JP2003124759A - Circuit and method for automatically controlling gain - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the time upto convergence to an ideal AGC gain by executing AGC at high speed in the automatic gain control device of a receiver when performing high speed data communications in a CDMA/TDD system. SOLUTION: The time slot (TS) closest to the received TS is selected out of TS received before the received TS as a reference TS while considering a data rate, the difference of ISCP and Doppler frequency. On the basis of the RSSI of the selected TS, the AGC gain of the received TS is calculated.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a CDMA (Code D
The present invention relates to an automatic gain control device in an ivision multiple access) receiving device.

[0002]

2. Description of the Related Art A signal sent from a communication partner is affected by the radio wave propagation environment, and the signal amplitude of the received signal may not be within a certain range when received by the receiving side. A reception signal having such power has poor demodulation accuracy and cannot satisfy a predetermined reception quality. Therefore,
Automatic gain control (hereinafter referred to as “AGC (Auto Gain Control)”) is performed so that the signal amplitude of the received signal falls within a certain range.

FIG. 18 is a block diagram showing a conventional AGC device. In FIG. 18, the gain of the received signal output from the input terminal 10 is controlled by the gain control amplifier 11 according to the control voltage of the D / A converter 17, and is output to the output terminal 12 and the RSSI measuring unit 13. RSS
The I measurement unit 13 measures RSSI from the signal after gain control, and stores the measurement result in the memory 14. The gain calculation unit 15 calculates the AGC gain of the reception TS (current reception time slot for performing AGC).
TS corresponding to the same position in the immediately preceding frame from the memory 14
RSSI is read and the AGC gain is calculated.
The AGC control unit 16 outputs the calculated AGC gain to the D / A converter 17 at a predetermined timing, and
In the A converter 17, the digital AGC gain value is converted into an analog control voltage and applied to the gain control amplifier 11.

When performing high-speed data communication by the CDMA / TDD system, a plurality of TSs are continuously assigned to the same user for communication as shown in FIG. FIG. 19 shows TS allocation during high-speed data communication.
TS2 to TS4 indicate downlink TSs. In this case, when AGC is performed on the TS2 of the frame (n + 1) (hereinafter, the TS performing the AGC is referred to as “the receiving TS”), the reception power of the TS2 of the frame n (RSSI: Rece).
The AGC gain is calculated based on the ived Signal Strength Indicator), and an example of the calculation is shown below.

G _{n + 1} = G _n + (D _R −D _n ) α where G _{n + 1} is the AGC of TS2 of frame (n + 1).
Gain, G _n is the AGC gain of TS2 of frame n, D _n is the RSSI of TS2 of frame n, D _R is the reference RSSI, and α is a constant. Although TS2 is taken as an example here, when calculating the AGC gain of TS3 of frame (n + 1), R of TS3 of frame n is calculated.
When calculating the AGC gain of the TS4 of the frame (n + 1), the SSI is obtained from the above formula with the RSSI of the TS4 of the frame n as a reference. Thus, the TS used as the reference for AGC gain calculation will be referred to as the reference TS.

Next, AGC in the case where the RSSI variation between frames is small will be described. FIG. 20 shows a received TS and its RS when the variation of RSSI between frames is small.
SI is shown. In this case, the TSs corresponding to the same positions in the frame n and the frame (n + 1) have almost the same RSS.
Since I is I and the RSSI of TS2 to TS4 of each frame does not change significantly, the signal amplitude of the received signal can be converged to the target value without any problem by performing AGC according to the above equation.

[0007]

However, as shown in FIG.
When the RSSI variation between frames is large as shown in (4), it takes a long time until the signal amplitude after gain control converges to the target value when AGC according to the above equation is performed. That is, if an ideal signal amplitude is to be obtained with the same position TS in the frame immediately preceding the received TS as a reference, the preceding and following TS are not used as a reference, and the RSSI of each TS in the same frame is set to the same level. It takes time.
As a result, it becomes impossible to follow the change in the propagation path, which deteriorates the reception performance and the bit accuracy. Especially 384kbps
In the case of high-speed data communication such as 2 Mbps and 2 Mbps, the bit accuracy decreases due to the limit of error correction capability, which leads to an increase in the number of retransmission requests and a decrease in throughput. Therefore, a user performing high-speed data communication needs a higher-speed AGC. Become.

[0008]

The automatic gain control circuit of the present invention is used when a CDMA / TDD system radio signal capable of allocating a plurality of time slots to one frame is received and amplified by a gain control amplifier. , An automatic gain control circuit for automatically adjusting the gain of the gain control amplifier by negative feedback control, wherein the RSSI (Res) of the immediately preceding time slot included in the frame to which the current time slot belongs.
Whether the received signal strength indicator can be used as a reference for calculating the gain to be set in the gain control amplifier, the data rate, the ISCP (Interferen
ce Signal Code Power), a determination unit that determines based on at least one of Doppler frequencies, and if the result of the determination is RSSI of a time slot that can be used as a reference for calculating the gain, That R
The gain is calculated based on the SSI value, and if there is no RSSI of the time slot that can be used as the reference for calculating the gain, the RSSI of the time slot at the same position in the immediately preceding frame is used as the reference. A reference time slot selecting means for calculating the gain or stopping the update of the gain of the gain control amplifier is employed.

With this configuration, high-speed and accurate AGC can be performed in high-speed data communication, the time required to converge to an ideal signal amplitude can be shortened, and the fluctuation in the reception level can be extremely fast. In addition to being able to follow, the risk of erroneous AGC on the basis of erroneous reference TS is greatly reduced, and due consideration is given to stability and reliability as well, resulting in reduced reception performance and bit error. It is possible to prevent a decrease in accuracy.

The automatic gain control circuit of the present invention comprises a gain control amplification means for controlling the signal amplitude of a received signal, an RSSI measurement means for measuring RSSI from the signal controlled by the gain control amplification means, and the RSSI measurement means. Storage means for storing the RSSI measured by the above, selection means for selecting a time slot as a reference for AGC gain calculation based on the data rate information acquired from the upper control unit, and the RSSI for the selected time slot is stored in the storage means. And a gain calculating means for calculating the AGC gain by using the RSSI of the time slot serving as the reference for calculating the AGC gain, and an AGC controlling means for outputting the AGC gain at a predetermined timing. take.

