KR100542491B1 - An isolation monitor of radio relay for mobile communication - Google Patents

Abstract

The present invention continuously monitors and quantifies the repeater's transmit / receive isolation in order to prevent oscillation occurring when the transmit / receive isolation including antennas is smaller than the gain of the repeater system due to internal or external factors in the bidirectional wireless repeater. As early as possible, the present invention relates to an isolation monitoring device for a repeater which prevents oscillation by adjusting the gain of the repeater. The apparatus of the present invention, in the repeater monitoring device for monitoring the repeater signal of the repeater to prevent the oscillation from occurring in the repeater, by receiving a portion of the relay signal to automatically maintain the constant repeating irregular relay signal at a constant intensity A gain control unit; A frequency converter for converting the stable relay signal into a narrow band filtering frequency band in an automatic gain control unit; A filter that receives the output of the frequency converter and filters the amplified and narrow band filter; A signal strength detector for converting the frequency domain signal filtered by the filter into a voltage signal; And a measurement and control unit which receives the voltage signal from the signal strength detection unit, calculates transmission and reception isolation degree, and controls the repeater according to a preset method to prevent oscillation from occurring in the repeater.

Repeater, Transceiver Isolation, Crystal Filter, Mobile Communication, CDMA, Surveillance, Oscillation

Description

Transmitting / receiving isolation monitor of two-way wireless repeater for mobile communication {An isolation monitor of radio relay for mobile communication}             

1 is a block diagram showing the configuration of a general repeater,

2 is a waveform diagram showing an ideal output waveform of one channel in a general repeater,

3 is a waveform diagram showing an output waveform when the oscillation is close to a condition in which the oscillation occurs;

4 is a schematic diagram showing the relationship between the isolation and the sinusoidal wave appearing in the output waveform;

5 is a schematic diagram showing a Bachhausen oscillation condition;

6 is a block diagram showing the configuration of an isolation monitoring device of a repeater according to the present invention;

7 is an example of a channel waveform in the isolation monitoring device according to the present invention,

8 is a schematic diagram illustrating a hopping concept applied to the present invention;

9 is an input / output signal waveform diagram of a signal strength detector when a point passing through a crystal filter is a high point of a sine wave;

10 is an input / output signal waveform diagram of a signal strength detector when a time passing through a crystal filter is a low point of a sine wave;

11 shows measurement waveforms when the amplitude of a sine wave is small;

12 shows measurement waveforms when the amplitude of a sine wave is large.

* Explanation of symbols for main parts of the drawings

100: repeater 102A, 102B: antenna

200: isolation monitoring device 210: AGC unit

211: Attenuator 212: Divider

213: amplifier 214: signal strength detector

220: frequency converter 221: mixer

222: local oscillator 230: filter unit

231: amplifier 232: crystal filter

240: signal strength detection unit 250: measurement and control

260: repeater gain control device 270: repeater output breaker

280: warning device

The present invention relates to a monitoring device for a mobile communication repeater, and more particularly, in order to prevent oscillation occurring when the transmission / reception isolation degree including an antenna is smaller than the gain of the repeater system due to internal or external factors in a two-way wireless repeater. The present invention relates to a repeater isolation monitoring device that continuously monitors transmission and reception isolation and digitizes it to control the gain of the repeater to prevent oscillation in advance.

In general, a two-way wireless repeater for mobile communication (hereinafter referred to as a repeater) is a base station and a mobile communication terminal (hereinafter referred to as a terminal) when the distance from the mobile communication base station (hereinafter referred to as a base station) is poor due to poor radio wave environment. It serves as an intermediate amplification function between and extends the service area of the corresponding base station. In addition, the repeater relays and amplifies the signal between the base station and the terminal when the call is not possible or the call quality is poor in a place such as a tunnel, subway section, or basement of a building which is a natural or artificial radio obstacle or a shade area of radio waves. It is to enable the mobile communication service in parallel.

