JP3162215B2 - Wireless communication device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication apparatus for optically transmitting a signal between an apparatus main body and an antenna unit, and more particularly to an IF communication apparatus.
The present invention relates to a wireless communication device based on an IF band optical transmission system for transmitting and receiving signals in an (intermediate frequency) band.

[0002]

2. Description of the Related Art In a conventional general radio transmitting apparatus, FIG.
As shown in the (B), and converts the baseband signal into a first intermediate frequency signal by using the first local oscillation frequency f _1,
Further, the first intermediate frequency signal is converted to a second local oscillation frequency f ₂
Is converted into an RF signal (frequency f _RF ) by using, and then sent to the bandpass filter 11, the RF amplifier 12, and the attenuator 13 and transmitted by radio waves.

On the other hand, in recent wireless communication systems such as mobile communication, as shown in FIG. 8, a service area is divided into a plurality of wireless zones (cells), and an antenna unit is installed in each wireless zone. Are transmitted to a centralized base station (corresponding to a group of conventional wireless base stations provided for each wireless zone). In this case, generally, the centralized base station 51 and the antenna unit are connected by an optical fiber, and the centralized base station 51 performs an electric / optical conversion of an RF signal in a radio frequency band and optically transmits the signal to each wireless zone. The optical / electrical conversion is performed by an antenna unit installed in each wireless zone, the RF signal is returned again, and a radio wave is radiated from the antenna. Further, the RF signal received by the antenna unit is optically transmitted to the centralized base station 51 by the above reverse operation. Analog transmission is used for this optical transmission.

[0004]

Since the analog optical transmission system requires considerable linearity, an optical transmission device that has excellent linearity is also required. However, when a transmission signal to be optically transmitted is a high-frequency signal in a radio frequency band, an optical transmission device having good linearity in the radio frequency band is expensive. Therefore, there is a problem that the higher the frequency of the wireless signal to be transmitted, the more expensive the optical transmission device becomes.

Therefore, as shown in FIG.
The transmission signal from the centralized base station is transmitted to the antenna section through the optical fiber at the level of the IF signal in the intermediate frequency band,
The second local oscillation frequency f ₂ is generated independently on the antenna unit side, and the optically transmitted IF signal is converted to the second local oscillation frequency f 2.
₂ , a method of converting to an RF signal and wirelessly transmitting the signal can be considered. However, in this method, although the second local oscillator is required for each antenna of each wireless zone, it is difficult to the oscillation frequency f ₂ of the second local oscillator to exactly the same, therefore each radio zone There is a problem that it is difficult to synchronize the frequency of the RF signal between the antenna units.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object the purpose of performing optical transmission between an apparatus main body and an antenna unit in an IF band while maintaining the I-band of each wireless zone.
The frequency of the F signal can be synchronized, and the band frequency in the linearity required for the optical transmission device can be changed from the RF band to the I band.
It is to lower to F band.

[0007]

FIG. 1 is an explanatory view of the principle according to the present invention. According to one aspect of the present invention, a wireless communication device configured to connect an apparatus main body and an antenna unit via an optical transmission line includes an intermediate frequency signal and a frequency of an intermediate frequency signal on a device main body side. A multiplexing unit 101 for superimposing a near unmodulated wave and an electric / optical conversion unit 102 for performing electric / optical conversion of the superimposed signal and transmitting the converted signal to an antenna unit. Optical / electrical conversion means 103 for performing electrical / electrical conversion, and demultiplexing means 104 for separating the optically / electrically converted signal into an intermediate frequency signal and an unmodulated wave
Multiplication means 105 for multiplying the separated unmodulated wave to obtain a local oscillator signal, and frequency conversion means 106 for converting the separated intermediate frequency signal to a radio frequency signal using the local oscillator signal. It is characterized by the following.

According to another aspect of the present invention, there is provided a wireless communication apparatus configured to connect an apparatus body and an antenna unit via an optical transmission line. A first electrical / optical converter for optically converting, a second electrical / optical converter for electrical / optical conversion of an unmodulated wave near the frequency of the intermediate frequency signal, and an optical signal of the intermediate frequency signal and the unmodulated wave. Multiplexing means for synthesizing and transmitting the signal to the antenna unit. The antenna unit includes a demultiplexing unit for separating the received optical signal into an intermediate frequency signal and an unmodulated wave, and an optical / optical signal for the separated intermediate frequency signal. First optical / electrical conversion means for electrical conversion, second optical / electrical conversion means for optical / electrical conversion of the separated unmodulated optical signal, and localization by multiplying the optical / electrically converted unmodulated wave Multiplying means for obtaining an oscillator signal; / It is characterized in that the electric converted intermediate frequency signal and a frequency converting means for converting the radio frequency signal.

