JP2011155512A - Rf optical transmission system, master-station radio equipment, and level stabilizing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an RF optical transmission system that can easily modify the system configuration. <P>SOLUTION: Master-station radio equipment 10 includes a frequency converting part 111 for converting radio-frequency signals of a plurality of systems to a plurality of intermediate-frequency (IF) signals of different frequencies, a signal combining/distributing part 112 for electrically combining the plurality of intermediate-frequency signals for distribution to the slave-station equipment, and a plurality of electrical/optical converting portions 113-1 to 113-n for converting the IF signals to the combined optical signals in order to output to the slave-station equipment 13-1 to 13-n via the optical fibers 121-1 to 121-n. Each level stabilizing device 16-11 to 16-n2 respectively includes a signal combining part 161 for distributing the IF signals sent from the slave-station equipment, a frequency converting part 162 for converting the distributed IF signals to radio signals in the predetermined radio-frequencies of the plurality of systems, amplifiers 163, 165 for amplifying the radio signals, and a plurality of antenna devices 169-0 and 169-1. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an RF optical transmission system, a master station radio apparatus, and a level stabilization apparatus that convert an RF (Radio Frequency) signal into an optical signal and transmit between the radio apparatuses.

  In a wireless communication system such as a mobile phone system or a personal handy-phone system (PHS) system, signal transmission / reception is performed by wireless communication between a terminal device such as a mobile phone terminal or a PHS terminal and a wireless base station device. . Since communication using radio waves is performed in such a wireless communication system, it is difficult to communicate between a radio base station apparatus and a terminal apparatus in a radio wave insensitive zone such as in a high-rise building or an underground mall. ROF (Radio over Fiber) technology is known as a technology for enabling communication in a radio wave insensitive zone. According to the ROF technology, an RF signal transmitted from a radio base station apparatus is converted into an optical signal by electrical / optical conversion, and transmitted using an optical fiber to a slave station apparatus installed in a radio wave insensitive zone. A radio signal is transmitted from the slave station device to the terminal device.

  In recent wireless communication systems, a MIMO (Multiple Input Multiple Output) system in which a plurality of antennas are provided in each of a wireless base station device and a terminal device has been used. A technique has been proposed in which ROF technology is applied to such a MIMO system to enable communication even in a radio wave insensitive zone. For example, Patent Document 1 describes a MIMO system that converts a radio frequency signal into an optical signal, multiplexes the optical signal, and transmits the signal between an access point and a centralized base station via a single optical fiber. Yes.

JP 2004-56821 A (paragraph 0010, FIG. 1)

  A system that distributes a signal transmitted from one slave station device using a coaxial cable or a distributor and transmits the distributed signal to a plurality of terminal devices (or a plurality of antennas) is a DAS (distributed antenna system). Called. In the conventional single transmission method in which signal transmission / reception is performed by one system, DAS also supports transmission of one system signal.

  However, in a MIMO radio base station apparatus that transmits signals of a plurality of systems in parallel, the conventional system in which one system of DAS is provided for transmission and reception of one system constructs DAS for the number of MIMO systems. Therefore, it was necessary to perform signal transmission for each system. For example, in the system described in Patent Document 1, an access point and a centralized base station are connected by a single optical cable. Therefore, when adding an access point, it is necessary to add a corresponding central base station and connect it with an optical cable. For this reason, it is not easy to change the system configuration.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an RF optical transmission system, a master station radio device, and a level stabilization device whose system configuration can be easily changed.

  An RF optical transmission system according to an embodiment of the present invention includes a master station radio device that receives a plurality of systems of radio signals transmitted at a predetermined radio frequency from a base station radio device, and the master station radio device and an optical line. An RF optical transmission system including at least one slave station device connected to the slave station device and at least one level stabilizing device connected to the slave station device by a coaxial cable, wherein the master station radio device includes the plurality of systems. First frequency converting means for converting a radio signal into a plurality of intermediate frequency band signals each having a different frequency; and electrically combining the plurality of intermediate frequency band signals to generate a first combined signal; A combining / distributing unit that distributes one combined signal to the slave station device; and an electric / optical device that converts the first combined signal into an optical signal and outputs the optical signal to the slave station device via the optical line. Conversion means and And the slave station device receives the optical signal sent via the optical line and converts it into an electrical signal, and distributes the electrical signal to the plurality of intermediate frequency band signals. A first distribution unit configured to electrically combine the plurality of intermediate frequency band signals to generate a second combined signal and output the second combined signal to the coaxial cable. The level stabilizing device includes: a second distribution unit that distributes the second combined signal to the plurality of intermediate frequency band signals; and a plurality of systems of the predetermined radio frequency that distribute the plurality of intermediate frequency band signals. Second frequency conversion means for converting the radio signals into a plurality of radio signals, a plurality of amplifying means for amplifying the radio signals of the plurality of systems, and a plurality of antenna devices for transmitting the radio signals of the plurality of systems amplified by the amplifying means Send including ; And a stage.

  In addition, a master station radio apparatus according to an embodiment of the present invention includes a master station radio apparatus that receives a plurality of radio signals transmitted from a base station radio apparatus at a predetermined radio frequency, the master station radio apparatus, and an optical An RF optical transmission system including at least one slave station device connected by a line and at least one level stabilizing device connected to the slave station device by a coaxial cable, wherein the slave station device includes the master station device The optical cable sent from the apparatus via the optical line is received and converted into an electric signal, and the electric signal is divided into a plurality of intermediate frequency band signals having different frequencies, and electrically combined to form the coaxial cable. The level stabilizing device distributes the signal from the slave station device to the plurality of intermediate frequency band signals, converts the signals into a plurality of radio signals of the predetermined radio frequency, A base station radio apparatus used in an RF optical transmission system that amplifies line signals and transmits them from a plurality of antenna apparatuses, and converts the plurality of systems of radio signals into the plurality of intermediate frequency band signals. And combining the plurality of intermediate frequency band signals electrically to generate a combined signal, distributing the combined signal to the slave station device, converting the combined signal into an optical signal, Electrical / optical conversion means for outputting the optical signal to the slave station device via a line.

