KR20100015076A - Apparatus and method for automatic gain control in mobile communication system - Google Patents

Abstract

PURPOSE: An apparatus and a method for automatic gain control in a mobile communication system are provided to effectively eliminate the adjacent channel interference by processing AGC process after the receiving filter. CONSTITUTION: A receiving signal measuring unit(202) measures the electricity of the received signal. A digital gain determining unit(204) decides the whole gain control value with the electricity of the received signal. The digital gain determining unit varies the digital gain control mode between the upper threshold according to the current digital gain mode and lower threshold and total gain control value with comparison. An analog gain determining unit(206) presently confirms the analog gain mode with the electricity of the received signal. The analog gain determining unit decides the discrete analog gain and continuous the analog gain with the gain mode between the critical value predetermining with comparison.

Description

Automatic gain control device and method for mobile communication system {APPARATUS AND METHOD FOR AUTOMATIC GAIN CONTROL IN MOBILE COMMUNICATION SYSTEM}

The present invention relates to an apparatus and method for automatic gain control of a mobile communication system, and more particularly, to perform an automatic gain control process after a receive filter in order to improve the reception performance of a receiver in a mobile communication system in which adjacent channel interference exists. An apparatus and method for performing gain control with signals only.

In general, a mobile communication system secures mobility of a terminal to allow a user to perform communication without restriction of a location and distance. In a recent mobile communication system, a mobile communication system can cover a wide dynamic range. Radio frequency (RF) technology and RF device control technology in a modem are required, and accordingly, much research has been conducted on RF and its control technology.

In a typical mobile communication system, a wireless device transmits a wireless signal at a constant power during data transmission, but the strength of the power of the transmitted signal changes according to the environment of the wireless channel.

Accordingly, the power of the radio signal received by the antenna of the receiving device is changed to a dynamic range so that the receiving device performs a demodulation process after performing an analog-to-digital conversion process by controlling the gain.

For example, in a heterodyne receiving apparatus, the received radio signal is down converted into a baseband signal through several steps, and a plurality of filters and gain amplifiers are used for the RF signal to the received signal. It is characterized by a filtering and amplification process. However, such a receiving device has a big problem in the implementation cost of the receiving device and the miniaturization of the receiving device as the filter and the gain amplifier are provided.

In order to solve the above-mentioned problem, a receiver which can receive a radio signal with a small number of parts without converting a received signal into a baseband signal at a time without an intermediate frequency (IF) processing unit in recent years (zero- IF type receiver).

However, such a receiving apparatus does not include the intermediate frequency processor, and thus, it is difficult to remove adjacent channel interference. In the heterodyne receiver, the adjacent channel interference, which can be removed by the intermediate frequency band filter and the analog low pass filter, needs to be eliminated only by the analog low pass filter in the zero-IF receiver.

Accordingly, when the receiving device is located at the edge of cell coverage and the location is assumed to be adjacent to the neighboring base station, the receiving device will receive a signal of an adjacent channel larger than the size of the original signal and the reception performance will be degraded.

In the adjacent channel interference environment as described above, a gain control process for digitally converting a desired signal and adjusting the signal to an appropriate size is necessary, but the reception apparatus determines both the received signal and the interference signal as the power of the received signal and performs the gain control process.

Therefore, there is a problem in that the size of the received signal of the receiving device is significantly smaller than the target of the receiving device.

The present invention was derived to solve the above problems, and an object of the present invention is to provide an apparatus and method for improving the reception performance of a receiving device in a mobile communication system in which adjacent channel interference exists.

Another object of the present invention is to provide an apparatus and method for performing an automatic gain control process after a reception filter to improve reception performance of a reception device in a mobile communication system in which adjacent channel interference exists.

It is still another object of the present invention to provide an apparatus and method for performing gain control using only a received signal through an automatic gain control process after a receive filter in order to improve the reception performance of a receiving device in a mobile communication system having adjacent channel interference. have.

According to a first aspect of the present invention for achieving the above object, an automatic gain control apparatus of a mobile communication system includes a reception signal measuring unit for measuring the power of the received signal filtered by the reception filter, and the received signal measuring unit A digital gain determiner for changing the digital gain control mode by comparing the upper and lower threshold values according to the current digital gain mode with the total gain control value by using the power of the received signal measured by the controller; Discrete analog gain including an analog gain determiner for changing the checked gain mode to a higher mode or a lower mode by using the remaining power obtained by subtracting the digital gain according to the digital gain control mode from the power of the received signal. After determining the digital gain and the power of the received signal The remaining minus the discrete analog gain is determined as the continuous analog gain.

