JPH11355374A - Demodulation method, modulation method, demodulator and modulator-demodulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out demodulation for transmission signals in plural modulation systems with a simple configuration. SOLUTION: This demodulator consists of a reception section 12 that amplifies a received signal and converts a frequency as required, a branch means 13 that branches a signal from the reception section 12 into two, synchronization detectors 14, 15 that carry out synchronization detection of a common- mode component and a quadrature component for the signals from the branch means 13 based on two reference carriers reproduced from the received signal and whose the phases differ by π/2, five-value-three-value conversion sections 17, 18 that 5 stages of level signals synchronously detected by the synchronization detectors 14, 15 are converted into data in 3-bit and a reception buffer 20 that forms 6-bit data by combining the 3-bit data from the five-value - three- value conversion sections 17, 18, discriminates a modulation system based on the bit expressing the modulation system among the 6-bit data to demodulate the received data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a demodulation method, a modulation method, a demodulation device, and an improvement of a modulation / demodulation device.

[0002]

2. Description of the Related Art As a receiving apparatus capable of receiving signals modulated by a plurality of modulation methods, for example, Japanese Patent Laid-Open No. 7-12 / 1995
No. 3017 is known. This is because, for a transmission signal that is transmitted from the transmitting side in a time-division manner using a plurality of modulation schemes using the same frequency, on the receiving side, a plurality of demodulation units corresponding to a plurality of modulation schemes, and which demodulation unit normally operates. A demodulation output means for detecting a demodulation method of the received signal depending on whether it is operating, and selectively deriving an output of the demodulation means corresponding to the detected demodulation method, and a transmission signal transmitted by a plurality of modulation methods. Can be demodulated.

[0003] As a device capable of switching a plurality of modulation methods, for example, Japanese Patent Application Laid-Open No. Hei 5-1300082 is known. This is likely to occur when the mobile terminal notifies the control station such as a base station of a desired modulation scheme in a time-division multiplexing tunable communication scheme, when the state of the transmission path is good, for example, when the base station and the terminal are close to each other. When the occupation time is shortened by using a value modulation method, and the condition of the transmission path is poor, for example, when the base station and the terminal are far apart, the occupation time is lengthened by reducing the number of multi-values, thereby providing substantial information. Control is performed to keep the transmission speed constant.

[0004]

However, the device disclosed in Japanese Patent Application Laid-Open No. Hei 7-123017 is provided with a plurality of demodulating means on the receiving side, detects which demodulating means is operating normally, and uses the result based on the result. The demodulation means for switching the demodulation means to output received data is required. Therefore, a detection means and a switching means for a plurality of demodulation systems are required, and there has been a problem that the configuration is complicated.

In Japanese Unexamined Patent Publication No. Hei 5-130082, it is necessary for a mobile terminal to notify a control station such as a base station of a desired modulation scheme. There was trouble to tell the control station. Moreover, when the control station is notified of the desired modulation method,
If the radio wave environment suddenly changes while notifying the desired modulated wave, the control station may not be able to receive the notification of the modulation method, and if there is no available channel because it is a time division multiplex communication method, There has been a problem that the switching of the modulation system cannot be reliably performed, for example, a case where communication cannot be performed with a desired modulation system.

Accordingly, the first aspect of the present invention provides a demodulation method capable of demodulating transmission signals of a plurality of modulation schemes with a simple configuration.

Further, the inventions according to claims 2 to 4 provide a modulation method which does not need to notify the other party of the modulation method when switching the modulation method, and therefore can realize the switching of the modulation method with simple control. I do.

The invention according to claim 5 provides a demodulation device capable of demodulating transmission signals of a plurality of modulation schemes with a simple configuration.

The invention according to claim 6 can demodulate transmission signals of a plurality of modulation schemes with a simple configuration, and does not need to notify the other party of the modulation scheme when switching the modulation scheme. And a modulation / demodulation device capable of realizing switching of a modulation system with simple control.

[0010]

According to the first aspect of the present invention,
Receives a signal modulated by a plurality of modulation schemes with different signal points each consisting of an in-phase component and a quadrature component. Divides this received signal into two, and synchronously detects each of the in-phase and quadrature components. Then, the multi-level data respectively corresponding to the in-phase component and the quadrature component obtained by the synchronous detection are converted into data consisting of a predetermined number of bits including bits for determining a modulation scheme, and thereafter, the in-phase component and the quadrature component are converted. A demodulation method for combining the converted data corresponding to each of the following, determining the modulation system from the bits representing the modulation system in the synthesized data, selecting a demodulation system according to the determined modulation system, and demodulating the received data. It is in.

