JP3576758B2 - Frequency conversion type relay amplifier - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a relay amplifying apparatus in mobile communication, and more particularly, to a frequency conversion type relay amplifying apparatus having a function of suppressing occurrence of abnormal oscillation due to looping between antennas for a base station and a mobile station.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a mobile communication system such as a car telephone, a direct relay system without performing frequency conversion is applied to a relay amplification system performed as a measure against a blind spot in an open space.
However, in the case of the direct relay system, there is a case where the relay amplifying apparatus abnormally oscillates due to the influence of the roundabout from the transmitting antenna to the receiving antenna. Therefore, to prevent abnormal oscillation, the input (output) antenna for the base station and the output (input) antenna for the mobile station of the relay amplifying device are fixed apart from each other, so that the input and output antennas having a gain equal to or larger than the gain of the relay amplifying device are provided. Propagation loss was secured.
[0003]
As one of the solutions to the above-mentioned problem, there is a frequency conversion type relay amplifying device that performs a normal relay operation without causing abnormal oscillation even if the propagation loss between the input and output antennas is small.
[0004]
FIG. 4 is a schematic diagram of a frequency conversion type relay system to which the present invention is applied. In the figure, 1 is a base station, 2 is a frequency converter of the base station, 3 is an antenna of the base station, 4 is an antenna for a base station of a relay device (relay amplification device 6), 5 is an antenna for a mobile station of the relay device, Reference numeral 6 denotes a relay amplification device (frequency conversion type), 7 denotes a blind spot, and MS denotes a mobile device. However, when the conversion is performed by the software of the one base station, the frequency conversion unit of the second base station is unnecessary.
[0005]
The signal frequencies _{F 1} outputted from the base station apparatus of the base station 1 is converted to the frequency converter unit 2 _(F 2 ₌ F 1 -Δf or _{F 1} + _Δf), sent to the relay amplification apparatus 6 from the antenna 3 I do. Relay amplification apparatus 6 sends the antenna 5 to the mobile station (MS) performs frequency conversion of the signal of frequency F ₂ received by the antenna 4 to the original frequency F _1. Accordingly, the output frequency and the transmission frequency of the repeater amplifier 6 of the base station apparatus are the same as the same F _1, and the normal use.
[0006]
FIG. 5 is a block diagram of a conventional frequency conversion type relay amplifying device, and FIG. 6 is a principle explanatory diagram showing a frequency spectrum of each part. For simplicity, only the downstream system of the bidirectional repeater is shown. In FIG. 5, 10 is a preamplifier (preamplifier), 11 is a frequency converter (converter), 12 is an IF (intermediate frequency) filter, 13 is a frequency converter (converter), 14 is a filter, 15 is an amplifier, Reference numeral 17 denotes a local oscillator (VCO: voltage controlled oscillator), and reference numeral 18 denotes an equalizing loop circuit (β circuit) between the antenna 5 and the antenna 4.
[0007]
FIG. 6A shows the spectrum of the frequency of each unit when there is no wraparound between the input and output antennas.
Desired wave A of a frequency f ₀ input is amplified by a preamplifier 10, is an intermediate frequency f _IF down-conversion (reduction conversion) by the converter 11. The signal D converted to the intermediate frequency _fIF is attenuated by the IF filter 12 in frequency components other than the own signal.
The output E of the IF filter 12 is up-converted (up-converted) by the converter 13 by offsetting the frequency f ₀ of the input signal A by Δf. The output F of the converter 13 is input to the filter 14, attenuates the local signal component, and is amplified by the amplifier 15 to a required output.
However, the illustration of the amplifier at the intermediate frequency stage is omitted for ease of explanation.
FIG. 6A shows the above contents in a spectrum. This is the state when there is no wraparound (β) 18 between the input and output antennas and when the antenna is offset to the + side.
[0008]
FIG. 6B shows a state in which the amount of wraparound (β) is larger than the gain of the relay amplifier by X (dB). Since the frequency of the wrapped signal B is converted to a frequency higher by Δf in the relay amplifier, the spectrum at the point C is as shown in the figure. When the received signal component (f ₀ ) and the wraparound component (f ₀ + Δf) at the point C pass through each of the blocks 10 to 15, the spectrum becomes D to F in FIG. 6B.
