JP2002290177A - Receiver and automatic gain control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an AGC drawing velocity compatible with AGC drawing precision at AGC control. SOLUTION: A radio part 102 amplifies a reception signal, performs a prescribed radio reception processing and obtains a baseband signal. An MAC part 104 control timing, based on the demodulated baseband signal and outputs a reception signal. A selection part 111 changes-over a correction coefficient, based on the control signal from the MAC part 104. In this case, the correction coefficient is set to a large value at first and changed into a small value, as the updating times in AGC increases. A subtracting part 107 obtains the difference between integration result obtained, by integrating the level of the base band signal for a prescribed time and a reference value. A multiplying part 108 multiplies the difference obtained by the subtracting part 107 using the correction coefficient. An addition part 110 adds the output of the multiplying part 108 to an AGC control signal, which is delayed by a unit control period by a delay part 109, generates the AGC control signal to be used in the present control period and controls the amplification gain of the ratio part 102.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a base station apparatus of a mobile communication system, a receiving apparatus used for a communication terminal apparatus, and an automatic gain control method.

[0002]

2. Description of the Related Art Automatic Gain Control (AGC)
rol) is to keep the reception level fluctuating according to the communication distance between the base station and the terminal constant in order to improve the demodulation accuracy.

FIG. 14 is a block diagram showing a configuration of a conventional receiving apparatus. Hereinafter, a conventional receiving apparatus will be described with reference to FIG.

A signal transmitted from a transmitting station is transmitted to an antenna 1
, The signal is amplified by the radio unit 2, the frequency of the signal is converted to a baseband, and the signal is converted to a baseband signal.
The baseband signal is demodulated by the demodulation unit 3 to become a demodulated signal. The demodulated signal is MAC (Media Access Control)
l) Access control is performed by the unit 4 to be a received signal.

[0005] The baseband signal output from the radio unit 2 is also output to the AGC control unit 5. The AGC control unit 5 generates an AGC control signal based on the reception level of the baseband signal. The AGC control signal controls the radio unit 2 so that the reception level becomes constant.

FIG. 15 is a block diagram showing a configuration of an AGC control section of a conventional receiving apparatus. Hereinafter, the signal flow in AGC control section 5 will be described with reference to FIG.

[0007] The level of the signal output from the radio section 2 is detected by the level detecting section 11 to obtain level information. Note that the level information can be generated by the wireless unit 2. The circuit configuration of the AGC control unit in this case is as follows:
There is no difference except that the level detector 11 is not required.

Next, the level information is integrated by the integrating unit 12 to obtain information obtained by integrating the level information. The information obtained by integrating the level information is subtracted by the subtraction unit 13 from the reference value REF of the reception level, and a difference between the reception level and the reference level is obtained. This reference value REF is such that the level of the signal output from the radio section 2 is equal to the reception level reference value REF.
The AGC control unit 5 controls the radio unit 2 to achieve this. The information on the difference between the reception level and the reference level is multiplied by the correction coefficient u1 by the multiplier 14 and added by the adder 16 to the previous AGC control information output by the delay 15 to obtain AGC control information. .

[0009]

However, in the conventional receiving apparatus, since the correction coefficient is fixed, AG
There is a problem that it is difficult to achieve both the C pull-in speed and the AGC pull-in accuracy.

That is, when the correction coefficient is set to a small value, the averaging number increases, so that the AGC pull-in accuracy improves, but the AGC pull-in speed decreases. Conversely, when the correction coefficient is set to a large value, the amount of change in one gain update becomes large, so that the AGC pull-in speed increases, but
AGC pull-in accuracy decreases.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing, and an object of the present invention is to provide a receiving apparatus and an automatic gain control method capable of achieving both AGC pull-in speed and AGC pull-in accuracy.

[0012]

A receiving apparatus according to the present invention comprises a radio processing means for adjusting the level of an input signal, and a gain control means for controlling a gain of the radio processing means so as to follow a level fluctuation of the input signal. And the gain control means controls the gain using one selected from a plurality of correction coefficients prepared.

[0013] The receiving apparatus of the present invention employs a configuration in which the gain control means selects a correction coefficient according to the number of times of gain updating.

According to these configurations, the correction coefficient used for AGC pull-in can be set independently by the number of AGC gain updates. Therefore, the correction coefficient is set to a large value at first, and the number of AGC updates is reduced. If the value is changed to a small value over time, both the AGC pull-in speed and the AGC pull-in accuracy can be achieved.