According to this configuration, the spreading factor is obtained from the data rate information, and the TS to be used as the reference for the AGC gain calculation is selected based on the spreading factor. Therefore, high-speed and accurate AGC can be performed in high-speed data communication. , It is possible to shorten the time until it converges to the ideal signal amplitude. In particular, it is effective for high-speed data communication with a spreading factor of 1, and in data communication other than the spreading factor of 1, it is possible to estimate whether or not other user signals are multiplexed, so that highly reliable AGC is performed. be able to.

The automatic gain control circuit of the present invention comprises a gain control amplification means for controlling the signal amplitude of a received signal, an RSSI measurement means for measuring RSSI from the signal controlled by the gain control amplification means, and the gain control amplification. ISCP measuring means for measuring ISCP from a signal controlled by the means, and RSS measured by the RSSI measuring means
I and ISCP measured by the ISCP measuring means
And a storage means for storing and a time slot immediately before the time slot in which AGC is performed to obtain the ISCP difference,
Selection means for selecting a time slot as a reference for AGC gain calculation based on the difference, control means for reading the RSSI of the selected time slot from the storage means, and R for the time slot as a reference for AGC gain calculation.
Gain calculating means for calculating an AGC gain using SSI and AGC for outputting the AGC gain at a predetermined timing
And a control means.

According to this configuration, since the TS to be used as the reference for AGC gain calculation is selected based on the difference in ISCP of each TS, other user signals are more accurately multiplexed than when the reference TS is selected based on the data rate. You can know what you are doing, and high speed and accurate AGC in high speed data communication
Can be performed, and the time required to converge to the ideal signal amplitude can be shortened.

The automatic gain control circuit of the present invention comprises a gain control amplification means for controlling the signal amplitude of a received signal, an RSSI measurement means for measuring RSSI from the signal controlled by the gain control amplification means, and the RSSI measurement means. Storage means for storing the RSSI measured by the above, a Doppler frequency measuring means for measuring the Doppler frequency based on the history of the RSSI stored in the storage means, and a reference time for AGC gain calculation depending on the magnitude of the Doppler frequency. Selecting means for selecting a slot; control means for reading the RSSI of the selected time slot from the storage means; gain calculating means for calculating the AGC gain using the RSSI of the time slot which is the reference for calculating the AGC gain; AGC control means for outputting gain at predetermined timing Employs a configuration having a.

According to this structure, the AGC is performed based on f _D.
Since the TS to be used as the reference for gain calculation is selected, it is possible to roughly know the variation of the RSSI between each TS, and therefore the best reference TS can be selected. As a result, high-speed and accurate AGC can be performed in high-speed data communication, and the time required to converge to an ideal signal amplitude can be shortened.

The automatic gain control circuit of the present invention comprises a gain control amplification means for controlling the signal amplitude of a received signal, an RSSI measurement means for measuring RSSI from the signal controlled by the gain control amplification means, and the gain control amplification. ISCP measuring means for measuring ISCP from a signal controlled by the means, and RSS measured by the RSSI measuring means
I and ISCP measured by the ISCP measuring means
A storage unit that stores the data rate information, the data rate information acquired from the upper control unit, and the difference calculated from the ISCP of the two time slots immediately before the time slot in which AGC is performed,
Control means for selecting a time slot as a reference for AGC gain calculation based on the Doppler frequency measured based on the history of the RSSI stored in the storage means, and reading the RSSI of the selected time slot from the storage means; , A gain calculating means for calculating the AGC gain by using the RSSI of the time slot which is the reference of the AGC gain calculation, and A for outputting the AGC gain at a predetermined timing.
And a GC control means.

According to this structure, the TS to be used as the reference for the AGC gain calculation is selected based on a plurality of parameters including the spreading factor obtained from the data rate information, the ISCP difference of each TS, and f _D. AG that takes into consideration various conditions
C can be performed, high-speed and accurate AGC can be performed in high-speed data communication, and the time until convergence to an ideal signal amplitude can be shortened.

The base station apparatus of the present invention has a configuration including any one of the above automatic gain control circuits.

Further, the communication terminal device of the present invention has a configuration including any one of the above automatic gain control circuits.

According to these configurations, high-speed and accurate AGC can be performed in high-speed data communication, and the time required to converge to an ideal signal amplitude can be shortened. Also, a wireless communication system can be constructed by combining these configurations.

The automatic gain control method of the present invention is a CD capable of assigning a plurality of time slots to one frame.
An automatic gain control method for automatically adjusting the gain of the gain control amplifier by negative feedback control when a MA / TDD radio signal is received and amplified by the gain control amplifier, to which a current time slot belongs. RSSI (Received Signa) of the previous time slot included in the frame
l Strength Indicator) can be used as a reference for calculating the gain to be set in the gain control amplifier, and the data rate and ISCP (Interference Signal Co
de Power), a step of making a decision based on at least one of the Doppler frequencies, and if the result of the decision is that there is an RSSI of a time slot that can be used as a reference for calculating the gain, If the RSSI of the time slot that can be used as a reference for calculating the gain is not calculated based on the value, the gain is calculated based on the RSSI of the time slot at the same position in the immediately preceding frame. Calculating or stopping the gain update of the gain control amplifier.

According to this method, high-speed and accurate AGC can be performed in high-speed data communication, the time required to converge to an ideal signal amplitude can be shortened, and the fluctuation in the reception level can be extremely fast. In addition to being able to follow, the risk of erroneous AGC on the basis of erroneous reference TS is greatly reduced, and due consideration is given to stability and reliability as well, resulting in reduced reception performance and bit error. It is possible to prevent a decrease in accuracy.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The essence of the present invention is CDMA-TD.
In the D system wireless communication, the receiving TS that is the AGC target
For the received TS immediately before, it is determined whether it can be used as a reference TS, that is, it is determined whether there is a large fluctuation in the reception level (RSSI), and if it can be used as the reference TS, AGC is performed using that received TS. By doing so, even if the fluctuation of the reception level is large due to high-speed fading, etc., the time until the signal amplitude converges to the ideal signal amplitude is shortened, and high-speed and accurate AGC is performed.

Here, the judgment as to whether or not it can be used as the reference TS, that is, the judgment as to whether or not the fluctuation of the reception level (RSSI) is large, should be made by using at least one of the data rate, ISCP and Doppler frequency. You can

When the data rate is used as the determination parameter, it is possible to determine whether or not the fluctuation of the reception level is large by confirming the usage status of the spreading factor. For example, when the spreading factor is confirmed and there is no interference from other users, it is considered that the fluctuation of the RSSI is small, so this received TS can be used as the reference TS according to the present invention.

