KR102262717B1 - Automatic gain controller and method thereof - Google Patents

Abstract

An automatic gain control apparatus according to an embodiment of the present invention includes: an analog signal gain control unit for adjusting a gain of an analog signal input to a set gain value; an analog-to-digital converter that converts the analog signal gain-adjusted by the gain adjuster into a digital signal; a gain control signal generating unit measuring the power of the digital signal and outputting a control signal for controlling a gain of the analog signal gain adjusting unit according to the power of the digital signal; a memory for storing a gain value and a gain adjustment time of the analog signal gain adjustment unit; and a signal gain compensator for compensating for the gain of the digital signal using the gain value and the gain adjustment time.

Description

Automatic gain controller and method thereof

The present invention relates to an automatic gain control apparatus and method, and more particularly, to an automatic gain control technique using past gain compensation after reception.

One trend of recent wireless communication system development is D2D communication. In addition, digital technology that requires gain control is being introduced in marine communication as well. D2D communication and maritime communication have in common that it is very difficult to control the gain of the received signal. If the gain of the received signal is less than the appropriate level and the received signal enters the ADC input too small, the quantization noise of the ADC increases significantly. Conversely, if the gain is too large than the proper level, the signal is saturated at the ADC and the received signal is completely ruined.

Conventional automatic gain control is not instantaneous, so it takes time to measure the power of the received signal to some extent. For example, even in the case of mobile communication, the base station always transmits a signal in the corresponding frequency band. Accordingly, the gain of the received signal is adjusted by measuring the power of this signal, and then finer gain control is performed using the signal that has been normally ADC, and the signal processing necessary for signal reception is performed. However, in the case of D2D communication and maritime communication, it is impossible to know the power of a received signal in advance because communication is mainly performed between terminals or between ships without interference from a base station.

This problem occurs because both D2D communication and maritime communication do not depend on a base station but depend on communication between terminals. For example, in the case of D2D communication, since the mobile terminals are not always in a fixed position, there is a problem in that the path loss between the terminals is not constant. At the same time, in many cases, it is not possible to know which terminal shoots at which slot time or number. Accordingly, a signal from a terminal close to me is received with high power, and a signal from a terminal far away from me is received with a small power. The difference in power of the received signal is very large, and there is a difference of 70 dB or more.

Similarly in maritime communications, I don't know which ship will signal me at which slot number or at what time. The difference between the signal from a ship far away from me and a signal from a nearby ship is more than 70dB different between a ship 100m away and a ship 200km away.

In particular, there is a problem in that it is difficult to use the existing automatic gain control method because it is not known which terminal (or ship) signal is received in the corresponding slot and with what power.

Patent Publication No. KR 2013-0074476

An embodiment of the present invention performs fast automatic gain control at the beginning of every receiving slot to quickly chase the power of the received signal, and restores the distortion of the analog-to-digital converter (ADC) while chasing the received power later in the digital domain to gain gain An object of the present invention is to provide an automatic gain control apparatus and method capable of generating this constant reception signal.

An automatic gain control apparatus according to an embodiment of the present invention includes: an analog signal gain control unit for adjusting a gain of an analog signal input to a set gain value; an analog-to-digital converter that converts the analog signal gain-adjusted by the gain adjuster into a digital signal; a gain control signal generating unit measuring the power of the digital signal and outputting a control signal for controlling a gain of the analog signal gain adjusting unit according to the power of the digital signal; a memory for storing a gain value and a gain adjustment time of the analog signal gain adjustment unit; and a signal gain compensator for compensating for the gain of the digital signal using the gain value and the gain adjustment time.

Also, the analog signal gain adjusting unit may set a start gain of the analog signal as a maximum gain value.

Also, the analog gain adjusting unit may adjust a gain during an entire reception period of one slot of the analog signal.

Also, the analog gain adjusting unit may adjust a gain during an initial partial period of one slot of the analog signal.

Also, the gain control signal generator may decrease the gain value of the analog signal gain controller when the power value of the digital signal is higher than a predetermined reference value.

In addition, the signal gain compensator may constant the digital signal received during the gain adjustment period of the signal gain control unit by using the gain value and the gain adjustment timing of the analog signal gain control unit after the gain adjustment of the analog signal gain control unit is finished. It can be compensated to be a gain value.