[0015] The receiving apparatus of the present invention employs a configuration in which the gain control means selects a correction coefficient in accordance with a receiving situation.

The receiving apparatus according to the present invention has a configuration in which the gain control means selects a correction coefficient having a relatively large value during continuous reception, and selects a correction coefficient smaller than the correction coefficient selected during continuous reception during intermittent reception. take.

With these configurations, the correction coefficient can be set to a large value during the continuous reception operation, and set to a small value during the intermittent reception operation. Therefore, even if the reception condition changes, the AGC pull-in speed and the AGC pull-in accuracy can be reduced. Can be compatible.

[0018] The receiving apparatus of the present invention employs a configuration in which the gain control means prepares a plurality of correction coefficients of a value that can be realized by bit shift.

With this configuration, the weighting process can be realized without using a multiplier, so that the circuit scale can be reduced.

[0020] The receiving apparatus of the present invention employs a configuration in which the gain control means selects a correction coefficient according to a difference between the detected level and a reference value.

In the receiving apparatus according to the present invention, when the difference between the detected level and the reference value is larger than a preset threshold value, the gain control means selects a relatively large correction coefficient. When the difference is equal to or smaller than the threshold value, a configuration is adopted in which a relatively small correction coefficient is selected.

With these configurations, the correction coefficient is adaptively changed according to the difference between the detected level and the reference value, so that even if the difference between the detected level and the reference value is large due to a sudden change in the propagation path, , AGC pull-in speed and AG
C pull-in accuracy can be compatible.

In the receiving apparatus according to the present invention, the gain control means may determine whether the number of times the difference between the detected level and the reference value has become larger than a preset threshold value has reached a preset value. A configuration in which a relatively large correction coefficient is selected is adopted.

According to this configuration, when the number of times that the difference between the detected level and the reference value becomes larger than the preset threshold value continues for a fixed number of times, the correction coefficient used for updating the AGC can be increased. AGC
Control errors can be reduced. This is based on the fact that when the reception level decreases, noise superimposed on the desired signal increases, so that the reception level detection error increases and the difference between the reception level and the reference value may increase. .

[0025] The receiving apparatus of the present invention is configured such that the gain control means sets a plurality of threshold values used for comparing the detected level with the difference between the reference value and selects the threshold value according to the line quality. take.

The receiving apparatus of the present invention employs a configuration in which the gain control means selects a large threshold value when the signal-to-thermal noise power ratio is low.

With these configurations, the threshold value for selecting the correction coefficient can be made variable, so that a large threshold value can be used when the signal-to-thermal noise power ratio is low. An optimal correction coefficient can be selected according to the quality.

In the receiving apparatus of the present invention, the gain control means sets a plurality of threshold values used for comparing the detected level with the difference between the reference value and the threshold value according to the magnitude of the correction coefficient selected last time. A configuration for selecting a threshold is adopted.

The receiving apparatus of the present invention employs a configuration in which the gain control means selects a large threshold value when the correction coefficient selected last time is small.

With these configurations, when the correction coefficient is changed to a larger value, the threshold value can be set to a larger value than when the correction coefficient is changed to a smaller value, so that the error can be reduced. This is because, when the reception level decreases, noise superimposed on the desired signal increases, so that the reception level detection error increases and the difference between the reception level and the reference value may increase. In such a case, it is based on the fact that a large correction coefficient is selected, and the automatic gain control error may increase.

The receiving apparatus of the present invention employs a configuration in which the gain is updated in the preamble section for automatic gain control and the guard interval section for the preamble for channel estimation.

According to this configuration, since the AGC gain can be updated in a section other than the preamble section for automatic gain control, the AGC error can be reduced without deteriorating the synchronization characteristics.

The receiving apparatus of the present invention employs a configuration in which the level information of the synchronization preamble section is used for integration when updating the gain of the guard interval section of the transmission path estimation preamble.

With this configuration, the accuracy of the level information can be further improved, and the AGC error can be further reduced without deteriorating the synchronization characteristics.

The receiving apparatus according to the present invention employs a configuration in which the correction coefficient for updating the gain in the guard interval section of the transmission path estimation preamble is increased.

According to this configuration, the correction coefficient for updating the gain in the guard interval section of the transmission path estimation preamble can be increased, so that the AGC error can be further reduced.

