JP2000101461A - Radio receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a radio receiver in which the possibility of deterioration in reception quality and of disabled reception is lowered. SOLUTION: A level detector 87 obtain a level of an orthogonal signal demodulated by an orthogonal demodulator 81. An inverse spread circuit 82 applies inverse spread processing to the orthogonal signal by using a spread code, after an error correction decoder 831 applies error correction decoding to the processing result, a convolution coder 85 re-encodes the result, a symbol comparator 86 compares the coding result with the data spread inversely before decoding to obtain an error rate of the data spread inversely. Then as long as the level obtained by the level detector 87 is higher than a specified level and the error rate exceeds a specified error rate, an IM detector 88 increases the attenuation of an RF signal amplifier at a pre-stage, through a distortion characteristics control signal to enhance the distortion characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio receiver used for, for example, a mobile communication system.

[0002]

2. Description of the Related Art FIG. 5 shows a CDMA (Code Division Multiple).
FIG. 2 is a circuit block diagram showing a configuration of a receiving system of a conventional mobile communication terminal device used in an iple Access) type mobile communication system.

[0005] A radio frequency signal transmitted from a base station (not shown) is received by an antenna 1, and only a radio frequency signal in a band to be received is output to an RF signal amplifier 3 via an antenna duplexer 2.

The RF signal amplifier 3 comprises a variable attenuator 31 and a front-end amplifier 32, as shown in FIG. The variable attenuator 31 attenuates the radio frequency signal input from the antenna duplexer 2 with an attenuation according to a distortion characteristic control signal from an IM detector 98 described later. The front end amplifier 32 amplifies the radio frequency signal output from the variable attenuator 31 at a high frequency with a predetermined gain, and outputs the radio frequency signal to the high frequency bandpass filter 4.

The high-frequency band-pass filter 4 removes unnecessary signals outside the reception band, and outputs the remaining high-frequency signals to the mixer 5. The mixer 5 mixes the high-frequency signal passed through the high-frequency band-pass filter 4 with a local oscillation signal generated by a synthesizer (not shown), and down-converts the high-frequency signal into an intermediate frequency signal.

From the intermediate frequency signal thus obtained, only a signal in a desired band is extracted by an intermediate frequency band pass filter 6 and output to an IF signal amplifier 7. The IF signal amplifier 7 amplifies the intermediate frequency signal passed through the intermediate frequency band pass filter 6 with a gain according to a gain control signal from the demodulation circuit 9 described later, and outputs the amplified signal to the demodulation circuit 9.

The demodulation circuit 9 demodulates an analog audio signal from the intermediate frequency signal amplified by the IF signal amplifier 7 and outputs a loudspeaker. The demodulation circuit 9 is configured as shown in FIG. The intermediate frequency signal is demodulated by a quadrature demodulator 91 into two quadrature signals I and Q. The quadrature demodulator 91 includes a local oscillator 910, mixers 911 and 912, a phase shifter (π / 2) 9
13, low-pass filters 914, 915, and A / D
It comprises converters (A / D) 916 and 917.

The intermediate frequency signal is supplied to mixers 911 and 91
2 is output. The mixer 911 includes a local oscillator 910
Is mixed with the intermediate frequency signal and converted into a baseband I signal.

On the other hand, the mixer 912 has a local oscillator 91
The local oscillation signal generated at 0 is a phase shifter (π / 2) 91
3 and is input after being phase shifted by π / 2. Then, the mixer 912 mixes the local oscillation signal from the phase shifter 913 with the intermediate frequency signal and converts it into a baseband Q signal having a 90 ° phase difference with the I signal.

After the high-band component is removed by the low-pass filter 914, the I signal is converted into a digital signal by the A / D converter 916, and output to the despreading circuit 92 and the level detector 97.

On the other hand, the Q signal is supplied to a low-pass filter 915
After the high-frequency component is removed by A / D converter 917, the signal is converted into a digital signal by A / D converter 917 and output to despreading circuit 92 and level detector 97.

The despreading circuit 92 uses an A / D converter 916, using a spreading code specified by the control unit 200 described later.
The digital signal from 917 is subjected to despreading processing, and the processing result is output to the reproducing unit 93.

