KR20010088138A - Radio relay system having a turnaround wave sense circuit - Google Patents

Abstract

PURPOSE: A wireless repeating system having a turn-around wave sensing circuit is provided to prevent an oscillation phenomenon of a system and offer a stable communication system by measuring a return-around input level between a base station directional antenna and a mobile station directional antenna and automatically adjusting a gain. CONSTITUTION: A turn-around wave detector(111) measures a level of a turn-around input signal among signals inputted from a low noise amplifier and measures a loop gain. A controller(112) compares the loop gain measured by the turn-around wave detector(111) with a predetermined loop gain, and outputs a control signal for adjusting the loop gain according to the compared result. A variable attenuator(113) corresponds to the control signal inputted from the controller(112) and attenuates an inputted signal so that a loop gain of the inputted signal is maintained as a certain value or less. A frequency converter(115) shifts the signal inputted from the variable attenuator(113) and obtains a signal with a desired frequency. A local oscillator(114) inputs each other frequency to the frequency converter(115).

Description

Radio relay system having a turnaround wave sense circuit

The present invention relates to a wireless relay system having a carrier detection circuit.

More specifically, a carrier wave for automatically adjusting the gain of the radio relay system by detecting a return input level returned between the transceivers in order to maintain a constant interval between the transceiver antennas (or RF cables) of the radio relay system. A wireless relay system having a sensing circuit.

The global telecommunications market is changing rapidly. Wired and wireless communication is the field where the daily changes in quantity and quality are different from those in other industries or technologies.

In particular, in the field of wireless communication, many countries around the world are making bold and active investments in order to accelerate the construction of the world's single communication network in the 21st century. Many years ago, pagers and city phones have changed the perception of wireless to many people and have been enough to unlock the potential of the future wireless mobile market.

In the wireless communication field described above, large companies have entered the mobile communication market with the introduction of cellular and PCS as the CDMA (code division multiplex) technology has been announced in the late 20th century and the digital revolution has spread rapidly. Since then, the market of data communication, wireless subscriber network (WLL) and TRS (frequency public communication) has emerged, and new concept of mobile communication that can overcome regional and spatial limitations by using satellite called IMT-2000, called next-generation mobile communication, is emerging. Reached the flag.

Therefore, the base station, the wireless relay system, the mobile station and the mobile terminal should be basically provided in order for the general subscribers to talk to the other party using the aforementioned wireless communication method.

At this time, the configuration and operation of a general wireless relay system is shown in Figure 1, the base station transmits a signal having a predetermined frequency, the base station direction antenna provided in the wireless relay system receives the above-described predetermined signal Output to the duplex filter 10.

Then, the duplex filter 10 filters only the preset frequencies among the above-described signals and outputs them to the low noise amplifier 20, and the low noise amplifier 20 amplifies only the low noise region among the signals having the filtered frequency.

The signal amplified by the low noise amplifier 20 is input to the up / down converter 30, and the up / down converter 30 is up to a frequency sufficient to transmit the frequency of the input signal through the mobile station antenna. Or down convert.

The signal having this up or down converted frequency is amplified to the maximum output through the driving amplifier 40 and the HPA 50, and the signal thus amplified to the mobile station through the duplex filter 10a and the mobile station direction antenna. It is sent out.

Conversely, the signal sent from the mobile station is again received through the mobile station directional antenna, and the signal filtered through the duplex filter 10a is linearly amplified by the low noise amplifier 20a.

The amplified signal is input to the up / down converter 30a, the up / down converter 30a upconverts the frequency of the input signal, and the upconverted signal is the drive amplifier 40a and the HPA 50a. Is amplified to have the maximum output power, and the signal thus amplified is transmitted to the base station through the base station direction antenna, so that the mobile station and the base station are mutually connected.

All the above operations are performed according to the control signal of the controller 60.

In other words, the above-mentioned wireless relay system is a system for amplifying the signal received from the base station to allow the subscriber to the subscriber in the shadowed area to be amplified again and send it to the subscriber. The wireless relay system has a close relationship with the surrounding environment. The signal input to the relay system has a problem that can not maintain a constant value by the surrounding environment.

That is, the received signal from the base station to the wireless relay system is a transmission signal amplified by the wireless relay system and output to the subscriber. When the signal is re-received by the antenna toward the base station, the strength of the retransmitted input signal It is changed by the surrounding environment.