In addition, the signal gain compensator adjusts a first section of the analog signal to a first gain value, adjusts a second section of the analog signal to a second gain value, and then adjusts a final gain value of the analog signal gain adjuster When it converges to the third gain value, the gain is adjusted by compensating the first section of the digital signal by the difference between the first gain value and the third gain value, and the second section of the digital signal is the second gain The gain may be adjusted by compensating for a difference between the value and the third gain value.

In addition, a third memory for storing the digital signal converted by the analog-to-digital converter; and a memory configured to store the signal compensated by the signal gain compensator.

An automatic gain control method according to the present invention includes: controlling a gain value for adjusting a gain of an analog signal; storing the gain value and a gain adjustment time while adjusting a gain of the analog signal according to the gain value; After the adjustment of the gain value is finished, compensating the gain of the digital signal received when the gain is adjusted to become a final gain value using the stored gain value and the gain adjustment time.

In addition, the adjusting the gain of the analog signal according to the predetermined start gain value may include setting the start gain value of the analog signal as a maximum gain value.

In addition, the controlling of the gain value may reduce the gain value of the analog signal gain adjusting unit when the power value of the digital signal is higher than a predetermined reference value.

In addition, the storing of the gain value and the gain adjustment time while adjusting the gain of the analog signal according to the gain value may include adjusting the gain during an entire period of one slot of the analog signal.

In addition, the step of storing the gain value and the gain adjustment time while adjusting the gain of the analog signal according to the gain value may adjust the gain during an initial partial period of one slot of the analog signal.

The method may further include reducing the final gain value by a predetermined value when the signal level received after the gain adjustment and gain compensation during the initial partial period of the slot is saturated in the analog-to-digital converter.

This technology enables automatic gain control even when the power of the received signal is not known. In addition, the present technology can work for small signal inputs by setting the gain of the input stage of the analog-to-digital converter to the maximum gain that the system can set at the beginning of the receive slot.

In addition, the present technology recovers the differences in gain due to the gain tracking process of the received signal later in the digital stage, so that the received signal has a constant gain for one slot, thereby preventing deterioration of the received signal due to automatic gain control. can

1A is an exemplary diagram for explaining a TDMA communication method according to an embodiment of the present invention.
1B is an exemplary diagram according to distance and reception power in a TDMA communication method according to an embodiment of the present invention.
2 is a graph illustrating gain adjustment when an initial reception gain is set to 50 dB.
3 is a graph illustrating gain adjustment when the initial reception gain is set to -30 dB.
4 is a graph illustrating an example in which the output of the analog-to-digital converter is saturated.
5 is a block diagram of an automatic gain control apparatus according to an embodiment of the present invention.
6 is a flowchart illustrating an automatic gain control method according to an embodiment of the present invention.
7A is a diagram illustrating an example of gain adjustment of an automatic gain control apparatus according to an embodiment of the present invention.
7B is a diagram illustrating an example of gain compensation of an automatic gain control apparatus according to an embodiment of the present invention.
8A is a diagram illustrating an example of gain adjustment in consideration of a delay time for gain adjustment of an automatic gain control apparatus according to an embodiment of the present invention.
8B is a diagram illustrating an example of gain compensation in consideration of a delay time for gain adjustment of an automatic gain control apparatus according to an embodiment of the present invention.
9A is a waveform diagram showing the power of the start and end of the received signal of the automatic gain control apparatus according to the embodiment of the present invention.
FIG. 9B is a waveform diagram illustrating an enlarged size of the initial signals of FIG. 9A .
10A is a waveform diagram of a signal when the reception gain of the automatic gain control apparatus according to an embodiment of the present invention is set to 60 dB.
10B is a waveform diagram of a signal whose gain is compensated by the automatic gain control apparatus according to an embodiment of the present invention.
11A is an enlarged view of the waveform of FIG. 10B and is a diagram for explaining a glitch.
11B is a waveform diagram when the glitch of FIG. 11A is removed.

Hereinafter, the most preferred embodiment of the present invention will be described with reference to the accompanying drawings in order to describe in detail enough that a person skilled in the art can easily implement the technical idea of the present invention.

The present invention proposes a method for receiving a signal by effectively controlling a gain when the power and delay time of the received signal are unknown. To this end, the present invention performs fast automatic gain control at the beginning of each receiving slot to quickly chase the power of the received signal, and restores the distortion of the analog-to-digital converter (ADC) while chasing the received power later in the digital domain to increase the gain. A constant reception signal.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 11B .

1 illustrates a general TDMA (Time Division Multiple Access) communication method between terminals. It is assumed that terminals A and B are transmitting terminals and terminal C is a receiving terminal.