In the reproducing section 93, first, the error correction decoder 93
1 performs Viterbi decoding on the processing result of the despreading circuit 92,
Error correction decoding is performed, and among the data obtained by this decoding, user data is output to a speech decoder 932 and a frame error rate measuring device (FER) 94 described later, and data related to a data rate is output to the control unit 200.

The audio decoder 932 includes an error correction decoder 93
The decompression processing is performed on the user data decoded in step 1 in accordance with the data rate notified from the control unit 200, and the compressed digital audio signal is reproduced on the transmission side.

This digital audio signal is converted into an analog audio signal by a D / A converter (D / A) 933 and then output from a speaker 934. The frame error rate measuring unit 94 measures the error rate of the user data decoded by the error correction decoder 931 in frame units, and notifies the control unit 200 of the measurement result. Here, the frame is a cycle of a data format determined in advance by this communication method.

The level detector 97 includes an A / D converter 91
In 6,917, the levels of the quadrature signals I and Q converted into digital signals are detected, and the detection results are output to an IM (Inter-Modulation) detector 98 as level information.

The level detector 97 detects the detected I,
A difference between the level value of the Q signal and a preset reference value is obtained and integrated, and the gain control signal corresponding to the integrated value is IF
The signal level is applied to the signal amplifier 7 to control the gain so that the level value becomes equal to the reference value.

The IM detector 98 monitors the level information notified from the level detector 97, and when the level information is larger than a predetermined value, the distortion of the RF signal amplifier 3 is transmitted through the distortion characteristic control signal. The distortion characteristics are improved by variably controlling the characteristics.

The control unit 200 controls the respective units of the mobile communication terminal device in a centralized manner. For example, as described above, the despreading circuit 92 supplies the base station to which the mobile station is connected and the spreading assigned to the own device. When the detection result of the frame error rate measuring unit 94 is equal to or more than a predetermined value, the transmission system (not shown) is controlled to retransmit data to the base station. Make a request.

The high-frequency signal received by the antenna 1 includes not only a desired wave but also a signal of a nearby frequency. Such an unnecessary signal is removed by the intermediate frequency band-pass filter 6.

However, as shown in FIG. 7, an interference component X generated at a desired frequency f1 due to intermodulation distortion in a stage preceding the intermediate frequency bandpass filter 6 cannot be removed by the intermediate frequency bandpass filter 6. .

The interference component X can be calculated as d when the own device is communicating at the frequency f1 (desired frequency C1).
This is caused by mutual interference between a communication wave C2 having a frequency f2 higher by f and a communication wave C3 having a frequency f3 higher by df. At this time, an interference component Y also occurs at a frequency f4 higher than the frequency f3 by df.

On the other hand, in the conventional mobile communication terminal, since it is not easy to discriminate the interference component X from the desired signal, the IM detector 98 monitors the levels of the quadrature signals I and Q. If the value is larger than a preset value, R
The amount of attenuation of the F signal amplifier 3 is increased to equivalently improve distortion characteristics and suppress the interference component X.

However, if the amount of attenuation is increased, the reception sensitivity is deteriorated, and the margin between the reception signal level and the reception sensitivity is reduced. For this reason, in the conventional mobile communication terminal apparatus, when the level of the demodulated quadrature signal exceeds the specified value, the reception sensitivity is deteriorated and the margin between the reception signal level and the reception sensitivity is reduced. Even if the level is small, if the received signal level suddenly decreases due to fading, there is a high possibility that the reception quality will deteriorate or reception will not be possible.

[0025]

In a conventional radio receiving apparatus, when the level of a received signal is high, even if the influence of interference is small, there is a possibility that the reception quality may be deteriorated due to fading or the reception may not be performed. There was a problem of high.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem. An object of the present invention is to provide a radio receiving apparatus which is less likely to cause deterioration in reception quality or a state in which reception cannot be performed due to fading when the level of a received signal is high. The purpose is to provide.

[0027]

In order to achieve the above object, a radio receiving apparatus according to the present invention is a radio receiving apparatus for receiving a radio frequency signal. Attenuating means for attenuating, demodulating means for demodulating a received signal output by the attenuating means, intensity detecting means for detecting the intensity of the demodulated result of the demodulating means, and quality detecting means for detecting the quality of the demodulated result of the demodulating means. When the intensity detected by the intensity detecting means is equal to or higher than a predetermined intensity and the quality detected by the quality detecting means is equal to or lower than a predetermined quality, an attenuation amount controlling means for increasing an attenuation amount of the attenuating means through a control signal. Are provided.

