device 200 due to the punching error due to the time offset of symbol synchronization. It can be said that the influence on the deterioration of the bit error rate characteristic is small. Therefore, Q
It is possible to reduce the roll-off coefficient for a signal modulated by a modulation method having a small number of modulation levels such as the PSK modulation method. As a result, the symbol transmission speed can be increased without degrading the signal.

When the modulation multi-value number is large, the bit error rate characteristic deterioration in the carrier power-to-noise power ratio of the receiving apparatus is greatly affected by the punching error caused by the time offset of the symbol synchronization. The off coefficient must be increased, and the symbol transmission rate becomes slower than when the modulation multi-level number is small.

As described above, in this embodiment, the roll-off coefficient is increased as the number of modulation levels is increased, so that the bit error rate characteristic in the carrier power to noise power ratio of the receiving apparatus 200 is improved. Has been done. Further, the symbol transmission efficiency can be improved by changing the symbol transmission rate according to the roll-off coefficient.

Thus, the smaller the multi-level number of the modulation method, the smaller the roll-off coefficient, so that the symbol transmission efficiency and the bit error rate characteristic in the carrier power to noise power ratio of the receiving apparatus 200 are both improved. It is possible to obtain the transmitting device 100 that operates.

According to the above configuration, a plurality of Nyquist filters 10 each having a roll-off coefficient selected corresponding to each modulation method and containing a modulated signal within a predetermined frequency bandwidth.
By providing Nos. 4 to 106, the symbol time of the modulation symbol can be changed according to the change of the roll-off coefficient. Therefore, the symbol transmission of the modulation symbol can be performed while the modulation symbol is contained in the specified frequency bandwidth. You can change the speed. As a result, the transmission rate of each modulation symbol can be easily selected to a desired value simply by changing the roll-off coefficient.

Further, by making the roll-off coefficient smaller for the Nyquist filter corresponding to a modulation signal having a smaller modulation multi-value number, it is possible to achieve both high symbol transmission speed and suppression of bit error rate.

Further, by correcting the roll-off coefficient according to the propagation path environment, it is possible to further suppress the decrease in the bit error rate when the symbol transmission speed is increased by changing the roll-off coefficient according to the modulation method. it can.

(Embodiment 2) In this embodiment, as shown in FIG. 5, a plurality of modulated signals are adaptively switched according to the propagation path environment, and carriers of the same frequency band whose center frequency is fδ are used. A receiver for receiving the transmitted signal will be described. Specifically, FIG. 5A shows a transmission signal on which a QPSK modulated signal is superimposed, and FIG. 5B shows 16Q.
FIG. 5C shows a transmission signal on which an AM modulation signal is superimposed.
Represents a transmission signal on which a 64QAM modulated signal is superimposed. As is clear from the figure, each transmission signal has a channel interval (frequency bandwidth) fw centered on the center frequency fδ.
I have

These transmission signals are transmitted to the radio section 10 in the transmission device 100 (FIG. 1) described above in the first embodiment.
A transmitting device (not shown) having substantially the same configuration as the transmitting device 100 except that the carrier waves generated by 9 are different.
It was sent from.

FIG. 6 shows a receiver 300 according to this embodiment.
Shows the configuration of. In FIG. 6 in which parts corresponding to those in FIG. 3 are assigned the same reference numerals, the receiving apparatus 300 sends the reception quadrature baseband signals output from the radio section 202 to the Nyquist filters 303 to 305, and also identifies the modulation method. -Transmits to the radio wave propagation environment estimation unit 301.

Modulation method identification / radio wave propagation environment estimation unit 301
Identifies the modulation scheme of the received signal based on, for example, the symbol rate of the received quadrature baseband signal, and estimates the radio wave propagation environment based on the pilot symbols included in the received quadrature baseband signal. Then, the modulation method identification signal S2 is sent to the digital signal selection unit 302. Further, the radio wave propagation environment estimation signal S3 is transmitted to the communication partner via a transmission unit (not shown). For example, the transmitter 100 of FIG. 1 receives this radio wave propagation environment estimation signal S3 by a receiver (not shown) and uses it as a control signal S1.

An output signal is obtained from each of the root Nyquist filters 303 to 305 of the receiving device 300 regardless of which modulation method the received signal is. This is because, as described with reference to FIG. 5, signals obtained by any modulation method are transmitted by being superimposed on subcarriers in the same frequency band, and the pass frequency bands of the root Nyquist filters 303 to 305 are This is because they are all selected the same. Output signals from the root Nyquist filters 303 to 305 are sent to the corresponding detection units 206 to 208.

The detectors 206 to 208 detect the output signals of the root Nyquist filters 303 to 305 by using the unique words to obtain the received signals after detection, and send them to the digital signal selector 302. The digital signal selection unit 302 selects and outputs the signal after detection input from the detection unit 206, 207 or 208 corresponding to the modulation method identification signal S2.

As described above, the receiving apparatus 30 of this embodiment
In the case of 0, only the signals subjected to the root Nyquist filter process and the detection process corresponding to the modulation system of the actually transmitted modulation signal are properly selected from the received signals of the multiple modulation systems transmitted in the same frequency band. be able to.