In the plurality of slots (Slot0 to Slot10) shown in FIG. 1A, in the third slot (Slot3), terminal A transmits a signal with a power of 20dBm, and in the sixth slot (Slot6), terminal B also transmits a signal with a power of 20dBm. do.

However, the receiving terminals receive a signal in every slot, check whether there is an actual signal or not, and receive a signal if there is a signal.

However, as shown in FIG. 1B , a difference in power of a received signal may be large. When terminals B and C are very close and terminals A and C are very far away, so that the communication situation is not good, terminal C receives the signal from terminal B at -30dBm and receives the signal from terminal A at -90dBm will do

In such a situation where the received power is unknown, the power of the received signal is measured, the gain is coarsely adjusted using the measured power, and then the gain is continuously traced finely. The gain during tracking and the signal after tracking is completed. Because the gain for α is not the same, the signal received during tracking may be difficult to use for actual communication.

2 shows a gain control result of a slot in which a -30 dBm signal is received when a -70 dBm signal can be properly received by setting the initial reception gain to 50 dB. At this time, assuming a TDMA signal, there is a guard time between the slot and the slot. Here, it is assumed that the power of the source signal itself is constant during every slot. In addition, when the gain control signal generator 400 measures the power of the received signal to control the gain of the analog signal gain adjuster 100 , there is a certain delay time until the actual gain of the analog signal gain adjuster 100 is adjusted. Occurs. That is, in order to control the gain, it is necessary to measure the power of the signal input to the analog-to-digital converter 200 , and to adjust the gain of the signal input to the analog-to-digital converter 200 using the measured power is required. need. As shown in FIG. 2, the received signal initially has a gain of 50 dB and then converges to a gain of 0 dB. While the gain converges to an appropriate gain, the output signal of the analog-to-digital converter 200 may be highly distorted.

3 shows a gain control result of a slot in which a signal of -90 dBm is received when the reception gain is set to -30 dBm. Because the initial signal is too small, it takes a long time to be properly received.

Referring to FIG. 4 , the time point at which one terminal transmits a signal in the TDMA scheme is generally after a guard time has passed from the start of the slot. And this signal is received by another terminal through a propagation delay between antennas. The problem is that this latency is usually not known. Therefore, it is difficult for the receiving terminal to know when to start the gain control.

If, it is assumed that gain control is performed from the point in time when the protection time has passed, and the propagation delay time is quite long. Then, the receive gain control determines that the signal is obviously small when the guard time has elapsed, and gradually increases the gain. Because the signal remains small even as you increase the gain, the gain eventually becomes the maximum gain. When the signal is actually received, the output of the analog-to-digital converter 200 may be saturated because the maximum gain value does not match the actual gain value. That is, when the magnitude of the input signal input to the analog-to-digital converter 200 exceeds the set maximum magnitude, the output of the analog-to-digital converter 200 is saturated. In this case, since the reception of the communication signal is impossible, the receiver must prevent the output value of the AD converter from being saturated.

In consideration of these characteristics, the present invention proposes a method of effectively controlling a gain to receive a signal when the power and delay time of the received signal are unknown.

5 is an automatic gain control apparatus according to an embodiment of the present invention, an analog signal gain control unit 100, an analog-to-digital converter 200, a memory 300, a gain control signal generation unit 400, a memory 500, A signal gain compensator 600 , a memory 700 , and a low-pass filter 800 are provided.

The analog signal gain adjusting unit 100 adjusts the gain of the input analog signal using a predetermined initial gain value and then outputs it. In addition, the analog signal gain adjusting unit 100 adjusts a gain value according to the gain control signal output from the gain control signal generating unit 400 and adjusts the gain of the input analog signal using the adjusted gain value.

The analog-to-digital converter 200 converts the analog signal output from the analog signal gain control unit 100 into a digital signal.

The memory 300 stores the received signal converted into a digital signal.

The gain control signal generation unit 400 measures the power of the digital signal output from the analog-to-digital converter 200 and outputs a control signal for controlling the gain value of the analog signal gain control unit 100 according to the measured power value. .

The memory 500 receives and stores the gain value of the current analog signal gain control unit 100 from the gain control signal generation unit 400 and stores the current time position value.

The signal gain compensator 600 compensates the gain of the digital signal stored in the memory 300 by using the gain value and the signal position value stored in the memory 500 . In this case, the signal gain compensator 600 may be driven after receiving all of one slot signal or at a time when only a small amount of the initial signal of the slot is received.