When ISCP is used as a determination parameter, it is possible to determine whether or not the variation in the reception level is large by obtaining the difference between the two reception TSs immediately before the reception TS that is the AGC target. For example, when the variation of ISCP between receiving TSs is small, RSSI
The received TS can be used as the reference TS according to the present invention, since it is considered that the fluctuation of the received TS is small.

When the Doppler frequency is used as the determination parameter, when the Doppler frequency is high, the RSSI variation between frames is large, but the RSSI variation between the immediately preceding received TS is considered to be small. The TS can be used as the reference TS according to the present invention. When the Doppler frequency is small,
Since it is considered that there is almost no variation in RSSI between TSs, only the reception TS at the beginning of the frame is changed and the subsequent T
S does not change.

The determination of the above-mentioned determination parameter can be performed by setting a predetermined threshold value for each determination parameter and judging whether the determination parameter is larger or smaller.

Further, when it is determined that the reception TS immediately before the reception TS which is the AGC target cannot be used as the reference TS, the same reception T of all frames as usual.
Use S as the reference TS.

That is, the RSSI of the reception TS closest to the reception TS is selected, and the AGC gain is calculated based on the RSSI to realize high-speed AGC and improve the bit accuracy.

In the case of FIG. 20 as an example, the frame (n +
The AGC gain of TS2 of 1) is calculated based on the RSSI of TS4 of frame n, and the AGC gain of TS3 of frame (n + 1) is the RSS of TS2 of frame (n + 1).
Calculate based on I.

However, the data rate, ISCP (Interference Signal Code Powe) are used as RSSI selection criteria.
r: interference wave power) and f _D (Doppler frequency) are used.

By using the data rate as a reference, it is possible to know the spreading rate of the reception TS and to judge the occupation rate of the reception TS.

In the TD-SCDMA (CDMA / TDD system, the same frequency is used for upstream and downstream, communication is performed by time division duplex, a plurality of TSs can be assigned to one frame, and a plurality of TSs can be assigned to one TS. In the case of a method in which user signals can be assigned), 5 TSs with SF (spreading factor) = 1 are used especially when the downlink is 2 Mbps, so that each TS contains signals of other users. Absent. Therefore, there is no interference from other users and R between TSs
Since the fluctuation of SSI is considered to be small, the reception T
It is effective to perform AGC based on the RSSI of S.

On the contrary, in the uplink, 128 kbps, 144
Although reception is performed in a plurality of TSs at kbps, 384 kbps, etc., it is considered that signals of other users are also included because SF = 2. In this case, the IS described below
Select a reference TS in a CP-based manner. Since ISCP represents the interference wave power in the reception TS, it is possible to determine whether or not the reception TS includes a signal of another user by using this as a reference.

If the ISCP of each TS is stored in a memory and the ISCP variation between TSs is small, it is considered that the RSSI variation between TSs is small. Therefore, based on the RSSI of the immediately preceding received TS, Performing AGC is effective.

On the other hand, when there is a large variation in ISCP between TSs, it is considered that there is a large variation in RSSI between TSs.
AGC is performed based on. Note that ISCP is to be measured by the UE.

Since the variation of RSSI between each reception TS is roughly known from f _D , it is possible to judge which reception TS RSSI should be used to perform AGC based on this variation.

RSS between frames when f _D is large
Since the fluctuation of I is large, it is effective to perform AGC based on the RSSI of the immediately preceding arbitrary received TS (judged from f _D ).

On the other hand, when f _D is very small, the variation of RSSI between TSs is small, so that A of consecutive reception TSs is small.
The GC gain does not have to be changed from the AGC gain of the reception TS at the beginning of the frame. This can reduce the amount of calculation. Note that f _D is calculated from the values of the RSSI of each received TS stored in the memory.

In a system using a smart antenna (generally an array antenna) like TD-SCDMA, since the transmission signal from the base station to each user has directivity, the interference wave power from other users is very high. Since it becomes smaller and the occupancy rate of each TS increases, the last received TS
The power fluctuations of and become smaller, and it is sufficient to follow only fading fluctuations. Therefore, the RSSI of the last received TS
Performing AGC based on is an effective means.

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

(Embodiment 1) FIG. 1 is a block diagram showing an AGC device according to Embodiment 1 of the present invention. Figure 1
In, the gain control amplifier 102 performs gain control on the received signal input from the input terminal 101 according to the control voltage from the D / A converter 109, and outputs the signal after gain control to the output terminal 103 and the RSSI measurement unit 104. Output.

RSSI measuring section 104 measures RSSI from the signal after gain control output from gain control amplifier 102, and outputs the measurement result to control section 105.

The control unit 105 writes the RSSI measured by the RSSI measuring unit 104 in the memory 106. Further, the control unit 105 selects a TS as a reference for AGC gain calculation based on the data rate information output from a host controller (not shown), reads the RSSI of the TS from the memory 106, and outputs the RSSI of the reference TS. Is output to the gain calculation unit 107. Details of the control unit 106 will be described later. In the present specification, the AGC gain is an amplification factor (gain) set in the gain control amplifier.

The gain calculation unit 107 calculates the AGC gain of the TS to be AGC from the RSSI of the reference TS output from the control unit 105, and calculates the AGC gain as AGC gain.
It is output to the control unit 108.

The AGC control unit 108 includes a gain calculation unit 10
The AGC gain output from the D / A converter 1 controls the AGC gain at the timing for controlling the target TS.
It outputs to 09.

The D / A converter 109 converts the digital AGC gain value output from the AGC control unit 108 into an analog control voltage and applies it to the gain control amplifier 102.

Next, the operation of the AGC device having the above configuration will be described. The received signal input from the input terminal 101 is controlled by the gain control amplifier 102 according to the control voltage output from the D / A converter 109 so that the signal amplitude falls within a predetermined range, and the signal after gain control is output terminal. 103 and the RSSI measurement unit 104.

The RSSI measuring section 104 measures the RSSI from the signal after gain control, and the measurement result is the control section 105.
Is output to.

In the control unit 105, the RSSI measuring unit 104
The output RSSI is written in the memory 106. Also, based on the data rate information output from a host controller (not shown), a TS that serves as a reference for AGC gain calculation is selected, the RSSI of the selected TS is read from the memory 106, and the gain calculation unit 107 is selected. Is output to.

The gain calculator 107 calculates the amount of change in the AGC gain from the RSSI of the reference TS output from the controller 105. That is, (change amount) = (reference RS
SI-RSS of reference TS) α. And
The AGC gain is obtained by adding the amount of change in the AGC gain to the previous AGC gain stored in the buffer in the gain calculation unit 107. The AGC gain calculated in this way is output to the AGC control unit 108.

