JP2002016507A - Transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmitter that suppresses increase in nonlinear distortion amounts caused in a transmission amplifier section so as to suppress further distortion deterioration in a modulation signal, even if the operating point of the transmission amplifier section is deviated due to environmental fluctuations. SOLUTION: The transmission amplifier section 14 amplifiers a modulation signal, received from a modulation section 13 and transmits the amplified signal from an antenna 18. A band limit processing section 12 applies convolution arithmetic processings between a transmission code received from a code processing section 11 and the output of a band limit filter, and can change each tap coefficient of the filter. Furthermore, a coefficient table storage section 15 stores a plurality of kinds of tables, that store tap coefficients of a Nyquist system filter. Then a control section 16 receives environment fluctuations from an environment fluctuation monitoring section 17, selects a tap coefficient of the filter, where no nonlinear distortion quantity is increased from a table of a coefficient table storage section 15, to select a tap of the filter of the band limit processing section 12. Then a peak average ratio of the transmission signal is changed, to suppress the increase in the nonlinear distortion quantity of the transmission amplifier section 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission device for digital communication, and more particularly to a transmission device for performing stable data transmission against environmental fluctuations.

[0002]

2. Description of the Related Art Normally, when data transmission is performed by digital communication, transmission data is encoded, converted into a modulated signal, and then amplified and transmitted. FIG. 5 is a block diagram showing a configuration of a conventional transmission device. That is,
In the figure, in the transmitting apparatus, a code processing unit 41 receives transmission data to be transmitted, performs an encoding process, and converts the data into a transmission code. Further, the band limitation processing unit 42 performs band limitation by applying a band limitation filter to the encoded transmission code, and converts the transmission code into a transmission signal. And the modulation unit 4
3 modulates the band-limited transmission signal and converts it to a modulated signal. Further, this modulated signal is transmitted to the transmission amplifier 4
4 and transmitted from the antenna 45.

[0003]

However, in the above-mentioned conventional transmitting apparatus, when environmental fluctuations such as temperature and voltage occur, the operating point of the transmission amplifier shifts, and the amount of nonlinear distortion generated by the transmission amplifier increases. And the modulated signal may be further degraded. Japanese Patent Application Laid-Open No. 9-46264 discloses a technique for preventing distortion deterioration of a modulation signal by varying the gain of a transmission amplifier according to the power supply voltage even if the power supply voltage is reduced. However, it is not possible to prevent the distortion of the modulation signal from being degraded with respect to the voltage fluctuation or the temperature change of the transmission signal.

The present invention has been made in view of such circumstances, and an object of the present invention is to reduce the amount of nonlinear distortion generated in a transmission amplification unit even if the operating point of the transmission amplification unit shifts due to environmental fluctuation. It is an object of the present invention to provide a transmission device capable of suppressing an increase and suppressing distortion deterioration of a modulation signal.

[0005]

In order to solve the above-mentioned problems, a transmitting apparatus of the present invention is a transmitting apparatus for performing data transmission in digital communication, and encodes transmission data to be transmitted into a transmission code. Code processing means, band limiting processing means for applying a band limiting filter to the transmission code coded by the code processing means to perform band limitation, and converting the transmission code into a transmission signal; Modulating means for modulating a signal and converting it to a modulated signal, transmission amplifying means for amplifying the modulated signal modulated by the modulating means, environmental fluctuation monitoring for monitoring environmental fluctuations and notifying environmental fluctuation values corresponding to the environmental fluctuations Means, a coefficient table accumulating means for storing as a table the tap coefficients of the band limiting filter corresponding to the environmental fluctuation value, and receiving the environmental fluctuation value from the environmental fluctuation monitoring means, based on the environmental fluctuation value. There are, by referring to the coefficient table storage unit, to select the tap coefficients of the band limiting filter for band limitation processing means, characterized by comprising a control means for updating the taps of the band limiting filter.

That is, in the transmitting apparatus of the present invention, the code processing means encodes the transmission data into a transmission code, and the band limitation processing means applies a band limitation filter to the transmission code to perform band limitation to convert to a transmission signal. Further, the modulating means modulates the transmission signal to convert it into a modulated signal, and transmits the signal after amplifying the modulated signal by the transmission amplifying means. On the other hand, the environmental change monitoring means monitors the environmental change and notifies the control means of the environmental change value. Then, the control means, based on the environmental fluctuation value,
The tap coefficient of the band limiting filter of the band limiting processing unit is selected by referring to the coefficient table storage unit, and the tap of the band limiting filter is updated.