According to a second aspect of the present invention, after a modulation scheme is determined, transmission data is converted into data having a predetermined number of bits representing different signal points each composed of an in-phase component and a quadrature component by the determined modulation scheme. Then, the converted data is distributed into two streams, the distributed two streams of data are converted into data having a plurality of levels, and then modulated into in-phase components and quadrature components, and the modulated in-phase components are modulated. And a modulation method for combining and transmitting data of orthogonal components.

According to a third aspect of the present invention, there is provided the modulation method according to the second aspect, wherein self-movement information is detected, and a modulation method is determined based on the detected movement information.

According to a fourth aspect of the present invention, in the modulation method of the second aspect, a reception level and a phase threshold are set for each of the received signal points, and the modulation method is switched when the signal point of the received signal deviates from the threshold. It is in.

According to a fifth aspect of the present invention, there is provided a receiving means for receiving a signal modulated by a plurality of modulation schemes in which signal points each composed of an in-phase component and a quadrature component are different from each other, and receiving the signal by the receiving means. Branching means for branching the received signal into two;
A synchronous detection means for synchronously detecting each of the in-phase component and the quadrature component from the signal branched by the branching means, and outputting data of a plurality of levels corresponding to the in-phase component and the quadrature component, and an in-phase component from the synchronous detection means And conversion means for converting data corresponding to the quadrature component into data consisting of a predetermined number of bits including bits for determining a modulation scheme, and conversion data respectively corresponding to the in-phase component and the quadrature component converted by the conversion means. Synthesizing means for synthesizing, and a modulation scheme determining means for determining a modulation scheme from bits representing the modulation scheme in the synthesized data synthesized by the synthesizing means;
There is provided a demodulation apparatus provided with data demodulation means for selecting a demodulation method according to the modulation method determined by the modulation method determination means and demodulating received data.

According to a sixth aspect of the present invention, there is provided a modulation / demodulation device including a modulation device and a demodulation device, wherein the modulation device uses a modulation method determination means for determining a modulation method and a modulation method determined by the modulation room determination means. First data conversion means for converting transmission data into data consisting of a predetermined number of bits representing different signal points composed of an in-phase component and a quadrature component, and distribution for distributing the data converted by the data conversion means into two streams Means for converting the two series of data distributed by the distribution means into data having a plurality of levels, respectively, and converting the data converted by the second data conversion means into an in-phase component and a quadrature component. A data modulating means for dividing and modulating the data, and a transmitting means for combining and transmitting data of the in-phase component and the quadrature component modulated by the data modulating means. The apparatus includes a receiving unit that receives a signal modulated by a plurality of modulation schemes, each of which has a signal point composed of an in-phase component and a quadrature component, and splits a received signal received by the receiving unit into two. Branching means, synchronous detection means for synchronously detecting each of the in-phase component and the quadrature component from the signal branched by the branching means, and outputting a plurality of levels of data respectively corresponding to the in-phase component and the quadrature component; and the synchronous detection means. Conversion means for converting the data corresponding to the in-phase component and the quadrature component from the data into data consisting of a predetermined number of bits including bits for determining the modulation scheme, and corresponding to the in-phase component and the quadrature component converted by the conversion means, respectively. Synthesizing means for synthesizing the converted data, and a modulation scheme determination for judging the modulation scheme from bits representing the modulation scheme in the synthesized data synthesized by the synthesizing means. And the step, in the modulation scheme determining unit modem comprising a data demodulation means for demodulating the received data to select the demodulation scheme in accordance with the modulation scheme determined.

[0016]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a signal point constellation in a modulation scheme, where 16 signal point constellations in a 16QAM modulation scheme are shown.
The signal point arrangement of four different 4-phase PSK modulation schemes is shown. That is, in FIG. 1, the horizontal axis represents the reception level of the in-phase component (I), the vertical axis represents the reception level of the quadrature component (Q), and the in-phase component (I) and the quadrature component (Q) are divided into five stages. −2, −1, 0, +1, +2 ″, and the black points indicate the signal point arrangement of the 16QAM modulation method.
The ellipse indicates the signal point arrangement of the four-phase PSK modulation method.