In the AGC controller 108, the gain calculator 1
The AGC gain output from 07 is output to the D / A converter 109 at the timing for controlling the target TS.

The D / A converter 109 converts the digital AGC gain value output from the AGC control unit 108 into an analog control voltage, and the gain control amplifier 102.
Applied to.

Next, the internal structure of the control unit 105 will be described with reference to FIG. FIG. 2 is a block diagram showing the internal configuration of the control unit 105. In FIG. 2, the data rate determination unit 201 is preset with a table in which the data rate and the spreading factor are associated with each other. The data rate information is acquired from a higher-order control unit (not shown), and the corresponding spreading factor is 1 or 1. Determine if other than. The determination result is the reference TS selection unit 203
Is output to.

The memory I / F 202 receives the input RSS
I is written in the memory 106, and the RSSI of the reference TS requested by the reference TS selection unit 203 described later is stored in the memory 10.
6, and outputs to the reference TS selection unit 203.

When the determination result output from the data rate determination unit 201 indicates a spreading factor of 1, the reference TS selection unit 203 selects the reception TS immediately before the reception TS as the reference TS, and the determination result If the spreading factor is other than 1, the TS at the same position in the previous frame is selected as the reference TS with respect to the received TS. It requests the memory I / F 202 for the RSSI of the selected TS, acquires the corresponding RSSI, and then outputs it to the gain calculation unit 107.

Next, the processing of the control unit 105 will be described with reference to FIG. FIG. 3 is a flowchart showing the process of selecting the reference TS using the data rate in the control unit 105. In step (hereinafter abbreviated as “ST”) 301, it is determined whether or not it is received by a plurality of TSs. If it is received by a plurality of TSs, the process proceeds to ST302, and if it is not received by a plurality of TSs, the process proceeds to ST305.

When receiving by a plurality of TSs, ST302
At, the data rate is obtained from the upper control unit and the spreading factor is obtained. In ST303, it is determined whether the spreading factor is 1, and if the spreading factor is 1, the process proceeds to ST304, and if the spreading factor is not 1, the process proceeds to ST305.

When the spreading factor is 1, in ST304,
The reception TS immediately before the reception TS is selected as a reference for AGC gain calculation. On the other hand, when not received by a plurality of TSs and when the spreading factor is not 1, in ST305, the same TS of the frame immediately preceding the received TS is used as the reference for AGC gain calculation.

Here, the reason why the reference TS is selected separately for the spreading factor 1 and other than 1 will be described. When the spreading factor is 1, only one type of spreading code can be used, and it is not time-multiplexed by a plurality of users. For this reason, since each TS does not include signals of other users, it is considered that the fluctuation of RSSI is small. As a result, the TS immediately before the received TS can be selected as the reference TS for AGC gain calculation.

On the other hand, when the spreading factor is other than 1, since there are a plurality of spreading codes that can be used, time multiplexing may be performed by a plurality of users, and RSSI fluctuation may be large. This situation will be described with reference to FIG. FIG. 4 shows the same T
An example in which multiple users are accommodated in S is shown. In FIG. 4, A indicates a user with a spreading factor of 2 occupying TS2 to TS4, and B and C indicate users with a spreading factor of 4 and multiplexed on TS3. When the TS3 of the frame (n + 1) is the reception TS, the TS2 which is the immediately previous TS is AGC.
When the gain calculation is used as a reference, the RSSI variation is large, so that highly accurate AGC cannot be performed. Therefore,
When there is a reception TS in which a plurality of users are multiplexed as shown in TS3, the same TS of the immediately preceding frame (TS3 of frame n in FIG. 4) is used as the reference for AGC gain calculation. This is because the TSs assigned to the users are the same. That is, referring to FIG. 4, user A,
The TS on which B and C are multiplexed is TS3, which lasts for a certain period of time.
Large fluctuations in RSSI are unlikely to occur. As a result, the same position TS of the immediately preceding frame may be selected as the reference TS for the received TS.

As described above, according to the present embodiment, by selecting the reference TS for AGC gain calculation based on the spreading factor obtained from the data rate, high-speed and accurate AGC can be performed in high-speed data communication. , It is possible to shorten the time until it converges to the ideal signal amplitude.

(Second Embodiment) FIG. 5 is a block diagram of an AGC device according to a second embodiment of the present invention. However,
5, parts that are the same as those in FIG. 1 are assigned the same reference numerals as in FIG. 1, and detailed descriptions thereof are omitted.

The gain control amplifier 102 has an input terminal 101.
Gain control is performed on a received signal input from the D / A converter 109 in accordance with a control voltage, and the received signal after the gain control is output to the output terminal 103 and the RSSI measuring unit 104.
It is output to the ISCP measuring unit 501.

The ISCP measuring section 501 calculates the ISC from the received signal after gain control output from the gain control amplifier 102.
P (Interference Signal Code Power) is measured, and the measurement result is output to the control unit 502.

The control unit 502 writes the RSSI measured by the RSSI measuring unit 104 and the ISCP measured by the ISCP measuring unit 501 in the memory 503. Also,
The control unit 502 measures the variation of ISCP between each TS,
TS as a reference for AGC gain calculation based on the measurement result
Is selected, the RSSI of the TS is retrieved from the memory 503, and the RSSI of the reference TS is output to the gain calculation unit 504. Details of the control unit 502 will be described later.

The gain calculation unit 504 calculates the AGC gain of the TS to be AGC from the RSSI of the reference TS output from the control unit 502, and calculates the AGC gain as AGC gain.
It is output to the control unit 108. Details of the gain calculator 504 will be described later.

Next, the operation of the AGC device having the above configuration will be described. However, the operation having a configuration different from that of the first embodiment will be mainly described. In the ISCP measuring unit 501,
ISCP is measured from the received signal after gain control, and the measurement result is output to control section 502.

In the control unit 502, the RSSI measuring unit 104
The RSSI output from the ISCP and the ISCP output from the ISCP measuring unit 501 are written in the memory 503. Further, the variation of ISCP between each TS is measured, the TS as the reference for AGC gain calculation is selected based on the measurement result, the RSSI of the selected TS is read from the memory 503, and the reference TS RSSI is gain calculation unit 50
4 is output.

The gain calculator 504 calculates the amount of change in the AGC gain from the RSSI of the reference TS output from the controller 502. That is, (change amount) = (reference RS
SI-RSS of reference TS) α. And
The AGC gain is obtained by adding the change amount of the AGC gain to the previous AGC gain stored in the buffer in the gain calculation unit 504. When the AGC gain is not updated, the previous AGC gain is calculated as the AGC gain of the reception TS. The AGC gain calculated in this way is output to the AGC control unit 108.

