JPH0661902A - Radio repeating amplifier - Google Patents

Abstract

PURPOSE:To reduce the size and the cost of a radio repeating amplifier for blind zone which is used in a mobile telephone system of an operating frequency band including the inhibited frequency bands in both up and down circuits. CONSTITUTION:Filter parts 5 and 6 contain the BPF 53/54 and 63/64 of characteristics Fd and FD which can transmit the bands fa and f1 set at both sides of an inhibited band fA. Then both parts 5 and 6 are connected to a down circuit through the positions between the antenna sharing units 1 and 2 and a down amplifier 3. Meanwhile the filter parts 7 and 8 which contain the BPF 73/74 and 83/84 having the characteristics Fe and FE equal to the characteristics Fd and FD are connected to an UP circuit. As a result, the relative band width of the BPF is reduced and the sufficient mutual attenuation is secured between the up and down circuits. Therefore even an inexpensive BPF of the small degree suffices.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless relay amplifying device used as a countermeasure for a dead zone of a car telephone system.

[0002]

2. Description of the Related Art For example, in a 900 MHz band mobile telephone system, a downlink frequency band transmitted from a base station to a mobile station and an uplink frequency band transmitted from a mobile station to a base station are spaced at predetermined intervals. Have been assigned. FIG. 3A is an explanatory diagram showing conventional frequency band allocation, where f ₁ represents a downlink frequency band allocated to a base station and f ₂ represents an uplink frequency band allocated to a mobile station. In such a car telephone system, in order to cope with the increase in the number of subscribers accompanying the spread of car telephones, the service zone is divided to improve the frequency usage rate, but the number of subscribers tends to increase. Therefore, there is no choice but to widen the allocated frequency band in FIG. When the allocated frequency band is widened, it is preferable that the upstream band and the downstream band can be continuously widened. However, since the adjacent frequency band is already allocated to another communication system for operation, as shown in FIG. Up and down are separated by f _A and f _B , respectively.
Frequency bands of _a and f _b are assigned.

[0003] A wireless relay amplifier for use in a dead zone countermeasure for a car telephone system that uses the frequency band set in this manner sets the prohibited bands f _A and f _B of the upstream _and downstream frequency bands. It needs to be removed and amplified.
FIG. 4 is a block diagram of a conventional wireless relay amplification device,
Reference numerals 1 and 2 are antenna duplexers, and 3 and 4 are downlink amplifiers and uplink amplifiers, respectively. Description will be given below with reference to the filter characteristics shown in FIG. Reference numerals 11 and 14 denote wideband bandpass filters (BPF) for the downlink, which are shown in FIG.
Characteristic of F ₁ of Eq. ₁ , that is, pass band width BW = f _a + f _A + f
_{It is 1} BPF. Reference numerals 12 and 13 denote band elimination filters (BE) that remove the response in the prohibited band f _A.
F), which has the characteristic of E ₁ shown by the broken line in FIG. Similarly, 15 to 18 are upstream filters, and 15 and 18 are pass band widths BW = f _b + f _B + f _2.
BPF, and has the characteristic F ₂ shown in FIG. Further, 16 and 17 are BEFs (characteristic E ₂ ) having a stop band width f _B.

[0004]

In such a wireless relay amplifying device, since the down amplifier 3 and the up amplifier 4 are connected in a loop through the antenna duplexers 1 and 2, the oscillating state causes oscillation. There is danger. Therefore, it is necessary to sufficiently increase the amount of attenuation of the BPF for the uplink and the BPF for the downlink with respect to each other's passbands. There was no problem if the interval between the downlink frequency band f ₁ and the uplink frequency band f ₂ was sufficiently separated as shown in FIG. 3A, but the frequency band was added as described above. Going up
When the downlink frequency interval becomes narrower as f _{C in} FIG. 3B, for example, the pass band width of the BPF for the uplink is widened from f ₂ to f _b + f _B + f ₂ and the attenuation gradient is made steep. The characteristic F ₂ must be realized. This causes a problem that the order of the filter is high, the cost becomes high, and the cost of the apparatus increases. An object of the present invention is to solve the above problems, and to provide a wireless relay amplifying device which suppresses an increase in filter price and reduces the price of the entire device.

[0005]

In the wireless relay amplifying apparatus of the present invention, frequency bands including a prohibited band are allocated in the middle as frequency bands of downlink and uplink between a base station and a mobile station. Use of the downlink frequency band inserted and connected on both sides of a downlink amplifier that amplifies the downlink signal between the base station antenna duplexer and the mobile station antenna duplexer to relay and amplify bidirectional radio waves Two downlink filter units each including a first BPF and a second BPF that pass the allocated frequency bands above and below the forbidden frequency band, and the uplink between the base station antenna duplexer and the mobile station antenna duplexer. A third BP that passes the allocated frequency bands above and below the prohibited frequency band of the upstream frequency bands inserted and connected on both sides of the upstream amplifier for amplifying the line signal When it is characterized in that a fourth two uplink filter unit consisting of BPF. Further, each of the filter units on the reception input side of each of the two downlink filter units and the two uplink filter units has a level of a signal that passes through the allocated frequency band above and below the prohibited frequency band on the output side of each BPF. It is characterized in that a variable gain amplifying means for adjusting the above is provided.

