JP2005065241A - Radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication system wherein the transmission of a radio signal with deteriorated quality can be stopped. <P>SOLUTION: In a control apparatus 10, an optical transmission part 102 converts a downstream electric signal to a downstream optical signal and transmits the downstream optical signal to a relay apparatus 20 via an optical transmission path 40. In the relay apparatus 20, an optical reception part 201 converts the downstream optical signal transmitted from the control apparatus 10 via the optical transmission path 40 to the downstream electric signal, and a transmission/reception antenna part 204 transmits the downstream electric signal converted by the optical reception part 201 as a radio signal to a radio communication terminal 30. A quality evaluation part 290 evaluates transmission quality in the optical transmission path 40 and judges whether the transmission quality fulfills predetermined conditions. When it is judged in the quality evaluation part 290 that the transmission quality does not fulfill the predetermined conditions, a power control part 209 stops the transmission of the downstream electric signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a system in which a control device communicates with a wireless communication terminal via a relay device, and more particularly to a system in which the control device and the relay device are connected via an optical transmission line.

  In recent years, a wireless communication system in which a relay station that communicates wirelessly with a wireless communication terminal is connected to a control device via an optical transmission path has been used (for example, Patent Document 1).

  FIG. 14 is a diagram illustrating a configuration of a conventional wireless communication system described in Patent Document 1. In FIG. In the wireless communication system shown in FIG. 14, the control device 19 converts the modulated signal into an optical signal and transmits the optical signal to the relay device 29 via the optical transmission path 59. The relay device 29 converts the optical signal transmitted from the control device 19 into an electrical signal by the photoelectric conversion unit 95, and as a wireless signal via the transmission / reception unit 93 and the antenna unit 92, the wireless communication terminal 39 in the area. Send to. The relay device 29 receives a radio signal transmitted from the radio communication terminal 39 by the antenna unit 92, converts the radio signal to an optical signal by the electro-optical conversion unit 94 via the transmission / reception unit 93, and transmits the optical signal to the optical transmission path 59. Send it out. In this manner, in the conventional wireless communication system, communication between the relay device and the wireless communication terminal is realized.

  When the relay device 29 amplifies a signal to be transmitted to the wireless communication terminal, an out-of-band frequency component may be output in addition to the signal component to be transmitted due to nonlinearity of the amplifier. Further, when the control device 19 converts an electrical signal to be transmitted to the relay device 29 into an optical signal, distortion may occur in the optical signal due to nonlinearity of the laser diode. When distortion occurs in the optical signal, when the relay device 29 converts the optical signal into the electrical signal, the converted electrical signal includes an out-of-band frequency component.

  Generation of such an unintended frequency component is called unnecessary radiation. When the unnecessary radiant power included in the wireless signal transmitted by the relay device 29 is large, it adversely affects the wireless communication of other communication devices and the operation of electrical devices existing around the wireless communication terminal. Therefore, it is desirable that the unnecessary radiant power included in the radio signal is as small as possible.

  The Radio Law defines quality conditions that a wireless signal transmitted and received by a communication device should satisfy in order to prevent the wireless communication from affecting other devices. The above-mentioned unnecessary radiant power is also one of the conditions defined in the Radio Law. In the Radio Law, an allowable value of unnecessary radiant power radiated into the air with transmission of a radio signal is defined for each frequency band.

  As described above, the wireless communication system can communicate without interfering with other devices by using the wireless signal that satisfies the conditions defined in the Radio Law.

  However, for example, when an abnormality occurs in the optical transmission path 59 that connects the control device 19 and the relay apparatus 29, a reflection point is generated in the optical transmission path 59, so that noise is mixed into the optical signal. As a result, when the relay device 29 converts the optical signal into an electrical signal and transmits it as a radio signal to the radio communication terminal, the unnecessary radiant power included in the radio signal increases, and the conditions stipulated in the Radio Law are satisfied. There is a risk of not being satisfied.

