KR20020044946A - BTS receiver in mobile communication system - Google Patents

Abstract

PURPOSE: A base station receiving apparatus for a mobile communication system is provided to decrease a noise and improve receiving sensibility by embodying an LNA(Low Noise Amplifier) module of a base station front end and an RF(Radio Frequency) down-converter in single module. CONSTITUTION: An RF down-converter(53) composes an LNA module of a base station front end and an LNA of an RF down-converter in single module, and performs the low noise amplification and path diversity of an RF signal received from a base station antenna in a single LNA module. A power detector(61) detects an IF(Intermediate Frequency) output of the RF down-converter(53) and controls an IF power inputted to an AGC(Automatic Gain Control) circuit unit(59) in the RF down-converter(53).

Description

BTS receiver in mobile communication system

A radio frequency (RF) block of a general mobile communication base station enables a transmission signal received from an intermediate frequency (IF) block to be transmitted to a terminal through frequency up-conversion, amplification, etc. to an RF, and the frequency of the RF reception signal received from the terminal. Down-converts to IF block. In hardware, it can be divided into front end and transceiver board, and functionally, the first end is divided into transmit / receive filter and amplifier (low noise amplification, high power amplification).

The transceiver board is further divided into a frequency uplinker, a frequency downlinker, and a frequency synthesizer. Here, the frequency uplinker of the transceiver board plays a role of up-dual converting the IF signal output from the IF board to convert the frequency into an RF signal and then send it to the pre-end. Additional functions include a variable output signal power control function for controlling the output signal power of the frequency uplinker, and a base station output signal on / off function. Here, the variable control of the output signal power is controlled by the modem unit, and the variable attenuator can be mounted with a variable attenuator using a pin diode in the IF signal band to obtain more linearity of the output power attenuation characteristics.

In addition, the frequency downlink of the transceiver plays a role of transmitting downlink dual conversion of the RF signal output from the low-end amplifier of the front end to the IF signal and converting the IF signal to the base station IF board. One transceiver board has a frequency downlink with two independent signal paths for diversity. The RF local and IF local oscillators from the frequency synthesizer are configured to share the frequency downlink together. In addition, each frequency downlink uses a surface acoustic wave (SAW) filter with excellent group delay and cut-off characteristics to satisfy single-tone desensitization characteristics and supplies a constant level to other base station IF boards. It has AGC (Automatic Gain Control) function.

Hereinafter, the RF block of the mobile communication base station will be described in detail with reference to the accompanying drawings.

1 is a diagram schematically illustrating an apparatus for receiving a base station of a mobile communication system according to the prior art.

The configuration of FIG. 1 illustrates a receiving antenna of a base station to an RF (Radio Frequency) down converter for outputting an intermediate frequency. As shown in FIG. 1, a receiving dedicated antenna for receiving a signal transmitted from a mobile station (not shown) is shown. Band pass filter (BPF) 15 for adjusting the signals received by the first antenna 10 and the second antenna 11 and the reception antennas 10 and 11 to the assigned use frequency. And two low noise amplifier modules for amplifying the output of the band pass filter 15 to a predetermined level, namely, a first low noise amplifier (LNA) module 12 and a second LNA module 13, and the LNA module. It consists of an RF down converter 14 which converts the high-frequency signal that has passed through to an intermediate frequency (IF).

The RF down converter 14 is a low noise amplifier (LNA) 16 that amplifies the output of the pass-through filter with less noise, and a flower attenuator of the signal amplified by the low noise amplifier 16 through a flower attenuator. A primary attenuator 17 for attenuating gain, a first mixer 18 for summing the output of the primary attenuator with a UHF local oscillator frequency, and the output of the first mixer for a signal of a corresponding communication scheme A surface acoustic wave (SAW) filter 19 for filtering a signal suitable for a bandwidth, a secondary attenuator 20 configured to attenuate the output of the SAW filter 19 again and including a pin diode, and 2 A second mixer 22 that sums the output of the difference attenuator 20 with an IF (Intermediate Frequency) local oscillation frequency, and an AGC (Automatic Gain Control) that maintains the output of the second mixer 22 at a constant level. Automatic gain control) circuit section 21.