In the above-described wireless communication apparatus, a radio frequency signal received by an antenna can be converted into an intermediate frequency signal by using a local oscillation signal obtained by the multiplication means and transmitted to the apparatus main body. .

[0010]

In the wireless communication apparatus of the first embodiment, the intermediate frequency signal and an unmodulated wave having a frequency close to the frequency of the intermediate frequency signal are superimposed by the multiplexing means 101 on the apparatus main body side, and the superimposed signal is electrically / optically transmitted. The electric / optical conversion is performed by using the conversion means 102 and transmitted to the antenna unit via the optical transmission path. On the antenna unit side, the optical signal received from the optical transmission line is optically / electrically converted by the optical / electrical conversion means 103, and the optically / electrically converted signal is separated into an intermediate frequency signal and an unmodulated wave by the demultiplexing means 104. . The separated unmodulated wave is multiplied by 105
Is used to obtain a local oscillator signal, and the intermediate frequency signal is converted into a radio frequency signal by the frequency conversion means 106 using the local oscillator signal.

[0011] In the wireless communication device of the second embodiment,
On the device main body side, the intermediate frequency signal is subjected to electric / optical conversion by the first electric / optical conversion means, and an unmodulated wave close to the frequency of the intermediate frequency signal is subjected to electric / optical conversion by the second electric / optical conversion means. The intermediate frequency signal and the unmodulated wave optical signal are combined by the multiplexing means and transmitted to the antenna unit via the optical transmission path. In the antenna unit, the optical signal received from the optical transmission line is separated into an intermediate frequency signal and an unmodulated wave by the demultiplexing unit, and the separated optical signal of the intermediate frequency signal is subjected to the optical / electrical conversion by the first optical / electrical conversion unit. Then, the separated optical signal of the unmodulated wave is converted to an optical / electrical signal by a second optical / electrical converting means.
Convert electricity. Further, the optically / electrically converted unmodulated wave is multiplied by a multiplying means to obtain a local oscillator signal, and the intermediate frequency signal is converted into a radio frequency signal by a frequency converting means using the local oscillator signal.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. Note that, throughout the following drawings, circuits having the same functions are denoted by the same reference numerals. FIG. 2 shows a wireless communication apparatus using an IF optical transmission system as one embodiment of the present invention. As shown in FIG. 8, this embodiment is applied to a wireless communication system in which a centralized base station and an antenna unit of each wireless zone are connected by an optical fiber.

In FIG. 2, the centralized base station is provided with a source oscillator 2 for generating a non-modulated wave for generating a second local oscillation frequency f _2. After the signal is multiplexed with the IF signal carrying the transmission data, the electric / optical converter 3 performs electric / optical conversion and sends the converted signal to the optical fiber transmission line. Here, the unmodulated wave has a frequency f ₀ close to the frequency of the IF signal, and this frequency f ₀ has a relationship of f ₂ = n × f ₀ with respect to the second local oscillation frequency f ₂ .
For example, if the IF signal is about 200 MHz, f ₀ is 300
N is a number such as 3, 5 or so.

On the antenna unit side, the optical signal in the IF band transmitted through the optical fiber is converted to an optical / electrical
After the electrical conversion, the signal is separated into an IF signal and an unmodulated wave by the splitter 5. The unmodulated wave (frequency f ₀ ) is further input to the multiplier 7 via the bandpass filter 6 and multiplied by n, thereby generating a second local oscillation signal (frequency f ₂ = n × f ₀ ). The second local oscillation signal is input to the frequency converter 10 through the bandpass filter 8 and mixed with the IF signal separated by the demultiplexer 5 to generate an RF signal. This RF signal is sent to the antenna 13 via the bandpass filter 11 and the amplifier 12, and is radiated as a radio wave. In this case, the frequency of the IF signal is f _IF , and the frequency of the RF signal is f _{IF
Assuming RF} , an RF signal (transmitted signal): f _RF = f _IF + f ₂ .

With the above-described configuration, if the unmodulated waves generated by the original oscillator of the centralized base station are sent to the antenna units of each radio zone, an RF signal can be generated by each antenna unit. In this case, since the frequency of the transmitted unmodulated wave is the same in all antenna units, the second local oscillation frequency is also equal, so that the frequency of the RF signal can be synchronized between the antenna units. Also, IF
Since the signal and the unmodulated wave close to the IF frequency are subjected to electrical / optical conversion and optically transmitted from the base station to the antenna unit, the band frequency in the linearity required for the optical transmission device becomes lower than the RF band. The cost of the optical transmission device can be reduced.