(Other Embodiments) In the above embodiment, the occupied frequency bandwidths fa, fb, fc of channel A, channel B, and channel C are fa = fb =
Although the description has been given under the condition of fc = fx ≦ fw (frequency channel interval), the present invention is not limited to this, and by setting the roll-off coefficient αa ≠ αb ≠ αc, the symbol transmission rate Ta can be obtained.
It suffices that ≠ Tb ≠ Tc and the condition of fa ≠ fb ≠ fc ≦ fw is satisfied. In short, the roll-off coefficient of the Nyquist filter may be appropriately selected according to the modulation method to change the symbol transmission rate of the modulated symbol within the specified frequency bandwidth.

In the above embodiment, the modulation method is Q.
PSK modulation system, 16QAM system, 64QAM system 3
Although the system has been described as an example, the modulation system to which the present invention can be applied is not limited to this. Further, the configurations of the transmitting device 100 and the receiving devices 200 and 300 are not limited to those shown in FIGS. 1, 3 and 6, and may be modified as appropriate.

[0068]

As described above, according to the present invention,
By appropriately selecting the roll-off coefficient of the Nyquist filter, the transmission data is modulated by selecting the symbol transmission rate to a desired value without changing the frequency bandwidth of the symbols after the modulation processing. When modulated by using the method and transmitted, the symbol transmission rate can be improved with a simple configuration while keeping the modulated signal within the specified frequency occupied bandwidth.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a transmission apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing channel allocation and frequency bands (channel intervals) of each modulated signal according to the first embodiment.

FIG. 3 is a block diagram showing the configuration of the receiving apparatus according to the first embodiment.

FIG. 4 is an eye pattern when the roll-off coefficient is 0.2 and when the roll-off coefficient is 0.5.

FIG. 5 is a diagram showing a frequency band of a transmission signal according to the second embodiment.

FIG. 6 is a block diagram showing a configuration of a receiving device according to a second embodiment.

FIG. 7 is a diagram showing a frame structure of transmission data.

[Explanation of symbols]

100 transmitter 101 QPSK modulation system mapping unit 102 16QAM system mapping unit 103 64QAM system mapping unit 104, 203, 303 QPSK modulation system route Nyquist filter 105, 204, 304 16QAM system route Nyquist filter 106, 205, 305 for 64QAM system Root Nyquist filter 107 In-phase component switching unit 108 Quadrature component switching unit 200, 300 Receiver 301 Modulation method identification / radio wave propagation environment estimation unit 302 Digital signal selection unit D1 Transmission data S1 Control signal S2 Modulation method identification signal S3 Radio wave propagation environment estimation signal

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Katsuaki Abe             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Masayuki Orihashi             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Akihiko Matsuoka             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F term (reference) 5K004 AA05 AA08 FA05 FA09 FE00                       FF01 FG00 FH01 JA03 JE00                       JF04 JG00 JH02

Claims (6)

[Claims] 1. A plurality of modulation means for modulating transmission data by a plurality of modulation methods each having a different modulation multi-value, and a plurality of modulation means provided corresponding to each modulation means and selected corresponding to each modulation method. A transmitting device comprising: a plurality of Nyquist filters each having a roll-off coefficient and containing a modulated signal modulated by each modulating unit within a predetermined frequency bandwidth; and a transmitting unit that transmits the filtered signal. 2. The transmission device according to claim 1, wherein the Nyquist filter is selected to have a smaller roll-off coefficient for a filter corresponding to a modulation unit having a smaller modulation multi-value number. 3. The transmitter according to claim 1, wherein the roll-off coefficient is corrected according to a propagation path environment. 4. A modulation method further comprising: a propagation state detecting means for detecting a state of a propagation path with a communication partner, wherein the better the propagation path state detected by the propagation state detecting means, the larger the modulation multi-value number. The transmitter according to any one of claims 1 to 3, which transmits the modulated signal obtained by the means. 5. A plurality of modulation means for modulating transmission data by a plurality of modulation methods each having a different modulation multi-value, and a plurality of modulation means provided corresponding to each modulation means and selected corresponding to each modulation method. Sent by a transmitter having a plurality of Nyquist filters having a roll-off coefficient and containing the modulated signal modulated by each modulator within a predetermined frequency bandwidth, and a transmitter that transmits the filtered signal. A receiving device for receiving and demodulating a signal, receiving means for receiving the transmission signal, a plurality of Nyquist filters having filter characteristics similar to the plurality of Nyquist filters provided in the transmitting device, and the plurality of Nyquist filters. The signal after the filter processing by the Nyquist filter is subjected to demodulation processing corresponding to the plurality of modulation means provided in the transmission device. Receiving apparatus comprising a plurality of demodulating means. 6. The transmission data is modulated by a plurality of modulation methods having different modulation levels, and the frequency band of the signal after modulation is within a predetermined width by a Nyquist filter having a roll-off coefficient according to the modulation level. A transmission method that limits and transmits the modulated signal after band limitation.