  The level stabilization device according to an embodiment of the present invention includes a master station radio device that receives a plurality of radio signals transmitted from a base station radio device at a predetermined radio frequency, the master station radio device, and an optical An RF optical transmission system including at least one slave station apparatus connected by a line and at least one level stabilization apparatus connected to the slave station apparatus by a coaxial cable, wherein the master station radio apparatus includes the plurality of master station radio apparatuses. System radio signals are converted into a plurality of intermediate frequency band signals having different frequencies, respectively, electrically combined and distributed to the slave station devices, converted into optical signals, and the optical signals via the optical line. Is output to the slave station device, the slave station device converts the optical signal transmitted via the optical line into an electrical signal, and distributes the electrical signal to the plurality of intermediate frequency band signals for electrical Synthesized into A level stabilizing device used in an RF optical transmission system that outputs to a coaxial cable, wherein the combined signal is a combined signal obtained by combining the plurality of radio signals and transmitted from the slave station device via the coaxial cable. Distributing means for distributing a signal to a plurality of intermediate frequency band signals, frequency converting means for converting the plurality of intermediate frequency band signals into a plurality of radio signals of the predetermined radio frequency, and the plurality of radio signals A plurality of amplifying means for amplifying each of the signals, and a transmitting means including a plurality of antenna devices for transmitting the plurality of systems of radio signals amplified by the amplifying means.

  According to the present invention, it is possible to provide an RF optical transmission system, a master station radio apparatus, and a level stabilization apparatus that can easily change the system configuration.

The block diagram which shows the structure of the part regarding signal transmission in the RF optical transmission system of 2x2 MIMO which concerns on one Embodiment of this invention. The block diagram which shows the structure of the part regarding loss correction | amendment in the RF optical transmission system of 2x2 MIMO which concerns on the said embodiment. The block diagram which shows the structure of the part regarding signal transmission in the RF optical transmission system of 4x4 MIMO which concerns on one Embodiment of this invention.

  Embodiments of an RF optical transmission system according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of a part related to signal transmission in a 2 × 2 MIMO RF optical transmission system according to an embodiment of the present invention. As shown in FIG. 1, in the downlink of this RF optical transmission system, radio signals (RF signals) of two systems (system 0 and system 1) of frequency F output from the base station radio apparatus 10 are the master station radio. The signal is received by the device 11 and converted into an optical signal, which is transmitted to the slave station devices 13-1 to 13-n via the optical fiber lines 121-1 to 121-n. The optical signals are converted again into electrical signals by the slave station devices 13-1 to 13-n, and distributed and supplied to the level stabilizing devices 16-11 to 16-n2 via the distributors 15-1 to 15-n. . The level stabilizing devices 16-11 to 16-n2 restore the supplied signals to two systems of radio signals of frequency F and send them to a terminal device (not shown).

  In the uplink for transmitting the radio signal (RF signal) transmitted from the terminal apparatus to the base station radio apparatus 10, signal transmission opposite to that in the downlink is performed. That is, the RF signal received by any of the level stabilization devices 16-11 to 16-n2 is sent to any one of the corresponding slave station devices 13-1 to 13-n and converted into an optical signal, Are transmitted to the master station apparatus 11 through the optical fibers 122-1 to 122-n. The master station device 11 converts the optical signal into an electrical signal, and transmits the signal to the base station radio device 10 at a frequency F as two systems (system 0 and system 1).

  The base station wireless device 10 is a wireless device that is provided in a wireless base station and supports wireless transmission of two systems (system 0 and system 1). The base station radio apparatus 10 includes a transmission / reception unit 10-0 corresponding to the system 0 and a transmission / reception unit 10-1 corresponding to the system 1. The transmission / reception unit 10-0 includes an antenna device corresponding to the system 0, a transmitter TX0, and a receiver RX0. The transmission / reception unit 10-1 includes an antenna device corresponding to the system 1, a transmitter TX1, and a receiver RX1. Yes.

  In the downlink, RF signals are transmitted from the transmitter TX0 and the transmitter TX1 to the master station device 11. On the uplink, the RF signal transmitted from the master station device 11 is received by the receiver RX0 and the receiver RX1.

  The master station device 11 includes a frequency conversion unit 111, a signal synthesis / distribution unit 112, electrical / optical (E / O) conversion units 113-1 to 113-n, and optical / electrical (O / E) conversion units 114-1 to 114-1. 114-n.

  The frequency conversion unit 111 includes an antenna device corresponding to system 0, a transmitter TX0 and a receiver RX0, an antenna device corresponding to system 1, a transmitter TX1 and a receiver RX1. The frequency converter 111 receives an RF signal having a frequency F transmitted from the base station radio apparatus 10 through two downlinks, and converts the RF signal into an IF signal that is an electrical signal in an intermediate frequency band. When the frequency converter 111 converts the frequency of the downlink RF signal, the RF signal of the system 0 and the RF signal of the system 1 are converted into IF signals of different frequencies (however, in the intermediate frequency band). In the following, the frequency of the IF signal obtained by frequency-converting the RF signal of system 0 is denoted by f0, and the frequency of the IF signal obtained by frequency-converting the RF signal of system 1 by f3.