The communication terminal device of the present invention employs a configuration including any one of the above-mentioned receiving devices. Further, the base station apparatus of the present invention employs a configuration including any one of the above-described receiving apparatuses.

With these configurations, it is possible to achieve both the AGC pull-in speed and the AGC pull-in accuracy.
Communication quality can be improved.

According to the automatic gain control method of the present invention, one correction coefficient is selected from a plurality of correction coefficients in accordance with the number of times of gain updating, and the selected correction coefficient is added to the difference between the detected level and the reference value. To obtain a multiplied value, add the multiplied value to the first gain used in the previous control period to obtain a second gain, and adjust the level of the input signal using the second gain.

According to this method, the correction coefficient used for pulling in the AGC can be independently set according to the number of AGC gain updates. If the value is changed to a smaller value, both the AGC pull-in speed and the AGC pull-in accuracy can be achieved.

According to the automatic gain control method of the present invention, the gain of the automatic gain control is updated in the automatic gain control preamble section and the transmission path estimation preamble guard interval section.

According to this method, the AGC gain can be updated in a section other than the preamble section for automatic gain control, so that the AGC error can be reduced without deteriorating the synchronization characteristics.

[0043]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the AGC control, if the correction coefficient is set to a small value, the number of averaging increases,
The pull-in accuracy is improved, but the AGC pull-in speed is reduced. Conversely, when the correction coefficient is set to a large value, the amount of change in one gain update becomes large, so that the AGC pull-in speed increases, but the AGC pull-in accuracy decreases.

The present inventor has come to the present invention by paying attention to the fact that the correction coefficient in the AGC control is a fixed value. That is, the gist of the present invention is that the correction coefficient used for AGC pull-in is independently set according to the number of AGC gain updates, that is, the correction coefficient is initially set to a large value, and becomes smaller as the number of AGC updates elapses. By changing the value, the AGC pull-in speed is increased,
The aim is to increase the AGC pull-in accuracy.

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

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

A signal transmitted from a communication partner is received by radio section 102 via antenna 101. Radio unit 10
In step 2, the base station amplifies the received signal, performs predetermined radio reception processing (down conversion, A / D conversion, etc.) to obtain a baseband signal, and outputs the baseband signal to the demodulation unit 103 and the level detection unit 105. Demodulation section 103 performs demodulation processing on the signal after the radio reception processing, and outputs the demodulated signal to MAC section 104. The MAC unit 104 performs processing such as timing control based on the demodulated signal and outputs a received signal. The MAC unit 104 outputs a control signal to the selection unit 111.

The level detector 105 detects the level of the baseband signal and outputs the detection result (level information) to the accumulator 106. The integrating unit 106 integrates (averages) the detection results for a predetermined period, and subtracts the integrated result from the subtracting unit 10.
7 is output. The subtraction unit 107 obtains a difference between the integration result and the reference value, and outputs the difference information to the multiplication unit 108.

The multiplication unit 108 multiplies the difference obtained by the subtraction unit 107 by the correction coefficient output from the selection unit 111. The difference multiplied by the correction coefficient is added to the adder 11
Output to 0. Selection section 111 switches between correction coefficients u1 and u2 based on a control signal (gain update timing) from MAC section 104.

The adder 110 adds the difference obtained by multiplying the AGC control signal delayed by the delay unit 109 by the unit control period (the AGC control signal used in the previous control period) by the correction coefficient, and adds the difference in the current control period. Generate an AGC control signal to be used;
This AGC control signal is output to radio section 102. Radio section 102 performs AGC control based on the AGC control signal. That is, control is performed between a base station apparatus and a wireless communication apparatus such as a communication terminal apparatus so that the reception level is constant even if the communication distance changes.

Next, the operation of the receiving apparatus having the above configuration will be described.

The AGC control is performed using the AGC preamble of the frame format shown in FIG. Specifically, in the preamble section for AGC,
The AGC gain is updated three times, and thereafter, the AGC gain is fixed until the next AGC preamble is received. In addition,
The number of AGC gain updates can be set arbitrarily.

First, the baseband signal is supplied to the level detector 1.
Level detection is performed at 05, and level information as a detection result is obtained. Here, the level information can be generated by the wireless unit 102. In this case, the circuit of the AGC control unit can be configured by omitting the level detection unit 105.

