JP3916894B2 - Radio base station adaptive array antenna transceiver apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transmitting / receiving apparatus for an adaptive array antenna of a wireless base station, which is used for a wireless communication base station and is reduced in size, power consumption, and installation.
[0002]
[Prior art]
FIG. 5 shows a configuration of a conventional base station device for radio communication for an array antenna (one transmission / reception system).
A radio communication base station apparatus includes a modulation apparatus 3 and a demodulation apparatus 14 installed in a base station building, a duplexer 2 installed outdoors, and a tower-mounted front end composed of a low-noise receiving amplifier 10. The antenna 1 is configured. The modulation device 3 and the duplexer 2, and the low noise amplifier 10 and the demodulation device 14 are connected via coaxial cables 5 ′ and 12 ′.
The signal input to the modulation device 3 is modulated, and the amplified RF signal is transmitted from the antenna 1 through the coaxial cable 5 ′ and the duplexer 2. The signal received by the antenna 1 is amplified by the low-noise receiving amplifier 10 through the duplexer 2 and input to the demodulator 14 through the coaxial cable 12 ′. The demodulator 14 demodulates the received signal and outputs the demodulated electrical signal.
[0003]
In addition, increasing the capacity of wireless communication systems using adaptive array antennas is being studied. The adaptive array antenna can suppress the beam by directing a null (zero point) with respect to the arrival direction of the interference wave, and can form a beam with respect to the arrival direction of the desired wave. For this reason, compared with the beam pattern by the conventional omni antenna or a sector antenna, the capacity | capacitance of a wireless communication system can be enlarged.
(1) In order to realize an adaptive array antenna, radio circuits of transmission systems and reception systems corresponding to the number of antenna elements are required. Further, in the wiring from the base station building to the antenna, high frequency (coaxial) cables corresponding to the number of antenna elements are required.
As described above, when a conventional omni antenna or sector antenna radio apparatus is applied to an adaptive array antenna, there are restrictions on mechanical conditions such as weight and volume when the antenna apparatus is installed on an existing antenna tower.
(2) In an adaptive array antenna radio apparatus, it is generally necessary to make the electrical lengths of the transmission systems the same. If there is an error in the electrical length of each system in the transmission system, the error is an error between the designed beam pattern and the actually radiated beam pattern. An error in the beam pattern is, for example, a null or a change in the position of the beam, and it becomes impossible to achieve the subscriber capacity as designed in the wireless system.
[0004]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to provide an array antenna transmission / reception device that is used in a base station device for radio communication for an array antenna and that can be installed on an antenna tower. In addition, in order to form a designed beam pattern, the electrical length of each system can be easily adjusted.
[0005]
[Means for Solving the Problems]
An array antenna transmission / reception device according to the present invention is an array antenna transmission / reception device having N (N is a natural number) transmission system and reception system,
The transmission system multiplexes electrical signals corresponding to N-system radio signals, converts them into optical signals, and outputs them to one transmission-side optical fiber, and the one transmission-side light. An optical signal transmitted through a fiber is converted into an electrical signal, and a transmission-side optical / electrical conversion circuit that demultiplexes the converted signal into N systems, and an N-input N-output that receives the electrical signals separated into the N systems With a multi-port amplifier ,
The receiving system multiplexes the N-system received signals amplified by the receiving amplifier and the N-system received signals that have been band-limited, and converts the N-system received signals into optical signals to be converted into one receiving-side optical fiber. A receiving-side electrical / optical converting circuit for outputting, and a receiving-side optical / electrical converting circuit for converting an optical signal transmitted through the receiving-side optical fiber into an electrical signal and demultiplexing the converted signal into N systems. ,
The transmission-side optical / electrical conversion circuit, the multi-port amplifier, the reception amplifier, and the reception-side electrical / optical conversion circuit are housed in the same housing as an RF transmission / reception circuit and installed on an antenna tower directly below the antenna. ,
The N-input N-output multiport amplifier has an input-side hybrid network, a plurality of feed-forward amplifiers, and an output-side hybrid network connected in cascade, and the electrical length of the delay line of each loop corresponding to the plurality of feed-forward amplifiers. Are identical to each other.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows the configuration of an array antenna transmitting / receiving apparatus according to a first embodiment of the present invention. An RF transmission / reception circuit including a duplexer 2, a multi-port amplifier 7, an optical / electrical conversion circuit 6 and the like is installed in an antenna tower immediately below the antenna, and a modulation device 3 and an electric / optical conversion circuit 4 are installed in the base station building. Etc. are installed.