Referring to the operation of the base station configured as described above, when receiving the signals of the mobile station in the two receiving antennas (10, 11) for spatial diversity, the band pass filter 15 removes the unwanted wave other than the desired frequency band This signal is amplified by the low noise amplifier module of the base station front-end, that is, the LNA modules 12 and 13. Thereafter, in the RF down converter 14, the received high frequency signal is down converted to an intermediate frequency (IF) for demodulation.

In the above-described base station receiver, two LNA modules 12 and 13 located at the very first stage in hardware are connected in parallel with two LNAs (low noise amplifiers), respectively, and are implemented in a balanced type. This is for spatial diversity. Referring to FIG. 1, the configuration of the RF down converter block 14 connected to the LNA modules 12 and 13 also has two independent paths for implementing spatial diversity.

As described above, implementing the respective spatial diversity considering the characteristics of the LNA modules 12 and 13 and the RF down converter 14 at the first stage of the base station corresponds to a dual design, which consumes manufacturing cost of the base station system. I have a problem.

In addition, the conventional technique has a problem that a signal loss occurs due to a cable or a connector between the LNA module of the base station stage and the RF down converter.

Accordingly, the present invention has been proposed to solve various problems according to the prior art as described above,

It is an object of the present invention to reduce the hardware design and implementation cost by unifying the system design by eliminating the diversity provided by the low noise amplifier of the base station and implementing diversity in a single module with the low noise amplifier of the RF down converter. The present invention provides an apparatus for receiving a base station of a mobile communication system by increasing the linearity of the AGC circuit by using integrated circuits (ICs) used in a detector in an automatic gain control (AGC) circuit of an RF down converter.

Features of the base station receiving apparatus of the mobile communication system according to the present invention for achieving the above object,

A mobile communication system including an RF down converter having an attenuator, a mixer, a SAW filter, and an automatic gain control circuit, as well as a first and second reception antenna unit and a band pass filter, and a base station front-end low noise amplifier module. In the base station receiving apparatus of

And a low noise amplifier for performing the diversity function of the low noise amplifier module of the base station first stage and the diversity function of the RF down converter in a single module.

In addition, the present invention for achieving the above object is characterized in that it comprises a power detector for performing the linearity enhancement function of the automatic gain control circuit unit by inputting the intermediate frequency output of the RF down converter.

1 is a diagram schematically illustrating an apparatus for receiving a base station of a mobile communication system according to the prior art;

2 is a block diagram illustrating a base station receiving apparatus of a mobile communication system according to the present invention.

<Explanation of symbols for the main parts of the drawings>

50: the first antenna

51: second antenna

54: Low Noise Amplifier (LNA)

57: SAW (Surface Acoustic Wave) Filter

61: power detector

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

2 is a block diagram illustrating a base station receiving apparatus of a mobile communication system according to the present invention.

The configuration of FIG. 2 shows a radio frequency (RF) down converter that outputs an intermediate frequency from a reception antenna of a base station. As shown in FIG. 2, a reception dedicated antenna for receiving a signal transmitted from a mobile station (not shown) Band pass filter (BPF) 52 which adjusts the first and second antennas 50 and 51 and the signals received by the receiving antennas 50 and 51 to the assigned frequency of use. And an RF down converter 53 for converting the high frequency signal passed through the band pass filter 52 into IF (Intermediate Frequency), which is an intermediate frequency.

The RF down converter 14 is again amplified by the low noise amplifier 54 through a low noise amplifier (LNA) 54 and a flower attenuator that amplifies the output of the pass-through filter with less noise. A primary attenuator 55 that attenuates the gain of the signal, a first mixer 56 that sums the output of the primary attenuator with a UHF local oscillator, and the output of the first mixer in a corresponding communication scheme. A surface acoustic wave (SAW) filter 57 for filtering a signal suitable for a signal bandwidth of the second filter; a second attenuator 58 including a pin diode and attenuating the output of the SAW filter 57; A second mixer 60 that sums the output of the secondary attenuator 58 with an intermediate frequency (IF) local oscillation frequency; and an AGC (Automatic) that maintains the output of the second mixer 60 at a constant level. Gain Control circuitry 59, and the AGC Connected to robu consists of the power detector 61 to increase the linearity.