As described above, by selecting the tap coefficient of the band limiting filter and changing the tap, the peak average ratio indicating the ratio of the peak value to the average value of the transmission waveform can be reduced, and environmental fluctuations can be reduced. Even if the operating point of the transmission amplifying unit shifts, the increase in the amount of non-linear distortion generated in the transmission amplifying unit can be suppressed, and further deterioration of the modulated signal can be suppressed.

[0008] In the transmission apparatus of the present invention, the control means may include:
By varying taps of the band limiting filter in the band limiting processing unit based on the acquired tap coefficients, the transmission amplifying unit generates a transmission signal suitable for nonlinear distortion characteristics in response to environmental fluctuations. And

That is, according to the transmitting apparatus of the present invention, the tap coefficient of the band-limiting filter is changed to an optimum value in response to the environmental fluctuation. Therefore, the distortion of the modulated signal is not further deteriorated.

The coefficient table storage means in the transmission apparatus of the present invention stores tap coefficients of Nyquist filters having different roll-off rates indicating attenuation rates of frequency versus amplitude characteristics as a table, or different window functions. The tap coefficients of the Nyquist filters are accumulated as a table.

That is, according to the transmitting apparatus of the present invention, by selecting a filter tap coefficient for generating a transmission signal suitable for the nonlinear distortion characteristic of the transmission amplifying means changed by environmental fluctuation, the roll-off rate or the The peak average ratio corresponding to the window function can be set. Therefore, even if the operating point of the transmission amplifier shifts due to environmental fluctuation, the distortion of the modulated signal is not further deteriorated.

Further, in the transmission apparatus according to the present invention, the environment fluctuation monitoring means monitors the voltage or temperature of the transmission apparatus and notifies the control means of the voltage fluctuation value or the temperature fluctuation value as the environment fluctuation value. .

That is, according to the transmitting apparatus of the present invention, the voltage and temperature of the transmitting apparatus are used as environmental fluctuation values, and the tap coefficient of the Nyquist filter is switched to an optimum value. Even if the operating point of the unit shifts, the distortion of the modulated signal is not further deteriorated.

Further, a communication apparatus can be configured by combining the transmitting apparatus of the present invention with a receiving apparatus, or a mobile station radio and a base station radio can be configured by using the transmitting apparatus together with the receiving apparatus. Furthermore, a wireless system can be constructed by using the transmitting device of the present invention together with the receiving device.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a transmitting apparatus according to the present invention will be described with reference to the drawings. FIG.
FIG. 2 is a block diagram illustrating a configuration of a transmission device according to one embodiment of the present invention. In the figure, the transmitting device of the present invention comprises:
A code processing unit 11 that encodes transmission data to be transmitted into a transmission code, a band limitation processing unit 12 that applies a band limiting filter to the transmission code encoded by the code processing unit 11 to limit the band, and converts the transmission code into a transmission signal. A modulation unit 13 that modulates the transmission signal subjected to band restriction by the band restriction processing unit 12 and converts the transmission signal into a modulation signal; a transmission amplification unit 14 that amplifies the modulation signal modulated by the modulation unit 13; A coefficient table storage unit 15 that stores a tap coefficient of a band-limiting filter to be performed as a table, and a tap coefficient of a band-limiting filter of the band-limiting processing unit 12 is selected by referring to the coefficient table storage unit 15 based on an environmental variation value. The control unit 16 updates the taps of the band limiting filter, and the environment change monitoring unit 17 monitors the environment change and notifies the control unit 16 of the environment change value.
And is constituted by.

Next, the operation of the transmitting apparatus configured as described above will be described. First, the code processing unit 11
However, the transmission data to be transmitted is encoded into a transmission code and transmitted to the band limitation processing unit 12. Then, the band limitation processing unit 12 performs band limitation by applying a band limitation filter to the received transmission code, converts the transmission code into a transmission signal, and transmits the transmission signal to the modulation unit 13. Further, the modulator 13 modulates the transmission signal subjected to the band limitation to convert the transmission signal into a modulated signal. Then, the transmission amplifier 14 amplifies the modulated signal, and transmits the amplified modulated signal from the antenna 18.

On the other hand, the environmental change monitoring unit 17 monitors environmental changes such as the voltage and temperature of the transmitting device, and notifies the control unit 16 of the environmental change value. Then, the control unit 16 refers to the coefficient table storage unit 15 to select and acquire the tap coefficient of the band limiting filter of the band limiting processing unit 12 based on the received environmental fluctuation value. And the control unit 16
Is based on the acquired tap coefficient,
The tap of the band limiting filter in step 2 is updated.

Here, the band limiting processing unit 12 is a processing unit that performs a convolution operation of the transmission code and the band limiting filter, and can change each tap coefficient of the band limiting filter arbitrarily. I have.