Further, the five-level signal "-2,-
As shown in FIG. 2, 1,0, + 1, + 2 "is 3-bit data" 000,010,001,100,110 ".
, And the in-phase component is leveled from the three bits (a1, a3, a5) and the quadrature component is leveled from the three bits (a2, a4, a6).
2, a3, a4, a5, a6) represent one signal point.

FIG. 3 is a block diagram showing a configuration of a demodulation device in a mobile terminal.
1. Amplify the signal received by the receiving antenna 11,
Receiving unit 12 for performing frequency conversion as necessary, branching unit 1
In-phase component by two reference carriers having different π / 2 phases recovered from the received signal with respect to the signal branched by 3
A synchronous detector 14, which performs synchronous detection of (I) and the quadrature component (Q),
15, a clock synchronization / reference carrier recovery unit 16 for synchronizing clocks and recovering a reference carrier, the synchronous detector 1
5 level signal "-" synchronously detected by
2, -1, 0, +1, +2 "are converted to 3-bit data" 00
Quinary-to-ternary conversion units 17 and 18 for converting the data into 0, 010, 001, 100, and 110 ″. The three-bit data from the two-series quinary-to-ternary conversion units 17 and 18 are combined into six bits. Out of the 6-bit data, demodulates the received data based on the bit representing the modulation scheme, and controls the receiving buffer 20 for outputting to the output terminal 19, the clock synchronization / reference carrier recovery unit 16, and the receiving buffer 20. It is configured by a control unit 21 that performs the control.

The reception buffer 20 has four
In-phase component (I) and quadrature component for phase PSK modulation
(Q) has a reception level of "0" and one of bits a5 and a6 has a value of "1". Of the 6-bit data obtained by combining the bit data, OR operations are performed on bits a5 and a6 representing the modulation method,
If the output is "0" according to the OR operation result, 16QA
It is determined that the M modulation method is used, and if "1", it is determined that the four phase PSK modulation method is used.

Next, the demodulation method will be described with reference to FIGS. The signal received by the receiving antenna 11 is amplified and frequency-converted by the receiving unit 12, and then branched into two by the branching unit 13. Then, the two synchronous detectors 14 and 15 use the reference carrier having the phase shifted by π / 2 to obtain the in-phase component.
(I) and the quadrature component (Q) are synchronously detected. Each of the synchronous detectors 14 and 15 divides the received signal into five levels of level signals “−2, −1, 0, +1 and +2” and sends them to the quinary-to-ternary converters 17 and 18.

The quinary-to-ternary conversion units 17 and 18 perform quinary-to-ternary conversion as shown in FIG.
According to the level signal of the stage, for example, the data is converted to predetermined 3-bit data, such as “100” if “+1”, or “000” if “−2”, and is sent to the reception buffer 20. At this time, when the modulation method is 16 QAM, the reception level of both the in-phase component (I) and the quadrature component (Q) is “0”.
However, when the modulation method is four-phase PSK, one of the reception level of the in-phase component (I) and the reception level of the quadrature component (Q) always becomes "0". This gives 5
When the reception level is "0", the value-three-value converters 17 and 18 set the last bits (a5 and a6) of the 3-bit data to be converted to "1", and when the reception level is other than 0, the last bit (a5). And a6) are converted to “0”.

The reception buffer 20 performs an OR operation on the bits a5 and a6 representing the modulation method. If the calculation result is "0", the modulation method is 16QA.
M, and among the bits a1 to a6 constituting the 16 signal points, the bits a1 to a4 are the received data as they are, so that the bits a1 to a4 as shown in FIG.
To a4 are sequentially output to the output terminal 19. If the OR operation result of the bit a5 and the bit a6 is “1”, it is determined that the modulation method is the 4-phase PSK, and as shown in FIG. In this case, it is converted to "01", and if it is "010110", it is converted to "10", and the output terminal 19 outputs the data shown in FIG.

