JPH0786996A - Receiver for base station for mobile communication - Google Patents

Abstract

PURPOSE:To receive the radio signals of mobile stations with different frequency bands by one receiver. CONSTITUTION:Antennas 1, 3 receive the radio signal S1 from the mobile station with the same frequency band as the reception frequency band of a base station 9. The radio signal S2 from the mobile station with another frequency band, after being captured by antennas 2, 4, is frequency-converted to a high frequency signal S5 with the same frequency band as that of the radio signal S1. Either the radio signal S1 or the high frequency signal S5 is switched by RF switches 7, 8 controlled by a control signal S4 from a switching control part 96, which goes to the reception signal S6 (S6a, S6b) of the base station 9. The reception signals S6a and S6b are demodulated with a diversity system after being detected by the base station 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving device for a mobile communication base station which is a base station for a car telephone system or the like, and more particularly to a receiving device for a mobile communication base station which employs a diversity reception system after detection.

[0002]

2. Description of the Related Art One of conventional receivers for mobile communication base stations of this type is disclosed in Japanese Unexamined Patent Publication No. Hei 2-97132 (Title of Invention: Diversity Receiver System). This receiving device receives the same radio signal transmitted from a mobile station by two receiving antennas forming space diversity. Radio signals from the two receiving antennas are respectively detected by different receivers to generate demodulated data. here,
The reception levels of the two radio signals are measured, and the demodulated data output by the receiver with the higher reception level is selected as the required data. This diversity reception method is called a post-detection diversity reception method or a selection diversity reception method. Such a diversity reception system after detection is implemented to improve the fading characteristic peculiar to mobile communication.

[0003]

The receiving device of the base station for mobile communication described above receives only the radio signal of one frequency band. However, if a plurality of mobile stations existing in the same zone of the car phone system are not all stations using the same frequency band, the base station needs to receive radio signals in the plurality of frequency bands used by the mobile station. is there. In order to receive the radio signals of the multiple frequency bands, it is necessary to install a receiving device according to the number of reception channels for each of the multiple frequency bands, which causes an increase in equipment cost and installation space of the base station. There was a problem.

[0004]

A mobile communication base station receiver according to the present invention comprises a mobile station that transmits a first radio signal belonging to a first channel group of a first frequency band, and the first station. A plurality of first antennas for receiving radio signals, and detection using the first radio signals from the plurality of first antennas provided for each receivable channel of the first channel group as reception signals In a receiver of a base station for mobile communication, which comprises a receiver of a rear diversity reception system, a second radio signal from a mobile station transmitting a second radio signal belonging to a second channel group of a second frequency band. The same number of second antennas as the first antennas,
Corresponding to each of the second antennas and the corresponding frequency conversion unit for frequency-converting the second radio signal from the antenna of the first channel group into the high-frequency signal of the first channel group. A high-frequency switch that is provided as a switch to switch one of the first wireless signal and the high-frequency signal from the first antenna to the received signal,
And a switching control unit that controls switching of the high-frequency switch.

One of the receiving devices of the mobile communication base station can adopt a configuration in which two first antennas and two second antennas are provided.

Further, in another one of the receiving devices of the mobile communication base station, the frequency converter is arranged outdoors and is supplied with power from an indoor device housing the receiver by a coaxial cable. Can be taken.

[0007]

The present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention. Further, FIG. 2 is a frequency allocation diagram of main signals in the present embodiment.

First, referring to FIGS. 1 and 2, the receiving device of the mobile communication base station will be described. The base station device of FIG. 1 is a digital car telephone system standard (a standard operating in Japan). RCR STD-27D,
A radio station S1 (S1a and S1b) in the first frequency band is received by a receiving antenna 1 and a receiving antenna 3 from a mobile station (not shown) of a car telephone system by a foundation (issued by the Radio System Development Center) for diversity reception To do. In addition, the base station device transmits a radio signal S2 (S2a and S2b) of a second frequency band different from the first frequency band from another mobile station (not shown) to the receiving antenna 2 and the receiving antenna 4. Receive and receive diversity.

The radio signal S1 is included in the 20 MHz band of 940.0 MHz to 960.0 MHz (950 MHz band) and constitutes a channel group of 800 channels (ch) at 25 KHz intervals. The base station 9 has these 800c
A radio signal S1 of a predetermined channel of h is received. On the other hand, the radio signal S2 is included in the 4 MHz band of 1439.0 MHz to 1443.0 MHz (1.4 GHz band) and constitutes a channel group of 80 ch at 25 KHz intervals. The base station 9 receives the radio signal S2 of a predetermined channel of these 80 channels.