Since the interfering wave (wrapped signal) B is shifted higher than f _IF by Δf at point D (the original signal is shifted by Δf), the component of f ₀ + Δf is sufficiently attenuated by the IF filter 12. , The level at the output E of the IF filter 12 is lower than the desired wave by Y (dB).
When the spectrum at the point E is reconverted by the converter 13, the spectrum becomes the spectrum of F. In (b), the influence of the wraparound is limited to only the first f ₀ + Δf, and the response at the point B is omitted because the component of the second f ₀ + 2Δf is extremely small.
[0009]
However, when the amount of wraparound further increases (the value of β decreases), the result becomes as shown in FIG. FIG. 6C shows a case where G is the gain of the relay amplifying device, L is an attenuation amount of a frequency component equal to or higher than f _IF + Δf of the IF filter 12, and β is a wraparound amount, and G + L + β = 0. As shown, when each block has an infinite linearity, the number of loops increases, and the loop wave oscillates at the same output level as the desired wave and is offset to infinity every Δf.
Conversely, the frequency conversion type relay amplifying apparatus shows that abnormal oscillation is unlikely to occur by the amount of attenuation L of the IF filter even if the amount of loopback β increases.
[0010]
The frequency conversion type relay amplification apparatus, as shown in FIG. 4, since the originally transmitted by shifting the frequencies F ₁ space wave towards low as -.DELTA.f, shifted to the higher + Delta] f in the relay amplifier 6 converting the original same F ₁ and wave.
[0011]
[Problems to be solved by the invention]
However, in the above-mentioned conventional frequency conversion type relay amplifying device, the amount of wraparound between the antennas is changed due to a change in the situation at the installation site or a change in the surrounding environment during the operation after the installation, so that the estimated value at the time of design or the When the value exceeds the time value, there is a very serious problem in that the increase in the amount of wraparound causes spurious emission to interfere with the own system and other systems.
[0012]
SUMMARY OF THE INVENTION An object of the present invention is to quickly detect abnormalities when the amount of wraparound between antennas of a frequency conversion type relay amplifying device increases from an estimated value at design time or a value at installation (initial value) due to a change in local conditions. It is an object of the present invention to provide a frequency conversion type relay amplifying device which can detect an alarm and generate an alarm or reduce an amplification gain of a system to suppress an abnormality.
[0013]
[Means for Solving the Problems]
The frequency conversion type relay amplifying device of the present invention is installed near a blind spot where radio waves from the base station do not reach, has an antenna for the base station and an antenna for the mobile station, and receives a signal from the base station and a signal from the mobile station. moving each frequency f ₀ of the received signal of intermediate frequency f _iF in increased conversion to only higher or lower frequency f ₀ + Delta] f or f ₀ -.DELTA.f predetermined frequency Delta] f from the received frequency after selecting amplified reduced conversion In a frequency conversion type relay amplifying device to be transmitted to a station and a base station,
A variable attenuator that is inserted and connected to a preceding stage, a middle stage, or a succeeding stage of the relay amplifying device and changes an amplification gain of the relay amplifying device by changing an amount of attenuation according to an input control signal;
The wraparound signal component of the transmission frequency f ₀ + Δf or f ₀ −Δf due to the coupling between the mobile station antenna and the base station antenna is down-converted into a wraparound signal component of f _IF + Δf or f _IF −Δf. , the transformed loop signal component has already passed through the IF filter together with the intermediate frequency f _IF, which is converted, the echo signal component branch output of the signal passed through the IF filter f _IF + Delta] f or f _IF -.DELTA.f only amplification is extracted selected is passed through a BPF passing is detected, the level of the echo signal component sends an alarm indicating that the wraparound amount becomes greater when exceeding a first predetermined value, the When the level of the sneak signal component is further higher than the first specified value and exceeds a second specified value indicating a level at which spurious emission interferes with others. A wraparound amount detection unit that outputs a signal for increasing the attenuation of the variable attenuator as the control signal and controls the amplification gain of the relay amplifying device to be low. is there.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a block diagram showing a first embodiment of the present invention. However, only a one-way system is shown. The same parts as those in the conventional example of FIG. 5 are denoted by the same reference numerals. In the figure, reference numeral 20 denotes a wraparound amount detection unit, 21 denotes a wraparound wave detection filter, 22 denotes an amplifier, 23 denotes a detector, and 30 denotes a variable attenuator.