FIG. 8 is a block diagram showing a configuration of a modulation device of a mobile terminal. This modulation device converts transmission data input from input terminal 31 into 6-bit data a1 to a6 representing a signal point and a modulation system by a modulation system. , And a
1, 2 and 3 bits of a3, a5 and a2, a4, a6
A transmission buffer 32 for converting data into a series of data, a 3-bit data for converting 3-bit data "000, 010, 001, 100, 110" into five-level signal "-2, -1, 0, +1, +2" Quinary converters 33 and 34, carrier is π / 2
A quinary amplitude modulator (AMMOD) 35, 3 for quaternary amplitude modulation of each of the in-phase component (I) and the quadrature component (Q) by shifting.
6. A synthesizing unit 37 for synthesizing the amplitude modulation signals from the respective amplitude modulators 35 and 36. The two series of modulated signals synthesized by the synthesizing unit 37 are frequency-converted as necessary and transmitted from the transmitting antenna 38. Whether the transmitting unit 39 is used by moving or receiving the terminal on the receiving side,
Alternatively, it controls the modulation scheme determining unit 40 and the modulation scheme determining unit 40 and the transmission buffer 32 which determine whether to use 16 QAM or 4-phase PSK based on the difference between the distance between the reception signal point and the reference signal point. The control unit 41 is configured.

The transmission data from the input terminal 31 is
Is converted into data of bits a1 to a6,
In order to perform modulation separately for (I) and the quadrature component (Q), a1,
The in-phase component (I) and the quadrature component (Q) are converted into two-series data of 3 bits each of a3, a5 and a2, a4, a6. 0, +1, +
This is for converting to 2 ″.

Next, the 16QAM modulation method and the four-phase PSK modulation method will be described with reference to FIGS. When the transmitting side performs 16QAM modulation, as shown in FIG. 9, the data sent to the transmission buffer 32 is divided into 4 bits, and stored in “a1 to a4” in the transmission buffer 32, and at the same time, the signal point is changed by the modulation method. To change the in-phase component
"0" is stored in "a5" and "a6" so that (I) and the quadrature component (Q) each have 3 bits, each having a total of 6 bits.

Then, among the 6-bit data a1 to a6, a1, a3, a
5 to one ternary-to-five-value conversion unit 33, and a2, a4, and a6 as data for quadrature component (Q) modulation.
The data is sent to two ternary-to-five-value conversion units 34, and the transmission data is divided into two streams. In the three-valued to five-value conversion units 33 and 34, FIG.
The data transmitted as shown in FIG.
"0" indicates "+1", and "000" indicates "-".
Two levels are assigned based on the conversion content predetermined as 2 ".

When the transmitting side performs 4-phase PSK modulation, the data sent to the transmission buffer 32 is divided into two bits at a time as shown in FIG. Is converted into 6-bit data based on. For example, if the transmission data is “01” in the switching unit, it is converted into 6-bit data of “000010”, and if it is “10”, it is converted into 6-bit data of “010110”. Stored in “a1 to a6”. At this time, four signal points are constituted by the bits “a1 to a6”.

Of the 6-bit data "a1 to a6", a1, a2 are used as data for modulating the in-phase component (I).
3, a5 is sent to one ternary-5 value conversion unit 33, and
The data a2, a4, and a6 are transmitted to another ternary-to-five-value conversion unit 34 as data for orthogonal component (Q) modulation, and the transmission data is divided into two streams. In the three-valued-to-five-value conversion units 33 and 34, the data transmitted as shown in FIG.
If "001", "0", and if "000", "-2" is assigned to five levels based on predetermined conversion contents.

The 6 bits "a1 to a6" and "-
2, -1, 0, +1, +2 "is assigned as 1 level.
These are the number of bits and the level necessary for efficiently configuring 20 different signal points of 6QAM modulation and four-phase PSK modulation, and are not limited to these numbers when other modulation methods are used.

Thereafter, the five levels “−2, −1,
The two series of data divided into 0, +1 and +2 "are sent to quinary amplitude modulators 35 and 36, and the in-phase component (I) and the quadrature component (Q) are respectively converted by carrier waves having phases shifted by π / 2. By combining the signals after amplitude modulation, a 16QAM modulated output or a four-phase PSK modulated output transmitted from the transmitting unit 39 via the transmitting antenna 38 is obtained.

Next, the function of the modulation scheme determining section 40 will be described. The modulation scheme determining unit 40 detects the movement information of the transmitter itself, and determines the modulation scheme based on the detected information.

Since the propagation state changes depending on whether the transmitter itself is moving or fixed, for example, a GPS is mounted on the transmitter to periodically check the position. Or is the terminal equipped with a sensor that can indicate that it is moving, such as a gyro sensor or altitude sensor, periodically detects the value of the sensor, and based on this detected information, is the transmitter itself moving? It is determined whether it is fixed, and if it is moving, the modulation method is 4-phase PSK, and if it is fixed, the modulation method is 16QAM.