1 is a block diagram showing the configuration of a general wireless repeater, the repeater 100 is a forward signal processing section 110 for transmitting a signal received from the base station direction to the terminal side, and a signal received from the terminal to the base station side The reverse signal processing portion 120 is formed. The forward signal processing section 110 includes a base station directional antenna 102A, a duplexer 104A, a forward low noise amplifier 112, a forward filtering and gain control unit 114, a forward high power amplifier 116, and a duplex. And a reverse direction signal processing portion 120. The reverse signal processing section 120 includes an antenna 102B, a duplexer 104B, a reverse low noise amplifier 122, a reverse filtering and gain control unit 124. ), A reverse high power amplifier 126, a duplexer 104A, and an antenna 102A.

Referring to FIG. 1, a forward signal input through a base station direction antenna 102A is amplified by a forward low noise amplifier (LNA) 112 through a duplexer 104A. This signal is filtered by the forward filtering and gain control section 114 and adjusted to an appropriate intensity according to the signal strength input to the repeater and input to the high power amplifier (HPA) 116. This signal is passed through the duplexer 104B to the terminal (not shown) of the service area through the terminal directional antenna 102B. In this case, the total gain of the repeater system (hereinafter, referred to as total gain) is the sum of all gains or attenuations of all the above-listed parts. That is, the total gain of the repeater system = base station antenna 102A gain + duplexer 104A attenuation + low noise amplifier 112 gain + filtering and gain controller 114 gain + high output amplifier 116 + duplexer 104B ) Attenuation amount + terminal direction antenna 102B gain.

The signal input through the base station direction antenna 102A is output from the terminal direction antenna 102B through the paths listed above, and a part of the signal is attenuated by space or obstacle and inputted back to the base station direction antenna 102A. The degree is referred to as transmit / receive isolation. In general, oscillation occurs in the repeater when the transmit / receive isolation is low. As the amplification degree increases, oscillation is more likely to occur.

Therefore, the best solution is to eliminate the cause of oscillation by securing sufficient isolation from the repeater's maximum gain when installing and operating the repeater. In many cases, the operator does not have the necessary degree of isolation and reduces the repeater's gain so that it does not become an oscillation condition. In this case, if the isolation is changed by various factors or the set gain of the repeater itself is changed, it may be a condition for the repeater to oscillate and unwanted oscillation may occur.

That is, when the conditions necessary for the oscillation are satisfied, the repeater enters the oscillation state. When this phenomenon occurs, a very large intensity wave is generated in the repeater and output through the transmitting antenna, and serious damage to the system of the repeater itself may cause a malfunction by disturbing the normal operation of equipment and parts. It also seriously affects the base station, preventing the base station from providing normal mobile communication services.

Therefore, in order to solve this problem, there is a conventional method of measuring and detecting the period and amplitude of the waveform by using a phenomenon that looks like a sine wave in the frequency domain when viewed through a spectrum analyzer immediately before oscillation. There is a method of firing a channel that does not use continuous waves at the repeater output, measuring it at the input terminal, and measuring the degree of return from the output terminal to the input terminal.

In the former case (sinusoidal monitoring method), when the intensity of radio waves reaching the repeater from the base station through the space is actually very irregular and the isolation is higher than the gain (for example, isolation = gain + 20 dB or more), it is measured. Since the amplitude of the sine wave is small and the signal input from the base station continuously changes irregularly, the output signal also changes irregularly, making it difficult to obtain reliable measurement values. And when the amplitude of the sine wave is very large, just enough amount of radio waves from the output to the input just before the oscillation phenomenon can be reliably measured. It is difficult to control automatically.

In the latter case (idle channel usage method), it is possible to make a very accurate measurement when the intensity of continuous wave is sufficient, but it is practically impossible to use due to the limitation of radio wave law.

The present invention measures the isolation degree of the repeater in real time within a certain range in order to solve the above problems, and according to the measurement results the oscillation phenomenon by the repeater to prevent the oscillation by controlling the gain itself or blocking the output The purpose of the present invention is to provide a monitoring device for transmitting / receiving isolation of a two-way wireless repeater for mobile communication which prevents damage to the repeater's own components and disrupts base station service.

Another object of the present invention is to measure the isolation degree of the repeater in real time within a certain range at a low cost, and according to the measurement result, the repeater performs gain control or operation such as output cutoff and generates an alarm to the operator. It is to provide a monitoring device for transmitting and receiving isolation of a two-way wireless repeater for mobile communication that can enable quick emergency action and provide convenience in operation.