According to a second aspect of the present invention for achieving the above objects, the automatic gain control method of the mobile communication system uses the power of the received signal filtered by the receive filter to total the upper and lower threshold values according to the current digital gain mode. A digital gain control process of changing a digital gain control mode in comparison with a gain control value, and confirming the current analog gain mode using the remaining power after subtracting the digital gain according to the digital gain control mode from the power of the received signal, The analog gain control process of changing the gain mode to a higher or lower mode by comparing the gain mode with a predetermined threshold value, and after determining the discrete analog gain, subtracting the digital gain and the discrete analog gain from the power of the received signal to obtain a continuous analog gain. And determining the gain control And applying a gain control value determined in the process.

As described above, the present invention allows an automatic gain control process to be performed after a reception filter in order to improve reception performance of a receiving device in a mobile communication system in which adjacent channel interference exists. By eliminating interference, the performance of the receiving device can be improved.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

In the following description, an apparatus and method for performing gain control using only a received signal by performing an automatic gain control process after a reception filter in order to improve reception performance of a reception device in a mobile communication system having adjacent channel interference will be described. .

1 is a block diagram illustrating a configuration of a receiving apparatus for performing an automatic gain control process according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the reception apparatus includes an RF processor 101, an analog gain amplifier (VGA) 103, an analog / digital converter (ADC) 105, a reception filter 107, and a digital device. And a VGA 109 and an Automatic Gain Control (AGC) 111.

Here, the RF processor 101 may include an analog filter, a low noise amplifier (LNA) capable of changing a gain mode, and the automatic gain controller adjusts gain after reception filtering. Therefore, the gain is adjusted using only the original received signal, so that the size of the received signal is properly maintained.

The receiving device amplifies a received signal received through an antenna using a low noise amplifier of the RF processor 101, and then processes an analog filter to filter the received signal.

The output signal of the RF processor 101 is input to the analog gain amplifier 103, and the analog gain amplifier 103 amplifies the signal of the RF processor 101 and then outputs the signal to the analog-to-digital converter 105. do.

The analog-to-digital converter 105 converts the received analog signal into a digital signal and then provides the received signal to the receive filter 107, and the receive filter 107 filters the received signal and provides the received signal to the digital gain amplifier 109. do.

Accordingly, the digital gain amplifier 109 uses a signal obtained by extracting only a signal of a desired frequency band, that is, an output signal of the reception filter 107 and adjusts the gain according to the gain control value of the automatic gain controller 111. Processing to output the amplified signal.

An automatic gain control (AGC) 111 determines the gain of the signal from which adjacent channel interference has been effectively removed and is located after the receive filter. That is, the automatic gain controller 111 adjusts the gain of the analog and digital stages.

The automatic gain controller 111 may use a fixed gain control value without controlling the discrete analog gain control value when the operating range of the analog gain amplifier is wide. However, when the operating range of the analog gain amplifier 103 is narrow, the analog gain is divided into a discrete analog gain value and a continuous analog gain value to perform gain adjustment.

2 is a block diagram illustrating in detail a configuration of an automatic gain controller for performing an automatic gain control process according to the present invention.

Referring to FIG. 2, the automatic gain controller 200 may include a reception signal measuring unit 202, a digital gain determining unit 204, and an analog gain determining unit 206.

Here, the automatic gain controller 200 determines the digital gain control value and the analog gain control value by using the received signal power of the receiving device.

The received signal measuring unit 202 performs a power measurement process on the received signal of the receiving device to check the digital gain control mode and the analog gain control mode.

The digital gain determiner 204 determines the gain control value of the digital gain amplifier 208 using the current digital gain control value according to the power of the received signal measured by the received signal measurer 202. Here, the digital gain determiner 204 may determine the digital gain control value by comparing a threshold of the gain control value of the current gain control mode with an overall gain control value, and the digital gain determiner 204 Level hysterisis may be applied to prevent the ping-pong phenomenon between thresholds of the gain control value.

The analog gain determiner 206 uses the current digital gain control value according to the power of the received signal measured by the received signal measurer 202, that is, the analog analog gain amplifier 212 and the RF processor 210, that is, Determine the gain control value for the low noise amplifier.

