KR20100018680A - Method and receiver for automatic gain control - Google Patents

Abstract

PURPOSE: An automatic gain control method and a receiver thereof are provided to maintain a stable reception status in the various radio environment by regularly maintaining the gain of an impulse signal inputted with ADC. CONSTITUTION: The variable gain amplification unit amplifies the gain of an impulse signal received. A quantized value is outputted by processing a quantization about the impulse signal with an amplified gain. Statistical information is generated by using the quantized value. The gain control width is determined based on the statistical information. The amplifying gain of the variable gain amplification unit is adjusted based on the gain control width. The frequency band of the received impulse signal is transformed to the base band. The matching filtering process between the quantized value and the digital impulse signal is operated.

Description

Automatic gain control method and receiver for performing the same {Method and receiver for automatic gain control}

The present invention relates to an automatic gain control method and a receiver for performing the same. More specifically, the present invention relates to an automatic gain control method in an impulse-based wireless communication system and a receiving apparatus for performing the same.

The present invention is derived from the research conducted as part of the IT growth engine technology development project of the Ministry of Knowledge Economy and the Ministry of Information and Communication Research and Development. [Task management number: 2006-S-070-03, Title: Development of Cognitive wireless system for home network ].

Recently, the impulse wireless technology has attracted much attention as a promising technology due to the low power and the unique distance estimation capability. Meanwhile, in an impulse-based wireless communication system, a loss due to radio wave attenuation occurs until a signal transmitted from a transmitter is received by a receiver, and the degree of signal loss is constantly changed by distance, wavelength of electromagnetic waves, and wireless environment. Therefore, in the impulse-based wireless communication system, in order to maintain a stable wireless communication state in a constantly changing wireless environment, the control of the gain of the received signal is automatically controlled so that the input of the data demodulation block such as an analog-to-digital converter or modem is at a desired level. An automatic gain control method is needed.

On the other hand, a typical wireless communication system modulates data using continuous carriers in the time domain, and the frequency bandwidth used is relatively narrow band. Therefore, the receiver extracts only the necessary band with a filter to determine the presence of a signal and feeds back a value for adjusting the gain of the received signal.

However, in the case of an impulse-based wireless communication system, an extremely low transmit power of less than -41.3 dBm / MHz, which is a spectrum mask regulation of the FCC (Federal Communication Commission), is used to transmit an impulse having a frequency bandwidth of 500 MHz or more. In the remote case, it may be difficult for the receiving device to distinguish the impulse and the noise from the received signal. In addition, since the modulation method using a very short impulse of several nsec is used, if the automatic gain control method used in the conventional wireless communication system using a continuous carrier is applied, the error becomes large in the result of the determination of the presence or absence of a signal. Occurs.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide an automatic gain control method for providing a stable wireless communication state in various wireless environments and an apparatus for performing the same.

In the impulse-based wireless communication system according to a feature of the present invention for achieving the above object, an automatic gain control method of a receiving apparatus including a variable gain amplifier,

Amplifying the gain of the received impulse signal through the variable gain amplifier; Performing quantization on the gain-amplified impulse signal to output a quantization value; Generating statistical information using the quantization value; Determining a gain adjustment range based on the statistical information; And adjusting amplification gain of the variable gain amplifier based on the gain adjustment range.

In addition, the receiver in the impulse-based wireless communication system according to another aspect of the present invention,

A variable gain amplifier for amplifying and outputting a gain of a received impulse signal; An analog-digital converter configured to output a quantization value by performing quantization on the signal output from the variable gain amplifier; And an automatic gain controller configured to generate statistical information using the quantization value output from the analog-digital converter, and to control the amplification gain of the variable gain amplifier based on the gain adjustment range calculated based on the statistical information. .

According to the present invention, there is an effect of providing a stable reception state in various wireless environments.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise. In addition, the terms “… unit”, “… group” described in the specification mean a unit that processes at least one function or operation, which may be implemented by hardware or software or a combination of hardware and software.