In the radio receiving apparatus having the above configuration, the attenuation of the attenuating means is increased when the strength of the received signal is equal to or higher than the predetermined strength and the reception quality is equal to or lower than the predetermined quality.

That is, even if the intensity of the received signal is equal to or higher than the predetermined intensity, the attenuation of the attenuation means is not increased if the reception quality exceeds the predetermined quality.

Therefore, according to the radio receiving apparatus having the above configuration, when the influence of interference is small and the influence on the reception quality is small, the reception sensitivity does not deteriorate, and the reception signal level sharply decreases due to fading. Even so, it is possible to reduce the possibility that the reception quality is deteriorated or the reception becomes impossible.

According to the present invention, the demodulation means demodulates the received signal output from the attenuation means into a coded signal, and the quality detection means converts the coded signal demodulated by the demodulation means. Error correction means for decoding and performing error correction processing; coding means for coding the processing result of the error correction means; a coded signal demodulated by the demodulation means; and a coding result of the coding means. And a comparison and detection unit for comparing the symbol error rate of the coded signal demodulated by the demodulation unit based on the difference in symbol units and detecting the symbol error rate as the quality of the demodulation result of the demodulation unit.

In the radio receiving apparatus having this configuration, to detect the quality of the demodulation result, the demodulated coded signal is decoded once, subjected to error correction processing, and then coded again.
By comparing this processing result with the coded signal before decoding on a symbol-by-symbol basis, the symbol error rate of the coded signal is detected. For this reason, according to the radio receiving apparatus having the above configuration, it is possible to control distortion characteristics (reception sensitivity) based on the reception quality in units of symbols.

According to the present invention, the demodulation means demodulates the reception signal output from the attenuation means into an encoded signal, and the quality detection means converts the received signal into an encoded signal demodulated by the demodulation means. An error rate occurring in an encoded signal within a predetermined period is detected as the quality of the demodulation result of the demodulation means based on the added error detection check bit.

For this reason, according to the radio receiving apparatus having the above configuration, when the received data has a periodic frame configuration, the distortion characteristic (reception sensitivity) is controlled based on the reception quality detected for each frame. be able to.

[0035]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention.
FIG. 3 shows a configuration of a wireless reception device according to the embodiment of FIG.
Here, a receiving system of a mobile communication terminal device of a CDMA mobile communication system is taken as an example.

The radio frequency signal received by the antenna 1 passes through the antenna duplexer 2, so that only the radio frequency signal in the band to be received is output to the RF signal amplifier 3. The RF signal amplifier 3 includes a variable attenuator 31 and a front-end amplifier 32, as shown in FIG.
The variable attenuator 31 attenuates the radio frequency signal input from the antenna duplexer 2 with an attenuation according to a distortion characteristic control signal from an IM detector 88 described later. The front end amplifier 32 amplifies the radio frequency signal output from the variable attenuator 31 at a high frequency with a predetermined gain, and outputs the radio frequency signal to the high frequency bandpass filter 4.

The high-frequency band-pass filter 4 removes unnecessary signals outside the reception band, and outputs the remaining high-frequency signals to the mixer 5. The mixer 5 mixes the high-frequency signal passed through the high-frequency band-pass filter 4 with a local oscillation signal generated by a synthesizer (not shown), and down-converts the high-frequency signal into an intermediate frequency signal.

From the intermediate frequency signal thus obtained, only a signal in a desired band is extracted by the intermediate frequency band pass filter 6 and output to the IF signal amplifier 7. The IF signal amplifier 7 amplifies the intermediate frequency signal that has passed through the intermediate frequency bandpass filter 6 with a gain according to a gain control signal from a demodulation circuit 8 described later, and outputs the signal to the demodulation circuit 8.

The demodulation circuit 8 demodulates an analog audio signal from the intermediate frequency signal amplified by the IF signal amplifier 7 and outputs a loudspeaker, and is configured as shown in FIG. The intermediate frequency signal is demodulated by an orthogonal demodulator 81 into two orthogonal signals I and Q. The quadrature demodulator 81 includes a local oscillator 810, mixers 811 and 812, a phase shifter (π / 2) 8
13, low-pass filters 814, 815, and A / D
It comprises converters (A / D) 816 and 817.