Here, when the analog gain determiner 206 determines that the current gain mode of the receiving device is a higher mode, the analog gain determiner 206 compares a threshold value for changing to a lower mode with a gain control value of the upper mode to the lower mode. Determine the change. On the contrary, when the current gain mode of the receiving device is the lower mode, the analog gain determiner 206 compares a threshold value for changing to a higher mode with a gain control value of the lower mode and determines a change to a higher mode. do.

In the above description, an apparatus for performing gain control using only a received signal by performing an automatic gain control process after a reception filter in order to improve reception performance of a reception device in a mobile communication system having adjacent channel interference has been described. In the description, in order to improve reception performance of a reception apparatus in a mobile communication system having adjacent channel interference using the apparatus according to the present invention, an automatic gain control process is performed after a reception filter to perform gain adjustment using only the reception signal. The method will be described.

3 is a flowchart illustrating a process of performing an automatic gain control operation in a receiving apparatus according to the present invention.

Referring to FIG. 3, the receiving device first measures the power of the received signal in step 301.

Here, the receiving device calculates the sum of the squares of the in-phase and quadrature-pahse components in a predetermined interval periodically or continuously, or calculates the sum by taking their absolute values. The power of the received signal may be measured using a general method. In this case, the power of the received signal is converted into power in dB unit.

In step 303, the receiving apparatus determines a digital gain control value, which is a gain adjustment amount required in the digital domain, by using the power of the received signal measured in step 301, and then proceeds to step 305 to adjust the gain required in the analog domain. Determine discrete and continuous analog gain values. Here, the digital gain control value refers to a gain control value for adjusting the gain of the digital VGA, and the analog gain value refers to setting of a high gain mode or a low gain mode of a low noise amplifier. For this purpose, it refers to a discrete analog gain value applied to a low noise amplifier and a continuous analog gain value for adjusting the gain of an analog variable gain amplifier (VGA).

In this case, the receiving device may determine the overall gain control value of the receiving device by comparing the power of the received signal measured in step 301 with the power value required by the receiving device.

Here, the receiving device may determine the digital gain control value according to the power of the received signal, and then determine the remainder obtained by subtracting the digital gain amount from the total gain control value as an analog gain control value.

In step 307, the receiving apparatus processes the digital gain control value determined in step 303 and the analog gain control value determined in step 305 to apply to the corresponding block.

That is, the receiving device applies the digital gain control value to the digital VGA and processes the analog gain value to the low noise amplifier and the analog variable gain amplifier (VGA).

Thereafter, the receiving device processes the present algorithm to operate until the end of wireless communication.

4 is a flowchart illustrating a process of determining a digital gain control value for an automatic gain control operation in a receiving apparatus according to an exemplary embodiment of the present invention.

Referring to FIG. 4, the receiver first measures power of a received signal in step 401, and then proceeds to step 403 to determine an upper threshold and a lower threshold according to the current digital gain mode according to the received signal power.

In step 405, the receiving device compares the checked upper and lower threshold values with the overall gain control value of the receiving device. In step 407, the receiving device checks the result of the comparing process. do.

If the lower threshold is greater than the total gain control value in step 407, the receiver proceeds to step 417 to process the temporary digital gain mode by one less than the current digital gain mode. Here, the temporary digital gain mode is a value before the gain control value is changed according to the automatic gain control process, and the temporary digital gain mode changes the gain control value of the receiving device when the timer for changing the gain mode expires. Is the gain mode value. In addition, the receiving apparatus may determine the temporary digital gain mode using Equation 1 below.

Here, GM_temp is the temporary digital gain mode and D_GM is the current digital gain mode.

On the other hand, if the lower threshold is less than the total gain control value in step 407, the receiver proceeds to step 409 and determines whether the upper threshold value according to the current digital gain mode is smaller than the total gain control value.

If the upper threshold is greater than the total gain control value in step 409, the receiving device terminates the present algorithm without changing the digital gain mode.

On the other hand, if the upper threshold value is less than the total gain control value in step 409, the receiving device proceeds to step 411 to process to adjust the temporary digital gain mode by one than the current digital gain mode. Here, the receiving device may adjust the temporary digital gain mode using Equation 2 below.

Here, GM_temp is the temporary digital gain mode and D_GM is the current digital gain mode.

