KR20030057051A - Apparatus and method for gain control of transmitting signal of mobile communication base station - Google Patents

Abstract

PURPOSE: A device for controlling a transmission signal gain of a mobile communication base station is provided to apply the biggest input signal even though the input signal is low, regardless of quantization noise levels of a digital/analog converter, thereby compensating signal strength and an SNR(Signal to Noise Ratio) as maintaining the SNR when converting a digital signal into an analog signal. CONSTITUTION: A signal compensator(41) measures size of a digital signal, and outputs the biggest size. A gain controller(31) mixes the output of the compensator(41) with the digital signal, and controls a gain. A modulator(32b) and a predistorter(32a) distort an output signal of the controller(31) to modulate the signal, and compensate an error. A digital/analog converter(33) converts the digital signal into an analog signal. An up converter(34) up-converts a frequency of the analog signal. An attenuator(35) attenuates an output signal of the up converter(34), and outputs the signal. A high power amplifier(36) amplifies and outputs the output signal of the attenuator(35). A coupler(37) couples output signals of the amplifier(36), and outputs the signals. A down converter(38) down-converts a frequency of the output signals of the coupler(37). An analog/digital converter(39) converts analog output signals into digital signals. A demodulator(40) demodulates output signals, and outputs the signals.

Description

Transmission signal gain adjusting device and method of mobile communication base station {APPARATUS AND METHOD FOR GAIN CONTROL OF TRANSMITTING SIGNAL OF MOBILE COMMUNICATION BASE STATION}

The present invention relates to an apparatus and method for adjusting the transmission signal gain of a mobile communication base station. In particular, the present invention relates to a signal transmission system having a signal level higher than the noise level of a digital / analog converter to obtain a sufficient signal strength and noise ratio. The present invention relates to a transmission signal gain adjusting apparatus of a mobile communication base station which can maintain a constant gain.

In general, the predistorter linearization device distorts an input signal in advance to have a characteristic opposite to that of the power amplifier in order to compensate for the nonlinearity of the power amplifier in the final stage of the mobile communication system. Even if the bandwidth of the input signal is wide like the next generation mobile communication (IMT-2000), the performance can be sufficiently improved, and it is more efficient and cheaper than the feedforward method, which is a popular linearization technology.

Recently, the predistortion linearization technology has been developed with the technology of adaptively optimizing against a change in the characteristics of the high power amplifier that changes over time due to a digital technology.

In addition, by using the digital intermediate frequency technology to reduce the effect of the gain / phase imbalance of the I / Q signal that can occur in the analog modulator, such a prior art will be described with reference to the accompanying drawings.

1 is a diagram illustrating a configuration of a transmission signal gain adjusting apparatus of a conventional mobile communication base station. As shown in FIG. 1, a digital eye (I) and a cue (Q) signal are distorted and modulated, and then transmitted to the modulated signal. A modulation and predistortion unit 11 for compensating and outputting the generated error; A digital / analog converter 12 for converting the digital signal of the modulation and predistorter 11 into analog; A low pass filter unit 13 for outputting only the low pass of the analog signal; An up-converter 14 for up-converting the frequency of the output signal of the low-pass filter unit 13 to a predetermined frequency; A high power amplifier 15 for amplifying and outputting the output signal of the up-converter 14; A coupler 16 for coupling and outputting the output signal of the high power amplifier 15; A down converter (17) for down-converting the frequency by mixing the output signal of the coupler (16) and the output signal of the local frequency oscillator; An analog / digital converter 18 for converting the analog output signal of the down converter 17 into digital; Comprising an error detection unit 19 for comparing the output signal of the analog / digital converter 18 and the digital eye (I), the cue (Q) signal and outputs an error to the modulation and pre-distortion unit, it is configured as The operation of the device is described as follows.

First, the modulation and predistortion unit 11 receiving the digital I and Q signals of the data generator 30 properly distorts the input signal with characteristics opposite to the high power amplifier 15, and then outputs the digital signal. Quadrature Phase Shift Keying (QPSK) is modulated to intermediate frequencies using digital intermediate frequency technology and then converted to analog signals using a digital / analog converter (12).

The up-converter 14 is used to upconvert the intermediate frequency signal to a high frequency signal, and then amplify the signal using the high power amplifier 15, and then sample a portion of the amplified signal and pass the down converter 17 again. Lower it to an intermediate frequency.