  On the other hand, when a signal is transmitted to the base station radio apparatus 10 via the uplink, the frequency conversion unit 111 converts IF signals having different frequencies into two types of RF signals having a frequency F, and transmits the signals to the base station radio apparatus 10. Send. Hereinafter, the frequency of the IF signal corresponding to the system 0 input to the frequency conversion unit 111 is expressed as f1, and the frequency of the IF signal corresponding to the system 1 is expressed as f4.

  In this way, by converting the two lines of RF signals in the downlink to IF signals f0 and f3 having different frequencies, these two lines of signals can be synthesized and distributed. In addition, since the two RF signals are converted to different frequencies in the intermediate frequency band, the circuit member constituting the signal synthesis / distribution unit or the like is an intermediate frequency band that is less expensive than using a circuit member for high frequency band signals. A member can be used. Therefore, the manufacturing cost of the RF optical transmission system can be suppressed.

  The signal combining / distributing unit 112 electrically combines the downlink IF signals (frequency is f0 and f3) input from the frequency converting unit 111 into one IF signal, and the combined IF signal is E / O converted. Distributed to the sections 113-1 to 113-n.

  The signal synthesis / distribution unit 112 distributes the IF signal input from the O / E conversion units 114-1 to 114-n into an IF signal having the frequency f 1 and an IF signal having the frequency f 4, and outputs the IF signal to the frequency conversion unit 111.

  The E / O converters 113-1 to 113-n convert the downlink IF signals into optical signals and output the optical signals to the corresponding optical fibers 121-1 to 121-n. On the other hand, the O / E converters 114-1 to 114-n convert the optical signal on the uplink into an IF signal that is an electrical signal and output the IF signal to the signal combining / distributing unit 112.

  The master station device 11 and the plurality of slave station devices 13-1 to 13-n are connected via corresponding optical fibers 121-1 to 121-n and optical fibers 122-1 to 122-n, respectively. The optical fibers 121-1 to 121-n are used for downlink connection, and the optical fibers 122-1 to 122-n are used for uplink connection.

  Each of the slave station devices 13-1 to 13-n is installed in a radio wave insensitive zone. FIG. 1 illustrates a configuration that the slave station devices 13-1 to 13-n have in common, and corresponding reference numerals are given to corresponding portions.

  Each of the slave station devices 13-1 to 13-n includes an optical / electrical (O / E) conversion unit 131, an electrical / optical (E / O) conversion unit 132, a signal synthesis / distribution unit 133, and an amplification corresponding to the frequency f0. , A low noise amplification unit 135 corresponding to the frequency f1, an amplification unit 136 corresponding to the frequency f3, a low noise amplification unit 137 corresponding to the frequency f4, and a hybrid combiner / distributor (H) 138.

  The O / E converter 131 converts the downlink optical signal transmitted from the master station device 11 through the corresponding optical fibers 121-1 to 121-n into IF signals (frequency f0, f3) that are electrical signals. To do. The E / O conversion unit 132 converts the IF signal output from the signal synthesis / distribution unit 133 into an optical signal, and transmits the optical signal to the master station device 11 via the corresponding optical fibers 122-1 to 122-n.

  The signal synthesis / distribution unit 133 electrically distributes the downlink IF signal from the O / E conversion unit 131 into the IF signal having the frequency f0 and the IF signal having the frequency f3. The distributed IF signal having the frequency f0 is sent to the amplifying unit 134, and the IF signal having the frequency f3 is sent to the amplifying unit 136.

  The signal combining / distributing unit 133 electrically combines the uplink IF signal having the frequency f1 input from the low noise amplifying unit 135 and the uplink IF signal having the frequency f4 input from the low noise amplifying unit 137, and E The data is output to the / O converter 132.

  The hybrid combiner / distributor 138 combines the downlink IF signals (frequencies f0 and f3) input from the amplifiers 134 and 136, and outputs the combined IF signals to one or more connected level stabilizing devices via a coaxial cable. In FIG. 1, the slave station device 13-1 is connected to the level stabilizing device 16-11 and the level stabilizing device 16-12. Similarly, the slave station device 13-n is connected to the level stabilizing device 16-n1 and the level stabilizing device. It is connected to the device 16-n2. The distributors 15-1 to 15-n distribute the electric signals output from the corresponding slave station devices 13-1 to 13-n to the level stabilizing devices. The number of level stabilizing devices connected to each slave station device is not limited to two, and the number of level stabilizing devices connected to the slave station devices can be increased by increasing the number of distributors. is there.

  The hybrid combiner / distributor 138 distributes the uplink IF signals (frequencies f1, f4) sent from the connected level stabilizer via the coaxial cable, and outputs them to the low noise amplifiers 135 and 137. .

  Each of the level stabilizing devices 16-11 to 16-n2 corresponds to two systems (system 0 and system 1) of wireless transmission. FIG. 1 shows a configuration that the level stabilizers 16-11 to 16-n2 have in common, and corresponding portions are denoted by corresponding reference numerals.

  Each of the level stabilizing devices 16-11 to 16-n2 includes a signal synthesis distribution unit 161, a frequency conversion unit 162, an amplification unit 163, a low noise amplification unit 164, an amplification unit 165, a low noise amplification unit 166, and a hybrid distribution synthesizer. (H) 167 and a hybrid distribution synthesizer (H) 168. An antenna device 169-0 corresponding to the system 0 is connected to the hybrid distributor / combiner 167. The hybrid distributor / combiner 168 is connected to an antenna device 169-1 corresponding to the system 1.

  The signal synthesizer / distributor 161 distributes the downlink IF signal transmitted via the coaxial cable into the IF signal having the frequency f0 and the IF signal having the frequency f3. The signal combiner / distributor 161 combines the uplink IF signal having the frequency f1 and the uplink IF signal having the frequency f4, and transmits the synthesized signal to the slave station apparatus via the coaxial cable.