FIG. 3 shows an IF according to another embodiment of the present invention.
1 shows a wireless communication device using an optical transmission system. In this embodiment, in addition to the configuration of the transmission unit of the above-described embodiment, a configuration of a reception unit is added.

That is, in the receiving side circuit of this embodiment,
First, on the antenna unit side, R
The F signal is input to the frequency converter 16 via the RF switch 14 and the low noise amplifier 15, where it is mixed with the second local oscillation signal (frequency f ₂ ) generated by the multiplier 7 and converted into an IF signal. The signal is input to an electric / optical converter 18 via a bandpass filter 17, converted into an optical signal, and transmitted to an optical fiber transmission line. At the centralized base station side, the optical signal received via the optical fiber transmission line is converted to an optical / electrical converter 19.
To convert to an IF signal. In the case of this embodiment, I
The frequency f _{IF of the} F signal is IF signal (received signal): f _IF = f _RF −f ₂ .

FIG. 4 shows a wireless communication apparatus using an IF optical transmission system as another embodiment of the present invention. This embodiment is different from the above-described embodiment in that, in the above-described embodiment, the IF signal and the unmodulated wave are combined and then the electric / optical conversion is performed. After each of the waves is converted from light to light, they are combined at the level of the optical signal.

That is, on the centralized base station side, I
The F signal is converted into an optical signal by the electric / optical converter 21, while
The unmodulated wave is converted into an optical signal by an electric / optical converter 22, and both optical signals are combined by a polarization multiplexer 23 so that their polarization planes are orthogonal to each other, and then transmitted to an optical fiber transmission line. I do.

On the antenna unit side, the optical signal received from the optical fiber transmission line is separated into two optical signals, an IF signal and an unmodulated wave, by the demultiplexer 24, and then the optical / electrical converters 25 and 26 are separated.
Performs optical / electrical conversion into electrical signals. The unmodulated wave converted into an electric signal is multiplied by n as described above to generate a second local oscillation signal (frequency f ₂ = n × f ₀ ), and the frequency converter 10 uses this second local oscillation signal. To convert the IF signal into an RF signal and radiate the radio signal from the antenna 13.

FIG. 5 shows a wireless communication apparatus using an IF optical transmission system as another embodiment of the present invention. This embodiment also has a configuration in which the IF signal and the unmodulated wave are respectively subjected to electrical / optical conversion and then combined at the level of the optical signal. However, the embodiment of FIG. This embodiment differs from the first embodiment in that two optical signals are combined by the polarization multiplexer 23, whereas in this embodiment, the two optical signals are combined by using the wavelength multiplexer 23 '. Other configurations are the same, and detailed description is omitted.

FIG. 6 shows a wireless communication apparatus using an IF optical transmission system as another embodiment of the present invention. This embodiment is similar to the embodiment of FIG. 3 described above except that the configuration of the transmission side is added to the configuration of the reception side, and a reception side circuit is added to the transmission side circuit of the embodiment of FIG.

That is, the RF signal received by the antenna 13 passes through the amplifier 15 and the bandpass filter 32 and is input to the frequency converter 16, where the second local oscillation signal obtained by the multiplier 7 is used to convert the RF signal into an IF signal. Is converted. This IF signal is input to an electric / optical converter 18 through a bandpass filter 17, converted into an optical signal, and transmitted to an optical fiber transmission line. On the centralized base station side, the optical signal received via the optical fiber transmission line is optically / electrically converted by the optical / electrical converter 19 into an IF signal. Note that the multiplier 7 described above may be replaced with a phase locked loop (PLL).

[0024]

As described above, according to the present invention, an unmodulated wave having a frequency near the intermediate frequency band is optically transmitted from the radio device main body side to the antenna portion side, so that the antenna portion of each radio zone is transmitted. Side can obtain a local oscillation signal of the same frequency. Therefore, if the optical transmission device is RF
Even if the linearity in the band is poor, it can be used if the linearity in the IF band is good. Therefore, the band frequency required for the device for optically transmitting the light from the radio unit to the antenna unit is lower than that in the RF band. be able to. Also, since the original oscillation frequency (f ₀ ) of the local oscillation signal in each wireless zone is shared by the wireless device main body, even if the transmission signal is transmitted to the antenna unit in the IF band, the transmission frequency may be different between the wireless zones. The frequency of the RF signal can be synchronized. As a result, the cost of the optical transmission system can be reduced.