Hereinafter, an automatic gain control method and a receiver for performing the same according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In the following description, a signal including an impulse corresponding to received data is referred to as an "impulse signal".

1 is a structural diagram illustrating a structure of a frame in a general impulse-based wireless communication system, and illustrates an IEEE 802.15.4a frame as an example.

Referring to FIG. 1, a wireless communication system constructs a frame using an impulse signal having a width of several nsec or less instead of a continuous signal. The preamble section of the frame is modulated using a ternary code consisting of {1, 0, -1}, and the header and payload sections are burst positions which are one of pulse position modulation. Modulation is performed using Burst Position Modulation (BPM) and Polarity Modulation (BPSK).

2 and 3 illustrate examples of an analog signal input to an analog to digital converter (hereinafter, referred to as 'ADC') of a receiver in a general impulse-based wireless communication system.

In the signal shown in FIG. 2, the gain of the signal received by the receiver is not sufficiently amplified by a variable gain amplifier (hereinafter referred to as VGA), and the full scale is 0.65Vpp. As an example, the input signal is input to an ADC having a bit resolution, and the signal of FIG. 2 is less than 0.04 Vpp corresponding to the 1 bit resolution of the ADC. Therefore, when the signal shown in FIG. 2 is input to the ADC, the output signals of the ADC are all zero and data demodulation fails. On the other hand, the signal of FIG. 3 is an example in which the gain of the signal received by the receiver is amplified to a sufficient size to be quantized by the VGA by the ADC and input to the aforementioned ADC, and the signal shown in FIG. When input to, ADC will quantize successfully and output digital signal.

Therefore, in order to perform successful data demodulation in the ADC, the gain of the signal input to the ADC must be sufficiently amplified. That is, the VGA needs to sufficiently amplify and output the gain of the signal input to the ADC.

Next, an automatic gain control method and an apparatus for performing the same in an impulse-based wireless communication system according to an embodiment of the present invention will be described in detail with reference to FIGS. 4 to 7.

4 is a structural diagram illustrating a receiving apparatus in an impulse-based wireless communication system according to an embodiment of the present invention. 5 and 6 illustrate examples of amplification gain variation of the VGA 130 according to an exemplary embodiment of the present invention.

Referring to FIG. 4, the receiver includes an antenna 110, an analog signal processor 120, a VGA 130, an ADC 140, an auto gain controller 154, and a digital signal processor 160.

The ADC 140 includes a down-mixer (not shown), and the downlink converter converts an impulse signal of a radio frequency (RF) frequency band received through the antenna 110 into a baseband frequency signal. Down-convert Also, the analog signal processor 120 may further include a matched filter (not shown), and the matched filter performs matched filtering on the received impulse signal.

The VGA 130 adjusts and outputs a gain of an impulse signal output from the analog signal processor 120. In addition, the ADC 140 performs quantization on the impulse signal output from the VGA 130 and outputs a quantization value which is a digital signal.

The automatic gain controller 150 includes a comparator 151, an adder 152, a gain calculator 153, and a gain controller 154, and calculates statistical information of quantization values output from the ADC 140. Based on the calculated statistical information, a control signal for controlling the amplification gain of the VGA 130 is output.

The comparator 151 compares the absolute value of the quantization value output from the ADC 140 with a threshold value.

The adder 152 generates statistical information by summing the number of quantization values determined that the absolute value is greater than the threshold value during the preset period, based on the comparison result in the comparer 151.

The gain calculator 153 generates a VGA (Equation 1) based on the statistical information generated by the adder 152, that is, the number y of the quantization values determined that the absolute value is greater than the threshold value during the preset period. The gain adjustment in 130 is calculated.

Here, C _L and C _H represent a gain adjustment ratio. If C _L or C _H is large, the gain adjustment width is increased, and if C _L or C _H is small, the gain adjustment width is decreased. On the other hand, the gain calculator 153 sets C _L and C _H to be large to enable fast searching in the search for the impulse signal to be received, and a sudden gain change is not desirable after the impulse signal to be received is searched. Therefore, C _L and C _H can be set small.