  The frequency converter 162 converts the downlink IF signals (frequency f0, f3) into high-frequency RF signals (frequency F). Conversely, on the uplink, the frequency converter 162 converts the RF signal of the system 0 (frequency F) and the RF signal of the system 1 (frequency F) into IF signals (frequency f1 and f4) having different frequencies.

  The amplifying unit 163 amplifies the downlink RF signal corresponding to the system 0 output from the frequency converting unit 162, and outputs the amplified RF signal to the antenna device 169-0 via the hybrid distribution synthesizer 167. The RF signal (frequency F) of system 0 is transmitted from the antenna device 169-0 into the air.

  Similarly, amplification section 165 amplifies the downlink RF signal corresponding to system 1 output from frequency conversion section 162 and outputs the amplified signal to antenna apparatus 169-1 via hybrid distribution synthesizer 168. The RF signal (frequency F) of system 1 is transmitted from the antenna device 169-1 into the air.

  On the other hand, on the uplink, the RF signal of the system 0 received by the antenna device 169-0 is output to the low noise amplification unit 164 via the hybrid combiner / distributor 167. Further, the RF signal of the system 1 received by the antenna device 169-1 is output to the low noise amplifying unit 166 via the hybrid divider / combiner 168. The low noise amplification unit 164 and the low noise amplification unit 166 perform low noise amplification on the RF signal and output to the frequency conversion unit 162.

  The hybrid distribution synthesizer 167 is used to distribute or combine the uplink signal of the system 0 and the downlink signal, and the hybrid distribution synthesizer 168 distributes the uplink signal and the downlink signal of the system 1. Or used for synthesis.

  RF signals having the same frequency (F) are transmitted from the antenna devices 169-0 and 169-1 to the wireless terminal device through two systems, system 0 and system 1.

  As described above, according to the RF optical transmission system having the configuration shown in FIG. 1, it is possible to collectively transmit 2 × 2 MIMO signals between the master station device and the slave station device. For this reason, even when the slave station device is added, it is not necessary to add two master station devices to construct two DAS systems, and the system configuration is simplified.

  In the RF optical transmission system shown in FIG. 1, since a signal is transmitted from the slave station device to the antenna device through a coaxial cable, the occurrence of cable loss is inevitable. In addition, distribution losses also occur in the distributors 15-1 to 15-n. In the present embodiment, the level stabilizing devices 16-11 to 16-n2 correct the coaxial cable loss and the distribution loss as described below.

  FIG. 2 is a block diagram illustrating a configuration of a portion related to loss correction in the 2 × 2 MIMO RF optical transmission system according to the present embodiment. 2 corresponding to those in FIG. 1 are given corresponding reference numerals.

  Below, the case where the output level from the level stabilization apparatus 16-11 is stabilized about the RF signal of the system | strain 0 as an example is demonstrated. In order to simplify the description, in FIG. 2, the configuration relating to the signal transmission of the system 1, the slave station devices 13-2 to 13-n, and the level stabilization devices 16-12 to 16-n2 are omitted. On the other hand, a control system related to transmission of a control signal for level stabilization is shown.

  As shown in FIG. 2, the master station device 11 includes a level stabilization control circuit 17 in addition to the configuration shown in FIG. The level stabilization control circuit 17 parameterizes a desired output level and generates a control signal 114 having a frequency fx (intermediate frequency band). The control signal having the frequency fx is superimposed on the downlink IF signal by the signal combining / distributing unit 112. The superimposed IF signal is converted into an optical signal by the E / O converter 113-1 and transmitted to the slave station device 13-1 through the optical fiber 121-1.

  In the slave station device 13-1, the downlink optical signal is converted into an intermediate frequency band electrical signal by the O / E converter 131. The signal synthesis / distribution unit 133 electrically distributes the downlink IF signal to the IF signals of the frequencies f0 and fx and the IF signal of the frequency f3. The IF signals having the frequencies f0 and fx are input to the amplifier 134, and the IF signal having the frequency f3 is input to the amplifier 136 and amplified.

  The hybrid combiner / distributor 138 combines the downlink IF signal input from the amplifying unit 134 and the downlink IF signal input from the amplifying unit 136, and outputs the synthesized signal to the level stabilizing device 16-11 via a coaxial cable. .

  The level stabilizing device 16-11 includes a signal detection / level control unit 170 in addition to the configuration shown in FIG. The signal combining / distributing unit 161 distributes the downlink IF signal to the IF signal having the frequency f0, the IF signal having the frequency f3, and the control signal having the frequency fx. The control signal of frequency fx is input to the signal detection / level control unit 170, the IF signal of frequency f 0 is input to the amplification unit 163, and the IF signal of frequency f 3 is input to the amplification unit 165. The signal detection / level control unit 170 detects the output level of the amplification unit 163, and calculates a difference from a desired output level obtained based on the control signal of the frequency fx.

  The calculated difference between the output levels is transmitted to the level stabilization control circuit 17. The level stabilization control circuit controls the signal detection / level control unit 170 based on the output level difference, and adjusts the drive parameter of the amplification unit 163. That is, the output level of the amplifying unit 163 is adjusted to match the desired output level.

  Therefore, the level stabilizing device 16-11 can transmit the RF signal at a constant level. In FIG. 2, illustration of the RF signal transmission system of the system 1 is omitted to simplify the description. However, similarly for the transmission of the RF signal of the system 1, the drive parameter of the amplification unit 165 may be adjusted based on the difference between the output level of the amplification unit 165 and the desired level. As a result, the output level of the amplifying unit 165 can also be stabilized. Further, similarly, the drive parameters of the low noise amplification unit 164 and the low noise amplification unit 166 can be adjusted to perform loss correction.