[0015]
The wraparound amount detection unit 20 detects the wraparound component ( _fIF + Δf) of the interference wave, and when the ( _fIF + Δf) component is larger than a specified value, the attenuation amount of the variable attenuator 30 is set to be equal to or smaller than the specified value. Increase the gain of the relay amplifier.
The filter 21 of the detection unit 20 in FIG. 1 passes only the signal of (f _IF + Δf), that is, only the sneaking interference wave. The output is amplified to a required level by the amplifier 22 and detected by the detector 23 to control the variable attenuator 30. The same applies to the case of f _IF −Δf.
[0016]
The insertion position of the variable attenuator 30 is on the input side (front stage) of the relay amplifying device in FIG. 1, but may be inserted into either the middle stage or the rear stage of the system depending on the required characteristics of the relay amplifying device.
[0017]
For example, if the variable attenuator 30 is inserted on the input side, the NF (noise figure) is degraded, but the output Ip (intercept point) indicating the linearity capability of the amplifier is not changed.
If the variable attenuator 30 is provided on the output side, the output Ip is deteriorated, but the NF is not changed.
Further, if the variable attenuator 30 is inserted in the intermediate stage, the NF and the output Ip both require a little deterioration.
[0018]
FIG. 2 is a block diagram illustrating a detection unit according to a second embodiment of the present invention. However, it is not limited to this.
The wraparound amount detection unit 20 ′ shown in FIG. 2 converts the output of the detector 23 into a digital amount by the A / D converter 24, controls the variable attenuator 30 from the digital processor 25, and outputs, for example, an alarm. It performs complicated control such as sending and abnormality recovery conditions.
[0019]
FIG. 3 is a block diagram showing a third embodiment of the present invention. This example is a method of converting a frequency of a signal containing the extracted loop signal component from the output of the preamplifier 10 before conversion into an intermediate frequency to an intermediate frequency F _IF, apart from the desired signal system, converter 31 Then, the extracted wave is down-converted by the VCO 32 and the interference wave F _IF + Δf included therein is selected by the filter 21. Except for the center frequency (F _IF + Δf) of the filter 21 of the detection unit 20, it is the same as the first embodiment of FIG.
[0020]
The frequency conversion type relay amplifying device of the present invention lowers the gain when the amount of wraparound increases, so that the relay area in the blind spot 7 in FIG. And it is unavoidable to eliminate interference with others.
[0021]
In addition, if the wraparound amount detection unit 20 of FIGS. 1, 2 and 3 sets a level that does not cause interference with others as a threshold value and makes a determination, the wraparound before lowering the gain of the relay amplifying device is determined. The amount can be determined and an alarm can be issued. However, since a specific circuit can be easily realized, the illustration is omitted.
[0022]
In the first to third embodiments of the present invention described above, only the downlink relay amplification section from the base station to the mobile station is shown and described, but the uplink relay amplification section from the mobile station to the base station is described. The same effect can be obtained by applying the present invention.
Actually, for example, when the gain of the uplink system and the gain of the downlink system are different, the present invention is preferably applied to only one system, such as the distance between the base station and the relay amplifier, the width of the dead zone, that is, the distance between the mobile unit. Thereby, the present invention can be applied to a one-way system, the present invention can be applied to a two-way system, and can be applied according to the local situation.
[0023]
【The invention's effect】
As described in detail above, the frequency conversion type relay system is a system that can perform the relay operation even if there is a wraparound between the antennas originally.However, if the amount of wraparound changes due to the surrounding environment, other spurious emission Therefore, by implementing the present invention, an interfering wave can be detected in advance, and the gain of the relay amplifier can be reduced, which is an excellent effect in practical use.