First, the intermediate frequency signal is supplied to a mixer 811,
812. In the mixer 811, the local oscillator 8
The local oscillation signal generated at 10 and the intermediate frequency signal are mixed and converted into a baseband I signal.

On the other hand, the local oscillator 81
The local oscillation signal generated at 0 is a phase shifter (π / 2) 81
3 and is input after being phase shifted by π / 2. Then, the mixer 812 mixes the local oscillation signal from the phase shifter 813 with the intermediate frequency signal and converts it into a baseband Q signal having a 90 ° phase difference with the I signal.

After the high-band component is removed by the low-pass filter 814, the I signal is converted into a digital signal by the A / D converter 816, and output to the despreading circuit 82 and the level detector 87.

On the other hand, the Q signal is supplied to the low-pass filter 815
After the high-frequency component is removed by A / D converter 817, the signal is converted into a digital signal by A / D converter 817 and output to despreading circuit 82 and level detector 87.

The despreading circuit 82 uses the spreading code specified by the control unit 100, which will be described later, to convert the A / D converter 816,
The digital signal from 817 is subjected to despreading processing, and the processing result is output to the reproducing unit 83 and the symbol comparator 86.

In the reproducing unit 83, first, the error correction decoder 83
1 performs Viterbi decoding on the processing result of the despreading circuit 82,
Perform error correction decoding. Then, of the data obtained by this decoding, the user data is output to a speech decoder 832, a frame error rate measuring device (FER) 84 and a convolutional encoder 85, which will be described later, Is output to the control unit 100.

The speech decoder 832 has an error correction decoder 83
The user data decoded in step 1 is subjected to a decompression process according to the data rate notified from the control unit 100, and the digital audio signal compressed on the transmission side is decompressed. This digital audio signal is supplied to a D / A converter (D / A) 833.
After being converted to an analog audio signal by the
More loudspeaker output.

The frame error rate measuring unit 84 measures the error rate of the user data decoded by the error correction decoder 831 for each frame, and notifies the control unit 100 of the measurement result. The error rate is measured based on a CRC check bit attached to the user data. The convolutional encoder 85 converts the user data decoded by the error correction decoder 831 into code symbols again, and
Output to

The symbol comparator 86 calculates the result of the despreading process output from the despreading circuit 82 and the convolutional coder 8
5. Compare the data with the code symbolized data again at 5.
Measure the symbol error rate. Here, the measured symbol error rate is output to the IM detector 88. Here, the data used for comparison is based on the same despreading processing result due to the delay.

The level detector 87 includes an A / D converter 81
In 6,817, the levels of the quadrature signals I and Q converted into digital signals are detected, and the detection results are output to an IM (Inter-Modulation) detector 88 as level information.

The level detector 87 detects the detected I,
A difference between the level value of the Q signal and a preset reference value is obtained and integrated, and the gain control signal corresponding to the integrated value is IF
The signal level is applied to the signal amplifier 7 to control the gain so that the level value becomes equal to the reference value.

The IM detector 88 monitors the level information notified from the level detector 87 and the symbol error rate measured by the symbol comparator 86, and the level information is larger than a predetermined value. In addition, when the symbol error rate exceeds a specified value, the distortion characteristic of the RF signal amplifier 3 is variably controlled through the distortion characteristic control signal described above,
Improve distortion characteristics.

The control section 100 controls the respective sections of the mobile communication terminal device in a centralized manner. For example, as described above, the despreading circuit 82 supplies the base station to which the mobile station is connected and the spreading assigned to the base station itself. When the detection result of the frame error rate measuring unit 84 is equal to or larger than a predetermined value, the transmission system (not shown) is controlled to retransmit data to the base station. Make a request.

Next, the control operation of the attenuation of the RF signal amplifier 3 in the receiving system of the mobile communication terminal having the above configuration will be described. The baseband orthogonal signals I and Q demodulated by the orthogonal demodulator 81 of the demodulation circuit 8 are output to the despreading circuit 82 and the level detector 87.

The quadrature signal input to the despreading circuit 82 is
The signal is despread by the spreading code specified by the control unit 100 and output to the error correction decoder 831 and the symbol comparator 86. Of these, the result of the despreading process input to the error correction decoder 831 is error-corrected and decoded by Viterbi decoding here.