The obtained level information is averaged by the integrating section 106, and the average value and the reference value (REF) are calculated by the subtracting section 107.
, And the multiplication unit 108 multiplies the difference by a correction coefficient. In the process of multiplying the difference between the reception level and the reference value by the correction coefficient in the AGC control, the level of the signal output from the radio unit 102 is changed to the reception level reference value (RE
The processing is equal to F). The wireless unit 102 is controlled by this processing.

When the difference between the level information and the reference value is multiplied by the correction coefficient by the multiplication section 108, a plurality of correction coefficients are prepared. In the present embodiment, two types of correction coefficients are prepared. There is no particular limitation on the number of correction coefficients.

For example, the correction coefficient u1 having a relatively large value
(For example, 1) and a correction coefficient u2 (for example, 0.5) having a relatively small value are prepared. The correction coefficients u1 and u2 are switched by the selection unit 111 and output to the multiplication unit 108. The selection unit 111 switches the correction coefficient based on the information from the MAC unit 104. That is, a control signal of information such as a gain update timing is output from the MAC unit 104 to the selection unit 111.
Sent to Then, the selection unit 111 switches the correction coefficient according to the number of times of the gain update based on the timing of the gain update. For example, when the AGC gain is updated three times in the preamble section for AGC, u1 is used for the first two times and u2 is used for the third time.

Next, the difference multiplied by the correction coefficient is added by the adder 110 to the AGC control information of the previous control period output by the delay unit 109, and is obtained as the AGC control information of the current control period. This AGC control information (AGC-
CONT (nT)) is represented by the following equation (1).

AGC-CONT (nT) = AGC-CONT (nT-T1) + u (REF-LEVEL (nT)) Expression (1) In the expression, u is a correction coefficient, and REF is a reference value (reference reception level). LEVEL (nT) is level information of the current time, T1 is a period (unit control period) for performing AGC gain update, T is a sample period, and n is 0,
1, 2, and 3.

FIG. 3 is a characteristic diagram for explaining the effect of the receiving apparatus of the present invention. In FIG. 3, when the correction coefficient is set to a small value (broken line in the figure), the averaging number increases, so that the AGC pull-in accuracy improves, but the AGC pull-in speed decreases. Also, when the correction coefficient is set to a large value (solid line in the figure), the amount of change in one gain update is large, and the AGC pull-in speed is high.
The pull-in accuracy decreases.

On the other hand, the present invention (dashed line in the figure)
Then, the correction coefficient is set to a large value (u1) in the first two AGC gain updates, and the correction coefficient is changed to a small value (u2) in the third AGC gain update. This makes it possible to increase the AGC pull-in speed and increase the AGC pull-in accuracy.

Here, as a method of changing the correction coefficient, a method of setting the largest value and the smallest value among the correction coefficients and monotonically decreasing the correction coefficient every time the AGC gain is updated can be considered. For example, the AGC gain update is performed three times, and the largest value among the correction coefficients is 1.0, and the smallest value is 0.25.
Then, the first time is 1.0, the second time is 0.5, and the third time is 0.25.

On the other hand, in the present invention, a correction coefficient is selected and set for each gain update. For example, if the AGC gain is updated three times and the correction coefficient is set to two types, 1.0 and 0.5, the first time can be 1.0, the second time can be 1.0, and the third time can be 0.5.

Here, when the dynamic range of the level information input from radio section 102 is much smaller than the AGC dynamic range (for example, when the AGC dynamic range is required to be 70 dB and the reception dynamic range is only 20 dB) Etc.).

In such a case, setting the correction coefficient independently of the number of updates (for example, setting the correction coefficient to a large value in the first two or three times and setting the correction coefficient to a small value thereafter) monotonously decreases. The accuracy of the pull-in speed is improved. Also,
According to the present invention, the circuit can be simplified as compared with the case where the largest value and the smallest value among the correction coefficients are set and monotonically decreased.

(Embodiment 2) In general, an AGC pull-in speed is required for continuous reception, and an AGC
The pulling precision is required.

In the second embodiment of the present invention, a case will be described in which a correction coefficient by which a difference between a detected level and a reference value is multiplied is switched according to a reception situation.

FIG. 4 is a block diagram showing a configuration of a receiving apparatus according to Embodiment 2 of the present invention. In FIG.
The same reference numerals as those in FIG. 1 denote the same parts, and a detailed description thereof will be omitted. The receiving device of FIG.
1 is different from FIG.