In step 413, the receiving device determines whether the timer expires to change the digital gain mode. If the reception device does not confirm the timer expiration in step 413, the receiving device terminates the present algorithm without changing the digital gain mode. That is, when the reception device does not confirm the expiration of the timer for changing the digital gain mode, the receiving device uses the preset digital gain mode.

On the other hand, when the receiving device confirms the timer expiration in step 413, the receiving device changes the temporary digital gain mode adjusted in step 411 or step 417 to the current digital gain mode in step 415.

In this case, the receiving device should determine the analog gain during the automatic gain control process, and then apply the digital gain at the time of applying the determined gain.

Accordingly, the reception device delays the application time by a predetermined time to apply the digital gain, and then applies the digital gain as much as the delay time to the digital VGA.

The receiving device may apply a gain value according to the digital gain mode in the following manner.

When the receiving device determines that the digital gain mode is "n", the receiving device may give a gain of 2 ⁿ to the digital VGA, that is, when n = 0, multiplies the received signal by '1' and n = If 1, multiply by '2', n = 2, multiply by '4', and when n = 3, multiply by '8' to give a digital gain. This type of gain control can be calculated with just a bit shift operation without the need for a multiplier in digital hardware.

In this case, the receiving device may perform gain control of the receiving device by using a gain control value for each gain mode defined as shown in Table 1 below.

Digital Gain Mode Digital gain control value (dB) 3 18 2 12 One 6 0 0

Thereafter, the receiving device ends the present algorithm.

5 is a diagram illustrating a process of determining a digital gain mode in a receiving apparatus according to an exemplary embodiment of the present invention.

Referring to FIG. 5, the reception apparatus applies level hysteresis to adjust the digital gain mode so that the ping-pong phenomenon does not occur at an upper threshold and a lower threshold according to the current digital gain mode.

For example, the receiving device compares the lower threshold D_TH_Ln (n = 0, 1, 2) with the upper threshold D_TH_Hm (m = 0, 1, 2) according to the power (RSS) of the received signal. = 0, 1, 2, 3).

In this case, the receiving device may prevent the ping-pong phenomenon by using an upper threshold and a lower threshold satisfying the following conditions.

First, D_TH_L0 ≤ D_TH_H0, D_TH_L1 ≤ D_TH_H1, D_TH_L2 ≤ D_TH_H2

Second, D_TH_L0 ≤ D_TH_L1 ≤ D_TH_L2

Third, D_TH_H0 ≤ D_TH_H1 ≤ D_TH_H2

If D_TH_Ln <D_TH_Hm (n = m) under the above conditions, level hysteresis is operated.

First, the receiving apparatus determines the upper threshold value and the lower threshold value according to the current digital gain mode.

If the lower threshold value according to the current digital gain mode is larger than the overall gain control value, the receiving device processes to adjust the digital gain mode.

For example, when the receiver determines that the current digital gain mode is "2" and determines that the lower threshold value according to the current gain mode is greater than the total gain control value, the receiver receives max (D_GM-1, 0). Can be used to adjust the temporary digital gain mode to "1".

On the contrary, when the receiver determines that the current digital gain mode is "2", when the lower threshold value according to the current gain mode is smaller than the total gain control value and the upper threshold value is smaller than the overall gain control value, the receiving device is set to min (G_DM +1,3) can be used to adjust the temporary digital gain mode to "3".

In addition, the receiving apparatus checks the setting timer before applying the adjusted digital gain control value as described above to the digital VGA so as not to change the temporary digital gain mode to the current digital gain mode before the timer expires. To increase the robustness against changing the digital gain control mode.

6 is a flowchart illustrating a process of determining an analog gain control value in a receiving apparatus according to an exemplary embodiment of the present invention.

Referring to FIG. 6, the receiving device first checks whether a condition for changing a gain mode is satisfied in step 601. Here, the receiving device may check whether the timer for performing the gain mode change expires and check whether the condition for the gain mode change is satisfied.

If the condition for changing the gain mode is not satisfied, that is, when the expiration of the timer is not confirmed, the receiving device repeats the process of step 601.

On the other hand, when it is confirmed that the condition for changing the gain mode is satisfied, that is, when the expiration of the timer is confirmed, the receiving field checks the current gain mode of the receiving apparatus in step 603.

In step 605, when the receiving device determines that the gain mode of the receiving device is not the lower mode, the receiving device proceeds to step 613 to determine whether the current gain control value is greater than or equal to a threshold for changing to the upper mode. Check it.