The RF signal received using the second local oscillation signal generated on the antenna side based on the unmodulated wave is converted into an I / O signal.
If the frequency is converted to an F signal, the received signal transmitted from the antenna unit in any wireless zone to the centralized base station can be in the IF band, and thus a device for optically transmitting the signal from the antenna unit to the base station is required. The band frequency can be reduced, and the cost of the optical transmission system can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory view of the principle according to the present invention.

FIG. 2 is a diagram showing a wireless communication device using an IF optical transmission system as one embodiment of the present invention.

FIG. 3 is a diagram showing a wireless communication apparatus using an IF optical transmission system as another embodiment of the present invention.

FIG. 4 is a diagram showing a wireless communication apparatus using an IF optical transmission system as still another embodiment of the present invention.

FIG. 5 is a diagram showing a wireless communication apparatus using an IF optical transmission system as still another embodiment of the present invention.

FIG. 6 is a diagram showing a wireless communication device using an IF optical transmission system as still another embodiment of the present invention.

FIG. 7 is a diagram illustrating a conventional method.

FIG. 8 is a diagram illustrating a conventional method.

[Explanation of symbols]

 Reference Signs List 1 multiplexer 2 original oscillator 3, 18, 21, 22, 41 electric / optical converter 4, 19, 25, 26, 42 optical / electric converter 5 demultiplexer 6, 8, 9, 11, 17, 32 Band filter 7 Multiplier 10, 16 Frequency mixer 12, 15 Amplifier 13 Antenna 23 Polarization multiplexer 23 'Wavelength multiplexer 24 Demultiplexer 43 Modulator 44 First local oscillator 45 Second local oscillator

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-277828 (JP, A) JP-A-57-1721 (JP, A) JP-A-64-18324 (JP, A) JP-A-4- 48832 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04B 1/04 H04B 9/00 H04B 7/26

Claims (3)

(57) [Claims] An apparatus main body and a plurality of antenna sections are connected by an optical transmission line, and a signal transmitted from the apparatus main body is transmitted to the plurality of antennas.
In a wireless communication device configured to transmit a wireless signal from the antenna unit, a multiplexing means (101) for superimposing an intermediate frequency signal and an unmodulated wave close to the frequency of the intermediate frequency signal on the device body side
And electrical / optical conversion means (102) for converting the superimposed signal into electrical / optical data and transmitting the converted signal to an antenna unit. The antenna unit includes an optical / electrical converter for optically / electrically converting the received optical signal. Means (103) and a demultiplexing means (10) for separating the optically / electrically converted signal into an intermediate frequency signal and an unmodulated wave.
4), multiplying means (105) for multiplying the separated unmodulated wave to obtain a local oscillator signal, and frequency converting means for converting the separated intermediate frequency signal to a radio frequency signal using the local oscillator signal ( 106) and includes a peripheral of the radio frequency signal transmitted from the antenna of the plurality of
A wireless communication device wherein wave numbers are synchronized . 2. An apparatus main body and a plurality of antenna sections are connected by an optical transmission line, and a signal transmitted from the apparatus main body is transmitted to the plurality of antennas.
A wireless communication device configured to transmit a wireless signal from the antenna unit;
Electrical / optical conversion means, second electrical / optical conversion means for electrical / optical conversion of an unmodulated wave close to the frequency of the intermediate frequency signal, and combining the intermediate frequency signal and the optical signal of the unmodulated wave Multiplexing means for transmitting to the antenna unit, the antenna unit includes a demultiplexing unit for separating the received optical signal into an intermediate frequency signal and an unmodulated wave, and an optical / electrical A first optical / electrical converting means for converting, a second optical / electrical converting means for optical / electrical conversion of the separated optical signal of the unmodulated wave, and a multiplication of the optical / electrical converted unmodulated wave Multiplying means for obtaining a local oscillator signal; and frequency converting means for converting the optical / electrically converted intermediate frequency signal to a radio frequency signal using the local oscillator signal, wherein the radio signals transmitted from the plurality of antenna units are provided . Frequency signal
A wireless communication device wherein wave numbers are synchronized . 3. Using a local oscillation signal obtained by said multiplying means,
3. The wireless communication device according to claim 1, wherein a radio frequency signal received by the antenna is converted into an intermediate frequency signal and transmitted to the device body.