Next, the internal structure of the controller 502 will be described with reference to FIG. FIG. 6 is a block diagram showing the internal configuration of the control unit 502. In FIG. 6, the memory I / F
601 stores the input RSSI and ISCP in the memory 50.
3 and read the ISCP requested by the ISCP determination unit 602, which will be described later, from the memory 503.
It outputs to the determination unit 602, and the reference TS selection unit 603 described later.
The RSSI of the reference TS requested from the memory 503 is read from the memory 503 and output to the reference TS selection unit 603.

The ISCP judging section 602 inputs the ISCP stored in the memory 503 via the memory I / F 601, measures the variation of ISCP between TSs, and outputs the measurement result to the reference TS selecting section 603.

If the difference in ISCP between TSs is small from the judgment result of the ISCP judgment unit 602, the reference TS selection unit 603 selects the reception TS immediately before the reception TS and stores the RSSI of the selected TS in the memory I / F 601. And outputs the corresponding RSSI to the gain calculation unit 504. ISCP
If the difference is large, the AGC gain is not updated. In addition, when not received by a plurality of TSs, the reception TS
Select the same TS in the frame immediately before, and select the R of the selected TS.
Request the SSI from the memory I / F 601 and send the corresponding RSS
I is output to the gain calculation unit 504.

Next, the processing of the control unit 502 will be described with reference to FIG. In ST701, it is determined whether a plurality of TSs have been received, and if a plurality of TSs have been received, ST702
If not received by multiple TSs, the process proceeds to ST706.

When receiving with a plurality of TSs, ST702
At I, the ISCPs of the immediately preceding two TSs are acquired from the memory 503 via the memory I / F 601 and the difference between them is obtained. In ST703, ISCP measurement section 602
The difference between CPs is judged to be large or small, and if the difference is small, ST70
4 and if the difference is large, the process proceeds to ST705. If the difference in ISCP between the two previous TSs is small, S
At T704, the reference TS selection unit 603 selects A of the current TS.
The previous TS is selected as the reference TS for calculating the GC gain. If there is a large difference in ISCP between the two TSs immediately before, ST70
5, the AGC gain is not updated and the reception T
The AGC gain used in the reception TS immediately before S is applied to the reception TS as it is. If not received by a plurality of TSs, in ST706, the same TS of the previous frame is selected as a reference TS for AGC gain calculation.

The reason why the reference TS is selected according to the difference in ISCP between TSs will be described. Since ISCP represents the interference wave power in the reception TS, it is possible to judge whether or not the signal of another user is multiplexed in the reception TS by using this as a reference. When the ISCP variation between TSs is small, it is unlikely that the signals of other users are multiplexed, and the RSSI variation between TSs is considered to be small. It can be selected as TS. On the other hand, when there is a large variation in ISCP between TSs, it is highly possible that the signals of other users are multiplexed, and it is considered that the variation in RSSI between TSs is large, so the AGC gain is not updated. As a result, it is possible to prevent the signal amplitude after gain control from unnecessarily increasing or unnecessarily decreasing.

Next, the AGC gain calculation process of the gain calculation unit 504 will be described with reference to FIG. FIG. 8 is a flowchart showing an AGC gain calculation process in gain calculation section 504. In ST801, gain calculation section 504
The previous AGC gain is obtained from the internal buffer. ST
In 802, information output from the control unit 502 (AGC
When the gain is updated, the RSSI of the reference TS is output), and it is determined whether or not the AGC gain is updated. If not updated, the process proceeds to ST803, and if updated, ST804.
Move to each.

When the AGC gain is not updated, ST80
3, the previous AGC gain is set to the AG of the receiving TS.
Calculate as C gain. On the other hand, when updating the AGC gain, in ST804, the control unit 502 outputs the reference T
Get the RSSI of S.

In ST805, the RSSI of the reference TS is subtracted from the reference RSSI in order to calculate the change amount of the AGC gain, and the subtracted value is multiplied by the constant α. In ST806, the amount of change calculated in ST805 is added to the previous AGC gain to calculate the AGC gain of the reception TS.

As described above, according to this embodiment, the immediately preceding 2
By selecting a reference TS for AGC gain calculation based on the difference in ISCP of two TSs, high-speed and accurate AGC can be performed in high-speed data communication, and the time until convergence to an ideal signal amplitude is shortened. be able to.

(Embodiment 3) FIG. 9 is a block diagram showing an AGC device according to Embodiment 3 of the present invention. However, in FIG. 9, portions common to FIG. 1 are denoted by the same reference numerals as those in FIG. 1, and detailed description thereof will be omitted.

The AGC device according to the third embodiment has the f _D measuring section 902 in addition to the components of the first embodiment, changes the gain calculating section 107 into a gain calculating section 504, and controls the control section 105.
Was changed to the control unit 901.

In FIG. 9, the RSSI measuring section 104 is
The RSSI is measured from the AGC gain output from the gain control amplifier 102, and the measurement result is output to the control unit 901.

The control unit 901 writes the RSSI measured by the RSSI measuring unit 104 in the memory 106. The control unit 901, based on the f _D output from the f _D (Doppler frequency) measurement unit 902 to be described later, AG
Select a TS to be used as a reference for C gain calculation, and then select that TS.
Of the reference TS from the memory 106
The SSI is output to the gain calculator 504. The details of the control unit 901 will be described later.

The f _D measuring unit 902 reads the RSSI history stored in the memory 106 via the control unit 901, and the graph showing the time change of the RSSI of each TS intersects with a predetermined threshold within a predetermined time. The frequency f _D is measured according to the number of times of measurement, and the measurement result is output to the controller 901.

The gain calculation unit 504 calculates the AGC gain of the TS that is the target of AGC from the RSSI of the reference TS output from the control unit 901, and calculates the AGC gain as AGC gain.
It is output to the control unit 108.

Next, the operation of the AGC device having the above configuration will be described. However, the operation having a configuration different from that of the first embodiment will be mainly described. In the control unit 901, the RSSI
The RSSI output from the measurement unit 104 is written in the memory 106. In addition, based on the magnitude judgment of f _D , AGC
A TS as a reference for gain calculation is selected, the RSSI of the selected TS is read from the memory 106, and the RSSI of the reference TS is output to the gain calculation unit 504.

In the f _D measuring section 902, the history of RSSI stored in the memory 106 is read out via the control section 901, and a graph showing the time change of RSSI of each TS is set to a predetermined threshold value within a predetermined time. F depending on the number of times
_D is measured, and the measurement result is output to the control unit 901.