The propagation state also depends on the moving speed of the transmitter. If there is no obstacle between the transmitter and the receiver and the speed is relatively low, communication can be performed in a favorable propagation state. Therefore, the moving speed is detected as the moving state of the transmitter, and the modulation method is determined based on the moving speed. To detect the moving speed, the GPS is installed in the transmitter, the current position and the time are periodically obtained, the position information and the time information are stored, and the information is transmitted from the immediately preceding information and the newly obtained information. There is a method of calculating the approximate speed of the transmitter, a method of mounting a speed sensor on the transmitter, and a method of monitoring the speed by a control unit of the transmitter. Then, the detected moving speed is compared with a speed value set in advance as a reference value, and if it is larger than the reference value, 4-phase PSK is set, and if it is smaller, 16QAM is set.

Further, instead of detecting the moving speed, the moving distance may be detected. That is, the GPS is mounted on the transmitter, the current position is obtained at predetermined time intervals, and the approximate moving distance of the transmitter is detected from the position information and the previous position information. Then, the moving distance is compared with a moving distance value set as a reference value in advance.
K, and 16QAM if smaller.

Next, an example in which a GPS is mounted on a terminal to determine a modulation method will be described. FIG. 14 shows a case where the terminal 51 has a GPS.
In the block diagram when the terminal 52 is mounted, the GPS 52 is a GPS control unit 54 that periodically inquires of the position from the terminal 51 and exchanges position information with the control unit 53 of the terminal 51.
And an antenna 55 for receiving radio waves from a satellite and a GPS
And a receiving unit 56. Then, the control unit 53 of the terminal 51
When the GPS 52 is inquired about the position information, the GPS 52 is driven and transmits the position information to the control unit 53 of the terminal 51. Alternatively, the GPS 52 is periodically driven, and when there is an inquiry about the position information from the control unit 53 of the terminal 51, the latest information is immediately transmitted to the control unit 53 of the terminal 51 at that time.

FIG. 15 is a flowchart showing the control in the case where the modulation method is determined by determining whether the transmitting terminal is moving or fixed, and the transmitting terminal first performs S1 and S2.
Before starting data communication with the receiving terminal, the current position of the own terminal is inquired to the GPS 52 in order to know whether the own terminal is moving or fixed.
Then, in S3, for example, the current modulation scheme is 16QA
When detecting that the moving state of the own terminal is moving in M, in S4, a change of the modulation method is determined, and in S5,
After waiting for a certain period of time, in S6, the modulation method is changed to 16QA.
M is changed to 4-phase PSK, and data communication is performed in S7. Further, if it is detected in S3 that the own terminal is fixed, it is determined in S4 that the modulation method is not changed. In this case, data communication is performed in S7 while the modulation method remains 16QAM. .

As described above, the transmitting terminal periodically checks the current position of its own terminal, determines whether to change the modulation scheme depending on whether the terminal is moving or fixed, and continues data communication. Become.

FIG. 16 is a flowchart showing the control when the modulation method is determined based on the moving speed of the transmitting terminal itself. The transmitting terminal first starts data communication with the receiving terminal in S11 and S12. Before the current position of the terminal itself is GPS5
Contact 2 to confirm. Then, in S13, a moving speed is obtained from the current position information and time information and the previous position information and time information.

Subsequently, in S14, the obtained moving speed is compared with a preset reference moving speed to determine a modulation method. For example, when it is detected that the current modulation method is 16QAM and the moving speed exceeds the reference speed, S1
At 5, it is determined that the modulation scheme has been changed. At S16, a predetermined period of time is waited. At S17, the modulation scheme is changed from 16QAM to 4-phase PSK, and at S18, data communication is performed. Further, if it is detected in S14 that the moving speed is equal to or lower than the reference speed, it is determined in S15 that the modulation method is not changed.
At 8, data communication is performed.

As described above, the transmitting terminal periodically detects the moving speed of its own terminal, determines whether to change the modulation scheme based on whether or not the moving speed exceeds the reference speed, and performs data communication. Will continue.

As another method of switching the modulation method, a storage device is provided in the modulation method determination unit 40, and the threshold value (reception level and phase) of the reception signal point as shown in FIG. Is stored, and when the signal point of the received signal deviates from a determinable threshold value when the 16QAM modulation method is used, switching to the four-phase PSK modulation method is performed.
Also, when the reception level falls within the threshold value when the 4-phase PSK modulation method is used, that is, when it is determined that 16 signal points can be identified even when switching to the 16QAM modulation method, 16QAM modulation is performed at the time. There is also a method in which it is determined that the system can be switched, and the modulation system is switched from the 4-phase PSK modulation system to the 16QAM modulation system.

