KR20070069478A - A channel adaptive automatic gain control method and apparatus in a mobile communication system. - Google Patents

Abstract

In the channel adaptive automatic gain control method and apparatus in a mobile communication system, the method includes measuring a signal level of an input channel signal, and using the measured value to determine an amount of change in a signal level compared to a previously received signal. Calculating, comparing the change amount with the measured value, updating the amplification control signal according to the change of the channel signal, adding the updated control signal, the measured value, and a preset reference value. And setting and outputting an appropriate power gain value, and providing an appropriate gain for the input channel signal with the power gain value.

Description

{Method and Apparatus for Channel Adaptive Automatic Gain Control in a mobile communication System}

1 is a diagram showing the structure of a general automatic gain controller.

2 is a diagram illustrating a structure of a receiving apparatus of a general mobile communication system.

3 illustrates the structure of a channel adaptive automatic gain controller in accordance with a preferred embodiment of the present invention.

4 is a flowchart illustrating an operation of determining a change of a channel in a comparator of a demodulator according to an exemplary embodiment of the present invention.

The present invention relates to a receiving apparatus of a mobile communication system, and more particularly, to an automatic gain control method and apparatus that operates to provide a received signal having a certain characteristic to a demodulator through proper gain adjustment according to a change degree of a channel in the receiving apparatus. .

In general, a receiver of a mobile communication system includes a variable gain amplifier, and changing a gain of a received signal is called automatic gain control. According to the mobile communication system having the automatic gain control function, when transmitting, the transmission power adjustment command transmitted differently from each base station to each mobile station in order to prevent performance degradation of the system due to mutual interference with other mobile station users. Properly adjust the gain of the transmit power amplifier to transmit at the appropriate transmit power.

On the contrary, in the reception, the gain of the reception amplifier is appropriately adjusted to compensate for fading, which is a change in distance from the base station and a temporal change in reception power due to the movement of a vehicle or a pedestrian. In other words, the input signal power to the terminal in the wireless channel environment is maintained within the dynamic range of the device, and the signal detector is supplied with a level of the signal maintained within the operating range. It plays a role.

1 is a diagram illustrating a structure of a general automatic gain controller.

Referring to FIG. 1, an automatic gain controller (hereinafter referred to as “AGC”) receives an intermediate frequency from a transmitter and passes through an intermediate frequency processing filter 110 to obtain a gain control amplifier (GCA). Amplifying the input signal of 120. The detector (130) receiving the amplified output signal measures the energy to measure the measured energy value (V _D (t)) and a predetermined reference value ( -V _R ) are added to each other in the adder 140 and passed to the filter 150.

The filter 150 filters the transmitted signal, and the filtered signal is fed back to a control (V _C (t)) signal of the gain control amplifier 120. The output of the filter, i.e., the control signal, stabilizes the energy of the output signal of the amplifier to match the reference value, and uses a gain constant. Here, the gain constant of the filter 150 is determined according to the requirements of the experiment and the wireless system.

In the case where a sudden change in the received signal level of the conventional wireless communication system operating as described above occurs, the gain for the signal according to the overall time constant design of the automatic gain controller during gain adjustment of the received signal. Adjustment may not be appropriate.

If the set time constant (time until the current increases and reaches a certain value) is too large, the control signal is transmitted late and the response is slow. If it is too small, the control signal is transmitted quickly and the level of the gain-adjusted signal vibrates. There was a problem that affects the performance of the receiving system.

Accordingly, the present invention devised to solve the problems of the prior art operating as described above, provides an adaptive automatic gain control method and apparatus that actively responds to changes in the radio channel.

The present invention provides a method and apparatus for gain control of a signal of a mobile communication system with a large channel change.

The present invention provides a method and apparatus for detecting the energy of a received signal, determining a change in signal level and adjusting the operation of the automatic gain controller according to the result.

According to an embodiment of the present invention, in a channel adaptive automatic gain control method in a mobile communication system, a process of measuring a signal level of an input channel signal, and an amount of change in a signal level compared to a previously received signal using the measured value Calculating a value, comparing the change amount with the measured value, updating the amplification control signal according to the change of the channel signal, adding the updated control signal, the measured value, and a preset reference value. And setting and outputting an appropriate power gain value according to the method, and providing an appropriate gain for the input channel signal with the power gain value.

Another embodiment of the present invention provides a channel adaptive automatic gain control apparatus in a mobile communication system, comprising: an energy detector for measuring a signal level of an input channel signal, and an amount of change in a signal level compared to a previously received signal based on the measured value; An energy average calculated to be equal to, a comparator for comparing the amount of change with the measured value to update the amplification control signal according to the change of the channel signal, a value obtained by adding the updated control signal, the measured value and a preset reference value; And a filter for setting and outputting an appropriate power gain value, and a gain adjusting amplifier for providing an appropriate gain for the input channel signal with the power gain value.

Hereinafter, the operating principle of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, if it is determined that a detailed description of a known function or configuration may unnecessarily flow the gist of the present invention, the detailed description thereof will be omitted. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification.

The present invention detects the energy of the received signal to determine how much the signal level has changed compared to the previous received signal, and adjusts the operation of the automatic gain controller according to the result.

2 is a diagram illustrating a structure of a receiving apparatus of a general mobile communication system.

Referring to FIG. 2, a radio frequency (RF) signal received through an antenna 101 of a receiver includes a low noise amplifier (LNA) 102 and a bandpass filter 1 (BPF) for removing noise. Band pass filter 103 is converted into the intermediate frequency by the frequency converter 104. The signal converted to the intermediate frequency is removed by the band pass filter 2 105 in addition to the received signal noise signals are converted by the gain control amplifier 106.