Then, of the data obtained by this decoding, the user data is output to a speech decoder 832, a frame error rate measuring unit 84, and a convolutional encoder 85,
On the other hand, control data related to the data rate
Is output to

The user data input to the convolutional encoder 85 is converted into a code symbol again here and output to the symbol comparator 86. Then, the symbol comparator 86
Then, the symbol error rate is measured by comparing the result of the despreading process from the despreading circuit 82 with the data that has been code symbolized again by the convolutional encoder 85. This measurement result is output to the IM detector 88.

On the other hand, the level of the orthogonal signal input to the level detector 87 is detected here, and the detected value is output to the IM detector 88 as level information. And I
The M detector 88 monitors the level information notified from the level detector 87 and the symbol error rate measured by the symbol comparator 86, and makes sure that the level information is larger than a predetermined value and that the symbol When the error rate exceeds a specified value, the amount of attenuation of the RF signal amplifier 3 is increased through the distortion characteristic control signal to improve the distortion characteristic.

As described above, in the receiving system of the mobile communication terminal having the above configuration, the error-corrected decoder 831 performs error-correction decoding on the despread data, and then the convolutional encoder 85 encodes the data again. By comparing the encoded result with the despread data before decoding by the symbol comparator 86, the error rate of the despread data is obtained.

Only when the level of the quadrature signal is larger than the specified value and the error rate exceeds the specified value, the IM detector 88 increases the attenuation of the RF signal amplifier 3 through the distortion characteristic control signal. ing.

That is, in the related art, the attenuation amount is variably controlled only in accordance with the level of the orthogonal signal. On the other hand, when such control is performed, the reception system of the mobile communication terminal having the above configuration further reduces the error rate It is subject to deterioration.

Therefore, according to the receiving system of the mobile communication terminal device having the above-described configuration, even if the received signal level sharply decreases due to fading in the state where the level of the orthogonal signal is high, the attenuation is provided if the error rate is not deteriorated. In order not to increase the amount,
It is possible to reduce the possibility of lowering the reception quality and causing a state in which reception cannot be performed as compared with the related art.

Next, a radio receiving apparatus according to a second embodiment of the present invention will be described. However, the radio receiving apparatus described in this embodiment is the same as the receiving system of the mobile communication terminal apparatus described in the first embodiment except for the configuration of the demodulation circuit 8 except for the configuration. Will be described only. FIG. 4 is a diagram illustrating a configuration of the demodulation circuit 8 of the mobile communication terminal device according to the second embodiment.

The intermediate frequency signal from the IF signal amplifier 7 shown in FIG.
Is demodulated. The quadrature demodulator 81 includes a local oscillator 81
0, mixers 811 and 812, phase shifter (π / 2) 813,
It comprises low-pass filters 814 and 815 and A / D converters (A / D) 816 and 817.

First, the intermediate frequency signal is supplied to a mixer 811,
812. In the mixer 811, the local oscillator 8
The local oscillation signal generated at 10 and the intermediate frequency signal are mixed and converted into a baseband I signal.

On the other hand, the local oscillator 81
The local oscillation signal generated at 0 is a phase shifter (π / 2) 81
3 and is input after being phase shifted by π / 2. Then, the mixer 812 mixes the local oscillation signal from the phase shifter 813 with the intermediate frequency signal and converts it into a baseband Q signal having a 90 ° phase difference with the I signal.

After the high-band component is removed by the low-pass filter 814, the I signal is converted into a digital signal by the A / D converter 816 and output to the despreading circuit 82 and the level detector 87.

On the other hand, the Q signal is supplied to the low-pass filter 815.
After the high-frequency component is removed by A / D converter 817, the signal is converted into a digital signal by A / D converter 817 and output to despreading circuit 82 and level detector 87.

The despreading circuit 82 uses a spreading code instructed by the control unit 100, which will be described later, to generate an A / D converter 816,
The digital signal from 817 is subjected to despreading processing, and the processing result is output to the reproducing unit 83.

In the reproducing section 83, first, the error correction decoder 83
1 performs Viterbi decoding on the processing result of the despreading circuit 82,
Perform error correction decoding. Then, of the data obtained by the decoding, the user data is output to the audio decoder 832 and a frame error rate measuring device (FER) 84 described later, while the control data relating to the data rate is output to the control unit 100.