[0007]
(Transmission system)
In the transmission / reception circuit , the RF signal from the modulation device 3 is converted into an optical signal by the electric / optical conversion circuit 4 in the base station building, and the converted optical signal is transmitted through the optical fiber 5. An optical / electrical conversion circuit 6 of the RF transmission / reception circuit converts the transmitted optical signal into an electrical signal.
The optical fiber 5 uses the number of transmission systems (1,..., N, N: natural number).
The RF signal converted into the electrical signal is input to the multiport amplifier 7. Here, it is amplified to a predetermined transmission power. The amplified signal is fed to the antenna 1 via the duplexer 2 and transmitted.
[0008]
(Reception system)
The signal received by the antenna 1 is input to the low noise receiving amplifier 10 of each receiving system (1,..., N) via the duplexer 2 and amplified. The amplified received signal is converted into an optical signal by the electrical / optical conversion circuit 11. The converted optical signal is transmitted to the signal processing device in the base station building through the optical fiber 12 corresponding to each receiving system.
In the base station building, an optical / electrical conversion circuit 13 that converts a transmitted optical signal into an electrical signal and a demodulator 14 that demodulates the converted electrical signal are installed.
[0009]
FIG. 2 shows the configuration of an array antenna transmission / reception apparatus according to the second embodiment of the present invention. The second embodiment is different from the optical transmission circuit of the first embodiment. That is, in the first embodiment, wiring (connection) is performed using N optical fibers for each transmission system and each reception system, but in the second embodiment, electrical signals of each transmission system and each reception system are respectively transmitted. Frequency multiplexing is performed (see FIG. 4). The frequency-multiplexed electric signal is converted into an optical signal by the electric / optical conversion circuit 4 and transmitted through one optical fiber 5. Such a single configuration can solve problems such as deviation due to a plurality of optical fibers and adjustment of the laser diode.
[0010]
FIG. 3 shows a configuration example of an 8-system multiport amplifier.
The multiport amplifier includes an input-side hybrid network 7-1, an individual amplifier (SAFF) 7-2, and an output-side hybrid network 7-3.
In the present invention, a self-adjusting feedforward amplifier using a pilot signal is used as an individual amplifier. The gain deviation and phase deviation between systems in the multi-port amplifier are due to the isolation characteristics of the hybrid network and the dispersion of the individual amplifiers. The isolation characteristics of multi-port amplifiers are shown in the literature (Shun-ichiro Egami, Makoto Kawai, “Multi-terminal power combining multi-beam transmission system” IEICE Transactions B, Vol. J69-B, No. 2, 1986.02) Has been. For example, in the case of 8 systems, if the isolation between systems is 30 dB, it is necessary to realize a multiport amplifier with a gain standard deviation of 0.7 dB or less and a phase standard deviation of 5 deg or less.
Conventionally, in order to reduce the gain deviation and phase deviation of the individual amplifiers to a predetermined value or less, it is necessary to individually adjust each amplifier. Also, there was no effective compensation method for characteristic deviation due to secular change. Thus, it has already been described that the gain deviation and the phase deviation can be easily reduced by using a feedforward amplifier as the individual amplifier. Further, it is known that a self-adjusting feedforward amplifier using a pilot signal can sufficiently reduce a gain deviation and a phase deviation to a predetermined value or less with respect to secular change and temperature change (Japanese Patent Publication No. 7-77330). (See Japanese Patent Application No. 63-23574), Shoichi Takahashi, Toshio Nojima “Ultra Low Distortion Multi-Frequency Common Amplifier SAFF-A for Mobile Communications”, RCS90-4,1990, Technical Report of Radio Communication System Society of IEICE.
[0011]
In this way, by using a self-adjusting feedforward amplifier using a pilot signal for the transmission system as a multiport amplifier, the gain deviation and phase deviation between the systems can always be kept below a predetermined value, and the supply power can be reduced. By achieving a reduction in power consumption by reducing the number of systems to one in comparison with an amplifier having an individual configuration, a small radiating fin or the like can be used, and the apparatus can be miniaturized. In the above description, the self-adjusting feedforward amplifier is used as the individual amplifier of the multi-port amplifier. However, a feedforward amplifier other than the self-adjusting feedforward amplifier can be used in the same manner. These are all effective in installing the array antenna RF circuit in the antenna tower.
Compared with the conventional example shown in FIG. 5, the transmission / reception apparatus according to the present invention enables the transmission power amplifier to be reduced in size and power consumption by a multiport amplifier, and is installed in the base station building and outdoors by optical fiber. Cable wiring is facilitated by connecting an RF transceiver circuit .
[0012]
FIG. 4 shows a configuration example of an optical transmission circuit that performs frequency multiplexing.
The optical transmission circuit includes frequency converters 4-1 and 6-4, a power combiner 4-3, an electric / optical signal converter 4-3, an optical fiber 5, and an optical / electrical signal converter 6-1. And a power distributor 6-2, a band pass filter (BPF) 6-3, and a frequency converter 6-4. The frequency converter is composed of a local oscillator and a mixer.