The coefficient table storage unit 15 stores several types of tap coefficient correspondence tables corresponding to environmental fluctuation values, using the tap coefficients of the Nyquist filter as tables. The Nyquist filter is a filter that creates a waveform response free of intersymbol interference.

Further, each table stored in the coefficient table storage unit 15 is classified into several stages by focusing on, for example, a roll-off rate α indicating an attenuation ratio of the frequency-amplitude characteristic, or a rectangular window, a Hanning window, or the like. They are classified by focusing on several types of window functions. If the roll-off rate α or the window function is changed, the peak average ratio, which indicates the ratio of the peak value to the average value of the transmission waveform, will change. By selecting the table based on the value, it is possible to suppress an increase in the amount of nonlinear distortion generated in the transmission amplifier 14, and to suppress further deterioration of the modulated signal.

The environment change monitoring unit 17 monitors the environment change of the transmission device configured as shown in FIG. 1, and notifies the control unit 16 of the change as an environment change value. The monitored environmental change includes a voltage, a temperature, and the like in the transmission device, but may be other values.

If the operating point of the transmission amplification unit 14 shifts due to environmental fluctuations, the amount of nonlinear distortion generated in the transmission amplification unit 14 increases, and the modulated signal is degraded. Then, the control unit 1
6 receives the environmental fluctuation value from the environmental fluctuation monitoring unit 17,
A tap coefficient that does not increase the amount of nonlinear distortion is selected from the coefficient table storage unit 15, and the tap of the filter is switched. As a result, the peak average ratio changes, so that an increase in the amount of nonlinear distortion generated in the transmission amplification unit 14 can be suppressed, and further deterioration of the modulated signal can be suppressed.

FIG. 2 is a table showing the relationship between the window function and the peak average ratio corresponding to the roll-off rate α at a certain tap coefficient, stored in the coefficient table storage section.
That is, this chart shows how the peak average ratio changes when the roll-off rate α and the window function of the Nyquist filter of the transmission route are changed. The conditions in this table are as follows: tap number 111 [tap], sampling frequency 38400 [Hz], modulation scheme 4 / π shift QPSK, frame number 4 [frame], symbol number 192 [symbol / frame], oversample number 8 [times] ].

That is, as shown in the table of FIG. 1, the peak average ratio is determined depending on whether the window function is a rectangular window or a Hanning window, and corresponding to each roll-off rate α. Therefore, by selecting an optimum roll-off rate α and window function, a desired peak average ratio is obtained, an increase in the amount of nonlinear distortion generated in the transmission amplification unit 14 can be suppressed, and deterioration of a modulated signal can be suppressed.

As described above, according to the transmitting apparatus of the present invention, the tap of the band-limiting filter in the band-limiting processing unit 12 is varied to lower the peak average ratio, thereby causing environmental fluctuation and causing transmission amplification. Even if the operating point of the unit 14 shifts, it is possible to suppress an increase in the amount of nonlinear distortion generated in the transmission amplifying unit 14 and suppress further deterioration of the modulated signal.

FIG. 3 is an example of a configuration diagram of a communication device in which the transmitting device shown in FIG. 1 is provided with a receiving device. In FIG. 3, the communication device 21 includes a transmitting device 22 that performs the transmitting process as described in the above-described embodiment, and a receiving device 23 that performs the receiving process. According to the communication device 21 configured as described above, the transmitting device 22 changes the tap coefficient of the band-limiting filter in accordance with the environmental fluctuation to lower the peak average ratio, thereby causing the environmental fluctuation and the transmission amplification. Even if the operating point of the unit shifts, it is possible to suppress an increase in the amount of nonlinear distortion generated in the transmission amplification unit, and to suppress further deterioration of the modulated signal.

FIG. 4 is an example of a configuration diagram of a wireless system constructed using the transmitting apparatus shown in FIG. In FIG. 4, the transmitting device described in the above-described embodiment is mounted on the mobile station radio 31 and the base station radios 32a and 32b that constitute the radio system, but these transmitting devices are not shown. Absent. That is, the transmitting device mounted on the mobile station radio 31 performs transmission processing, and the base station radio 3
The transmission device mounted on the base station 2 performs transmission processing, and also in a wireless system, the transmission device mounted on the mobile station radio 31 or the base station radio 32 performs transmission processing.

Such mobile station radios and base station radios,
Alternatively, according to the wireless system, the transmitting device (not shown) lowers the peak average ratio in which the tap coefficient of the band-limiting filter is changed, so that even if the operating point of the transmission amplifying unit is shifted due to environmental fluctuation, the transmission amplifying unit does not. It is possible to suppress an increase in the amount of nonlinear distortion that occurs, and to suppress further deterioration of the modulated signal.