  Therefore, in general, a test for evaluating whether or not an abnormality has occurred in the optical transmission line is performed (for example, Non-Patent Document 1). The presence or absence of an abnormality in the optical transmission line is evaluated by, for example, an optical pulse test or an optical loss test. The optical pulse test is a test for determining the quality of the optical transmission line by measuring the loss and reflection amount at the connection point of the optical fiber. The optical loss test is a test for determining whether the optical transmission line is good or bad by transmitting an optical signal for testing and examining the increase or decrease in the light receiving power of the optical signal.

Thus, according to the conventional test method, it can be determined whether or not an abnormality has occurred in the optical transmission line.
JP-A-9-233050 Fumi Izumida, “Latest Trends in Access Fiber Optic Network Monitoring Technology”, Latest Trends in Distributed / Multipoint Optical Sensing, Optical Technology Contact, Japan Opto-Mechatronics Association, 2004, Vol. 42, No. 2 , P. 69-77

  However, since the conventional test method is merely for detecting an abnormality in the optical transmission path, it is not possible to stop the transmission of a radio signal with degraded quality. Therefore, a radio signal with a deteriorated quality continues to be transmitted from the relay device until the system is stopped after the abnormality of the optical transmission path is discovered. In that case, there is a possibility that other devices may be affected by the radio signal having degraded quality.

  Even if no abnormality occurs in the optical transmission line, noise may be mixed in the optical signal or the electric signal due to an abnormality in a circuit in the control device or the relay device. Even in this case, the quality of the radio signal transmitted from the relay device may deteriorate, and the quality of the radio signal may not satisfy the conditions defined in the Radio Law. However, since the conventional test method is for detecting an abnormality in the optical transmission line, it cannot detect a deterioration in the quality of the radio signal due to other factors.

  Therefore, an object of the present invention is to provide a wireless communication system capable of stopping transmission of a wireless signal with degraded quality.

  The present invention is a wireless communication system in which an optical signal transmitted from a control device connected via an optical transmission path is converted into an electrical signal by a relay device and transmitted as a wireless signal to a wireless communication terminal. Includes a first optical transmission unit that converts a downstream electrical signal into a downstream optical signal and transmits the downstream optical signal to the relay device via the optical transmission path, and the relay device is transmitted from the control device via the optical transmission path. An optical transmission path comprising: a first optical receiver that converts a downstream optical signal into a downstream electrical signal; and an antenna that transmits the downstream electrical signal converted by the first optical receiver as a wireless signal to a wireless communication terminal. When the transmission quality is determined not to satisfy the predetermined condition by the quality evaluation means that evaluates the transmission quality in the network and determines whether or not the transmission quality satisfies the predetermined condition. Signal transmission And a signal transmission stopping means for stopping.

  Thereby, when the transmission quality in an optical transmission line falls, transmission of a radio signal can be stopped. Therefore, for example, a radio signal that does not satisfy official conditions stipulated in the Radio Law or the like is not transmitted. Therefore, it is possible to prevent other communication devices and electrical devices from being adversely affected.

  For example, the quality evaluation unit and the signal transmission stop unit are provided in the repeater, and the quality evaluation unit evaluates the quality of the downstream optical signal and determines whether the quality of the downstream optical signal satisfies a predetermined condition. The signal transmission stopping unit stops the transmission of the radio signal when the quality evaluation unit determines that the quality of the downstream optical signal does not satisfy the predetermined condition.

  Thereby, the relay apparatus can stop transmission of a radio signal, when the quality of the downstream optical signal received from the control apparatus falls. Therefore, a radio signal with degraded quality is not transmitted.

  As an example, the quality evaluation unit is a received light power detection unit that detects the power of the downstream optical signal received by the relay device and determines whether the power is equal to or less than a predetermined value. When the detection unit determines that the power of the downstream optical signal is equal to or lower than the predetermined value, the transmission of the radio signal is stopped.

  According to this, when the power of the downstream optical signal transmitted from the control device decreases, the relay device stops transmitting the radio signal. For example, when an abnormality occurs in the optical transmission path, signal transmission loss increases. When the signal transmission loss increases, the power of the downstream optical signal decreases. Therefore, the relay apparatus can evaluate the transmission loss of the signal by detecting the power of the downstream optical signal.