As described above, since the signal point differs depending on the modulation method, the receiving side splits the received signal into two and then performs synchronous detection to obtain data representing the in-phase component (I) and the quadrature component (Q). The data is combined, the modulation method can be determined from the bits indicating the modulation method in the data, and demodulation can be performed in accordance with the determined modulation method. Therefore, a single demodulator can demodulate transmission signals of a plurality of modulation schemes, thereby simplifying the configuration.

Further, a transmission buffer 32 is provided in the modulator,
The signal is converted into data consisting of a predetermined number of bits representing different signal points composed of an in-phase component (I) and a quadrature component (Q) according to the modulation method, and a modulated signal is generated based on the converted data. A plurality of modulation schemes having different points can be realized. Therefore, one modulator can cope with transmission using a plurality of modulation schemes, and the configuration can be simplified. Further, when the modulation method is switched, there is no need to notify the other party of the modulation method, and therefore, the modulation method can be switched with simple control. Further, by switching the modulation method by the modulation method determination unit 40 of the modulator depending on the state of the terminal on the modulator side and the use environment, communication interruption due to a change in the radio wave environment is eliminated.

In this embodiment, the case where the 16QAM modulation system and the four-phase PSK modulation system are used as the modulation system has been described as an example, but the modulation systems used are not limited to these two.

[0045]

According to the first aspect of the present invention, it is possible to provide a demodulation method capable of demodulating transmission signals of a plurality of modulation schemes with a simple configuration. According to the second to fourth aspects of the present invention, it is not necessary to notify the other party of the modulation method when switching the modulation method, and therefore, it is possible to provide a modulation method capable of realizing switching of the modulation method with simple control. .

According to the fifth aspect of the present invention, it is possible to provide a demodulator capable of demodulating transmission signals of a plurality of modulation schemes with a simple configuration. According to the invention of claim 6, it is possible to demodulate transmission signals of a plurality of modulation schemes with a simple configuration, and it is not necessary to notify the other party of the modulation scheme when switching the modulation scheme. It is possible to provide a modulation / demodulation device capable of realizing switching of a modulation method with simple control.

[Brief description of the drawings]

FIG. 1 is a diagram showing a signal point arrangement of a modulation method according to an embodiment of the present invention.

FIG. 2 is a diagram showing a correspondence relationship between a 5-level level and 3-bit data in the embodiment.

FIG. 3 is a block diagram showing a configuration of a demodulator of the mobile terminal according to the embodiment.

FIG. 4 is a view showing the contents of quinary-to-ternary conversion performed by a quinary-to-ternary conversion unit of the demodulation device according to the embodiment.

FIG. 5 is a diagram for explaining an operation of a reception buffer of the demodulation device in the case of a 16QAM modulation method according to the embodiment.

FIG. 6 is a view showing the contents of data conversion in a switching section of a reception buffer of the demodulation device according to the embodiment.

FIG. 7 is an exemplary view for explaining the operation of the reception buffer of the demodulation device in the case of the four-phase PSK modulation method in the embodiment.

FIG. 8 is a block diagram showing a configuration of a modulation device of the mobile terminal according to the embodiment.

FIG. 9 is a diagram for explaining the operation of the transmission buffer of the modulation device in the case of the 16QAM modulation scheme according to the embodiment.

FIG. 10 is a diagram showing the contents of ternary to quinary conversion performed by the ternary to quinary conversion unit of the modulation device in the case of the 16QAM modulation method in the embodiment.

FIG. 11 is a diagram for explaining the operation of the transmission buffer of the modulation device in the case of the four-phase PSK modulation method in the embodiment.

FIG. 12 is a view showing the content of data conversion in a transmission buffer switching unit of the modulation device according to the embodiment.

FIG. 13 is a diagram showing the contents of ternary to quinary conversion performed by the ternary to quinary conversion unit of the modulation device in the case of the four-phase PSK modulation method in the embodiment.

FIG. 14 is a block diagram when a GPS is mounted on the mobile terminal in the embodiment.

FIG. 15 is a flowchart showing an example of modulation scheme determination control by the transmitting mobile terminal according to the embodiment.