If it is determined in step 613 that the current gain control value is equal to or greater than a threshold for changing to a higher mode, the receiving device repeats the process of step 601.

On the other hand, if it is determined in step 613 that the current gain control value is greater than or equal to the threshold for changing to the higher mode, the receiving apparatus proceeds to step 615 to process the current gain mode, that is, the upper gain mode to change to the lower gain mode. .

In operation 605, when the current gain mode is determined to be a lower mode, the receiver proceeds to step 607 and compares the current gain control value with a threshold for changing the gain mode.

In operation 609, the receiving apparatus determines whether the comparison result of operation 607 is a threshold for changing the current gain control value to a higher mode.

If it is determined in step 609 that the current gain control value is not greater than or equal to a threshold for changing to a higher mode, the receiving device repeats the process of step 601.

On the other hand, if it is determined in step 609 that the current gain control value is greater than or equal to the threshold for changing to the higher mode, the receiving apparatus changes the current gain mode, which is the constant mode, to the higher mode in step 611.

Thereafter, the receiving device ends the present algorithm.

7 is a diagram illustrating a process of determining an analog gain control value in a receiving apparatus according to an exemplary embodiment of the present invention.

Referring to FIG. 7, the receiver determines a current gain mode using an analog gain control value by subtracting a digital gain control value from an overall gain control value. The current gain mode may be divided into an upper gain mode and a lower gain mode.

Thereafter, the receiving device may determine the gain mode of the receiving device by comparing the total analog gain control value with a predetermined threshold value LNA_TH_L or LNA_TH_H according to the characteristics of the LNA. Here, the threshold has a relationship of LNA_TH_L? LNA_TH_H, and level hysteresis is applied when the two threshold values are not the same. In addition, temporal hysteresis may be applied for a more robust implementation at the time when the LNA gain mode is converted.

That is, when the current gain mode is the upper gain mode in the receiving device, the threshold for changing to the lower gain mode is compared with the overall gain of the current mode, and when the threshold value equal to or greater than the overall gain is checked, the upper gain mode is referred to as the lower gain mode. To be changed.

In this case, the receiving device may control the gain of the receiving device by using a gain control value for each gain mode as shown in Table 2 below.

LNA Gain Mode Analog Gain Control Value (dB) One 10 0 -15

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 determined not only by the scope of the following claims, but also by the equivalents of the claims.

1 is a block diagram showing the configuration of a receiving apparatus for performing an automatic gain control process according to an embodiment of the present invention;

2 is a block diagram showing in detail the configuration of an automatic gain controller for performing an automatic gain control process according to the present invention;

3 is a flowchart illustrating a process of performing an automatic gain control operation in a receiving apparatus according to the present invention;

4 is a flowchart illustrating a process of determining a digital gain control value for an automatic gain control operation in a receiving apparatus according to an exemplary embodiment of the present invention;

5 is a diagram illustrating a process of determining a digital gain mode in a receiving apparatus according to an exemplary embodiment of the present invention.

6 is a flowchart illustrating a process of determining an analog gain control value in a receiving apparatus according to an exemplary embodiment of the present invention;

7 is a diagram illustrating a process of determining an analog gain control value in a receiving apparatus according to an exemplary embodiment of the present invention.

Claims (2)

In the automatic gain control device of a mobile communication system, A reception signal measuring unit measuring power of the reception signal filtered by the reception filter; The total gain control value is determined using the power of the received signal measured by the received signal measuring unit, and the digital gain control mode is changed by comparing the upper and lower threshold values according to the current digital gain mode with the total gain control values. With digital gain deciding part to do, After checking the current analog gain mode by using the power of the received signal, the analog gain determiner for determining the discrete analog gain and continuous analog gain to change to the higher mode or lower mode by comparing the checked gain mode with a predetermined threshold value. Apparatus comprising a. In the automatic gain control method of a mobile communication system, A digital gain control process of determining a total gain control value using power of a received signal filtered by a reception filter, and changing a digital gain control mode by comparing an upper threshold value and a lower threshold value according to the mode with an overall gain control value; , Discrete analog gain control and continuous analog gain control process of checking the current analog gain mode using the power of the received signal, and changing the checked gain mode to a higher mode or a lower mode by comparing with the predetermined threshold value; And applying a gain control value determined in the gain control process.

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