The memory 700 stores the signal in which the gain compensated by the signal gain compensator 600 is compensated. Thereafter, demodulation may be continued using the gain-compensated signal stored in the memory 700 .

The low-pass filter 800 removes glitches of the signal in which the gain compensated by the signal gain compensator 600 is compensated.

At this time, the memory 300, the gain control signal generator 400, the memory 500, the signal gain compensator 600, the memory 700, and the low-pass filter 800 are integrated one field-programmable (FPGA) It can be implemented as a gate array).

As described above, according to the present invention, the gain of the already received signal is secondarily compensated for in the digital stage after receiving by controlling the gain in the analog stage.

That is, the gain of the analog signal input to the analog-to-digital converter 200 is adjusted at the beginning of the slot, the digital signal converted by the analog-to-digital converter 200 is stored in the memory 300, and the adjustment gain and gain are adjusted After the information on the time point is stored in the memory 500 , after the gain control is finished, the received signal stored in the memory 300 and the adjusted gain value stored in the memory 500 and the information about the gain adjustment time point are used for the received signal. reward the gains Accordingly, the gain-compensated received signal has a constant gain.

As described above, the present invention allows the demodulation performance to be ideally maintained by equalizing the overall gain of the received signal by compensating for the past gain of the received signal. As described above, the present invention enables efficient automatic gain control even in a situation where the power and propagation delay time of the received signal are unknown.

Hereinafter, an automatic gain control method according to an embodiment of the present invention will be described in detail with reference to FIG. 6 .

When the analog signal is received (S101), the analog signal gain control unit 100 adjusts the gain of the input analog signal using a predetermined initial gain value and then outputs it (S102).

First, in the step of setting the reception gain to the desired gain by the receiving system at the start of the desired reception period, the start gain is set to the desired gain by the system at the beginning of the slot, or more precisely, at the end of the guard time. In this case, the gain desired by the system may be set as a settable maximum gain. For example, if the terminal is designed to receive a signal of -30dBm to -100dBm with a reception gain of 0dB to 70dB, the terminal may set the gain to 70dB at the end of the initial slot guard time.

Next, the analog-to-digital converter 200 converts the analog signal output from the analog signal gain control unit 100 into a digital signal (S103). At this time, the received signal converted into a digital signal is stored in the memory 300 .

Thereafter, the gain control signal generator 400 measures the power of the digital signal output from the analog-to-digital converter 200 and controls the gain value of the analog signal gain adjuster 100 according to the measured power value. is output (S104).

For example, when the starting gain is the maximum gain, if the power of the digital signal output from the analog-to-digital converter 200 is greater than a predetermined power value, the gain of the analog signal gain adjusting unit 100 is lowered and smaller than the predetermined power value. Otherwise, the gains remain the same. If the gain is adjusted in this way, even if there is no signal received during the propagation delay time after the guard time, the gain value is not affected. Also, when the reception signal starts to be received, the gain value will start to decrease. However, when the received signal is very small, the maximum gain value is maintained. However, in most cases, since the received signal is greater than the designed minimum level, the gain value will gradually decrease.

In this way, when the start gain is set to the maximum gain, the LN (Low-noise amplifier) A performance of the analog receiver should be considered. Because, if the receive signal is too strong when the start gain is set to the maximum gain, the LNA will This is because it can distort or break without being physically able to withstand it.

On the other hand, when the minimum gain of the system is set as the start gain, it cannot be known whether the power of the digital signal output from the analog-to-digital converter 200 is small because the received signal power is actually small or whether the signal is not received yet. If the signal has not yet arrived at the terminal due to the propagation delay of the signal when the gain control is started after the guard time of the initial slot has elapsed, the terminal determines that the signal is small, so the gain is different from the actual appropriate gain value. will increase Therefore, setting the minimum gain as the starting gain requires great care.

One of the effective methods is to use the intermediate gain of the system as the starting gain. This method can protect the LNA at the front end of the signal, while the gain fluctuates less than the minimum gain method.

Thereafter, the gain control signal generating unit 400 stores the current gain value of the analog signal gain adjusting unit 100 and the time at which the gain is adjusted (the current time position value) in the memory 500 ( S105 ).

The changed gain value and the adjustment time point are stored in the memory 500 while adjusting the gain appropriately using various algorithms. Here, the period for adjusting the gain by the algorithm must be determined according to the system. That is, the gain adjustment period may be the whole of one slot, or may be for some time from the beginning of the slot.