Furthermore, since the amount of wraparound can be detected in the present invention, an alarm indicating that the amount of wraparound is large can be sent in advance before the gain of the relay amplifier is lowered, so that the practical effect is large.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first embodiment of the present invention.
FIG. 2 is a block diagram showing a second embodiment of the present invention.
FIG. 3 is a block diagram showing a third embodiment of the present invention.
FIG. 4 is a schematic diagram of a system to which the present invention is applied.
FIG. 5 is a block diagram of a conventional relay amplifying device.
6 is a frequency spectrum of each part of the relay amplification device of FIG.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 Base station 2 Base station frequency converter 3 Base station antenna 4 Antenna for base station of relay apparatus 5 Antenna for mobile station of relay apparatus 6 Relay amplifying apparatus 7 Dead area 10, 15 Amplifier 11, 13 Frequency converter 12 IF filter 14 Filter 16,17 VCO
18 β circuit 20, 20 ′ Sneak amount detector 21 BPF
22 amplifier 23 detector 24 A / D converter 25 digital processor 30 variable attenuator 31 frequency converter 32 VCO

Claims (2)

It is installed near a blind spot where radio waves from the base station do not reach, has an antenna for the base station and an antenna for the mobile station, and sets each frequency f ₀ of the received signal from the base station and the received signal from the mobile station to an intermediate frequency. frequency conversion to be sent to the mobile station and the base station f _iF to increased conversion only higher or lower frequency f ₀ + Delta] f or f ₀ -.DELTA.f predetermined frequency Delta] f from the received frequency after selecting amplified reduced conversion Type repeater
A variable attenuator that is inserted and connected to a front stage, a middle stage, or a rear stage of the relay amplifying device, and changes an amount of attenuation according to an input control signal, thereby changing an amplification gain of the relay amplifying device,
The sneak signal component of the transmission frequency f ₀ + Δf or f ₀ −Δf due to coupling between the mobile station antenna and the base station antenna is down-converted to a sneak signal component of f _IF + Δf or f _IF −Δf. , the transformed loop signal component has already passed through the IF filter together with the intermediate frequency f _IF, which is converted, the echo signal component branch output of the signal passed through the IF filter f _IF + Delta] f or f _IF -.DELTA.f only the extracted selected is passed through a BPF passing amplified, detection, frequency transformation type relay amplification apparatus characterized by being configured to detect the echo signal. It is installed near a blind spot where radio waves from the base station do not reach, has an antenna for the base station and an antenna for the mobile station, and each frequency f of the received signal from the base station and the received signal from the mobile station ₀ Is the intermediate frequency f _IF And then selectively amplify, and then increase or decrease the frequency f by a predetermined frequency Δf from the reception frequency. ₀ + Δf or f ₀ In a frequency conversion type relay amplifying apparatus which converts the signal to -Δf and sends it to the mobile station and the base station,
  A variable attenuator that is inserted and connected to a preceding stage, a middle stage, or a succeeding stage of the relay amplifying device and changes an amplification gain of the relay amplifying device by changing an amount of attenuation according to an input control signal;
  The transmission frequency f due to coupling between the mobile station antenna and the base station antenna ₀ + Δf or f ₀ The wraparound signal component of −Δf is represented by f _IF + Δf or f _IF -Δf is converted to a sneak signal component, and the converted sneak signal component is converted to the intermediate frequency f. _IF At the same time, the signal passes through the IF filter, and the branched output of the signal passing through the IF filter becomes the sneak signal component f _IF + Δf or f _IF The signal is extracted, selected, amplified and detected by passing through a BPF that passes only -Δf, and when the level of the wraparound signal component exceeds a first specified value, an alarm is transmitted to notify that the wraparound amount has increased. And increasing the attenuation of the variable attenuator when the level of the sneak signal component becomes larger than the first specified value and exceeds a second specified value indicating a level at which spurious emission interferes with others. And a wraparound amount detection unit for controlling the amplification gain of the relay amplifying device to be lower by outputting a signal for the same as the control signal.

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