KR20010057831A - Apparatus for controlling transmission gain in a mobile communication cell site - Google Patents

Abstract

PURPOSE: An apparatus for controlling a transmission gain in a base station system of mobile communication is provided to make a TPTL(Transmit Power Tracking Loop) function performed easily, by detecting a final output of a base station and an output from an IF(Intermediate Frequency) signal output terminal, and then keeping the difference between the two outputs constant. CONSTITUTION: A splitter(20) divides an input IF signal into two signals. A variable attenuator(23) controls a level of a signal. A detection part(21) detects intensity of the IF signals output from the splitter(20), and thereby converts them to DC signals according to the intensity thereof. An up-converter(24) converts an IF signal applied from the variable attenuator(23) to an RF(Radio Frequency) signal. An amplifier(25) amplifies the RF signal output from the up-converter(24). A band pass filter(26) filters a noise signal out of a transmission band from the amplified RF signal. A variable attenuator(28) attenuates the signal filtered by the band pass filter(26) so that a ratio of input output signals can be controllable.

Description

Apparatus for controlling transmission gain in a mobile communication cell site}

The present invention relates to a transmission gain control apparatus of a mobile communication base station system. In particular, a TPTL (Transmit Power Tracking Loop) function used in a mobile communication base station operation can always perform a TPTL regardless of the terminal user's presence or use time. A transmission gain control apparatus for a mobile communication base station system.

In general, the transmission gain control in the mobile communication base station system detects the final output of the base station transmitter transmitted to the antenna side, and controls the variable attenuator of the base station in the base station controller (BSM) operating the base station system according to the detected value. Control the transmit gain.

1 is a block diagram of a transmission gain control apparatus of a mobile communication base station system according to the prior art. Referring to the configuration, the intermediate frequency signal IF and the local oscillation frequency obtained from the local oscillator 1 are shown. A first mixer 2 for mixing and upconverting to a high frequency, a variable attenuator 3 for attenuating the output frequency of the first mixer 2 corresponding to a set attenuation level, an output signal of the variable attenuator 3, A second mixer 5 for up-converting the frequency by mixing the oscillation frequency output from the local oscillator 4, a power amplifier 6 for power amplifying the output signal of the second mixer 5, and a power amplifier 6 Bandpass filter 7 for band-pass filtering the output signal of the signal to the antenna 8, an output level detector 9 for detecting the output level of the bandpass filter 7, and an output level detector 9 Search for the detected transmission output level The base station controller 11 for transmitting a control signal for controlling the transmission gain to the base station according to the search result, and the controller 10 for controlling the attenuation level of the variable attenuator 3 under the control of the base station controller 11. It consists of.

The operation of the transmission gain control apparatus of the conventional mobile communication base station system having such a configuration will be described.

First, the first mixer 2 mixes the transmission IF signal modulated by the CDMA modulation method with the oscillation frequency obtained by the local oscillator 1 and up-converts the frequency to high frequency.

The up-converted high frequency is attenuated on the basis of the attenuation level initially set in the variable attenuator 3, and then mixed with the oscillation frequency obtained by the local oscillator 4 in the second mixer 5 so as to produce a power amplifier 6 at a high frequency. Is delivered).

The power amplifier 6 power amplifies the input high frequency, and the band pass filter 7 filters the power amplified transmission high frequency into a set band and radiates it out through the antenna 8.

The output level detector 9 then detects the output level of the band pass filter 7 as the base station transmission output level and transmits it to the controller 10 as a DC voltage.

The controller 10 transmits the detected base station transmit power level value to the base station controller 11 that operates and controls the base station, and the base station controller 11 receives and analyzes the received base station transmit power level. In addition, the control signal for controlling the transmission gain of the base station is calculated in software according to the analyzed result, and then transmitted to the controller 10.

Accordingly, the controller 10 sets the attenuation level of the variable attenuator 3 according to the control data, and attenuates the high frequency input to the variable attenuator 3 according to the set attenuation level.

The conventional CDMA base station performs a TPTL function by selecting a night time without a terminal user in order to maintain a constant output, that is, a transmitter gain.

This is because, when there is a terminal user, the transmission power varies depending on the number of users, so that the operator cannot set the reference value to exactly how large the transmission output standard should be. Therefore, the TPTL function currently used in the CDMA base station cannot be completely implemented.

As a result, TPTL of the conventional CDMA base station detects only the final output power and adjusts the variable attenuation portion at the intermediate stage. Therefore, it is difficult to set the exact reference output value to be maintained during base station operation when the final output is changed. The current situation is to maintain a constant output.

Accordingly, an object of the present invention is to solve the above-described problems according to the prior art, and an object of the present invention is to detect a base station final output detection and an IF output terminal simultaneously to maintain a constant difference between two values even if there is a base station to terminal user. The present invention provides a transmission gain control apparatus of a mobile communication base station system capable of performing a TPTL function without difficulty.

A characteristic of a transmission gain control apparatus of a mobile communication base station system according to the present invention for achieving the above object is, up-converting an input IF signal to a high frequency, and amplifying the up-converted frequency to radiate to the outside through an antenna. A wireless transmitter of a mobile communication base station system, comprising: a first detector for detecting a magnitude of an input IF signal and outputting a DC value corresponding to a detected signal size; A second detector for detecting a magnitude of a final output signal output through the antenna and outputting a DC value corresponding to the detected signal size; A comparator for comparing the DC signals output from the first and second detectors and outputting a difference value; And a variable attenuation unit for setting an attenuation level corresponding to the signal level output from the comparison unit and attenuating the level of the IF signal input at the set attenuation level.