From MAC section 104, a control signal is sent to selection section 111, and a reception mode signal is sent to selection section 301. The selection unit 111 switches the correction coefficients u1 and u2 based on the control signal from the MAC unit 104. Selector 3
01 switches the correction coefficient based on the reception mode signal from the MAC unit 104. That is, the correction coefficient (u1 or u2) selected by the selection unit 111 is selected during continuous reception, and a smaller correction coefficient (u3) during intermittent reception.
Select

The multiplication unit 108 multiplies the difference between the level information and the reference value by the correction coefficient selected by the selection unit 301.
Other operations are the same as those in the first embodiment.

As described above, by setting the correction coefficient to a large value in the continuous reception operation and to a small value in the intermittent reception operation, the AGC can be performed even when the reception condition changes.
The pull-in speed and the AGC pull-in accuracy can be made compatible.

(Embodiment 3) In Embodiment 3 of the present invention, a case will be described in which a correction coefficient which can be realized by a bit shift is used as an AGC update coefficient.

FIG. 5 is a block diagram showing a configuration of a receiving apparatus according to Embodiment 3 of the present invention. In FIG.
The same reference numerals as in FIG. 1 denote the same parts as in FIG. 1, and a detailed description thereof will be omitted. The receiving apparatus of FIG. 5 differs from that of FIG. 1 in that a bit shift unit 401 is provided.

MAC section 104 outputs a control signal such as gain update timing information to bit shift section 401.
Then, bit shift section 401 switches the correction coefficient according to the number of times of gain update based on the timing of gain update.

For example, two correction coefficients of 0.5 and 0.25
When one of them is selected, it can be realized by 1-bit shift and 2-bit shift, respectively. This will be described with reference to FIG. The 1-bit shift unit 501 performs a 1-bit shift process on the subtraction signal, and the 2-bit shift unit 502 performs a 2-bit shift process. In the selection unit 503, the MAC
Based on the control signal from unit 104, one of the signals obtained from 1-bit shift unit 501 and 2-bit shift unit 502 is selected. Other operations are the same as those in the first embodiment.

The correction coefficient value is not limited to the above two cases, but can be set arbitrarily as long as the value can be realized by bit shift. For example, 1, 0.125, 0.0625 and the like can be used.

As described above, by setting the correction coefficient to a value that can be realized by a bit shift, a weighting process can be realized without using a multiplier, so that the circuit scale can be reduced.

(Embodiment 4) In Embodiment 4 of the present invention, a case will be described in which the correction coefficient is adaptively changed by the difference between the detected level and the reference value.

FIG. 7 is a block diagram showing a configuration of a receiving apparatus according to Embodiment 4 of the present invention. In FIG. 7, FIG.
The same reference numerals as those in FIG. 1 denote the same parts, and a detailed description thereof will be omitted. 7 differs from FIG. 1 in that it includes an absolute value detection unit 601 and a magnitude comparison unit 602.

The subtraction section 107 outputs the difference between the detected level and the reference value to the multiplication section 108 and the absolute value detection section 601. The absolute value detection unit 601 detects the absolute value of the difference between the detected level and the reference value. The magnitude comparison unit 602 compares the absolute value detected by the absolute value detection unit 601 with a preset threshold value, and outputs the result to the selection unit 111. The selecting unit 111 sets the correction coefficient to a large value when the absolute value is larger than the threshold value, and sets the correction coefficient to a small value when the absolute value is equal to or smaller than the threshold value. Other operations are the same as those in the first embodiment.

As described above, by adaptively changing the correction coefficient based on the difference between the detected level and the reference value, even when the difference between the detected level and the reference value is large due to a sudden change in the propagation path, AGC pull-in speed and AGC pull-in accuracy can be compatible.

(Embodiment 5) In Embodiment 5 of the present invention, a case will be described in which a threshold used for selecting a correction coefficient used for updating AGC is variable.

FIG. 8 is a block diagram showing a configuration of a receiving apparatus according to Embodiment 5 of the present invention. In FIG. 8, FIG.
The same reference numerals as those in FIG. 7 denote the same parts, and a detailed description thereof will be omitted. The receiving device of FIG.
1 is different from FIG.