If the entire slot is set as the gain adjustment time, the burden of implementation increases because the signal of the entire slot must be buffered and signal processing must also be performed on the entire slot. On the other hand, if the gain is adjusted only for a short period of time at the beginning of the slot, the amount of the buffered signal is reduced and the signal processing is performed only for the signal during the gain adjustment time, so it is easy to implement. Therefore, the present invention proposes to make the gain adjustment period as small as possible.

Thereafter, the signal gain compensator 600 restores the digital signal stored in the memory 300 by using the gain value and the signal position value stored in the memory 500 and then compensates to have a constant reception gain (S106).

In the step of compensating the slot signal to have a constant reception gain using the received signal, the stored adjustment gain value, and the adjustment time, the received signal stored during the gain adjustment time is compensated with the adjustment gain and adjustment time stored together.

For example, as shown in Figure 7a, the initial gain is 70 dB, 100 samples are input during the gain adjustment time, the adjustment gain is changed to 60 dB after receiving the 20th sample, and the final set gain is changed to 50 dB after receiving the 90th sample. Assume 50 dB. Then, as shown in FIG. 7B , a gain of -20dB from the 1st sample to the 20th sample, -10dB from the 21st sample to the 90th sample, and 0dB from the 91st sample to the 100th sample is compensated in the digital domain. Then, the overall gain of the received signal becomes 50 dB. 7A and 7B are cases in which it is assumed that there is no delay time required for changing the adjustment gain.

However, depending on the system, the adjustment gain is changed and the delay time is different. Therefore, for accurate gain compensation, the gain should be compensated in consideration of this delay time. In the previous case, it is assumed that the gain change delay time takes 3 sample times.

As shown in FIG. 8A, the gain adjustment of the received signal is started after 3 sample times. As shown in FIG. 8B, a gain of -20dB from the 1st sample to the 23rd sample, -10dB from the 24th sample to the 93th sample, and 0dB from the 94th sample to the 100th sample should be compensated in the digital domain. The signal compensated with such a constant gain does not cause performance degradation during demodulation signal processing.

For reference, although the present invention can be applied to various types of systems, it is particularly effective for a TDMA system. This is because, in the case of a TDMA signal, a filter is used to prevent spuriousness in the transmit spectrum and to limit the transmit signal to a given frequency band. Due to the use of the filter, the start and end of the signal have a form in which the power gradually increases or decreases as shown in FIG. 9A . 9B is an enlarged view of the signal initial values in FIG. 9A. The signal initial values are in the form of increasing power. Therefore, when the signal starts to saturate after setting the start gain to the maximum gain, the method of gradually decreasing the gain can be applied very effectively.

FIG. 10a shows a received signal waveform when the antenna input signal is set to -30dBm power and the start gain is set to 60dB in a system in which the reception gain is set from 0dB to 60dB for a signal from -30dBm to -90dBm. The initial waveform of the received signal is shown as the gain is changed until it reaches the proper gain of 0dB. Referring to FIG. 10A , in the gain change region, the initial received signal has a greater gain than the normal gain until it is set to an appropriate gain. Here, the power of the original signal source is as shown in FIG. 9B.

10B is an initial waveform of a signal obtained by compensating for a gain by applying the present invention. The waveform of this signal is substantially the same as that of Fig. 9B. From this, it can be seen that the present invention can perform signal reception without distortion by using gain compensation without a preamble for AGC.

In real hardware implementation, it is not easy to know exactly the delay time. Although it takes into account the delay time required for the adjustment gain to change, it can be difficult to fully implement the hardware depending on the system. In such a case, a glitch is generated. For example, if gain adjustment occurs in the nth sample and it takes 3.5 sample time to change the actual adjustment gain, the n+4th sample has a large gain at the input terminal of the actual analog-to-digital converter 200, but in the gain compensation process A glitch is created because it is compensated for by a small gain. An example of such a glitch is shown in FIG. 11A . These glitches can be removed with a low-pass filter. In this case, the bandwidth of the low-pass filter should be larger than the signal bandwidth. 11B is an exemplary view in which the glitch of FIG. 11A is removed.

Finally, there is one more consideration regarding the efficient use of the present invention. An example of the most effective use of the present invention is to quickly control the gain at the beginning of the signal and compensate the gain after reception, and then continue to use the gain of the input stage of the analog-to-digital converter as the gain value finally set in the front until the end of the slot. Such an application method is easy to implement in hardware and is not a problem in most cases.