FIG. 16 is a flowchart showing another example of modulation scheme determination control by the transmitting mobile terminal in the embodiment.

FIG. 17 shows a modulation scheme of 16QAM in the embodiment.
The figure showing the threshold value of the signal point for switching between a modulation system and a four-phase PSK modulation system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 ... Receiving part 13 ... Branching means 14, 15 ... Synchronous detector 17, 18 ... Five-value-three-value conversion part 20 ... Reception buffer 32 ... Transmission buffer 33, 34 ... Three-value-five-value conversion part 39 ... Transmission part 40 … Modulation method determination unit

Claims (6)

[Claims] 1. A signal modulated by a plurality of modulation schemes, each having a signal point composed of an in-phase component and a quadrature component, respectively, is received, and the received signal is divided into two to separate the in-phase component and the quadrature component. Are synchronously detected, and a plurality of levels of data respectively corresponding to the in-phase component and the quadrature component obtained by the synchronous detection are converted into data having a predetermined number of bits including bits for determining a modulation scheme. The converted data respectively corresponding to the in-phase component and the quadrature component are combined, the modulation method is determined from the bits representing the modulation method in the combined data, and the demodulation method is selected according to the determined modulation method to select the demodulation method. A demodulation method characterized by performing demodulation. 2. After a modulation scheme is determined, the transmission data is converted into data having a predetermined number of bits representing different signal points each composed of an in-phase component and a quadrature component by the determined modulation scheme. Is divided into two sequences, the distributed two sequences of data are converted into data having a plurality of levels, and then divided into in-phase components and quadrature components, and the modulated in-phase components and quadrature components are modulated. A modulation method characterized by combining and transmitting. 3. The modulation method according to claim 2, wherein the mobile station detects its own movement information, and determines a modulation method based on the detected movement information. 4. The modulation method according to claim 2, wherein a threshold of a reception level and a phase are set for each of the received signal points, and a modulation method is switched when the signal point of the received signal deviates from the threshold. 5. A receiving means for receiving a signal modulated by a plurality of modulation schemes, each of which has a signal point composed of an in-phase component and a quadrature component, and a receiving signal received by the receiving means. Branching means for branching, synchronous detection means for synchronously detecting each of the in-phase component and the quadrature component from the signal branched by the branching means, and outputting a plurality of levels of data respectively corresponding to the in-phase component and the quadrature component; Conversion means for converting data corresponding to the in-phase component and the quadrature component from the detection means into data having a predetermined number of bits including bits for determining a modulation scheme; and Synthesizing means for synthesizing the corresponding converted data; and a modulation scheme judging unit for judging a modulation scheme from bits indicating the modulation scheme in the synthesized data synthesized by the synthesizing means. A demodulation device comprising: a setting unit; and a data demodulation unit for selecting a demodulation system according to the modulation system determined by the modulation system determination unit and demodulating received data. 6. A modulation / demodulation device comprising a modulation device and a demodulation device, wherein the modulation device determines a modulation method, and modulates transmission data with an in-phase component according to the modulation method determined by the modulation room determination device. First data conversion means for converting data having a predetermined number of bits representing mutually different signal points constituted by a signal and orthogonal components; distribution means for distributing the data converted by the data conversion means into two streams; Second data converting means for converting the two series of data distributed by the means into data having a plurality of levels, and modulating the data converted by the second data converting means into an in-phase component and a quadrature component Data demodulating means, and transmitting means for synthesizing and transmitting data of the in-phase component and the quadrature component modulated by the data modulating means and transmitting the data. Receiving means for receiving signals modulated by a plurality of modulation schemes, each of which has a signal point composed of a component and an orthogonal component, and branching means for splitting a received signal received by the receiving means into two, A synchronous detection means for synchronously detecting each of the in-phase component and the quadrature component from the signal branched by the branching means and outputting a plurality of levels of data respectively corresponding to the in-phase component and the quadrature component; and an in-phase component from the synchronous detection means. And the data corresponding to the orthogonal components,
Conversion means for converting data having a predetermined number of bits including bits for determining a modulation method; synthesizing means for synthesizing conversion data respectively corresponding to the in-phase component and quadrature component converted by the conversion means; And a demodulation method judging means for judging the modulation method from the bits representing the modulation method in the data synthesized by the method, and a demodulation method for selecting a demodulation method according to the modulation method judged by the modulation method judging means and demodulating the received data. And a modulating / demodulating device.