[0083] MAC section 104 outputs the line quality signal to selection section 701. Selection section 701 switches the threshold based on the channel quality information from MAC section 104. When the line quality information indicates that the signal-to-thermal noise power ratio is low, the selecting unit 701 sets the threshold value to a large value.
The line quality information can use, for example, an RSSI or CRC result. The magnitude comparison unit 602 compares magnitudes of absolute values based on the threshold value selected by the selection unit 701. Other operations are the same as in the fourth embodiment.

When the signal-to-thermal noise power ratio is low, the superimposed thermal noise level increases, and the reception level detection error increases. Therefore, if the absolute value detected by the absolute value detection unit 601 is large and the threshold value is fixed by the magnitude comparison unit 602, the selection unit 111 cannot select the optimal correction coefficient. Therefore, in the present embodiment, the threshold value for selecting the correction coefficient is made variable, and when the signal-to-thermal noise power ratio is low, a large threshold value is used. Thereby, an optimal correction coefficient can be selected.

(Embodiment 6) In Embodiment 6 of the present invention, the threshold used for selecting the correction coefficient used for updating the AGC is made variable depending on whether the coefficient is increased or decreased. explain.

FIG. 9 is a block diagram showing a configuration of a receiving apparatus according to Embodiment 6 of the present invention. In FIG. 9, FIG.
The same reference numerals as in FIG. 7 denote the same parts as in FIG. 7, and a detailed description thereof will be omitted. 9 is different from FIG. 7 in that a size comparison unit 801 is provided.

The absolute value detector 601 detects the absolute value of the difference between the detected level and the reference value. Large and small comparison unit 801
Is compared with the threshold value and the absolute value detected by the absolute value detection unit 601. Note that the size comparison unit 801
A threshold value 1 having a large value and a threshold value 2 having a small value are provided, and the threshold value is selected according to the correction coefficient selected by the selection unit 111. That is, when a small correction coefficient is selected by the selection unit 111, the magnitude comparison unit 80
At 1, a large threshold value 1 is selected. Conversely, when the correction coefficient having a large value is selected by the selection unit 111, the threshold value 2 having a small value is selected by the magnitude comparison unit 801.

The result compared by the size comparison unit 801 is output to the selection unit 111. In the selection unit 111, when the result of the magnitude comparison unit 801 indicates that the absolute value is larger than the threshold value,
If a large correction coefficient is selected and the absolute value is smaller than the threshold value, a small correction coefficient is selected. Which correction coefficient is selected is output to the magnitude comparing unit 801. Other operations are the same as in the fourth embodiment.

When the reception level decreases, noise superimposed on the desired signal increases, so that the reception level detection error increases and the difference between the reception level and the reference value may increase. In such a case, a large correction coefficient may be selected, and the automatic gain control error may increase. Therefore, when the correction coefficient is changed to a large value, it can be said that the error is smaller when the threshold is set to a larger value than when the correction coefficient is changed to a smaller value.

(Embodiment 7) In Embodiment 7 of the present invention, a case will be described in which the absolute value of the difference between the level information and the reference value exceeds the threshold value for a fixed number of times.

FIG. 10 is a block diagram showing a configuration of a receiving apparatus according to Embodiment 7 of the present invention. In FIG. 10, the same reference numerals as in FIG. 7 denote the same parts as in FIG. 7, and a detailed description thereof will be omitted. The receiving apparatus of FIG. 10 differs from that of FIG.

In the magnitude comparing section 602, the absolute value detecting section 60
A magnitude comparison between the absolute value detected in step 1 and the threshold value is performed. This result is output to the counter 901. The counter 901 counts the number of times the absolute value exceeds the threshold value in the magnitude comparing unit 602. When this number reaches a preset number, the selection unit 111 is instructed to increase the correction coefficient. Other operations are the same as in the fourth embodiment.

[0093] When the reception level decreases, noise superimposed on the desired signal increases, so that the reception level detection error increases and the difference between the reception level and the reference value may increase. However, by adding a condition that such a case continues for a certain number of times and increasing the correction coefficient used for updating the AGC, it is possible to further reduce the AGC control error.

(Eighth Embodiment) In an eighth embodiment of the present invention, a case will be described in which the gain of automatic gain control is updated in other sections in addition to the preamble section for automatic gain control.

Not only the preamble section for AGC but also
The AGC error can be reduced by performing the AGC gain update in other sections.