The transmission system, the frequency converter 4-1 ₁ ～4-1 ₈ by an electric signal of each transmission system (input 1-8), respectively different carrier frequencies (f1 to f8) at a frequency multiplexer of the base station in the building Perform band conversion. The electrical / optical conversion circuit (E / O) 4-3 collectively converts frequency-multiplexed electrical signals into optical signals. The converted optical signal is transmitted through the optical fiber 5.
In this transmission / reception apparatus, optical signals transmitted through the optical fiber 5 are collectively converted into electrical signals by an optical / electrical conversion circuit (O / E) 6-1. The converted electric signal is separated by a band pass filter (BPF) 6-3 having each carrier frequency as a center frequency. Each separated electric signal is converted to the original frequency band by the carrier frequency (f9 to f16) by the frequency converter 6-4 to obtain outputs 1 to 8. Since the reception system is the same as the transmission system, description thereof is omitted.
In this manner, the number of optical fibers required in the first embodiment can be two. According to the second embodiment, the installation property of the RF transmission / reception circuit to the antenna tower is further improved.
[0013]
In the second embodiment, the transmission signals of the respective transmission systems are frequency-multiplexed. Similarly, it can be combined with known multiplexing techniques such as wavelength multiplexing, time multiplexing, and code multiplexing.
This transmission / reception apparatus can be used as an RF circuit of a radio apparatus using an array antenna system such as an array antenna for multi-beams as well as an adaptive array antenna.
[0014]
【The invention's effect】
As described above, the present invention has the following effects.
(1) Compared with a conventional adaptive array antenna radio apparatus, it is possible to reduce the size, reduce the power consumption, and improve the installation property.
(2) The RF transmission / reception circuit can be easily installed on the antenna tower.
(3) Compared with a conventional adaptive array antenna radio apparatus, the scale of the radio apparatus can be reduced.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an array antenna transmission / reception apparatus according to a first embodiment of the present invention;
FIG. 2 is a configuration diagram of an array antenna transmission / reception apparatus according to a second embodiment of the present invention;
FIG. 3 is a configuration diagram of an 8-system multiport amplifier.
FIG. 4 is a configuration diagram of a frequency multiplexing optical transmission circuit.
FIG. 5 is a configuration diagram of a conventional array antenna transmission / reception system.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Antenna 2 Duplexer 3 Modulator 4, 4-3, 11 Electricity / optical conversion circuit 4-1, 6-4 Frequency converter 4-2 Power combiner 5, 12 Optical fiber 6, 6-1 13 Light / Electric conversion circuit 6-2 Power distributor 6-3 BPF
7 Multi-port amplifier 7-1 Input side hybrid network 7-2 Feed forward amplifier 7-3 Output side hybrid network 10 Low noise receiving amplifier 14 Demodulator

Claims (1)

N (where N is a natural number) a transmission / reception device for an adaptive array antenna of a radio base station having a transmission system and a reception system,
The transmission system multiplexes electrical signals corresponding to N-system radio signals, converts them into optical signals, and outputs them to one transmission side optical fiber, and the one transmission side light. A transmission-side optical / electrical conversion circuit that converts an optical signal transmitted through a fiber into an electric signal, and demultiplexes the converted signal into N systems in the original frequency band by independent signals of different frequencies; passing the amplified separated electrical signals, and a multi-port amplifier you output an electric signal separated into N systems N inputs N outputs, the transmission band in the output electrical signal of the multiport amplifier of the N-input N-output And a transmission filter that feeds N antennas,
The reception system is a reception filter that passes N desired reception bands from signals received by the N antennas, a reception amplifier that amplifies the band-limited N reception signals, and is amplified by the reception amplifier. Multiplex N-system received signals, convert them to optical signals, output to one receiving-side optical fiber, and convert the optical signals transmitted on the receiving-side optical fiber into electrical signals And a receiving side optical / electrical conversion circuit that demultiplexes the converted signal into N systems with independent signals of different frequencies ,
The transmission-side optical / electrical conversion circuit, the multiport amplifier, the transmission filter, the reception filter, the reception amplifier, and the reception-side electrical / optical conversion circuit are housed in the same housing as an RF transmission / reception circuit. Installed on the antenna tower directly below,
The N-input N-output multiport amplifier has an input-side hybrid network, a plurality of feed-forward amplifiers, and an output-side hybrid network connected in cascade, and the electrical length of the delay line of each loop corresponding to the plurality of feed-forward amplifiers. Are identical to each other,
A radio base station adaptive array antenna transceiver apparatus.

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