It is then converted to baseband by frequency converter 107, passed through low pass filter (LPF) 108, and then passed to demodulator 109.

The demodulator 109 senses the power change of the received signal through the input signal, and transfers the gain constant to the gain control amplifier 106 for processing. Here, the demodulator 109 may include other features depending on the communication system to which the receiving device is applied.

3 is a diagram illustrating a structure of a channel adaptive automatic gain controller according to a preferred embodiment of the present invention.

Referring to FIG. 3, the noise-received received signal is converted by the gain control amplifier 106, and then converted to the baseband by the frequency converter 107, so that the low pass filter (LPF) 108 After passing, it is passed to the demodulator 109.

In the demodulator 109, the energy detector 201 measures the signal level of the signal output to the IF amplifier 106, and the result is transmitted to the energy averager 202 and the comparator 203 to the The operation of the filter 204 is determined according to the result. The energy averager 202 is composed of N shift buffers for storing an output value V _D (t) of the energy detector 201, and a received signal before an operation time of the energy detector 201. And store the energy detector 201 output values V _D (t) for the field.

The number N of buffers of the energy averager 202 is determined experimentally according to the channel structure of the communication system. The energy _averager 202 calculates an average value V _{D_AVE} (t) between the currently received signal and the value stored as the previously received signal and transmits the average value V _{D_AVE} (t) to the comparator 203. The comparator 203 compares the value detected at the time of operation of the energy detector 201 with the average value V _{D_AVE} (t) of previous detection values V _D (t) transmitted from the energy _{averager 202.} The current received signal determines how much the signal level has changed compared to the previous received signal, and updates the amplification control signal according to the change in the channel signal to the filter 204. A more detailed description of the comparator 203 will be described with reference to FIG. 4 below.

4 is a flowchart illustrating an operation of determining a change of a channel in a comparator of a demodulator according to an exemplary embodiment of the present invention.

3 to 4, the detection value V _D (t) detected at the operation point of the energy detector 201 and the average value V _{D_AVE} (t) from the energy detector are compared in step ₄₁₀ . Calculate as shown in Equation 1 below.

| V _{D_AVE} (t) × Factor-V _D (t) | > Thrs

Here, the factor and threshold are preset values and are determined according to channel characteristics and received signal characteristics of the communication system to which the automatic gain controller is applied.

If the value calculated as in Equation 1 is larger than the threshold value, the signal level is greatly changed, which means that the width of the change is greatly changed. Therefore, in step 420, an amplification control signal is transmitted to the filter 204 including a command for causing a large gain constant to be used. If the comparison value is smaller than the threshold value, the change in the signal level is changed within the threshold range. In step 430, the amplification control signal is transmitted to the filter 204 such that a normal gain constant is used as the filter 204.

In this way, the amplification control signal according to the channel change transmitted to the filter 204 is used as information for determining the update gain value of the filter 204, the filter 204 is the amplification control signal and the energy detector 201 The control signal V _c (t), which is an appropriate power gain value, is set according to the sum of the measured value and the predetermined reference value, and is transmitted to the gain control amplifier 106.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by those equivalent to the scope of the claims.

In the present invention operating as described in detail above, the effects obtained by the representative ones of the disclosed inventions will be briefly described as follows.

The present invention enables the gain adjustment of the received signal to be appropriately performed by defining the operation of the automatic gain controller according to the difference in the signal level, thereby enabling the gain adjustment to be more aggressive than before.

Claims (8)

In the channel adaptive automatic gain control method in a mobile communication system, Measuring the signal level of the input channel signal; Calculating a change amount of a signal level compared to a previously received signal by using the measured value; Updating the amplification control signal according to the change of the channel signal by comparing the change amount with the measured value; Setting and outputting an appropriate power gain value according to the updated control signal, the measured value and a preset reference value; And providing an appropriate gain for the input channel signal as the power gain value. The method of claim 1, wherein the calculating of the change amount comprises: And calculating an average value of the measured value and the measured value with respect to the previously received signal as the change amount. The process of claim 1, wherein the comparing of the variation amount and the measured value comprises: And a value obtained by multiplying the change amount by a predetermined factor, and comparing the absolute value of the subtracted value with the threshold value. The process of claim 1, wherein the comparing of the variation amount and the measured value comprises: If the compared value is greater than a preset threshold, updating the amplification control signal including an instruction to use a relatively large gain constant; And if the compared value is less than a preset threshold, updating the amplification control signal including a command to use a normal gain constant that is less than the large gain constant. In the channel adaptive automatic gain control apparatus in a mobile communication system, An energy detector for measuring a signal level of an input channel signal, An energy averager for calculating the measured value as an amount of change in signal level compared to a previously received signal; A comparator for comparing the amount of change with the measured value and updating an amplification control signal according to a change in a channel signal; A filter for setting and outputting an appropriate power gain value according to the updated control signal, the measured value and a preset reference value; And a gain control amplifier providing an appropriate gain for the input channel signal as the power gain value. The method of claim 5, wherein in the energy averager The change amount calculation, the automatic gain control device, characterized in that the process of calculating the average value and the previously received signal value. The method of claim 5, wherein the comparator, And a value obtained by multiplying the change amount by a preset factor, and comparing the absolute value of the subtracted value with the threshold value. The method of claim 5, wherein the comparator, If the compared value is greater than a preset threshold, update the amplification control signal including a command to use a relatively large gain constant with the filter, And if the compared value is less than a preset threshold, updating the amplification control signal including an instruction to use a normal gain constant smaller than the large gain constant to the filter. .

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