Here, in the transmission method called OFDM or OFDM-CDMA, generally, the last waveform of each OFDM symbol is copied to the forefront (generally called a guard interval). The guard interval of the transmission path estimation preamble is neither used for pull-in, nor used for transmission path estimation. Therefore, as shown in FIG. 11, the AGC gain is updated even in the guard interval section of the transmission path estimation preamble, thereby further increasing the AGC.
Errors can be reduced.

[0097] When the AGC gain is updated in the synchronization preamble section, the synchronization characteristic deteriorates. Therefore, the AGC gain update should not be performed in the synchronization preamble section. Further, if the AGC gain is updated in the data guard section, the amplitude characteristics of the transmission path estimation preamble and the data will be different, so the AGC gain update should not be performed in the data guard section.

(Embodiment 9) As described above, AGC gain update should not be performed in the synchronization preamble section. However, even if the level information of the synchronization preamble section is used for integration, the synchronization characteristics do not deteriorate. Thus, a ninth embodiment of the present invention describes a case where the number of integrations in the AGC gain update using the guard interval section of the transmission path estimation preamble is increased.

FIG. 12 is a block diagram showing a configuration of a receiving apparatus according to Embodiment 9 of the present invention. In FIG. 12, the same reference numerals as in FIG. 9 denote the same parts as in FIG. 9, and a detailed description thereof will be omitted. The receiving apparatus of FIG. 12 differs from FIG. 9 in that it includes an integrating section 106-1, an integrating section 106-2, and a selecting section 1101.

Level detecting section 105 outputs level information to integrating sections 106-1 and 106-2. Accumulator 1
Reference numeral 06-1 integrates level information in the synchronization preamble section, and the integration section 106-2 integrates level information in the guard interval section of the transmission path estimation preamble and outputs the result to the selection section 1101. Selector 11
01 selects the integration information obtained from the integration units 106-1 and 106-2 based on the control timing. Other operations are the same as in the sixth embodiment.

As described above, in the AGC gain update using the guard interval section of the transmission path estimation preamble, the accuracy of the level information can be further improved by integrating the level information of the synchronization preamble section. AGC error can be further reduced without deteriorating.

(Embodiment 10) Embodiment 1 of the present invention
A case will be described where the correction coefficient is increased in the AGC gain update using the guard interval section of the transmission path estimation preamble at 0.

FIG. 13 is a block diagram showing a configuration of a receiving apparatus according to Embodiment 10 of the present invention. 13, parts that are the same as in FIG. 12 are given the same reference numerals as in FIG. 12, and detailed descriptions thereof are omitted. The receiving apparatus of FIG. 13 differs from that of FIG.

The selecting section 111 selects the correction coefficient u1 or u2 based on the comparison result of the magnitude comparing section 801.
The selection unit 1201 selects A in the synchronization preamble section.
When performing the GC gain update, the correction coefficient (u1 or u2) obtained by the selection unit 111 is selected, and when performing the AGC gain update in the guard interval section of the transmission path estimation preamble, the value is larger than u1 and u2. u3
Select The multiplication unit 108 multiplies the correction information obtained by the selection unit 301 with the subtraction information output from the subtraction unit 107. Other operations are the same as those in the ninth embodiment.

As described above, in the AGC gain update using the guard interval section of the transmission path estimation preamble, the accuracy of the level information can be further improved by integrating the level information of the synchronization preamble section. The AGC error can be further reduced by increasing the coefficient.

[0106]

As described above, according to the present invention,
Since the correction coefficient used for AGC pull-in can be set independently according to the number of AGC gain updates, the correction coefficient is initially set to a large value and changed to a small value as the number of AGC updates elapses. By doing, AG
The C pull-in speed and the AGC pull-in accuracy can be compatible.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a frame format.

FIG. 3 is a characteristic diagram for explaining the effect of the receiving device of the present invention.

FIG. 4 is a block diagram showing a configuration of a receiving apparatus according to Embodiment 2 of the present invention.

FIG. 5 is a block diagram showing a configuration of a receiving apparatus according to Embodiment 3 of the present invention.

FIG. 6 shows an AGC of a receiving apparatus according to Embodiment 3 of the present invention.
FIG. 2 is a block diagram showing a configuration of a bit shift unit in the control unit.

FIG. 7 is a block diagram showing a configuration of a receiving apparatus according to Embodiment 4 of the present invention.

FIG. 8 is a block diagram showing a configuration of a receiving apparatus according to Embodiment 5 of the present invention.

FIG. 9 is a block diagram showing a configuration of a receiving apparatus according to Embodiment 6 of the present invention.