  The quality evaluation unit and the signal transmission stop unit are provided in the relay device, and the quality evaluation unit evaluates the quality of the downlink electrical signal and determines whether the quality of the downlink electrical signal satisfies a predetermined condition. The signal transmission stopping unit may stop the transmission of the radio signal when the quality evaluation unit determines that the quality of the downlink electrical signal does not satisfy the predetermined condition.

  Thereby, the relay apparatus can stop the transmission of the radio signal when the quality of the downlink electrical signal is deteriorated. Therefore, a radio signal with degraded quality is not transmitted.

  As another example, the quality evaluation unit includes a radio signal level detection unit that detects a level of a frequency band component of a radio signal to be transmitted from the antenna unit, from a downlink electrical signal converted by the first optical reception unit, An unnecessary radiation level detection unit that detects a level of a component outside the frequency band of the radio signal to be transmitted from the antenna unit from the downlink electrical signal converted by the one optical reception unit, and a frequency band detected by the radio signal level detection unit It consists of a level determination unit that determines whether the level of the component outside the frequency band detected by the unnecessary radiation level detection unit with respect to the component level is equal to or higher than a certain level. When it is determined that the level of the component outside the frequency band with respect to the level of the frequency band component is equal to or higher than a certain level, the transmission of the radio signal is stopped.

  Thereby, the relay apparatus can stop transmission of a radio signal with a high level of the component outside the frequency band. When the level of the out-of-frequency band component included in the radio signal is large, there is a risk of adversely affecting communication equipment that communicates using the same frequency band as the out-of-frequency band component. Moreover, since the level of a specific frequency should just be detected, the structure of a radio | wireless communications system can be simplified.

  As another example, the control device further includes a test signal generation unit that generates two test signals of different frequencies, and the first optical transmission unit is a downlink in which the test signal generated by the test signal generation unit is superimposed. A test signal level detection unit that converts the electrical signal into a downstream optical signal, and the quality evaluation unit detects the level of the frequency band component of the test signal superimposed on the downstream electrical signal converted by the first optical reception unit; A distortion level detector for detecting the level of intermodulation distortion of the test signal superimposed on the downstream electrical signal converted by the first optical receiver, and the level of the frequency band component detected by the test signal level detector And a level determination unit that determines whether or not the level of intermodulation distortion detected by the distortion level detection unit is above a certain level. Is the level determination unit, when the intermodulation distortion level is determined to be a predetermined level or more on the level of the frequency band component of the test signal, it stops the transmission of the radio signal.

  Thereby, the relay apparatus can stop the transmission of the radio signal whose intermodulation distortion is increased and the quality is deteriorated. Moreover, since the level of a specific frequency should just be detected, the structure of a radio | wireless communications system can be simplified.

  As another example, the control device further includes a test signal generation unit that generates a test signal, and the first optical transmission unit transmits the downstream electrical signal on which the test signal generated by the test signal generation unit is superimposed as downstream light. The quality evaluation means converts the signal into a signal, the test signal level detector for detecting the level of the frequency band component of the test signal superimposed on the downlink electrical signal converted by the first optical receiver, and the first light Distortion level detection unit that detects the harmonic distortion level of the test signal superimposed on the downstream electrical signal converted by the receiver unit, and distortion level detection for the frequency band component level detected by the test signal level detection unit A level determination unit that determines whether or not the level of harmonic distortion detected by the unit is equal to or higher than a certain level, and the signal transmission stop means is If the level of harmonic distortion on the level of the frequency band component of the test signal is determined to be a certain level or more, it stops the transmission of the radio signal.

  Thereby, the relay apparatus can stop the transmission of the radio signal whose harmonic distortion is increased and the quality is deteriorated. Moreover, since the level of a specific frequency should just be detected, the structure of a radio | wireless communications system can be simplified.