θ _L and θ _H are lower limit thresholds and upper limit thresholds of a predetermined range defined for determining a gain adjustment range based on the number y of quantization values determined that an absolute value is greater than a threshold value during a predetermined interval. It depends on the characteristics of the impulse signal.

Referring to Equation 1, the gain calculator 153 is a case where the number y of the quantization values determined that the absolute value is greater than the threshold value during the preset period is included in the preset range, that is, more than θ _L and less than θ _H. In this case, the current amplification gain is maintained. In other words, the gain adjustment range is zero. On the other hand, a group for a set interval, and the absolute value of the number (y) of the quantized value is determined larger than the threshold value determining the gain control width to less than the θ _L to increase the amplification gain, in reducing the amplification gain in many cases than θ _H Determine gain adjustment range

The gain controller 154 outputs a control signal for controlling the amplification gain of the VGA 130 based on the gain adjustment range calculated by the gain calculator 153. Here, the control signal is output as a digital signal or an analog signal according to the characteristics of the VGA (130). 5 and 6 illustrate the VGA 130 by the aforementioned auto gain controller 150 when a signal having a low signal-to-noise ratio (SNR) and a signal having a high SNR are applied to an input of the ADC 140. As shown in FIG. 5 and FIG. 6, it can be seen that the amplification gain of the VGA 130 is appropriately adjusted by the automatic gain control unit 150.

Referring back to FIG. 4, the digital signal processor 160 includes a matched filter (not shown) that performs matched filtering between the quantization values output from the ADC and the digital impulse signal, and acquires received data from the quantization values. Do this.

Meanwhile, in the embodiment of the present invention, it is assumed that a predetermined rule exists in the received impulse signal. That is, it is assumed that the number of impulses included in the impulse signal received within a certain time interval is constant, and that the quantization value is large at the point where the impulse exists and the quantization value is small at the other place. Therefore, according to an embodiment of the present invention, it is possible to control the amplification gain of the VGA 130 such that the number of quantization values having a magnitude greater than or equal to a threshold value is maintained within a predetermined range as in Equation 1 described above. .

In addition, the method of determining the gain adjustment width may be equally applicable to the case where the size of the impulse included in the received impulse signal is small, that is, when the impulse is buried in noise and is difficult to see or see. This is because the above-described auto gain control method is for adjusting the received impulse signal to an appropriate size to quantize the impulse signal, not to distinguish the impulse from the impulse signal.

Meanwhile, in the embodiment of the present invention, as the statistical information for determining the gain adjustment width, the number of quantization values having an absolute value greater than the threshold value is used during the preset period, but the gain adjustment width is used by using other statistical information using the quantization value. It is also possible to determine. For example, it is also possible for the ADC 140 to calculate a histogram for a predetermined interval for all quantization values that can be generated, and to determine a gain adjustment width using the generated statistical information. In this case, the automatic gain control unit 150 determines the gain adjustment width based on the distribution of the quantization values during the preset period.

7 is a flowchart illustrating an automatic gain control method of a receiving apparatus in an impulse based wireless communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 7, when the impulse signal is received through the antenna 110, the receiver amplifies the gain of the impulse signal received through the VGA 130 (S101). In operation S102, a quantization value of the gain-improved impulse signal is performed through the ADC 140 to generate a quantization value that is a digital signal. Meanwhile, an embodiment of the present invention may further include converting an impulse signal of an RF frequency band into a baseband frequency signal or performing analog match filtering before the gain amplification step S101.

When the quantized value is generated, the auto gain controller 150 compares the absolute value of the threshold value and the quantization value through the comparator 151 and sums the number of quantization values having an absolute value greater than the threshold value for a predetermined period. Generate statistical information (S103). On the basis of the generated statistical information, a gain adjustment range is calculated as in Equation 1 (S104). In addition, a control signal for controlling the amplification gain of the VGA 130 is generated in response to the calculated gain adjustment range, and the amplification gain of the VGA 130 is adjusted using the control signal (S105).