The output signal of the down converter 17 is inputted to the modulation and predistortion unit 11 to correct an error obtained by comparing the output signal converted to digital through the analog / digital converter 18 so as to reduce the error. .

However, the conventional apparatus operating as described above has a function of reducing the desired gain and attenuation of the input signal. However, if the input signal is low, the digital / analog converter has a function when converting the analog signal using the digital / analog converter. Since it is not much larger than the level of quantization noise, there is a problem in that the signal strength and signal to noise ratio (SNR) included in the signal become worse.

Accordingly, the present invention has been made to solve the above problems, and adds a function capable of fixing the gain of the transmission path while maintaining the size of the predistortion input signal sufficiently large, even when the input signal is low. By applying the largest input irrespective of the quantization noise of the analog converter, it is possible to compensate for the strength ratio of the signal lost in the digital / analog converter and the noise ratio included in the signal. It is an object of the present invention to provide an apparatus and method for adjusting a transmission signal gain of a mobile communication base station to attenuate the signal to an appropriate magnitude while maintaining the strength ratio of noise included in the signal.

1 is an exemplary view showing the configuration of a transmission signal gain adjusting apparatus of a conventional mobile communication base station.

2 is an exemplary view showing a configuration of a transmission signal gain adjusting apparatus of a mobile communication base station of the present invention.

*** Explanation of symbols for main parts of drawing ***

30: data generator 31: gain control unit

31a, 31b: first and second mixers 41a, 41b: first and second mixers

32: modulation and predistorter 32a: predistorter

32b: modulator 33: first digital-to-analog converter

34 upconverter 35 attenuator

36: high power amplifier 37: coupler

38: Downconverter 39: Analog-to-Digital Converter

40: demodulation part 41: signal correction part

41a: power measurement unit 41b: digital signal processing unit

41c: digital-to-analog converter

The present invention for achieving the above object, the signal correction unit for measuring the magnitude of the digital signal and outputs the maximum magnitude of the digital signal; A gain adjuster for adjusting gain by mixing the output of the signal corrector and the digital signal; A modulation and predistorter for distorting and modulating an output signal of the gain adjusting unit and compensating for an error occurring when transmitting the modulated signal; A first digital / analog converter for converting the digital signal of the modulation and predistortion unit into an analog; An upconverter for upconverting the frequency of the analog signal to a predetermined frequency; An attenuator for attenuating the output signal of the up-converter by an output signal of the signal adjusting unit; A high power amplifier for amplifying and outputting the output signal of the attenuation unit; A coupler for coupling and outputting an output signal of the high power amplifier; A down converter for down converting the output signal frequency of the coupler; An analog / digital converter for converting the analog output signal of the down converter into digital; And a demodulator configured to demodulate and output the output signal of the analog / digital converter.

The present invention for achieving the above object, the step of receiving the signal to be transmitted and measuring the magnitude of the input signal; Detecting the maximum magnitude of the input signal, adjusting and outputting a gain of the input signal, and converting the analog signal into an analog signal; Attenuating a predetermined amount of attenuation at the maximum magnitude of the input signal and converting the analog signal into an analog signal; And attenuating the signal converted into the analog signal to correct and transmit the signal.

Hereinafter, an embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

2 is an exemplary view showing a configuration of a transmission signal gain adjusting apparatus of a mobile communication base station according to the present invention. As shown in FIG. 2, a signal correction unit 41 measures a magnitude of a digital signal and outputs a maximum magnitude of the digital signal. Wow; A gain adjuster 31 for adjusting gain by mixing the output of the signal corrector 41 and the digital signal; A modulation and predistorter (32) for distorting and modulating the output signal of the gain control unit (31), and then compensating for and outputting an error generated during transmission of the modulated signal; A digital / analog converter 33 for converting the digital signal of the modulation and predistorter 32 into analog; An up converter (34) for upconverting the frequency of the analog signal to a predetermined frequency; An attenuator (35) for attenuating and outputting the output signal of the up-converter (34) by the output signal of the signal adjusting unit (41); A high power amplifier (36) for amplifying and outputting the output signal of the attenuator (35); A coupler (37) for coupling and outputting the output signal of the high power amplifier (36); A down converter (38) for downconverting the output signal frequency of the coupler (37); An analog / digital converter 39 for converting the analog output signal of the down converter 38 into digital; The demodulator 40 is configured to demodulate and output the output signal of the analog / digital converter 39. The operation of the present invention configured as described above will be described below.