The gain calculator 504 calculates the amount of change in the AGC gain from the RSSI of the reference TS output from the controller 901. That is, (change amount) = (reference RS
SI-RSS of reference TS) α. And
The AGC gain is obtained by adding the change amount of the AGC gain to the previous AGC gain stored in the buffer in the gain calculation unit 504. When the AGC gain is not updated, the previous AGC gain is calculated as the AGC gain of the reception TS. The AGC gain calculated in this way is output to the AGC control unit 108.

Next, the internal structure of the controller 901 will be described with reference to FIG. FIG. 10 is a block diagram showing the internal configuration of the control unit 901. In FIG. 10, the memory I / F 1001 stores the input RSSI in the memory 106.
Written to and stored in the memory 106
The history of I is read and output to the f _D measuring unit 902, and the RSSI of the reference TS requested by the reference TS selecting unit 1003 described later is read from the memory 106 and output to the reference TS selecting unit 1003.

The f _D determining section 1002 determines the magnitude of f _D output from the f _D measuring section 902 based on a predetermined threshold value, and outputs the determination result to the reference TS selecting section 1003.

The reference TS selection unit 1003 is the f _D determination unit 1
002 selects the reference TS based on the determination result output from 002 and the head reception TS of the frame, etc.
RSSI of the memory 10 via the memory I / F 1001
6 and reads the RSSI of the reference TS from the gain calculation unit 5
Output to 04.

Next, the processing of the control unit 901 will be described with reference to FIG.
Will be explained. FIG. 11 shows that in the control unit 901,
It is a flow diagram that illustrates the processing of the reference TS selection using f _D. In ST1101, it is determined whether or not it is received by a plurality of TSs, and if it is received by a plurality of TSs, the process proceeds to ST1102,
If not received by multiple TSs, the mobile terminal makes a transition to ST1107.

[0095] and retrieving the f _D from f _D measuring unit 902 in ST1102, performs size determination of f _D in ST 1103. If f _D is large, the process proceeds to ST1104, and if f _D is small, the process proceeds to ST1105.

In ST1104, the reception TS immediately before the reception TS is selected as the reference TS. In ST1105, it is determined whether the received TS is located at the beginning of the frame. If the received TS is not located at the beginning of the frame, ST
If the received TS is located at the head of the frame, the process proceeds to ST1107.

In ST1106, the AGC gain is not updated and the same AGC gain as that of the reception TS located at the beginning of the frame is used. In ST1107, the same T of the previous frame
Select S as the reference TS.

Here, the reason why the reference TS is selected according to the magnitude of f _D will be described. RS of received TS from f _D
The variation of SI is roughly known, and by using this as a reference, it is possible to determine which RSS of the received TS should be used to perform AGC. f _D changes depending on the moving speed of the communication terminal, etc., and when f _D is large, R between frames is increased.
Since the SSI varies greatly, it is advisable to use the TS closest to the received TS as the reference TS. On the other hand, f _D
Is small, the RSSI variation between TS is small,
As the AGC gain of continuous reception TS, the AGC gain of the frame head TS may be used as it is, and it is not necessary to calculate the AGC gain. This can reduce the amount of calculation. However, when the received TS is the first TS of the frame, the same TS of the previous frame is selected as the reference TS.

As described above, according to the present embodiment, by selecting the reference TS for calculating the AGC gain based on the determination of the magnitude of f _D , the high-speed and accurate A in the high-speed data communication can be obtained.
GC can be performed, and the time required to converge to an ideal signal amplitude can be shortened.

(Embodiment 4) FIG. 12 is a block diagram showing an AGC device according to Embodiment 4 of the present invention. However, in FIG. 12, portions common to FIG. 1 are assigned the same reference numerals as those in FIG. 1, and detailed description thereof will be omitted.

The AGC apparatus according to the fourth embodiment has the ISCP measuring section 501 and the f _D measuring section 9 as the constituent elements of the first embodiment.
02, the control unit 105 is changed to the control unit 1201, the memory 106 is changed to the memory 503, and the gain calculation unit 107 is changed to the gain calculation unit 504.

RSSI measuring section 104 measures RSSI from the gain-controlled signal output from gain control amplifier 102, and outputs the measurement result to control section 1201.

The ISCP measuring section 501 calculates the ISCP from the signal after gain control output from the gain control amplifier 102.
(Interference Signal Code Power) is measured and the measurement result is output to the control unit 1201.

The control unit 1201 uses the RSSI measuring unit 104.
The RSSI measured by the ISCP and the ISCP measured by the ISCP measuring unit 501 are written in the memory 503. In addition, the control unit 1201 controls the data rate information output from the host controller, the ISCP variation between TSs, and f _D
A TS to be used as a reference for AGC gain calculation is selected based on the above, the RSSI of the TS is retrieved from the memory 503, and the RSSI of the reference TS is output to the gain calculation unit 504. Details of the control unit 1201 will be described later.

The gain calculation unit 504 calculates the AGC gain of the TS that is the target of AGC from the RSSI of the reference TS output from the control unit 1201 and sets the AGC gain to AG.
It is output to the C control unit 108.

Next, the operation of the AGC device having the above configuration will be described. The ISCP measuring section 501 measures ISCP from the received signal after gain control output from the gain control amplifier 102, and outputs the measurement result to the control section 1201.

In the control unit 1201, the RSSI measuring unit 10
4 and the ISCP measured by the ISCP measuring unit 501 are written in the memory 503. Further, the control unit 1201, to the data rate information outputted from the host controller, the variation in the ISCP between the TS, a reference for AGC gain calculated on the basis of the f _D T
S is selected and the RSSI of the TS is stored in the memory 503.
And the RSSI of the reference TS is extracted from the gain calculation unit 5
It is output to 04.

In the gain calculation section 504, the control section 1201
The change amount of the AGC gain is calculated from the RSSI of the reference TS that is output. That is, (change amount) = (reference R
SSI-RSSI of reference TS) α. Then, the AGC gain is obtained by adding the variation amount of the AGC gain to the previous AGC gain stored in the buffer in the gain calculation unit 504. When the AGC gain is not updated, the previous AGC gain is calculated as the AGC gain of the reception TS. The AGC gain calculated in this way is output to the AGC control unit 108.