  2 shows only the slave station device 13-1 and the level stabilizing device 16-11. However, other level stabilizing devices connected to the slave station device 13-11 (for example, the level shown in FIG. 1). Similarly, the stabilizing device 16-12) can stabilize the transmission / reception level.

  Further, although one slave station device 13-1 is shown in FIG. 2, the level stabilizing devices 16-21 to 16-n2 connected to the other slave station devices 13-2 to 13-n are also shown. Similarly, the transmission / reception level can be stabilized.

  As described above, according to the RF optical transmission system according to the present embodiment, it is not necessary to install DASs for the number of systems, installation costs for equipment, wiring costs for optical fiber cables and coaxial cables, and coaxials for the number of systems. Equipment costs such as cable distributor cost can be greatly reduced. In addition, there is no need to provide dedicated devices for the number of systems on each of the transmission side and the reception side as in the case of installing a plurality of systems of DAS, and the optical fusion splicing process in each dedicated device and the optical fiber at each installation location are eliminated. Extra cable length processing (two locations for one optical cable) is also unnecessary. For this reason, construction cost can also be reduced.

  Further, in the RF optical transmission system according to the present embodiment, the level stabilizing devices 16-11 to 16-n2 can equalize the transmission output level of each antenna, so that it is possible to compensate for coaxial cable loss and distribution loss. it can. Therefore, level correction calculation tailored to the site such as the wiring length and installation status is not required, and the design cost can be reduced.

  According to the RF optical transmission system according to the present embodiment, signals of a plurality of systems of a MIMO-compatible base station radio apparatus are transmitted collectively by one master station apparatus 11. For this reason, even if the number of antenna devices to which signals are distributed is increased, it is not necessary to increase the number of master station devices 11, and the system configuration can be simplified. The master station device 11 has interfaces for the number of MIMO systems, and converts a plurality of RF signals having the same frequency into IF signals having different frequencies. Further, the master station device 11 electrically synthesizes the IF signals having different frequencies and converts them collectively from an electric signal to an optical signal. For this reason, it is possible to bundle a plurality of RF signals of the same frequency, and the system configuration can be simplified. The optical signal transmitted from the master station device 11 is photoelectrically converted into an IF signal in the slave station device.

  In the RF optical transmission system according to the present embodiment, a level stabilizing device is connected in the vicinity of the antenna. A level stabilization device installed in the immediate vicinity of the antenna device (for example, a cable loss of about 0 dB to 1 dB) converts IF signals of different frequencies into RF signals of the same frequency in a plurality of systems in the downlink.

  Further, the implementation of the RF optical transmission system according to the present embodiment is not limited to the 2 × 2 MIMO system. For example, as shown in FIG. 3, it can also be applied to a 4 × 4 MIMO system.

  FIG. 3 is a block diagram showing a configuration of a part related to signal transmission in a 4 × 4 MIMO RF optical transmission system according to an embodiment of the present invention. As shown in FIG. 3, in the downlink of this RF optical transmission system, radio signals (RF signals) of four systems (system 0, system 1, system 3 and system 4) of frequency F output from the base station radio apparatus 20 are provided. ) Is received by the master station radio device 21, converted into an optical signal, and transmitted to the slave station devices 23-1 to 23-n via the optical fiber lines 221-1 to 221-n. The optical signals are converted again into electrical signals by the slave station devices 23-1 to 23-n, and distributed and supplied to the level stabilizing devices 26-11 to 26-n2 through the distributors 25-1 to 25-n. . The level stabilizing devices 26-11 to 26-n2 restore the supplied signals to four radio signals of frequency F and send them to a terminal device (not shown).

  In the uplink for transmitting the radio signal (RF signal) transmitted from the terminal device to the base station radio device 20, signal transmission opposite to that in the downlink is performed. That is, the RF signal received by any of the level stabilization devices 26-11 to 26-n2 is sent to any one of the corresponding slave station devices 23-1 to 23-n and converted into an optical signal, and the optical fiber 222- 1 to 222-n and transmitted to the master station device 21. The master station device 21 converts the optical signal into an electric signal, and transmits it to the base station radio device 20 at a frequency F as four systems of radio signals.

  The base station radio apparatus 20 is a radio apparatus that is provided in a radio base station and supports four systems of radio transmission. The base station radio apparatus 20 includes a transmission / reception unit 20-0, a transmission / reception unit 20-1, a transmission / reception unit 20-3, and a transmission / reception unit 20-4 corresponding to the system 0, the system 1, the system 3, and the system 4, respectively. . The transmission / reception unit 20-0 includes an antenna device corresponding to the system 0, a transmitter TX0, and a receiver RX0, and the transmission / reception unit 20-1 includes an antenna device corresponding to the system 1, a transmitter TX1, and a receiver RX1, The transceiver unit 20-3 includes an antenna device, a transmitter TX3, and a receiver RX3 corresponding to the system 3, and the transceiver unit 2-4 includes an antenna device, a transmitter TX4, and a receiver RX4 corresponding to the system 4. Yes.

  In the downlink, RF signals are transmitted from the transmitters TX0, TX1, TX3, and TX4 to the master station device 21. On the uplink, the RF signal transmitted from the master station device 21 is received by the receivers RX0, RX1, RX3, and RX4.

  The master station device 21 includes a frequency converting unit 211, a signal combining / distributing unit 212, an electric / optical (E / O) converting unit 213-1 to 213-n, and an optical / electrical (O / E) converting unit 214-1. 214-n.