The frequency conversion unit 5 receives 1 from the receiving antenna 2.
The frequency of the radio signal S2a of 439.0 MHz to 1443.0 MHz is converted into the high frequency signal S5a of 940.0 MHz to 944.0 MHz. Similarly, the frequency conversion unit 6 receives the radio signal S2b of 1439.0 MHz to 1443.0 MHz from the receiving antenna 4 by 940.0 M.
The frequency is converted into a high frequency signal S5b of Hz to 944.0 MHz.

Radio signal S1a and high frequency signal 2a
Is a high frequency (RF) controlled by the switching control signal S4
Either one of the signals is selected by the switch 7 and supplied to the reception terminal 901 of the base station 9 as the reception signal S6a. Similarly, the radio signal S1a and the high frequency signal 2a
Causes the frequency band in the radio signals S1 and S2 to be RF by the RF switch 8 that is switched in synchronization with the RF switch 7.
The same signal as the signal selected by the switch 7 is selected, and this selected signal is supplied to the reception terminal 902 of the base station 9 as the reception signal S6b.

The base station 9 receives the reception signal S6a of the same channel.
And S6b are detected after diversity reception and demodulated data S
96 (S96a, S96b, ..., S96n).
The base station 9 uses the demodulation data S96 whose communication quality has been improved by this diversity reception to execute a call connection and a call between the mobile station and an exchange (not shown) connected via the terminal 905. And control.

Next, the transmitter of this base station device will be described. The base station 9 of FIG.
The radio signal S3 is transmitted to the mobile station belonging to this mobile communication system via the transmission terminal 903 and the transmission antenna 10 using the transmission channel paired with 2. This radio signal S
3 includes signals in the first frequency band and the second frequency band.

The base station 9 is housed indoors, and the frequency converters 5 and 6 are arranged near the receiving antennas 2 and 4 installed outdoors to avoid an increase in received noise. Further, between the receiving antenna 1 and the RF switch 7, R
Between the F switch 7 and the base station 9, between the receiving antenna 2 and the frequency converter 5, between the frequency converter 5 and the RF switch 5, between the receiving antenna 3 and the RF switch 8, and between the RF switch 8 and Coaxial cables connect the base station 9, the receiving antenna 4 and the frequency conversion unit 6, the frequency conversion unit 6 and the RF switch 8, and the base station 9 and the transmission antenna 10. .

Next, the base station 9 will be described in detail.

The reception signal S supplied from the reception terminal 901
6a includes n (n is an integer) received signals S91 (S91a, S91b, ..., S) by a hybrid (HYB) 92 connected via a DC blocking capacitor C91.
91n). These received signals S91a, S9
1b, ..., S91n are n transceivers (TRX) 95.
(95a, 95b, ..., 95n), respectively. Each of the transceivers 95 receives the reception signal S91 of a channel that is different from each other and is predetermined. That is, the base station 9 can receive the n-channel radio signal S1. Similarly, the reception signal S6b supplied from the reception terminal 902 is received by n (S92a, S92b, ..., S92n) reception signals S92 by the hybrid (HYB) 93 connected through the DC blocking capacitor C92.
Will be distributed to. These received signals S92a, S92b,
..., S92n also includes n transceivers (TRX) 95 (95
a, 95b, ..., 95n), respectively.

The transmitter / receiver 95 has two series of receiving circuits and separately receives and demodulates the received signals S91 and S92. Further, the transmitter / receiver 95 uses the two received signals S91.
Then, the reception levels of S92 and S92 are measured, and the post-detection diversity reception for selecting the demodulated data from the reception circuit which has received the reception signal having the high reception level is executed. This selected demodulated data is sent to the transceiver 95 (95a, 9a
5b, ..., 95n) demodulated data S94 (S94a, S)
, 94b, ..., S94n). The control unit 97 uses the demodulated data S94 to control the transmitter / receiver 95, control the call with the exchange, and control the connection.

Transceiver 95 (95a, 95b, ..., 95)
Each of n) also transmits the transmission signal S93 to the mobile station.
(S93a, S93b, ..., S93n) are generated. The transmission signal S93 from the transmitter 95 is signal-coupled by the hybrid (HYB) 94 and supplied to the transmission terminal 903.

The switching control unit 96 simultaneously supplies the switching control signal S4 to the control terminals of the RF switches 7 and 8 via the switching control terminal 904. Then, the RF switches 7 and 8 select either the radio signal S1 (S1a and S1b) side or the high-frequency signal S5 (S5a and S5b) side, and supply them to the base station 9. The power supply (PS) 91 supplies the DC power P1 to the choke coil L91, the receiving terminal 901,
It is supplied to the frequency conversion unit 5 via the RF switch 7 and the coaxial cable for connection, and the DC power P1 is supplied to the frequency conversion unit 6 via the choke coil L92, the receiving terminal 902, the RF switch 8 and the coaxial cable for connection. Supply to.