In particular, in Korea, which has a distinct four seasons with a severe temperature difference in each season, it is more sensitive to the above-mentioned return input signal. This return input signal has a great influence on the operation of the communication network, and not only disables the subscriber's call. In addition, the wireless relay system, of course, affects the base station, causing several base stations to cause anomalies or oscillations, saturating the base station, and severely interrupting the service of the base station.

Accordingly, an object of the present invention is to detect the return input level between the transmission and reception in order to maintain a constant interval between the transmitting and receiving antennas (or the RF cable) of the wireless relay system to solve the above-mentioned problems, the wireless relay system The present invention provides a wireless relay system having a carrier wave detection circuit for automatically adjusting the gain of the circuit.

1 is a block diagram schematically illustrating the configuration of a wireless relay system according to the prior art;

2 is a block diagram schematically illustrating the configuration of a wireless relay system according to the present invention;

3 is a block diagram schematically illustrating a configuration of a carrier wave detection circuit unit applied to FIG. 2;

4 is a graph showing the output and transmission input signal detection levels of the wireless relay system.

* Description of Signs of Main Parts of Drawings

110: gain control unit

111: carrier detector 112: controller

113: variable attenuator 114: local oscillator

115: frequency converter

In order to achieve the above object, a radio signal received from the base station according to the present invention is received through the base station antenna and amplified, and the amplified signal is transmitted through the mobile station antenna to establish a communication connection between the base station and the mobile station. A relay system comprising: a low noise amplifier for amplifying only a low noise region by receiving a signal inputted from a base station antenna and a signal inputted from a base station antenna and a signal output from the base station to a mobile station; And an up / down converter including a carrier detection unit that detects an input signal and adjusts an overall loop gain in response to the detected return input signal.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a block diagram schematically illustrating the configuration of a wireless relay system according to the present invention. In the present invention, the carrier detection circuit 110 is included in the wireless relay system, in particular, the up / down converter 100. Although limited and described, the carrier wave detection circuit 110 may be variously configured externally or separately according to the range and characteristics of the above-described wireless relay system.

Meanwhile, components except for the carrier wave detection circuit 110 are similar to those of FIG. 1, and thus a detailed description thereof will be omitted.

As shown in FIG. 3, the carrier wave detection circuit 110 detects a loop gain by receiving a return input signal from a signal transmitted through a mobile station direction antenna (or a base station direction antenna), and detects loop gain. Gain control is performed so as not to exceed 1 and then amplified to maximum output.

3 is a block diagram schematically illustrating a configuration of a carrier wave detection circuit 110 applied to FIG. 2.

As shown, the carrier detector 111 measures the loop gain by measuring the level of the feedback input signal among the signals input from the low noise amplifier 20 described above.

The controller 112 compares the loop gain measured by the carrier wave detector 111 described above with a preset loop gain, and outputs a control signal for adjusting the loop gain according to the comparison result.

The controller 112 includes the same components as the control unit 60 of FIG. 2 when the carrier detection circuit 110 is provided inside the wireless relay system, or the control unit (when provided outside the wireless relay system). 60 is a component that can be configured separately.

Therefore, the detailed description of the present invention will be limited to the controller 112.

The variable attenuator 113 attenuates the input signal so that the loop gain of the signal input through the antenna can be maintained below a predetermined value in response to the control signal input from the controller 112 described above.

The frequency converter 115 shifts the frequency of the signal input from the variable attenuator 113 described above to have a frequency preset by the local oscillator 114 to obtain a signal having a desired frequency.

The above-described local oscillator 114 inputs different frequencies to the frequency converter 115 according to frequencies allocated to cellular phones, PCS, and the like.

With reference to the accompanying drawings, the operation of the radio relay system having the carrier wave detection circuit according to the present invention configured as described above will be described in more detail.

First, the carrier detection technique of the carrier detector 111 is a method of measuring a coupling loss between a base station direction antenna and a mobile station direction antenna in an operating state of a wireless relay system, and offsets the frequency of the transmission signal from the received signal. As a technique for detecting a bit of a signal, it will be described using a formula as follows.

In order to operate in a stable condition, the return signal loop gain must be smaller than 1 as described above.

According to the above equation, the carrier detector 111 detects the loop gain of the transmitted signal, and the detected loop gain is input to the controller 112. The above-described controller 112 compares the loop gain detected by the carrier wave detector 111 with the preset loop gain, and outputs a control signal according to the comparison result.