As described above, in the exemplary embodiment of the present invention, the gain of the impulse signal input to the ADC 140 is adjusted by automatically controlling the amplification gain of the VGA 130 based on statistical information of the quantization value output from the ADC 140. By keeping constant, it is possible to maintain stable reception in various wireless environments.

The embodiments of the present invention described above are not only implemented by the apparatus and method but may be implemented through a program for realizing the function corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded, The embodiments can be easily implemented by those skilled in the art from the description of the embodiments described above.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

1 is a structural diagram illustrating a structure of a frame in a general impulse-based wireless communication system, and illustrates an IEEE 802.15.4a frame as an example.

2 and 3 illustrate examples of analog signals input to an analog-to-digital converter of a receiver in a general impulse-based wireless communication system.

4 is a structural diagram illustrating a receiving apparatus in an impulse-based wireless communication system according to an embodiment of the present invention.

5 and 6 illustrate examples of amplification gain variation of the variable gain amplifier according to an exemplary embodiment of the present invention.

7 is a flowchart illustrating an automatic gain control method of a receiving apparatus in an impulse based wireless communication system according to an exemplary embodiment of the present invention.

Claims (11)

In the impulse-based wireless communication system, in the automatic gain control method of the receiving device including a variable gain amplifier, Amplifying the gain of the received impulse signal through the variable gain amplifier; Performing quantization on the gain-amplified impulse signal to output a quantization value; Generating statistical information using the quantization value; Determining a gain adjustment range based on the statistical information; And Adjusting the amplification gain of the variable gain amplifier based on the gain adjustment range Automatic gain control method comprising a. The method of claim 1, Prior to the amplifying step, Converting a frequency band of the received impulse signal into a baseband Automatic gain control method further comprising. The method of claim 1, Performing matched filtering between the quantization value and the digital impulse signal Automatic gain control method further comprising. The method of claim 1, Generating the statistical information, Generating the number of quantization values having an absolute value greater than a threshold value for a predetermined interval as the statistical information; Automatic gain control method. The method of claim 4, wherein Determining the gain adjustment range, Determining the gain adjustment width to increase the amplification gain if the number of quantization values having an absolute value greater than the threshold is less than a lower limit threshold of a preset range; And Determining the gain adjustment width to reduce the amplification gain if the number of quantization values having an absolute value greater than the threshold is greater than an upper limit threshold of the preset range. Automatic gain control method comprising a. The method of claim 1, Generating the statistical information, Generating the statistical information by calculating a histogram for a predetermined interval with respect to all quantization values that can be generated by a receiver; Automatic gain control method. The method of claim 6, Determining the gain adjustment range, Determining the gain adjustment width based on the histogram of the quantization value during the preset period Automatic gain control method. In the receiver in an impulse-based wireless communication system, A variable gain amplifier for amplifying and outputting a gain of a received impulse signal; An analog-digital converter configured to output a quantization value by performing quantization on the signal output from the variable gain amplifier; And Automatic gain control unit for generating statistical information using the quantization value output from the analog-to-digital converter, and controlling the amplification gain of the variable gain amplifier based on the gain adjustment range calculated based on the statistical information. Receiving device comprising a. The method of claim 8, The automatic gain control unit, A comparison unit comparing the quantization value with a threshold value; An adder configured to sum the number of quantization values having an absolute value greater than a threshold value during a preset period and output statistical information; A gain calculator for calculating the gain adjustment range based on the statistical information output from the adder; And A gain control unit for outputting a control signal for controlling the amplification gain based on the gain adjustment range calculated by the gain calculator Receiving device comprising a. The method of claim 9, And the control signal is an analog signal. The method of claim 9, And the control signal is a digital signal.

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