Referring to the operation of the base station configured as described above, when receiving the signals of the mobile station in the two receiving antennas (50, 51) for spatial diversity, the bandpass filter 52 removes the unwanted wave other than the desired frequency band In the RF down converter 53, the received high frequency signal is down-converted to an intermediate frequency (IF) for demodulation.

The down-converted intermediate frequency is input to the I and Q signal demodulators to demodulate the received signal, and the I and Q signals mean reception frequencies of in-phase and quadrature components, respectively.

Compared to the configuration of FIG. 1 according to the prior art, the conventional configuration of FIG. 1 receives a signal received through a reception antenna and a band pass filter into a low noise amplifier module having a low noise balanced type. In the configuration of FIG. 2 according to the present invention, it can be seen that the low noise amplifier module is removed and a signal from which unwanted waves are removed through a band pass filter is directly input to the RF down converter.

The first stage of the base station system is very closely related to the reception sensitivity, which is very dependent on the noise characteristic. In other words, the more complex the base station first stage is, the more serious the noise generation from the base station to the first stage and the RF down converter is, which is a major cause of adverse effects on the reception sensitivity of mobile communication. On the other hand, the design of the base station's first stage and the RF down converter focused on the diversity implementation rather than the complexity of the circuit and the importance of the noise characteristics by the cable and the connector.

Therefore, the dual design can be referred to as diversity at the base station stage and diversity by independent path in the RF down converter. Thus, the complexity of the circuit itself due to the diversity and the cable for the connection, Overlooking the damage caused by excessive connector use is overlooked.

2 according to the present invention is a low-noise amplifier having a harmonious configuration at the base station first stage, and a low-noise amplifier in the RF down converter is a single module that is distributed to each module, the spatial diversity (path diversity) of the base station The circuit is simply implemented so that it does not affect the noise characteristics of the base station at the very first stage without excluding the implementation of Citi. This naturally reduces noise generated by excessive use of cables and connectors, contributing to improved reception.

In other words, the diversity of the low-noise amplifier (LNA) and the RF down converter at the base station is implemented, but the circuit is made simpler while avoiding the double design.

In addition, the AGC (automatic gain control) circuit unit 59 hardly expects normal operation when the power level difference for each signal due to the change of the mobile communication subscriber is severe or the power level difference is severe due to spurious.

That is, since the AGC circuit unit calculates the automatic gain control value based on the power level value, a signal having a small power difference due to a signal having a large power difference may be rather extinguished by performing automatic gain control by the AGC circuit unit. This reduces the linearity of the AGC circuit portion.

Therefore, in the present invention, the AGC circuit unit is configured to include a power detector for estimating the power of the signal by inputting the intermediate frequency output signal, that is, the output signal of the second mixer 60 in FIG. Gain control was performed.

According to the base station receiving apparatus of the mobile communication system of the present invention described above, by implementing a low-noise amplifier module and an RF down converter of the base station stage in a single module, in the implementation of the circuit, noise reduction due to cost savings and savings in cables, connectors, etc. And an improvement in reception sensitivity.

In addition, the use of the power detector in the AGC circuit portion has the effect of performing active automatic gain control and increasing the linearity of the automatic gain control circuit portion.

Claims (1)

A base station receiver of a mobile communication system comprising an RF down converter, a band pass filter, and an LNA (low noise amplifier) module, An RF down converter for performing a low noise amplification and path diversity of a high frequency signal received from a base station antenna in a single LNA module by modularizing the LNA module of the base station first stage and the LNA of the RF down converter; And a power detector for detecting an intermediate frequency output of the RF down converter and controlling an intermediate frequency power input to an automatic gain control circuit in the RF down converter.