[0029]

As described above, according to the transmitting apparatus of the present invention, by changing the tap coefficient of the band limiting filter and lowering the peak average ratio in accordance with the environmental fluctuation, the fluctuation of the environment is caused and the transmission amplifier Even if the operating point is shifted, it is possible to suppress an increase in the amount of nonlinear distortion generated in the transmission amplifying unit and suppress further deterioration of the modulation signal. Therefore, even if there is an environmental change such as a voltage or a temperature in the transmitting device, a stable modulated signal whose distortion factor does not change can be transmitted.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a transmission device according to an embodiment of the present invention.

FIG. 2 is a table showing a relationship between a window function and a peak average ratio corresponding to a roll-off rate α at a certain tap coefficient stored in a coefficient table storage unit.

FIG. 3 is an example of a configuration diagram of a communication device in which a receiving device is mounted on the transmitting device shown in FIG. 1;

FIG. 4 is an example of a configuration diagram of a wireless system constructed using the transmission device shown in FIG. 1;

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

[Explanation of symbols]

 11, 41 Code processing unit 12, 42 Band limitation processing unit 13, 43 Modulation unit 14, 44 Transmission amplification unit 15 Coefficient table storage unit 16 Control unit 17 Environment change monitoring unit 18, 45 Antenna 21 Communication device 22 Transmitting device 23 Receiving device 31 mobile station radio 32a, 32b base station radio

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ken Akiyama 4-3-1 Tsunashima Higashi, Kohoku-ku, Yokohama-shi, Kanagawa Prefecture Inside Matsushita Communication Industrial Co., Ltd. No.3-1 Matsushita Communication Industrial Co., Ltd. (72) Inventor Takehiro Fujii 4-3-1 Tsunashima Higashi, Kohoku-ku, Yokohama-shi, Kanagawa Prefecture F-term inside Matsushita Communication Industrial Co., Ltd. 5K004 AA01 BA01 BA02 BB01 BC01 5K060 BB07 HH11 HH39 KK06

Claims (10)

[Claims] 1. A transmission device for performing data transmission in digital communication, comprising: code processing means for coding transmission data to be transmitted into a transmission code; and a band for the transmission code coded by the code processing means. A band limiting processing unit that performs band limiting by applying a limiting filter and converts the transmission signal into a transmission signal; a modulation unit that modulates the transmission signal subjected to the band limitation by the band restriction processing unit and converts the transmission signal into a modulated signal; Transmission amplification means for amplifying the modulated signal; environmental fluctuation monitoring means for monitoring environmental fluctuations and notifying environmental fluctuation values corresponding to the environmental fluctuations; and a tap coefficient of a band limiting filter corresponding to the environmental fluctuation values, A coefficient table storage unit that stores the data as a table, and based on the environment change value received from the environment change monitoring unit, by referring to the coefficient table storage unit.
A transmitting means for selecting a tap coefficient of the band-limiting filter of the band-limiting processing means and updating taps of the band-limiting filter. 2. The transmission amplification means, wherein the control means comprises:
The transmission signal suitable for nonlinear distortion characteristics is generated in response to environmental fluctuations by varying taps of a band-limiting filter in the band-limiting processing unit based on the acquired tap coefficients. 2. The transmission device according to 1. 3. The coefficient table accumulating means accumulates, as a table, tap coefficients of Nyquist filters having different roll-off rates indicating attenuation rates of frequency-amplitude characteristics as a table. Transmission device. 4. The transmission apparatus according to claim 2, wherein said coefficient table storage means stores tap coefficients of Nyquist filters having different window functions as a table. 5. The apparatus according to claim 1, wherein the environmental fluctuation monitoring unit monitors a voltage of the transmitting device and notifies the control unit of a voltage fluctuation value as an environmental fluctuation value. The transmitting device according to the above. 6. The apparatus according to claim 1, wherein the environmental change monitoring means monitors a temperature of the transmitting device and notifies the control means of a temperature change value as an environmental change value. The transmitting device according to the above. 7. The transmitting device according to claim 1, wherein the transmitting device is used for a receiving device that performs a receiving process. 8. The transmitting apparatus according to claim 7, wherein the transmitting apparatus is used in a mobile station radio together with the receiving apparatus. 9. The transmitting apparatus according to claim 7, wherein the transmitting apparatus is used for a base station radio together with the receiving apparatus. 10. The transmitting device according to claim 7, wherein the transmitting device is used in a wireless system together with the receiving device.