The present invention can fix the gain of the transmission path while keeping the magnitude of the input signal large enough to the existing predistorter.

First, the I / Q data, which is an output signal of the data generator 30, is input to the first mixer 41a1 and the second mixer 41a2 of the power measuring unit 41a, mixed, and output.

The outputs of the first and second mixers 41a1 and 41a2 are added by the adder 41a3 and then output the measured power of the I / Q data to the digital signal processor 41b.

Accordingly, the digital signal processor 41b receives the output signal of the power measuring unit 41a and the output signal of the demodulator 40 and outputs the output signal to the predistorter 32a and the gain control unit 31.

Therefore, the first mixer 31a and the second mixer 31b of the gain adjuster 31 multiply the value calculated by the digital signal processor 41b by the I / Q data, which is the output signal of the modem, to obtain an appropriate size. The I / Q signal is output to the predistorter 32a.

When the input signal of the first digital / analog converter 33 is small, this is because the noise level due to the quantization noise of the first digital / analog converter 33 basically is high, so that it is included in the sufficient signal strength and the signal. This is to ensure that the input of the first digital-to-analog converter 33 always has the highest value in order to obtain the SNR of the noise.

The predistorter 32a distorts and outputs the signal in advance so as to be opposite to the characteristics of the high power amplifier 36 in an appropriate size according to the magnitude of the input signal, and modulates the output of the predistorter 32a to intermediate frequency. It is input to the modulator 32b for outputting a band signal.

The output of the modulator 32b is converted into an analog signal through the first digital / analog converter 33 and input to the up-converter 34, thereby converting an intermediate frequency analog signal into a high frequency analog signal.

Through the above process, the attenuator 35 receiving the signal converted from the digital signal to the analog signal has increased the size enough for the dynamic range of the first digital / analog converter 33 again. The output signal of the up-converter 34 receives the output signal of the second digital-to-analog converter 41c and the output signal of the up-converter 34 appropriately considers a desired attenuation value to the high power amplifier 36. Output

Accordingly, the high power amplifier 36 outputs an output signal to the coupler 37, and the coupler 37 samples the output signal and converts the high frequency band signal into an intermediate frequency band signal, thereby modulating the intermediate frequency band signal. Demodulate by digital demodulation.

The digital demodulation is performed by the demodulator 40 and input to the digital signal processor 41.

Accordingly, the digital signal processing unit 41 compares the signal passing the high frequency band signal with the output signal of the power measuring unit 41a and outputs an output signal for controlling the predistorter so that the error thereof is reduced.

As described in detail above, the present invention applies the largest input regardless of the quantization noise level of the digital / analog converter even when the input signal is low, and thus the signal strength and the signal strength that can be weakened by the digital / analog converter. The signal-to-noise ratio (SNR) included in the compensation can be compensated for, and the signal-to-noise ratio (SNR) can be sufficiently maintained even when the digital signal is converted into an analog signal.

Claims (3)

A signal correcting unit measuring a magnitude of the digital signal and outputting a maximum magnitude of the digital signal; A gain adjuster for adjusting gain by mixing the output of the signal corrector and the digital signal; A modulation and predistorter for distorting and modulating the output signal of the gain control unit; A first digital / analog converter for converting the digital signal of the modulation and predistortion unit into an analog; An upconverter for upconverting the frequency of the analog signal to a predetermined frequency; An attenuator for attenuating the output signal of the up-converter by an output signal of the signal adjusting unit; A high power amplifier for amplifying and outputting the output signal of the attenuation unit; A coupler for coupling and outputting an output signal of the high power amplifier; A down converter for down converting the output signal frequency of the coupler; An analog / digital converter for converting the analog output signal of the down converter into digital; And a demodulator for demodulating and outputting the output signal of the analog / digital converter. The apparatus of claim 1, wherein the signal corrector comprises: a power measurer configured to measure and output power of a transmission signal; A digital signal processor for comparing the output signal of the power measuring unit with a high frequency transmission signal and outputting a signal such that there is no error between the two signals; And a digital / analog converter configured to convert the output signal of the digital signal processor to an analog signal and output the analog signal. Receiving a signal to be transmitted and measuring a magnitude of an input signal; Detecting the maximum magnitude of the input signal, adjusting and outputting a gain of the input signal, and converting the analog signal into an analog signal; Attenuating a predetermined amount of attenuation to a maximum magnitude of the input signal and converting the signal into an analog signal; And attenuating the signal converted into the analog signal to correct and transmit the signal.