FIG. 10 is a block diagram showing a configuration of a receiving apparatus according to Embodiment 7 of the present invention.

FIG. 11 shows a frame format according to Embodiment 8 of the present invention.

FIG. 12 is a block diagram showing a configuration of a receiving apparatus according to Embodiment 9 of the present invention.

FIG. 13 is a block diagram showing a configuration of a receiving apparatus according to Embodiment 10 of the present invention.

FIG. 14 is a block diagram showing a configuration of a conventional receiving apparatus.

FIG. 15 is a block diagram showing a configuration of an AGC control unit of a conventional receiving apparatus.

[Explanation of symbols]

Reference Signs List 101 antenna 102 radio section 103 demodulation section 104 MAC section 105 level detection section 106 accumulation section 107 subtraction section 108 multiplication section 109 delay section 110 addition section 111, 301, 503, 701, 1101, 1201
Selection unit 401 Bit shift unit 501 1-bit shift unit 502 2-bit shift unit 601 Absolute value detection unit 602, 801 Size comparison unit 901 Counter

Claims (19)

[Claims] 1. A wireless processing means for adjusting a level of an input signal, and gain control means for controlling a gain of the wireless processing means so as to follow a level change of the input signal, wherein the gain control means comprises: A receiving apparatus for controlling a gain using one selected from a plurality of correction coefficients prepared. 2. The receiving apparatus according to claim 1, wherein said gain control means selects a correction coefficient according to the number of times of gain updating. 3. The gain control unit according to claim 1, wherein the gain control unit selects a correction coefficient according to a reception state.
The receiving device according to the above. 4. The gain control means selects a correction coefficient having a relatively large value at the time of continuous reception, and selects a correction coefficient smaller than the correction coefficient selected at the time of continuous reception at the time of intermittent reception. 3. The receiving device according to 3. 5. The receiving apparatus according to claim 1, wherein said gain control means prepares a plurality of correction coefficients of a value realizable by a bit shift. 6. The receiving apparatus according to claim 1, wherein the gain control means selects a correction coefficient according to a difference between the detected level and a reference value. 7. When the difference between the detected level and the reference value is larger than a preset threshold, the gain control means selects a correction coefficient having a relatively large value, and the difference is determined by the threshold. 7. The receiving apparatus according to claim 6, wherein a relatively small correction coefficient is selected when the value is equal to or less than the value. 8. The gain control means, when the number of times that the difference between the detected level and the reference value becomes larger than a preset threshold value reaches a preset value, sets a relatively large value. 7. The receiving device according to claim 6, wherein a correction coefficient is selected. 9. The gain control means sets a plurality of thresholds used for comparing a difference between the detected level and a reference value, and selects a threshold according to line quality. The receiving device according to any one of claims 6 to 8. 10. The receiving apparatus according to claim 9, wherein said gain control means selects a large threshold value when the signal-to-thermal noise power ratio is low. 11. The gain control means sets a plurality of threshold values used for comparing a detected level with a difference between a reference value and a threshold value.
9. The receiving device according to claim 6, wherein a threshold value is selected according to a magnitude of a correction coefficient selected last time. 12. The receiving apparatus according to claim 11, wherein the gain control means selects a large threshold value when the correction coefficient selected last time is small. 13. The receiving apparatus according to claim 1, wherein the gain is updated in a preamble section for automatic gain control and a guard interval section for a preamble for transmission path estimation. 14. The receiving apparatus according to claim 13, wherein the level information of the synchronization preamble section is used for integration when updating the gain of the guard interval section of the transmission path estimation preamble. 15. The receiving apparatus according to claim 14, wherein the correction coefficient in updating the gain in the guard interval section of the transmission path estimation preamble is increased. 16. A communication terminal device comprising the receiving device according to claim 1. Description: 17. A base station apparatus comprising the receiving apparatus according to claim 1. Description: 18. A correction coefficient is selected from a plurality of correction coefficients according to the number of times of gain update, and a difference between a detected level and a reference value is multiplied by the selected correction coefficient to obtain a multiplication value. An automatic gain control method, wherein the second gain is obtained by adding the multiplied value to the first gain used in the previous control period, and adjusting the level of the input signal using the second gain. 19. An automatic gain control method, wherein the automatic gain control gain is updated in an automatic gain control preamble section and a guard interval section of a transmission path estimation preamble.