Next, the internal structure of the control unit 1201 will be described with reference to FIG. FIG. 13 is a block diagram showing the internal configuration of the control unit 1201. In FIG. 13, the memory I / F 1301 has the input RSSI and ISCP.
Is written in the memory 503, and the ISCP determination unit 6 described later is written.
02, the ISCP requested by 02 is read from the memory 503 and output to the ISCP determination unit 602. In addition, the history of RSSI requested from the f _D measuring unit 902 is stored in the memory 503.
It is read out and output to the f _D measuring unit 902. RS of the reference TS requested by the reference TS selection unit 1302 described later
The SI is read from the memory 503, and the reference TS selection unit 13
Output to 02.

The ISCP decision unit 602 uses the ISCP output from the ISCP measurement unit 501 as the memory I / F 1301.
Via I.C., the ISCP variation between TSs is measured, and the measurement result is output to the reference TS selection unit 1302.

The f _D judging section 1002 judges the magnitude of f _D output from the f _D measuring section 902 based on a predetermined threshold value, and outputs the judgment result to the reference TS selecting section 1302.

The data rate determining unit 201 has a table in which the data rate and the spreading factor are associated with each other. The data rate information is obtained from a higher-order control unit (not shown), and the corresponding spreading factor is other than 1 or 1. To determine. The determination result is output to the reference TS selection unit 1302.

Next, the processing of the control unit 1201 will be described with reference to FIG.
4 will be described. FIG. 14 is a flowchart showing the process of selecting the reference TS in the control unit 1201. In ST1401, it is determined whether a plurality of TSs have been received, and if a plurality of TSs have been received, the operation proceeds to ST1402, and if a plurality of TSs have not been received, the operation proceeds to ST1411.

When receiving with a plurality of TSs, ST140
2 obtains f _D from the f _D measuring section 902, and ST1
In 403, the magnitude of f _D is determined. If f _D is large, ST1404 is entered. If f _D is small, ST 1409 is entered.
Move to each.

In ST1404, the data rate is acquired from the upper control section, and in ST1405 it is determined whether or not the spreading factor is 1. When the spreading factor is 1, ST140
If the spreading factor is other than 1, the process proceeds to ST1406.

In ST1406, the memory I / F 1301
The ISCPs of the immediately preceding two TSs are acquired from the memory 503 via the, and the difference between them is calculated.
Judgment of CP difference is made. When the difference in ISCP is large, ST1410 is set. When the difference in ISCP is small, ST1 is set.
408 respectively.

In ST1408, the reception TS immediately before the reception TS is selected as the reference TS.

When f _D is small, in ST1409,
It is determined whether or not the received TS is located at the beginning of the frame. If not located at the beginning of the frame, ST1410
If the frame is located at the beginning of the frame, the process proceeds to ST1411.

In ST1410, the AGC gain is not updated, and the A used in the reception TS immediately before the reception TS concerned is updated.
The GC gain is applied to the reception TS as it is. ST
At 1411, the same TS of the previous frame is selected as the reference TS.

Now, referring to FIG. 15 and FIG.
The process progress of C is divided into a conventional process and the present invention and will be described in comparison. FIG. 15 is a conceptual diagram showing the progress of processing by the conventional method. Further, FIG. 16 is a conceptual diagram showing the processing progress according to the method of the present invention. Frames n to (n + 3) are shown, TS2 to TS4 show received TSs, the upper stage shows the RSSI of each TS, the middle stage shows the AGC gain, and the lower stage shows the signal amplitude after gain control. . Figure 1
5 and FIG. 16, the RSSI of each reception TS is the same.

In FIG. 15, the gain of the gain control amplifier is set in such a direction that the variation of the received power value of the current time slot is rather increased by the variation of the output of the gain control amplifier in the past. Alternatively, if the received signal changes abruptly and stepwise, it may not be possible to follow this variation at all, and effective control of the amplifier gain may not be performed.

On the other hand, according to the method of the present invention, it is possible to accurately update the amplifier gain with reference to the received power value of the latest time slot, and follow the fluctuation of the received signal at high speed. On the other hand, time slots that are judged to have a large error should be excluded from the criteria for gain calculation, or the update of the gain itself should be stopped to ensure that the situation is not adversely affected by erroneous control. High reliability because it is made.

In the system of the present invention, fluctuations in the reception level can be tracked very quickly, and the risk of erroneous AGC control based on an erroneous reference is greatly reduced, and stability and reliability are improved. Consideration is given to the aspect.

As described above, according to this embodiment, the spreading factor obtained from the data rate, the difference in ISCP between TSs, and f
By selecting the reference TS for AGC gain calculation based on _D , high-speed and accurate AGC can be performed in high-speed data communication, and the time until convergence to an ideal signal amplitude can be shortened.

In the system using the array antenna as shown in FIG. 17, since the transmission signal from the base station to each user (A, B, C) has directivity, the interference wave power by other users is Since it becomes extremely small and the occupancy rate of each TS increases, the power fluctuation with the immediately preceding received TS becomes small, and it is sufficient to follow only the fading fluctuation. Therefore, the RS of the reception TS immediately before the reception TS
Performing AGC based on SI is an extremely effective means.

[0126]

As described above, according to the present invention,
High-speed and accurate AGC can be performed in high-speed data communication, and the time required to converge to an ideal signal amplitude can be shortened, which can follow changes in the propagation path and deteriorate reception performance. , It is possible to prevent a decrease in bit precision.

[Brief description of drawings]

FIG. 1 is a block diagram showing an AGC device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing an internal configuration of a control unit according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing a process of selecting a reference TS using a data rate in the control unit according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a state in which multiple users are accommodated in the same TS.

FIG. 5 is a block diagram showing an AGC device according to a second embodiment of the present invention.

FIG. 6 is a block diagram showing an internal configuration of a control unit according to the second embodiment of the present invention.

FIG. 7 shows I in the control unit according to the second embodiment of the present invention.
Flowchart showing processing of reference TS selection using SCP

FIG. 8 is a flowchart showing an AGC gain calculation process in a gain calculation section according to the second embodiment of the present invention.

FIG. 9 is a block diagram showing an AGC device according to a third embodiment of the present invention.

FIG. 10 is a block diagram showing an internal configuration of a control unit according to a third embodiment of the present invention.

FIG. 11 shows f in the control unit according to the third embodiment of the present invention.
Flow chart showing the process of selecting the reference TS using _D

FIG. 12 is a block diagram showing an AGC device according to a fourth embodiment of the present invention.

FIG. 13 is a block diagram showing an internal configuration of a control unit according to a fourth embodiment of the present invention.

FIG. 14 is a flowchart showing a process of selecting a reference TS in the control unit according to the fourth embodiment of the present invention.