In order to achieve the above object, the apparatus of the present invention, in the repeater monitoring device for monitoring the repeater signal of the repeater to prevent the oscillation from occurring, irregular relay signal that changes rapidly by receiving a portion of the relay signal Automatic gain control unit for maintaining a constant intensity; A frequency converter converting the stable relay signal into a narrow band filtering frequency band in the automatic gain control unit; A filter that receives the output of the frequency converter and filters the amplified and narrow band filter; A signal strength detector for converting the frequency domain signal filtered by the filter into a voltage signal; And a measurement and control unit which receives the voltage signal from the signal strength detector to calculate the transmission / reception isolation degree, and controls the repeater according to a preset method to prevent oscillation from occurring in the repeater.

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

First, the oscillation phenomenon occurring in the repeater will be briefly described to facilitate understanding of the present invention.

The bidirectional repeater for mobile communication is difficult to distinguish between the signal received from the base station and the signal amplified by the repeater and output to the terminal because the frequency of the signal received in one direction and the frequency of the signal transmitted in the other direction are the same and differ only in intensity. The ideal output waveform of one normal channel of the repeater has a wide bandwidth of 1.23 MHz due to the nature of CDMA, as shown in FIG. And when the analysis is performed by using a spectrum analyzer in the corresponding service band when the oscillation is close to the conditions, it can be seen that the output waveform of the repeater in the frequency domain has the form of a sine wave as shown in FIG. have. As described above, the sine wave appears in the channel signal waveform as a part of the output of the repeater is input to the repeater and is related to the propagation delay characteristics of the repeater.

4 is a schematic diagram showing the relationship between the isolation of the repeater and the sinusoidal wave appearing in the output waveform.

As shown in Fig. 4, the peak value of the sinusoidal wave appearing in the signal waveform is related to the propagation delay, and the difference (amplitude) between the highest signal and the lowest signal of the sinusoidal wave is related to the transmission / reception isolation. In general, the lower the transmit / receive isolation, the larger the amplitude of the sine wave. In the installation and operation of such a repeater, the repeater's transmit / receive isolation can be changed by various internal or external factors.In this case, if the repeater's gain is equal to or greater than the repeater's transmit / receive isolation, the output from the repeater A portion of the signal is returned to the input terminal of the repeater to cause the repeater to oscillate.

This case is the oscillation condition of Barkhausen shown in FIG. 5. As shown in FIG. 5, when the gain of the repeater is A, and the feedback ratio (ratio of return to input to output: related to isolation) is β, oscillation occurs when "│Aβ│≥1". Get up.

Repeater transmission and reception isolation monitoring device of the present invention (hereinafter referred to as "monitoring device") uses a phenomenon that occurs when the signal output from the output terminal of the repeater back to the input of the instrument to prevent the oscillation phenomenon as described above It is a device to monitor the transmit / receive isolation level of the repeater.

6 is a block diagram showing the configuration of an isolation monitoring device according to the present invention.

As shown in FIG. 6, the isolation monitoring apparatus 200 according to the present invention includes an AGC (Auto gain control) unit 210 which maintains a radio wave of a very fast changing irregular intensity from a base station at a constant intensity, and The frequency converter unit 220 converts the radio wave of the mobile communication service into the band of the narrow-band crystal filter, the filter unit 230 which filters the signal from the frequency converter 220 into the narrowband filter, and passes through the filter. Detecting unit 240 for converting a signal into a voltage and a measurement and control unit 250 for controlling the repeater by calculating the transmission and reception isolation of the repeater by receiving the voltage from the detector (240) Depending on the measured isolation, the repeater gain control device 260 controls the gain of the repeater 100 or the repeater output breaker 270 blocks the output of the repeater 100, and / or the alarm generator 280 alerts. Happens There is so. That is, the isolation monitoring device 200 monitors a signal input from the repeater 100, extracts a sine wave signal, calculates the isolation using the level, and if the calculated isolation falls outside the set value, the repeater 100 Control gain or cut off the output and generate a warning.