The audio decoder 832 includes an error correction decoder 83
The user data decoded in step 1 is subjected to a decompression process according to the data rate notified from the control unit 100, and the digital audio signal compressed on the transmission side is decompressed. This digital audio signal is supplied to a D / A converter (D / A) 833.
After being converted to an analog audio signal by the
More loudspeaker output.

The frame error rate measuring unit 84 measures the error rate of the user data decoded by the error correction decoder 831 for each frame, and compares the measurement result with the control unit 100 and the IM.
(Inter-Modulation) Notify the detector 88. The error rate is measured based on a CRC check bit attached to the user data.

The level detector 87 includes an A / D converter 81
In 6,817, the levels of the quadrature signals I and Q converted into digital signals are detected, and the detection results are output to an IM (Inter-Modulation) detector 88 as level information.

The level detector 87 detects the detected I,
A difference between the level value of the Q signal and a preset reference value is obtained and integrated, and the gain control signal corresponding to the integrated value is IF
The signal level is applied to the signal amplifier 7 to control the gain so that the level value becomes equal to the reference value.

The IM detector 88 monitors the level information notified from the level detector 87 and the frame error rate measured by the frame error rate measuring device 84, and determines that the level information is higher than a predetermined value. If the frame error rate is larger than the specified value and the frame error rate exceeds a specified value, the distortion characteristic of the RF signal amplifier 3 is variably controlled through the distortion characteristic control signal to improve the distortion characteristic.

The control section 100 controls the respective sections of the mobile communication terminal apparatus in a centralized manner. For example, as described above, the despreading circuit 82 supplies the base station to which the mobile station is connected and the spreading station assigned to its own apparatus. When the detection result of the frame error rate measuring unit 84 is equal to or larger than a predetermined value, the transmission system (not shown) is controlled to retransmit data to the base station. Make a request.

Next, the control operation of the attenuation of the RF signal amplifier 3 in the receiving system of the mobile communication terminal having the above configuration will be described. The baseband orthogonal signals I and Q demodulated by the orthogonal demodulator 81 of the demodulation circuit 8 are output to the despreading circuit 82 and the level detector 87.

The orthogonal signal input to the despreading circuit 82 is
The signal is despread by the spreading code specified by the control unit 100 and output to the error correction decoder 831. Error correction decoder 83
The result of the despreading process input to 1 is error-corrected and decoded by Viterbi decoding here.

Then, of the data obtained by this decoding, the user data is output to the audio decoder 832 and the frame error rate measuring device 84, while the control data relating to the data rate is output to the control section 100.

In the user data input to the frame error rate measuring device 84, the error rate is measured on a frame basis based on the CRC check bit.
0 is notified to the IM detector 88. And the control unit 10
When the detection result is equal to or larger than a predetermined value, 0 controls a transmission system (not shown) to request the base station to retransmit data.

On the other hand, the level of the orthogonal signal input to the level detector 87 is detected here, and the detected value is output to the IM detector 88 as level information. And I
The M detector 88 monitors the level information notified from the level detector 87 and the frame error rate measured by the frame error rate measuring device 84, and the level information is larger than a predetermined value, and When the frame error rate exceeds a specified value, RF signal is transmitted through a distortion characteristic control signal.
The amount of attenuation of the signal amplifier 3 is increased to improve the distortion characteristics.

As described above, in the receiving system of the mobile communication terminal device having the above-described configuration, the IM detector 88 operates with the distortion characteristic only when the level of the orthogonal signal is higher than the specified value and the frame error rate exceeds the specified value. The attenuation of the RF signal amplifier 3 is increased through the control signal.

That is, in the related art, the attenuation is variably controlled only in accordance with the level of the orthogonal signal. Is subject to deterioration.

Therefore, according to the receiving system of the mobile communication terminal device having the above-described configuration, even if the received signal level is sharply reduced due to fading while the level of the orthogonal signal is high, the frame error rate is not deteriorated. Since the amount of attenuation is not increased, it is possible to reduce the possibility that the reception quality is reduced or reception is not performed as compared with the related art.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the mobile communication terminal device has been described as an example, but the present invention is also applicable to a non-moving wireless receiving device.