The receiver of FIG. 1 is particularly useful for adding a receiving channel of a mobile communication base station. That is, 9
For 50MHz band (first frequency band) and 1.4GHz
In a mobile communication base station that is already equipped with both receiving devices for the band (second frequency band), if the receiving device of FIG. 1 is added, this receiving device gives priority to a radio signal in a frequency band with a large call volume. Since switching reception is possible, there is an advantage that the number of additional reception channels (the number of transceivers 95 of the base station 9) can be reduced.

FIG. 3 shows the frequency converter 5 used in this embodiment.
It is a detailed block diagram of (6).

The preamplifier 51 of the frequency converter 5 receives the radio signal S2 (S2a) of the frequency f1 received from the terminal 501.
Is amplified with low noise to generate a radio signal S51. This radio signal S51 is frequency-mixed with the local oscillation signal S52 of the frequency f _L from the local oscillator 52 by the reception frequency converter 53, and the high frequency signal S of the frequency fr = (f1−f _L ).
The frequency is converted to 53. Now, assuming that the frequency f _L of the local oscillation signal S52 is 499.0 MHz, the radio signal S2
Of the frequency f1 of 1,439,0 MHz (first channel of the second frequency band), the frequency fr of the high-frequency signal S53 is 940.0 MHZ (first c of the first frequency band).
h). In this way, the frequency converter 53 performs frequency band conversion of the reception frequency band of this mobile communication system.
The high frequency signal S53 is subjected to noise and spurious reduction by the band pass filter 54 having a bandwidth slightly wider than 4 MHz, and further the direct current blocking capacitor C51.
Via the terminal 502 as a high frequency signal S5 (S5a)
Is output to.

A DC power P1 is supplied to the terminal 502, and the DC power P1 is supplied to the local oscillator 52 and the preamplifier 51 as a power source through the choke coil L1. Since the frequency converter 5 is installed outdoors and is subject to large temperature fluctuations, the local oscillator 5
2 uses a crystal oscillator with high frequency stability as a source oscillator.

[0025]

As described above, according to the present invention, one base station commonly receives the first radio signal in the first frequency band and the second radio signal in the second frequency band. In addition to the base station that receives the signal in the first frequency band, a frequency conversion unit that frequency-converts the second radio signal in the second frequency band into a high frequency signal in the same frequency band as the first frequency band. Is provided, and either the first radio signal or the high-frequency signal is switched / selected by a high-frequency switch to be a reception signal of the base station. Therefore, a base station is installed for each frequency band of the radio signal to be received. Therefore, there is an effect that the equipment cost of the base station can be reduced and the installation space can be saved.

The receiving device of the mobile communication base station according to the present invention, in particular, responds to a request for increasing the number of receiving channels in a base station device which is already equipped with receiving equipment for a plurality of frequency bands.
There is an advantage that the number of receivers to be added is small.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a frequency allocation diagram of main signals in the present embodiment.

FIG. 3 is a detailed block diagram of a frequency conversion unit used in the base station apparatus of this embodiment.

[Explanation of symbols]

1-4 reception antennas 5,6 frequency conversion unit 7,8 radio frequency (RF) switch 9 base station 10 transmission antenna 51 preamplifier 52 local oscillator 53 reception frequency converter 54 band pass filter 501,502 terminal 91 power supply 92 ~ 94 Hybrid (HYB) 95 (95a, 95b, ..., 95n) Transceiver (T
RX) 96 switching control section 97 control section 901,902 receiving terminal 903 transmitting terminal 904 switching control terminal 905 terminal C51, C91, C92 capacitor L51, L91, L92 choke coil

Claims (3)

[Claims] 1. A plurality of first antennas for receiving the first radio signal from a mobile station that transmits a first radio signal belonging to a first channel group in a first frequency band, and the first channel. Reception of a mobile communication base station, which is provided for each receivable channel of the group, and includes a receiver of a diversity reception system after detection using the first wireless signal from the plurality of first antennas as a reception signal In the device, the same number of second antennas as the first antennas for receiving the second radio signals from the mobile station transmitting the second radio signals belonging to the second channel group of the second frequency band, A frequency conversion unit corresponding to each of the second antennas for frequency-converting the second radio signal from the second antenna into a high-frequency signal of the first channel group, and for each of the first antennas. Correspondingly provided A high frequency switch for switching one of the first radio signal and the high frequency signal from the first antenna to the received signal, and a switching control unit for switching control of the high frequency switch. A receiving device for a mobile communication base station, comprising: 2. The receiving device for a mobile communication base station according to claim 1, wherein two of the first antenna and two of the second antenna are provided. 3. The frequency converter is arranged outdoors and is supplied with power from an indoor device housing the receiver by a coaxial cable.
A receiving device for a mobile communication base station as described above.