The AGC unit 210 amplifies the attenuator 211 for attenuating and outputting an input signal according to a control signal, a divider 212 for dividing the output of the attenuator 211 in two directions, and an output of the divider 212. The amplifier 213 and the signal strength detector 214 for outputting a control signal for adjusting the degree of attenuation by detecting the strength of the input signal from the output of the amplifier 213. The attenuator 211 of the AGC unit is a voltage variable attenuator whose attenuation amount is varied according to the applied voltage, and in front of the AGC unit 210, the repeater 100 receives a signal received from the base station from the base station 200. It may further include a coupler or divider 202 to deliver.

The frequency converter unit 220 may hop the local frequency at a high speed of several nanoseconds with the mixer 221 for converting the received frequency according to the frequency of the local oscillator (LOCAL oscillator) 222. A local digital oscillator (LOCAL oscillator) 222 of a direct digital synthesizer (DDS) method is included.

The filter unit 230 includes an amplifier 231 for amplifying the output of the mixer 221 and a crystal filter 230 for filtering the output of the amplifier 231 to perform an amplification and filtering function, and the detection unit 240 is Hide the strength of the filtered signal.

In addition to the function of controlling the monitoring device, the control unit 250 may set an operation preset by the operator when the isolation level exceeds a threshold set by the operator or when the repeater causes oscillation, for example, gain control 260 or output blocking. 270, and alert generation 280.

In the embodiment of the present invention will be described the principle of detecting the transmission and reception isolation of the repeater.

The signal from the repeater's receiving antenna 102A is input to the AGC unit 210 of the isolation monitoring device via the coupler or divider 202. The signal from the AGC unit 210 through the attenuator 211 is divided in two directions by the divider 212, and part of the signal is amplified by the amplifier 213 and then measured by the signal strength detector 214. The strength of the measured signal is converted into a voltage and transmitted to the first attenuator 211. Since the attenuator 211 is a voltage-variable attenuator that varies according to the voltage, the attenuation amount varies according to the signal strength. In other words, the larger the signal strength, the larger the attenuation amount, and the smaller the signal strength, the smaller the attenuation amount. Therefore, the output of the AGC unit 210 can always obtain a constant output even if the input intensity changes. The signal passing through the AGC unit 210 is input to the frequency converter unit 220. The frequency converter 220 lowers the frequency of the input signal to the frequency band of the crystal filter so as to pass through the crystal filter 221.

7 is an example of a channel waveform in the isolation monitoring apparatus according to the present invention.

Referring to FIG. 7, the 800 KHz band will pass through the crystal filter 232 in the ± 400 KHz range at the center frequency of any channel transmitted from the base station of the LOCAL oscillator 212 of the frequency converter 220. As shown in FIG. 8, the hopping is repeated at a low frequency of 5 KHz sequentially from a low frequency. 7 and 8, the channel band is 1.23 MHz, but the bandwidth of the crystal filter 232 is about 30 KHz. Therefore, in order to sequentially pass the approximately 800KHz band, it is necessary to sequentially hop at 5KHz intervals.

The signal passing through the crystal filter 232 through the above process is input to the signal detector 240. One period of the sinewave shown above is wider than the passband of the crystal filter 232. Therefore, the signal strength of the high and low points of the sine wave is distinguished.

When the signal passing through the crystal filter 232 is input to the signal strength detector 240, the signal strength detector 240 outputs a voltage according to the strength of the input signal. 9 and 10 illustrate signal waveforms output according to the strength of an input signal.

9 is an input / output signal waveform of the signal strength detector 240 when the time passing through the crystal filter 232 is the high point of the sine wave, wherein the left signal waveform represents the input signal in the frequency domain, and the right signal waveform is the time domain. Indicates the output signal from. It can be seen that the waveform of the output signal is similar to the waveform of the input signal.

FIG. 10 is an input / output signal waveform of the signal strength detector 240 when the time passing through the crystal filter 232 is the low point of the sine wave, wherein the left signal waveform represents an input signal in the frequency domain, and the right signal waveform represents time. Indicates an output signal in the area. It can be seen that the waveform of the output signal is similar to the waveform of the input signal.

Through the above process, the sine wave phenomenon appearing in the frequency domain can be sampled at a predetermined interval and converted into a voltage. Sampling interval can be freely changed from 1KHz to 100KHz, and very fast hopping of 2 to 3 nanoseconds (1 / 10-12) seconds using the local oscillator 222 using the Direct Digital Synthesizer (DDS) method. Can have speed. The hopping speed is adjusted in consideration of the reaction speed of the semiconductor chip AD8307 (manufacturer: analog device) used in the signal strength detector 240.