  The frequency conversion unit 211 includes an antenna device corresponding to system 0, a transmitter TX0 and a receiver RX0, an antenna device corresponding to system 1, a transmitter TX1 and a receiver RX1, an antenna device corresponding to system 3, and a transmitter TX3. A receiver RX3, an antenna device corresponding to the system 4, a transmitter TX4, and a receiver RX4 are provided. The frequency converter 211 receives the RF signal of frequency F transmitted from the base station radio apparatus 20 through the four downlinks, and converts it into an IF signal in the intermediate frequency band. When the frequency converter 211 converts the frequency of the downlink RF signal, the RF signal of each system is converted into IF signals having different frequencies. In the following, the frequency of the IF signal obtained by frequency conversion of the RF signal of system 0 is f0, the frequency of the IF signal obtained by frequency conversion of the RF signal of system 1 is f3, and the frequency of the IF signal obtained by frequency conversion of the RF signal of system 3 is f5. And the frequency of the IF signal obtained by frequency-converting the RF signal of the system 4 is denoted as f7.

  On the other hand, when transmitting a signal to the base station radio apparatus 20 via the uplink, the frequency conversion unit 211 converts IF signals having different frequencies into four types of RF signals of frequency F, and sends the signals to the base station radio apparatus 20. Send. In the following, the frequency of the IF signal corresponding to the system 0 input to the frequency converter 211 is f1, the frequency of the IF signal corresponding to the system 1 is f4, the frequency of the IF signal corresponding to the system 3 is f6, and the system 4 The frequency of the corresponding IF signal is expressed as f8.

  In this way, by converting the four RF signals into IF signals having different frequencies, these four signals can be synthesized and distributed as in the example shown in FIG. Become.

  The signal combining / distributing unit 212 electrically combines the downlink IF signals input from the frequency converting unit 211 into one IF signal, and the combined IF signals are E / O converting units 213-1 to 213- distribute to n.

  The signal synthesis / distribution unit 212 distributes the IF signals input from the O / E conversion units 214-1 to 214-n to the IF signals of each system and outputs the IF signals to the frequency conversion unit 211.

  The E / O converters 213-1 to 213-n have the same functions as the E / O converters 113-1 to 113-n shown in FIG. 1, and convert the downlink IF signals into optical signals. Output to the corresponding optical fibers 221-1 to 221-n. On the other hand, the O / E converters 214-1 to 214-n have the same functions as the O / E converters 114-1 to 114-n shown in FIG. The signal is converted into a signal and output to the signal synthesis / distribution unit 212.

  The master station device 21 and the plurality of slave station devices 23-1 to 23-n are connected via corresponding optical fibers 221-1 to 221-n and optical fibers 222-1 to 222-n, respectively. The optical fibers 221-1 to 221-n are used for downlink connections, and the optical fibers 222-1 to 222-n are used for uplink connections.

  Each of the slave station devices 23-1 to 23-n is installed in a radio wave insensitive zone. Similar to FIG. 1, FIG. 2 illustrates a configuration that the slave station apparatuses 23-1 to 23-n have in common, and corresponding portions are denoted by corresponding reference numerals.

  Each of the slave station devices 23-1 to 23-n includes an optical / electrical (O / E) conversion unit 231, an electrical / optical (E / O) conversion unit 232, a signal synthesis distribution unit 233, an amplification unit 234, a low noise An amplifying unit 235, an amplifying unit 236, a low noise amplifying unit 237, an amplifying unit 238, a low noise amplifying unit 239, an amplifying unit 240, a low noise amplifying unit 241 and a hybrid combiner / distributor (H) 242 are provided.

  The O / E conversion unit 231 has a function similar to that of the O / E conversion unit 131 illustrated in FIG. 1, and converts a downlink optical signal transmitted via an optical fiber into an IF signal that is an electrical signal. The E / O conversion unit 232 has the same function as the E / O conversion unit 132 shown in FIG. 1, converts the IF signal output from the signal synthesis / distribution unit 233 into an optical signal, and passes through an optical fiber. Transmit to the master station device 21.

  The signal combining / distributing unit 233 electrically distributes the downlink IF signal into an IF signal having a frequency f0, an IF signal having a frequency f3, an IF signal having a frequency f5, and an IF signal having a frequency f7. The distributed IF signal of frequency f0 is sent to the amplifying unit 234, the IF signal of frequency f3 is sent to the amplifying unit 236, the IF signal of frequency f5 is sent to the amplifying unit 238, and the IF signal of frequency f7 is sent to the amplifying unit 240.

  Further, the signal synthesis / distribution unit 233 receives an uplink IF signal of frequency f1 input from the low noise amplification unit 235, an uplink IF signal of frequency f4 input from the low noise amplification unit 237, and a frequency input from the low noise amplifier 239. The IF signal of f6 and the IF signal of frequency f8 input from the low noise amplifier 241 are electrically combined and output to the E / O converter 232.

  The hybrid combiner / distributor 242 combines the downlink IF signals input from the amplifying units 234, 236, 238, and 240 and outputs the combined signals to one or more connected level stabilizing devices via a coaxial cable. The hybrid combiner / distributor 242 distributes the uplink IF signal sent from the connected level stabilizer via the coaxial cable, and outputs it to the low noise amplifying units 235, 237, 239, and 241.

  The level stabilizers 26-11 to 26-n2 respectively correspond to four systems of wireless transmission, and other functions are the same as those of the level stabilizers 16-11 to 16-n2 shown in FIG. FIG. 2 illustrates a configuration that the slave station devices 26-11 to 26-n2 have in common, and corresponding reference numerals are given to corresponding portions.