That is, as a result of the comparison, when the loop gain detected by the carrier detector 111 is greater than the preset gain, the controller 112 controls the control signal to attenuate the magnitude of the signal input through the base station direction antenna (or mobile station direction antenna). Will print

The control signal of the controller 112 is input to the variable attenuator 113, and the variable attenuator attenuates the signal input through the base station direction antenna (or mobile station direction antenna) by the above-described control signal to the frequency converter 115. Output

Then, the frequency converter 115 shifts the input signal by the frequency input from the local oscillator 114 and outputs it to the mobile station through the amplifier 116. The loop gain at this time is obtained by Equation 2 to be described later. Can be.

In addition, when double detection of a neighboring signal input through the base station direction antenna (or mobile station direction antenna) described above, a bit is generated, and the carrier detector 111 compares the DC component and the AC component of the bit described above. The loop gain can be measured.

In addition, as described later, the carrier detector 111 compares the DC and AC components of the bit to measure the loop gain.

As described above, the loop gain detected by the carrier detector 111 and the output characteristics of the detection unit and the output characteristics of the wireless relay system will be described with reference to an example illustrated in FIG. 4. The loop gain is usually unchanged at -10dB, rapidly increasing around 0dB, and reaching oscillation.

Therefore, the inspection of the output of the existing wireless relay system cannot detect the signs until just before the oscillation. Therefore, the call quality deteriorates when the loop gain is lower than -5 dB, and rapidly deteriorates near the oscillation point.

Therefore, the carrier wave detector 111 performs gain control by adjusting the gain of the oscillation prevention radio relay system with the variable attenuator 113 so that the return signal does not increase when the risk of oscillation increases so that the loop gain does not exceed one. .

The above-described carrier detection unit 110 may be operated by being inserted at the front end, the rear end, or in the middle of each circuit element of the up / down converter. It can also be installed separately outside the wireless relay system.

As described above, the present invention can provide a stable communication service by preventing oscillation of the system by first adjusting the gain by automatically measuring the return input level between the base station direction antenna and the mobile station direction antenna.

Second, the present invention is applicable to all wireless communication fields including cellular, PCS, IMT-2000, and TRS, and by applying the present invention, the failure rate of equipment can be reduced and reliability can be secured.

Third, the wireless relay system to which the present invention is applied has an effect of significantly reducing maintenance and reinvestment costs.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below It will be appreciated.

Claims (4)

A wireless relay system for receiving and amplifying a signal transmitted from a base station through a base station direction antenna, and transmitting the amplified signal through a mobile station direction antenna to establish a communication connection between the base station and the mobile station, Receives a signal input to the mobile station through the mobile station direction antenna and a signal transmitted from the base station through a base station direction antenna to detect the return input signal, and adjust the overall loop gain in response to the detected return input signal Wireless relay system having a carrier detection circuit, characterized in that it comprises a carrier detection unit. The method of claim 1, wherein the carrier detection unit A carrier detector for measuring a loop gain by measuring a level of a transmission input signal among signals input through the base station directional antenna; A controller for comparing the loop gain measured by the carrier detector with a preset loop gain and outputting a control signal for adjusting the loop gain according to the comparison result; A variable attenuator configured to attenuate the signal in response to a control signal input from the controller so that the loop gain of the signal input through the antenna is kept below a predetermined value; And And a frequency converter configured to shift the frequency of the signal input from the variable attenuator to have a preset frequency by a local oscillator. A wireless relay system for receiving and amplifying a signal transmitted from a base station through a base station direction antenna, and transmitting the amplified signal through a mobile station direction antenna to establish a communication connection between the base station and the mobile station, Receiving the signal input to the mobile station through the mobile station direction antenna and the signal transmitted from the base station through the base station direction antenna to detect the return input signal, outputs the detected return input signal, this return input signal A carrier detection section for adjusting the overall loop gain in response to a control signal input corresponding to the control signal; And And a control unit for checking a loop gain of the wireless relay system through the return input signal input from the carrier detection unit and outputting a control signal for increasing or decreasing the total loop gain of the wireless relay system according to the check result. Wireless relay system having a carrier detection circuit characterized in that. The method of claim 3, wherein the carrier detection unit A carrier detector for measuring a loop gain by measuring a level of a transmission input signal among signals input through the base station directional antenna; A variable attenuator configured to attenuate a signal such that a loop gain of a signal input through an antenna is maintained below a predetermined value in response to a control signal input from the controller; And And a frequency converter configured to shift the frequency of the signal input from the variable attenuator to have a preset frequency by a local oscillator.