In addition, another feature of the present invention, after attenuating the final output signal through the antenna to a predetermined attenuation level, and further comprising a second variable attenuator provided to the second detector, the comparison unit is made of a differential amplifier have.

In still another aspect of the present invention, the variable attenuator is configured to maximize the attenuation level when the voltage output from the comparator is positive and to vary the attenuation level to a minimum when the voltage is negative.

1 is a block diagram illustrating an apparatus for controlling a transmission gain of a mobile communication base station system according to the prior art;

2 is a block circuit diagram of a transmission gain control apparatus of a mobile communication base station system according to the present invention;

<Explanation of symbols for main parts of drawing>

20: splitter 21, 29: detector

22: differential amplifier 23, 28: variable attenuator

24: upshifter 25: large power amplifier

26: band pass filter 27: coupler

Hereinafter, a transmission gain control apparatus of a mobile communication base station system according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram of a transmission gain control apparatus of a mobile communication base station system according to the present invention. Referring to the configuration, a splitter 20 for separating an input IF signal into two identical signals and a + V , The first variable attenuator 23 for adjusting the signal level to a maximum attenuation value at -V and a minimum value at -V, and the magnitude of the IF signal separated and output from the splitter 20 according to the detected signal size. The first detection unit 21 converts the DC signal.

In addition, the up-converter 24 up-converts the IF signal attenuated by the first variable attenuator 23 to an RF signal to be transmitted, and a high-power amplifying the RF signal converted by the up-converter 24. A band pass filter 26 for filtering out a noise signal outside the transmission band from the RF signal amplified by the amplifier 25, the large power amplifier 250, and a predetermined level attenuation of the signal filtered by the band pass filter 26 to the input and output signal It consists of a second variable attenuator 28 which makes the ratio arbitrarily adjustable.

In addition, the second detector 29 detects the magnitude of the attenuated signal in the second variable attenuator 28 and converts the signal into a DC signal according to the detected signal size, and converts the first and second detectors 21 and 29 respectively. After determining the magnitude of the output according to the difference value of the DC level, the differential amplifier 22 which provides the determined signal level (voltage) to the first variable attenuator 23 so that the attenuation level is adjusted in the first variable attenuator 23. It is composed of

The operation of the transmission gain control apparatus of the mobile communication base station system according to the present invention having such a configuration will be described.

The splitter 20 shown in FIG. 2 is a 2-way splitter, which separates an input IF signal into 2WAYs and outputs them to the first variable attenuator 23 and the first detector 21, respectively.

The first detector 21 converts the input IF signal output from the splitter 20 into a DC value and outputs the DC signal to the inverting terminal (−) of the differential amplifier 22.

In addition, the signal detected at the final output stage is converted into DC at the second detector 29 via the second variable attenuator 28 and then also input to the non-inverting terminal (+) of the differential amplifier 22.

Assuming the system is in a steady state, the value of the second variable attenuator 28 can be adjusted so that the final output is output at the desired value. Therefore, it serves to tune the output value of the second variable attenuator 28 to a predetermined value.

If the input remains constant and the initial block is tuned, the DC value of the first detector 21 will remain constant and the DC of the second detector 29 will also remain constant.

However, if the gain of the path falls due to some factor, the final output will be lower than the initially adjusted output, and the output value of the second detector 29 will be smaller.

Therefore, the potential difference input to the differential amplifier 22 also changes. At this time, the generated potential change will be moved to reduce the attenuation value of the first variable attenuator 23, thereby returning to the output value to be initially adjusted.

Assuming that the input changes continuously, the DC value of the first detector 21 will also change and change, and the output DC value of the second detector 29 will also change.

However, the output change values of the first and second detectors 21 and 29 that occur while the input is continuously changed are changed to the same width, and thus the output voltage of the differential amplifier 22 is not changed.

That is, since the output of the differential amplifier 22 changes only in the gain change in the path as in the case where the input is kept constant, the TPTL operation for maintaining the constant output regardless of the change in the magnitude of the input signal can be performed. (TPTL is converted from output reference to path gain rather than power)

Therefore, the TPTL function, which operates only at night in the CDMA base station, can be extended to the daytime zone where the terminal user exists.

The transmission gain control apparatus of the mobile communication base station system according to the present invention as described above determines the attenuation value of the variable attenuator according to the result of comparing the detected power value by detecting the power of the input and output terminals, so that the CDMA base station system operates only at night There is an advantage that can extend the TPTL function to the day time zone that the terminal user is present.

In addition, it is possible to provide stable cell service by continuously guaranteeing the change of the operating cell due to the change of the transmitter gain even during the operation of the CDMA base station.

Claims (4)

In the wireless transmission apparatus of the mobile communication base station system for up-converting the input IF signal to a high frequency, and amplifying the up-converted frequency and then radiating to the outside through an antenna A first detector for detecting a magnitude of the input IF signal and outputting a DC value corresponding to the detected signal size; A second detector for detecting a magnitude of a final output signal output through the antenna and outputting a DC value corresponding to the detected signal size; A comparator for comparing the DC signals output from the first and second detectors and outputting a difference value; And a variable attenuation unit configured to set an attenuation level corresponding to the signal level output from the comparator, and attenuate the level of the IF signal inputted at the set attenuation level. The method of claim 1, And a second variable attenuator provided to the second detector after attenuating a signal finally outputted through the antenna to a predetermined attenuation level. The method of claim 1, The comparison unit is a transmission gain control device of a mobile communication base station, characterized in that consisting of a differential amplifier. The method of claim 1, The variable attenuator maximizes the attenuation level when the voltage output from the comparator is positive, and varies the attenuation level to a minimum when negative. .