FIG. 15 is a diagram showing a process progress according to a conventional method.

FIG. 16 is a diagram showing the progress of processing according to the method of the present invention.

FIG. 17 is a conceptual diagram showing a system using an array antenna.

FIG. 18 is a block diagram showing a conventional AGC device.

FIG. 19 is a diagram showing TS allocation during high-speed data communication.

FIG. 20 is a diagram showing a case where RSSI variation between frames is small.

FIG. 21 is a diagram showing a case where there is a large variation in RSSI between frames.

[Explanation of symbols]

101 input terminal 102 gain control amplifier 103 output terminal 104 RSSI measuring unit 105, 502, 901, 1201 control unit 106, 503 memory 107, 504 gain calculation unit 108 AGC control unit 109 D / A converter 201 data rate determination unit 202, 601 , 1001, 1301 memory I / F 203, 603, 1003, 1302 reference TS selection unit 501 ISCP measurement unit 602 ISCP determination unit 902 f _D measurement unit 1002 f _D determination unit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Keiichi Kitagawa             3-1, Tsunashima-Higashi 4-chome, Kohoku-ku, Yokohama-shi, Kanagawa             Matsushita Communication Industry Co., Ltd. F term (reference) 5J100 JA01 JA02 KA01 LA09 LA11                       QA01 SA02                 5K022 EE01 EE21 EE31                 5K028 AA11 AA14 BB06 CC02 CC05                       EE08 KK01 KK12 LL12 RR02                 5K061 AA11 BB11 CC52

Claims (8)

[Claims] 1. When a CDMA / TDD system radio signal capable of allocating a plurality of time slots to one frame is received and amplified by a gain control amplifier, the gain of the gain control amplifier is automatically controlled by negative feedback control. This is an automatic gain control circuit for dynamically adjusting the RSSI (Received Signal Streak) of the immediately preceding time slot included in the frame to which the current time slot belongs.
ngth Indicator) can be used as a reference for calculating the gain to be set in the gain control amplifier, by determining the data rate, ISCP (Interference Signal Code Pow).
er), determining means for determining based on at least one of the Doppler frequencies, and as a result of the determination, if there is an RSSI of a time slot that can be used as a reference for calculating the gain, If the RSSI of the time slot that can be used as a reference for calculating the gain is not calculated based on the value, the gain is calculated based on the RSSI of the time slot at the same position in the immediately preceding frame. An automatic gain control circuit, comprising: a reference time slot selecting unit that calculates or stops updating the gain of the gain control amplifier. 2. A gain control amplification means for controlling a signal amplitude of a received signal, an RSSI measurement means for measuring an RSSI from a signal controlled by the gain control amplification means, and an RSSI measured by the RSSI measurement means. Storing means, selecting means for selecting a time slot as a reference for AGC gain calculation based on the data rate information acquired from the higher-order control part, and controlling means for reading the RSSI of the selected time slot from the storing means. A
RSSI of time slot used as a reference for calculating GC gain
Gain calculation means for calculating the AGC gain using
An automatic gain control circuit, comprising: an AGC control unit that outputs a GC gain at a predetermined timing. 3. A gain control amplification means for controlling a signal amplitude of a received signal, an RSSI measurement means for measuring an RSSI from a signal controlled by the gain control amplification means, and a signal controlled by the gain control amplification means. ISCP
An ISCP measuring means for measuring, an storing means for storing the RSSI measured by the RSSI measuring means and the ISCP measured by the ISCP measuring means,
A selection unit that obtains a difference in ISCP from two time slots immediately before a time slot in which C is performed and selects a time slot that serves as a reference for AGC gain calculation based on the difference, and a storage unit that stores the RSSI of the selected time slot And a gain calculation unit that calculates an AGC gain using RSSI of a time slot that is a reference for AGC gain calculation, and an AGC control unit that outputs the AGC gain at a predetermined timing. The automatic gain control circuit according to claim 2. 4. A gain control amplification means for controlling a signal amplitude of a received signal, an RSSI measurement means for measuring an RSSI from a signal controlled by the gain control amplification means, and an RSSI measured by the RSSI measurement means. Storage means, a Doppler frequency measuring means for measuring a Doppler frequency based on the history of the RSSI stored in the storage means, and a selecting means for selecting a time slot as a reference for AGC gain calculation according to the magnitude of the Doppler frequency. , Using the control means for reading the RSSI of the selected time slot from the storage means and the RSSI of the time slot used as the reference for the AGC gain calculation.
The automatic gain control circuit according to claim 2, further comprising: a gain calculation unit that calculates a C gain and an AGC control unit that outputs the AGC gain at a predetermined timing. 5. A gain control amplification means for controlling the signal amplitude of a received signal, an RSSI measurement means for measuring RSSI from the signal controlled by the gain control amplification means, and a signal controlled by the gain control amplification means. ISCP
ISCP measuring means for measuring the, the storage means for storing the RSSI measured by the RSSI measuring means and the ISCP measured by the ISCP measuring means, the data rate information acquired from the host controller, and the time slot for performing AGC. Of the last two time slots of ISCP
And the R stored in the storage means.
A control means for selecting a time slot as a reference for AGC gain calculation based on the Doppler frequency measured based on the history of SSI and reading the RSSI of the selected time slot from the storage means, and a reference for AGC gain calculation. 3. The automatic gain control circuit according to claim 2, further comprising: a gain calculation unit that calculates an AGC gain by using the RSSI of the time slot to be generated, and an AGC control unit that outputs the AGC gain at a predetermined timing. . 6. A base station apparatus comprising the automatic gain control circuit according to any one of claims 2 to 6. 7. A communication terminal apparatus comprising the automatic gain control circuit according to claim 2. Description: 8. When a CDMA / TDD wireless signal capable of allocating a plurality of time slots to one frame is received and amplified by a gain control amplifier, the gain of the gain control amplifier is automatically controlled by negative feedback control. This is an automatic gain control method for adjusting the received signal strength of the previous time slot included in the frame to which the current time slot belongs.
ngth Indicator) can be used as a reference for calculating the gain to be set in the gain control amplifier, by determining the data rate, ISCP (Interference Signal Code Pow).
er), a step of determining based on at least one of the Doppler frequencies, and as a result of the determination, if there is an RSSI of a time slot that can be used as a reference for calculating the gain, the value of the RSSI If there is no RSSI of a time slot that can be used as a reference for calculating the gain, the gain is calculated using the RSSI of the time slot at the same position in the immediately preceding frame as a reference. Or canceling the update of the gain of the gain control amplifier, the automatic gain control method.