  Each of the level stabilizing devices 26-11 to 26-n2 includes a signal synthesis distribution unit 261, a frequency conversion unit 262, an amplification unit 263, a low noise amplification unit 264, an amplification unit 265, a low noise amplification unit 266, an amplification unit 267, A low noise amplification unit 268, an amplification unit 269, a low noise amplification unit 270, and hybrid distribution synthesizers (H) 271 to 274 are provided. An antenna device 281-0 corresponding to the system 0 is connected to the hybrid distributor / combiner 271. The hybrid distributor / combiner 272 is connected to the antenna device 281-1 corresponding to the system 1. The hybrid distributor / combiner 273 is connected to the antenna device 281-3 corresponding to the system 3. The hybrid distributor / combiner 274 is connected to the antenna device 281-4 corresponding to the system 4.

  The signal synthesizer / distributor 261 distributes the downlink IF signal transmitted via the coaxial cable into an IF signal having a frequency f0, an IF signal having a frequency f3, an IF signal having a frequency f5, and an IF signal having a frequency f7. The signal combiner / distributor 261 combines the uplink IF signal of the frequency f1 line, the uplink IF signal of the frequency f4, the uplink IF signal of the frequency f6, and the uplink IF signal of the frequency f8, and coaxially The data is transmitted to the slave station device via the cable.

  The frequency converter 262 converts the downlink IF signal into a high-frequency RF signal (frequency F). Conversely, on the uplink, the frequency conversion unit 262 converts the RF signals of each system into IF signals having different frequencies.

  The amplifying unit 263 amplifies the downlink RF signal corresponding to the system 0 output from the frequency converting unit 262, and outputs the amplified RF signal to the antenna device 281-0 via the hybrid distribution synthesizer 271. The RF signal (frequency F) of system 0 is transmitted from the antenna device 281-0 into the air.

  Similarly, the amplifying unit 265 amplifies the downlink RF signal corresponding to the system 1 output from the frequency converting unit 262 and outputs the amplified RF signal to the antenna device 281-1 via the hybrid distribution synthesizer 272. The RF signal (frequency F) of system 1 is transmitted from the antenna device 281-1 into the air.

  The amplifying unit 267 amplifies the downlink RF signal corresponding to the system 3 output from the frequency converting unit 262, and outputs the amplified RF signal to the antenna device 281-3 via the hybrid distribution synthesizer 273. The RF signal (frequency F) of system 3 is transmitted from the antenna device 283-0 into the air.

  The amplifying unit 269 amplifies the downlink RF signal corresponding to the system 4 output from the frequency converting unit 262, and outputs the amplified RF signal to the antenna device 281-4 via the hybrid distribution synthesizer 274. The RF signal (frequency F) of the system 4 is transmitted from the antenna device 284-1 into the air.

  On the other hand, on the uplink, the RF signal of the system 0 received by the antenna device 281-0 is output to the low noise amplifying unit 264 via the hybrid combiner / distributor 271. Further, the RF signal of the system 1 received by the antenna device 281-1 is output to the low noise amplifying unit 266 via the hybrid divider / combiner 272. The system 3 RF signal received by the antenna device 281-3 is output to the low noise amplification unit 268 via the hybrid combiner / distributor 273. The RF signal of the system 4 received by the antenna device 281-4 is output to the low noise amplification unit 270 via the hybrid distribution synthesizer 274. The low noise amplification units 264, 266, 268 and 270 perform low noise amplification on the RF signal and output to the frequency conversion unit 262.

  The hybrid distribution synthesizer 271 is used to distribute or combine the uplink signal of the system 0 and the downlink signal, and the hybrid distribution synthesizer 272 distributes the uplink signal and the downlink signal of the system 1. Or used for synthesis. Further, the hybrid distribution synthesizer 273 is used to distribute or combine the uplink signal of the system 3 and the downlink signal, and the hybrid distribution synthesizer 274 converts the uplink signal of the system 4 and the downlink signal. Used to distribute or synthesize.

  RF signals of the same frequency (F) are transmitted from the antenna devices 281-0 to 281-4 to the wireless terminal device through four systems of system 0, system 1, system 3, and system 4.

  As described above, according to the RF optical transmission system having the configuration shown in FIG. 3, it is possible to collectively transmit 4 × 4 MIMO four-way signals between the master station device and the slave station device. For this reason, even when the slave station device is added, it is not necessary to construct the four DAS systems by adding the master station device, and the system configuration is simplified.

  Also in 4 × 4 MIMO shown in FIG. 3, the transmission output level can be made constant by a signal system similar to the control system shown in FIG. In this case, the master station device 21 is provided with the same level stabilization control circuit 17 as in FIG. 2, and the level stabilization devices 26-11 to 26-n2 are each provided with the signal detection / level control unit 170.

  Thus, even a MIMO system with an increased number of supported systems can achieve the same effects as the 2 × 2 MIMO system shown in FIG.

  The RF optical transmission system according to the present embodiment is assumed to be applied to a mobile phone system or a PHS system. For example, in the case of a mobile phone system, the third generation W-CDMA, HSPA, CDMA2000 1X, The present invention can be applied to a system such as CDMA2000 1X EV-DO. Also, in mobile communication systems such as IEEE802.16 and other mobile WiMAX standards, LTE systems, 4th generation and later systems, when transmitting signals of MIMO compatible base station wireless devices using optical cables and coaxial cables, The RF optical transmission system according to this embodiment can be used.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention at the stage of implementation. Further, each of the embodiments includes inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in one embodiment or the constituent elements shown in some embodiments are combined, they are described in the column of the problem to be solved by the invention. In the case where the problems described above can be solved and the effects described in the “Effects of the Invention” can be obtained, a configuration in which these constituent requirements are deleted or combined can be extracted as an invention.