[0006]

1 is a block diagram (A), a frequency band diagram (B) and a filter characteristic diagram (C) showing a first embodiment of the present invention. In the figure, reference numerals 1, 2 and 3 and 4 denote the same antenna duplexer, downlink amplifier and uplink amplifier as in the conventional case of FIG. 5, 6 are downlink filter units, 7, 8
Is an upstream filter unit. 53 and 63 in the downlink filter 5,6 is the BPF characteristic F _d having a pass band width f _a, as shown in FIG. (C), 54,6
Reference numeral 4 is a BPF having a characteristic F _D having a pass band width f ₁ .
Similarly, 73, 83 in the upstream filter units 7, 8
Is the BPF of characteristic F _e with passband width f _b , 7
Reference numerals 4 and 84 are BPFs of F _E having a pass band width f ₂ . 51, 52, 61, 62, 71, 7 of each filter section
Reference numerals 2, 81 and 82 are duplexers for separating and combining two types of filters. The BPF having the characteristic shown in FIG.
Compared with the conventional BPF shown in FIG. 3C, the passband width is narrower, and the detuning frequency up to the other frequency band with a frequency interval f _C is large. The order is small. Therefore, the cost of the filter is reduced _, which is extremely effective for downsizing the device and reducing _the cost.

FIG. 2 is a partial block diagram of the second embodiment of the present invention, in which the filter parts 5 and 7 in the embodiment of FIG.
10 shows another embodiment of the above. In the figure, 51,5
3, 54 are the same as in the case of FIG. 55 and 56 are amplifiers, 57 and 58 are variable attenuators, and 59 is a combiner. The four types of BPFs in the above-described first embodiment have different characteristics from each other, and variations in input loss cause variations in the gain at each frequency from the input to the output of the relay amplifier. In order to correct this variation, an amplifier and a variable attenuator are provided at one position for each frequency to adjust the gain at each frequency. In addition, the amplifiers 55 and 56
Compensates for the loss of the attenuators 57 and 58 and the combiner 59 having a loss of about 6 dB, and the NF (noise figure) of the filter unit 5 is
Functions so that it does not deteriorate significantly.

[0008]

As described above in detail, by implementing the present invention, the cost reduction of the wireless relay amplification device for the dead zone countermeasure of the car telephone system in which the operating frequency band including the prohibited frequency band is widened is achieved. And it is extremely effective in miniaturization.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention and a filter characteristic example diagram.

FIG. 2 is a partial block diagram showing a second embodiment of the present invention.

FIG. 3 is a conventional frequency allocation explanatory diagram and a filter characteristic example diagram.

FIG. 4 is a block diagram of a conventional device.

[Explanation of symbols]

1, 2 Antenna duplexer 3, 4 Amplifier 11, 14, 15, 18 BPF 12, 13, 16, 17 BEF 5, 6, 7, 8 Filter section 51, 52, 61, 62, 71, 72, 81, 82 Duplexer 53, 54, 63, 64, 73, 74, 83, 84 B
PF 55,56 Amplifier 57,58 Variable attenuator 59 Combiner

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Michio Norioka, 2-13-13 Toranomon, Minato-ku, Tokyo Within Kokusai Electric Co., Ltd. (72) Hiroshi Noguchi 2-3-13 Toranomon, Minato-ku, Tokyo International Electric Co., Ltd. (72) Inventor Toshihiko Hamada 2-3-3 Toranomon, Minato-ku, Tokyo International Electric Co., Ltd.

Claims (2)

[Claims] 1. A base station side for relaying and amplifying bidirectional radio waves in which frequency bands including a prohibited band are allocated in the middle as frequency bands of downlink and uplink between a base station and a mobile station. Of the downlink frequency bands inserted and connected on both sides of the downlink amplifier for amplifying the downlink signal between the antenna duplexer and the mobile station side antenna duplexer, pass the allocated frequency bands above and below the prohibited frequency band. Two downlink filter sections consisting of a first BPF and a second BPF, and an uplink amplifier for amplifying an uplink signal between the base station antenna duplexer and the mobile station antenna duplexer are inserted and connected on both sides. In addition, two uplink line filters each including a third BPF and a fourth BPF that pass the allocated frequency bands above and below the prohibited frequency band of the above-mentioned uplink frequency band. Wireless relay amplification apparatus that includes a data portion. 2. The two downlink filter sections and the two uplink filter sections according to claim 1, wherein each of the filter sections on the reception input side has an assigned frequency above and below the prohibited frequency band on the output side of each BPF. 2. The wireless relay amplifying device according to claim 1, further comprising variable gain amplifying means for adjusting the level of a signal passing through the band.