  The antenna unit receives a radio signal transmitted from the radio communication terminal to generate an upstream electrical signal, and the relay device further converts the upstream electrical signal received by the antenna unit into an upstream optical signal for optical transmission. A second optical transmission unit configured to transmit to the control device via the path, and the control device further includes a second optical signal that converts the upstream optical signal transmitted from the relay device via the optical transmission path into an upstream electrical signal. The optical evaluation unit and the signal transmission stopping unit are provided in the repeater, and the quality evaluation unit evaluates the quality of the upstream optical signal, and whether the quality of the upstream optical signal satisfies a predetermined condition. The signal transmission stop means may stop the transmission of the radio signal when the quality evaluation means determines that the quality of the upstream optical signal does not satisfy the predetermined condition.

  Thereby, the relay apparatus can stop the transmission of the radio signal when the quality of the upstream optical signal is deteriorated. Therefore, a radio signal with degraded quality is not transmitted.

  As an example, the quality evaluation unit includes an optical coupler unit that branches the upstream optical signal converted by the second optical transmission unit and the reflected light reflected from the optical transmission path, and a reflection branched by the optical coupler unit. An optical power detection unit that detects the power of light and determines whether or not the power of the reflected light is greater than or equal to a certain value. When it is determined that the value is greater than or equal to the value, transmission of the radio signal is stopped.

  Thereby, for example, when the light reflection increases due to an abnormality in the optical transmission path connecting the control device and the relay device, the relay device can stop the transmission of the radio signal. As a result, a signal with degraded quality transmitted from the control device via the optical transmission line in which an abnormality has occurred is not converted into a radio signal and transmitted. In addition, since it is only necessary to detect reflected light from the optical transmission path, the configuration of the wireless communication system can be simplified.

  The quality evaluation unit and the signal transmission stop unit are provided in the control device, and the quality evaluation unit evaluates the quality of the downstream optical signal and determines whether or not the quality of the downstream optical signal satisfies a predetermined condition. The signal transmission stop means, when the quality evaluation means determines that the quality of the downstream optical signal does not satisfy the predetermined condition, stops the transmission of the downstream optical signal, thereby May be stopped.

  According to this, the control device stops the transmission of the downstream optical signal when the quality of the downstream optical signal is deteriorated. As a result, transmission of the downstream optical signal from the control device is stopped, so that transmission of a radio signal with reduced quality from the relay device can be stopped.

  As an example, the quality evaluation unit includes an optical coupler unit that branches the downstream optical signal converted by the first optical transmission unit and the reflected light reflected from the optical transmission path, and a reflection branched by the optical coupler unit. An optical power detection unit that detects the power of light and determines whether or not the power of the reflected light is greater than or equal to a certain value. If it is determined that the value is greater than or equal to the value, transmission of the downstream optical signal is stopped.

  Thereby, for example, when light reflection increases due to an abnormality in the optical transmission line connecting the control device and the relay device, the control device stops transmission of the downstream optical signal, thereby Transmission can be stopped. Therefore, a radio signal with degraded quality is not transmitted from the relay device. In addition, since it is only necessary to detect reflected light from the optical transmission path, the configuration of the wireless communication system can be simplified.

  The antenna unit receives a radio signal transmitted from the radio communication terminal to generate an upstream electrical signal, and the relay device further converts the upstream electrical signal received by the antenna unit into an upstream optical signal for optical transmission. A second optical transmission unit configured to transmit to the control device via the path, and the control device further includes a second optical signal that converts the upstream optical signal transmitted from the relay device via the optical transmission path into an upstream electrical signal. The optical receiver includes a quality evaluation unit and a signal transmission stop unit provided in the control device, the quality evaluation unit evaluates the quality of the upstream optical signal, and the signal transmission stop unit transmits the upstream optical signal by the quality evaluation unit. When it is determined that the quality of the radio signal does not satisfy the predetermined condition, the transmission of the radio signal from the relay apparatus may be stopped by stopping the transmission of the downstream optical signal.

  According to this, for example, when an abnormality occurs in the optical transmission path and the quality of the upstream optical signal is deteriorated, the control device stops transmission of the downstream optical signal. As a result, it is possible to prevent a downstream optical signal whose quality has deteriorated due to transmission through an optical transmission line in which an abnormality has occurred from being transmitted as a radio signal from the repeater.