  DESCRIPTION OF SYMBOLS 10 ... Base station radio | wireless apparatus, 11 ... Master station radio | wireless apparatus, 13-1 to 13-n ... Slave station apparatus, 16-11 to 16-n2 ... Level stabilization apparatus, 20 ... Base station radio | wireless apparatus, 21 ... Parent station Wireless device, 23-1 to 23-n ... slave station device, 26-11 to 26-n2 ... level stabilizing device.

Claims (9)

A master station radio device that receives a plurality of systems of radio signals transmitted from a base station radio device at a predetermined radio frequency, at least one slave station device connected to the master station radio device by an optical line, and the slave station An RF optical transmission system comprising at least one level stabilization device connected to the device by a coaxial cable,
The master station radio device is
First frequency conversion means for converting the plurality of radio signals into a plurality of intermediate frequency band signals each having a different frequency;
Combining and distributing means for electrically combining the plurality of intermediate frequency band signals to generate a first combined signal and distributing the first combined signal to the slave station device;
Electrical / optical conversion means for converting the first combined signal into an optical signal, and outputting the optical signal to the slave station device via the optical line;
Comprising
The slave station device is
Optical / electrical conversion means for receiving the optical signal sent via the optical line and converting it into an electrical signal;
First distribution means for distributing the electrical signal to the plurality of intermediate frequency band signals;
A combining means for electrically combining the plurality of intermediate frequency band signals to generate a second combined signal and outputting the second combined signal to the coaxial cable;
Comprising
The level stabilizing device includes:
Second distribution means for distributing the second synthesized signal to the plurality of intermediate frequency band signals;
A second frequency converting means for converting the plurality of intermediate frequency band signals into a plurality of radio signals of the predetermined radio frequency;
A plurality of amplifying means for amplifying the plurality of radio signals;
Transmitting means including a plurality of antenna devices for transmitting the plurality of systems of radio signals amplified by the amplifying means;
An RF optical transmission system comprising: The level stabilizing device includes:
Detecting means for detecting a difference between an output level of the plurality of amplifying means and a desired output level;
Adjusting means for adjusting the driving of the amplifying means based on the detected difference so that the output level of the amplifying means becomes the desired output level;
The RF optical transmission system according to claim 1, further comprising: The master station radio apparatus further includes a control unit that provides the adjustment unit with the desired output level as a control signal, and controls the operation of the adjustment unit.
The RF optical transmission system according to claim 2, wherein the combining / distributing unit generates the first combined signal by electrically combining the plurality of intermediate frequency band signals and the control signal. The master station radio device receives two systems of radio signals,
2. The RF optical transmission system according to claim 1, wherein the transmission unit includes two antenna devices for transmitting the two systems of radio signals. The master station radio device receives four radio signals,
2. The RF optical transmission system according to claim 1, wherein the transmission unit includes four antenna devices for transmitting the four systems of radio signals. A master station radio device that receives a plurality of systems of radio signals transmitted from a base station radio device at a predetermined radio frequency, at least one slave station device connected to the master station radio device by an optical line, and the slave station An RF optical transmission system including at least one level stabilizing device connected to a device by a coaxial cable, wherein the slave station device receives the optical signal transmitted from the master station device via the optical line. And converting the electric signal into a plurality of intermediate frequency band signals each having a different frequency, electrically synthesizing and outputting the signal to the coaxial cable. Are divided into a plurality of intermediate frequency band signals, converted into a plurality of radio signals of the predetermined radio frequency, and the plurality of radio signals are respectively amplified to obtain a plurality of antenna devices. A master station radio apparatus used in an RF optical transmission system for transmitting,
A frequency conversion means for converting the plurality of radio signals into the plurality of intermediate frequency band signals;
A combining and distributing unit that electrically combines the plurality of intermediate frequency band signals to generate a combined signal and distributes the combined signal to the slave station device;
Electrical / optical conversion means for converting the combined signal into an optical signal and outputting the optical signal to the slave station device via the optical line;
A master station radio apparatus. A master station radio device that receives a plurality of systems of radio signals transmitted from a base station radio device at a predetermined radio frequency, at least one slave station device connected to the master station radio device by an optical line, and the slave station An RF optical transmission system including at least one level stabilizing device connected to a device by a coaxial cable, wherein the master station radio device converts the plurality of radio signals into a plurality of intermediate frequency band signals having different frequencies. Each of them is electrically combined and distributed to the slave station device, converted into an optical signal, and the optical signal is output to the slave station device via the optical line. An RF optical transmission system which converts the optical signal sent via an optical line into an electrical signal, distributes the electrical signal to the plurality of intermediate frequency band signals, electrically synthesizes them, and outputs them to the coaxial cable. A level stabilizing apparatus for use,
Distributing means for distributing a combined signal obtained by combining the wireless signals of the plurality of systems and transmitted from the slave station device via the coaxial cable to a plurality of intermediate frequency band signals;
A frequency conversion means for converting the plurality of intermediate frequency band signals into a plurality of radio signals of the predetermined radio frequency;
A plurality of amplifying means for amplifying the plurality of radio signals;
Transmitting means including a plurality of antenna devices for transmitting the plurality of systems of radio signals amplified by the amplifying means;
A level stabilizing device comprising: Detecting means for detecting a difference between an output level of the plurality of amplifying means and a desired output level;
Adjusting means for adjusting the driving of the amplifying means based on the detected difference so that the output level of the amplifying means becomes the desired output level;
The level stabilization device according to claim 7, further comprising:   9. The level stabilizing device according to claim 8, wherein the control signal giving the desired output level is electrically combined with the plurality of intermediate frequency band signals and transmitted from the slave station device.

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