Although the CDMA system has been described as an example of the communication system, the same effect can be obtained by applying the present invention to a wireless communication device of another communication system, for example, the FDMA system or the TDMA system. It goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0086]

As described above, according to the present invention, the attenuation of the attenuating means is increased when the intensity of the received signal is equal to or higher than the predetermined intensity and the reception quality is equal to or lower than the predetermined quality. ing. That is, even if the strength of the received signal is equal to or higher than the preset strength, if the reception quality exceeds the preset quality, the attenuation amount of the attenuation means is not increased.

Therefore, according to the present invention, when the influence of interference is small and the influence on the reception quality is small, the reception sensitivity does not deteriorate. Therefore, even if the reception signal level sharply decreases due to fading, It is possible to provide a wireless reception device that is less likely to cause a state in which reception quality is deteriorated or reception cannot be performed.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing a configuration of a wireless reception device according to the present invention.

FIG. 2 is an RF signal amplifier 3 of the wireless receiving apparatus shown in FIG.
FIG. 2 is a circuit block diagram showing the configuration of FIG.

FIG. 3 is a circuit block diagram showing a configuration of a demodulation circuit 8 of the wireless reception device according to the first embodiment of the present invention.

FIG. 4 is a circuit block diagram illustrating a configuration of a demodulation circuit 8 of a wireless reception device according to a second embodiment of the present invention.

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

6 is a demodulation circuit 9 of the conventional radio receiving apparatus shown in FIG.
FIG. 2 is a circuit block diagram showing the configuration of FIG.

FIG. 7 is a diagram for explaining intermodulation distortion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Antenna 2 ... Antenna duplexer 3 ... RF signal amplifier 4 ... High frequency band pass filter 5 ... Mixer 6 ... Intermediate frequency band pass filter 7 ... IF signal amplifier 8 ... Demodulation circuit 31 ... Variable attenuator 32 ... Front end amplifier 81 ... Quadrature demodulator 810 local oscillator 811 812 mixer 813 phase shifter (π / 2) 814 815 low-pass filter 816 817 A / D converter (A / D) 82 despreading circuit 83 reproduction Unit 831 error correction decoder 832 speech decoder 833 D / A converter (D / A) 834 speaker 84 frame error rate measurement (FER) 85 convolutional encoder 86 symbol comparator 87 Level detector 88 ... IM detector 100 ... Control unit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Mikio Hayashibara 3-1, 1-1 Asahigaoka, Hino-shi, Tokyo Inside the Toshiba Hino Plant Co., Ltd. (72) Nobuyuki Takeuchi 21-3-1 Asahigaoka, Hino-shi, Tokyo F-term (reference) in Toshiba Communication Technology Corporation 5K014 AA01 BA10 EA01 GA02 HA05 5K052 BB08 CC06 DD04 EE13 EE17 EE24 FF01 GG12 GG48

Claims (3)

[Claims] 1. A radio receiving apparatus for receiving a radio frequency signal, comprising: an attenuating means for attenuating a received signal with an amount of attenuation according to a control signal; a demodulating means for demodulating a received signal output by the attenuating means; Intensity detection means for detecting the intensity of the demodulation result of the demodulation means; quality detection means for detecting the quality of the demodulation result of the demodulation means; and the intensity detected by the intensity detection means is equal to or greater than a predetermined intensity, and the quality A wireless receiving apparatus comprising: an attenuation control unit that increases an attenuation amount of the attenuating unit through the control signal when the quality detected by the detecting unit is equal to or less than a predetermined quality. 2. The demodulation means demodulates a received signal output from the attenuating means into a coded signal, wherein the quality detection means comprises a coded signal demodulated by the demodulation means. Error correcting means for decoding the data and performing error correction processing; coding means for coding the processing result of the error correcting means; a coded signal demodulated by the demodulating means; Comparing the result with each other in symbol units, and comparing and detecting the symbol error rate of the coded signal demodulated by the demodulation means from the difference as a quality of the demodulation result of the demodulation means. Claim 1
The wireless receiving device according to claim 1. 3. The demodulation means demodulates a received signal output from the attenuating means into a coded signal, and the quality detection means comprises a coded signal demodulated by the demodulation means. 2. The method according to claim 1, wherein an error rate occurring in the encoded signal within a predetermined period is detected as a quality of a demodulation result of the demodulation means, based on an error detection check bit added to the demodulation means. Wireless receiving device.