However, a problem may occur when the gain of the radio channel is fluctuated so much that the gain of the channel is very small at the beginning of the slot and the gain of the channel increases toward the end of the slot. In such a channel situation, even if an appropriate gain value is found and set at the beginning of the slot, the output of the analog-to-digital converter 200 is saturated because the channel gain increases thereafter. Of course, there will be no problem if gain control and gain compensation are performed in one slot, but this has the disadvantage of being very complicated and difficult to implement.

Accordingly, the present invention proposes a method of preventing signal saturation after the initial slot in the case where the final gain is determined at the beginning of the slot to compensate for the gain of the initial received signal and the final gain is used thereafter. It is to decrease the finally determined gain value by a certain amount when the signal is saturated. In this way, it is possible to mostly prevent the received signal from being saturated. A point to be noted here is that there is no more gain compensation after the final gain after signal gain compensation is reduced, unlike compensation for the gain of the received signal after gain control at the beginning of the slot. This is because even if the saturated signal is multiplied by a gain greater than 1 to compensate for the gain, the signal is still saturated.

According to the present invention, since the start gain of the AD converter input stage can be set to the maximum gain that can be set by the system at the start of the reception slot, it is possible to operate even for a small signal input. In addition, since the received signal recovers the differences in gain due to the gain tracking process later in the digital stage, the received signal has a constant gain for one slot, and consequently, it is possible to prevent deterioration of the received signal due to automatic gain control. have.

The present invention can be very usefully used in a system that occasionally communicates between terminals without a base station that always transmits a signal, such as D2D communication and maritime communication.

The above-described preferred embodiments of the present invention are for the purpose of illustration, and those skilled in the art will be able to make various modifications, changes, substitutions and additions through the spirit and scope of the appended claims, and such modifications and changes are described in the following patents. It should be considered as being within the scope of the claims.

Claims (16)

In a time division multiple access (TDMA) wireless communication system,
an analog signal gain control unit for adjusting a gain of an input analog signal to a set gain value for one TDMA slot;
an analog-to-digital converter that converts the analog signal gain-adjusted by the gain adjuster into a digital signal;
a gain control signal generating unit measuring the power of the digital signal and outputting a control signal for controlling a gain of the analog signal gain adjusting unit according to the power of the digital signal;
a memory for storing a gain value and a gain adjustment time of the analog signal gain adjustment unit; and
a signal gain compensator for compensating for a gain of the digital signal using the gain value and the gain adjustment time;
Automatic gain control device comprising a. The method according to claim 1,
The analog signal gain control unit,
The automatic gain control apparatus of claim 1, wherein the starting gain of the analog signal is set to a maximum gain that can be set by the analog signal gain control unit. The method according to claim 1,
The analog signal gain control unit,
Automatic gain control apparatus, characterized in that the gain is adjusted during the entire reception period of the one TDMA slot. The method according to claim 1,
The analog signal gain control unit,
The automatic gain control apparatus, characterized in that the gain is adjusted during an initial partial period of the one TDMA slot. The method according to claim 1,
The gain control signal generator,
and reducing a gain value of the analog signal gain control unit when the power value of the digital signal is higher than a predetermined reference value. delete delete delete delete delete In a time division multiple access (TDMA) wireless communication system,
adjusting a gain of an input analog signal by a predetermined start gain value for one TDMA slot;
converting the gain-adjusted analog signal into a digital signal;
measuring the power of the digital signal and controlling a gain value for adjusting the gain of the analog signal according to the power of the digital signal;
storing the gain value and a gain adjustment time while adjusting a gain of the analog signal according to the gain value;
compensating for the gain of the digital signal using the stored gain value and the gain adjustment time after the adjustment of the gain value is finished;
Automatic gain control method comprising a. 12. The method of claim 11,
The step of adjusting the gain of the analog signal by the predetermined starting gain value includes:
The automatic gain control method, characterized in that the starting gain value of the analog signal is set to the maximum gain value that the TDMA wireless communication system can set. 12. The method of claim 11,
The step of controlling the gain value,
The automatic gain control method of claim 1, wherein the gain value is decreased when the power value of the digital signal is higher than a predetermined reference value. 12. The method of claim 11,
Storing the gain value and the gain adjustment time while adjusting the gain of the analog signal according to the gain value,
The automatic gain control method, characterized in that the gain is adjusted during the entire reception period of the one TDMA slot. 12. The method of claim 11,
Storing the gain value and the gain adjustment time while adjusting the gain of the analog signal according to the gain value,
The automatic gain control method, characterized in that the gain is adjusted during an initial partial period of the one TDMA slot. delete

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