When the voltage obtained through the above process is input to the measurement and control unit 250 and the amplitude of the voltage output from the signal strength detection unit 240 is measured, as shown in FIGS. 11 and 12. FIG. 11 shows the measurement waveform when the amplitude of the sine wave is small. It can be seen that the amplitude of the voltage V is also small in the time domain when the amplitude of the signal waveform in the frequency domain is small. 12 shows the measurement waveform when the amplitude of the sine wave is large, and it can be seen that the amplitude of the voltage V is also large in the time domain when the amplitude of the signal waveform in the frequency domain is large.

Referring to FIGS. 11 and 12, in order to obtain a reliable measurement value in a short time, the local oscillator 222 is output at a very high speed by repeatedly hopping at a narrow interval (1 KHz to 30 KHz) at a bandwidth of 800 KHz. Read the voltage at 3000 speeds per second. With this data, the appropriate amplitude is used to find the amplitude of the voltage. The transmission / reception isolation degree of the repeater is measured by the amplitude obtained here, and the gain of the repeater 100 is adjusted according to the measurement result, the output is cut off, or an alarm is generated.

The AGC unit 210 of the isolation monitoring device 200 stabilizes a received signal whose strength is fast and irregularly changed, and measures the isolation with the data of a predetermined band repeated many times, thereby greatly increasing the error that may occur. In short, reliable measurements can be obtained even when the transmit / receive isolation is greater than the repeater's gain (for example, up to the repeater gain plus 25 dB).

As described above, according to the present invention, by measuring the amplitude of the sine wave component included in the relay signal in the bidirectional wireless repeater, the transmitter continuously monitors the transmission / reception isolation (isolation) and digitizes the gain of the repeater when the threshold value determined by the user is reached. You can prevent the repeater from generating oscillation by adjusting the power supply, interrupting the output or generating a warning. Accordingly, it is possible to prevent the unwanted wave from being output through the transmitting antenna and to stably operate the repeater to improve the quality of the mobile communication service.

Claims (6)

In the repeater monitoring device for monitoring the repeater signal of the repeater to prevent the occurrence of oscillation in the repeater, An attenuator for attenuating and outputting an input signal according to a control signal, a divider for dividing the output of the attenuator in two directions, an amplifier for amplifying the output of the divider, and detecting and attenuating the intensity of the input signal from the output of the amplifier An automatic gain control unit having a signal strength detector for outputting a control signal for adjusting the degree, the automatic gain control unit receiving a portion of the relay signal and maintaining a rapidly changing irregular relay signal at a constant intensity; Local oscillator of DDS (Direct Digital Synthesizer) method which can hop local frequency at high speed, and mixer which mix the frequency of the relay signal with the frequency of local oscillator, which is stable in the automatic gain control unit. A frequency converter for converting the signal into a narrow band filtering frequency band; A filter unit including an amplifier for amplifying the output of the frequency converter and a narrow band crystal filter for filtering the output of the amplifier, and filtering the output of the frequency converter with a narrow band filter; A signal strength detector for converting the frequency domain signal filtered by the filter into a voltage signal; And Mobile communication bidirectional communication comprising a measurement and control unit for receiving the voltage signal from the signal strength detection unit to calculate the transmission and reception isolation degree, and by controlling the repeater according to a preset method to prevent the oscillation from occurring in the repeater Transmission and reception isolation monitoring device of wireless repeater. According to claim 1, The isolation monitoring device, Transmitting and receiving isolation monitoring device of a two-way radio repeater for mobile communication, characterized in that it further comprises a warning generating means for generating a warning when the isolation degree calculated by the measurement and control is outside a predetermined set value. delete delete delete The method of claim 1, wherein the measurement and control unit Mobile communication bidirectional communication, characterized in that by calculating the transmission and reception isolation of the repeater is isolated the predetermined reference value control the gain of the repeater through the repeater gain control device or the output of the repeater through the repeater output blocker Transmission and reception isolation monitoring device of wireless repeater.

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