  As an example, the quality evaluation unit detects the power of the upstream optical signal received by the control device, and determines whether or not the power of the upstream optical signal is equal to or lower than a predetermined value. The signal transmission stop means stops transmission of the downstream optical signal when the light reception power detection unit determines that the upstream optical signal power is equal to or lower than a predetermined value.

  Thereby, transmission of a downstream optical signal can be stopped when the light receiving power is reduced in the control device. Moreover, since the control apparatus should just have the function to detect received light power, the structure of a radio | wireless communications system can be simplified.

  The antenna unit receives a radio signal transmitted from the radio communication terminal to generate an upstream electrical signal, and the relay device further converts the upstream electrical signal received by the antenna unit into an upstream optical signal for optical transmission. A second optical transmission unit configured to transmit to the control device via the path, and the control device further includes a second optical signal that converts the upstream optical signal transmitted from the relay device via the optical transmission path into an upstream electrical signal. The optical evaluation unit and the signal transmission stop unit are provided in the control device, the quality evaluation unit evaluates the quality of the uplink electrical signal, and the signal transmission stop unit is connected to the uplink electrical signal by the quality evaluation unit. When it is determined that the quality of the radio signal does not satisfy the predetermined condition, the transmission of the radio signal from the relay apparatus may be stopped by stopping the transmission of the downstream optical signal.

  As a result, when the signal quality deteriorates and the control device cannot normally demodulate the signal, the transmission of the downstream optical signal is stopped, thereby preventing the relay device from transmitting the wireless signal with the deteriorated quality. can do.

  As an example, the quality evaluation means includes a signal level detector that detects the level of the frequency band component of the radio signal to be received from the radio communication terminal from the upstream electrical signal converted by the second optical receiver; An unnecessary radiation level detector that detects the level of the component outside the frequency band of the radio signal to be received from the radio communication terminal from the upstream electrical signal converted by the optical receiver, and the frequency band component detected by the signal level detector A level determination unit that determines whether or not the level of the component outside the frequency band detected by the unnecessary radiation level detection unit with respect to the level is equal to or higher than a certain level. When it is determined that the level of the component outside the frequency band with respect to the component level is equal to or higher than a certain level, transmission of the downstream optical signal is stopped.

  Thereby, the control apparatus can stop transmission of a radio signal including an out-of-band frequency component equal to or higher than a specified level.

  As another example, the relay apparatus further includes a test signal generation unit that generates two test signals of different frequencies, and the second optical transmission unit is an uplink in which the test signal generated by the test signal generation unit is superimposed. A test signal level detection unit that converts the electrical signal into an upstream optical signal, and the quality evaluation unit detects a level of a frequency band component of the test signal superimposed on the upstream electrical signal converted by the second optical reception unit; A distortion level detector for detecting the level of intermodulation distortion of the test signal superimposed on the upstream electrical signal converted by the second optical receiver, and the frequency band level detected by the test signal level detector The signal transmission stop means comprises a level determination unit that determines whether or not the level of intermodulation distortion detected by the distortion level detection unit is equal to or higher than a certain level. By the level determination unit, when the intermodulation distortion level is determined to be a predetermined level or more on the level of the frequency band component of the test signal, it stops the transmission of the downstream optical signal.

  Thereby, the control apparatus can stop the transmission of the radio signal whose intermodulation distortion is increased and the quality is deteriorated. Moreover, since the level of a specific frequency should just be detected, the structure of a radio | wireless communications system can be simplified.

As another example, the relay apparatus further includes a test signal generation unit that generates a test signal, and the second optical transmission unit outputs an upstream electrical signal on which the test signal generated by the test signal generation unit is superimposed. The quality evaluation means converts to an upstream optical signal, and the quality evaluation means detects a level of a frequency band component of the test signal superimposed on the upstream electrical signal converted by the second optical receiver, and a second The distortion level detector detects the harmonic distortion level of the test signal superimposed on the upstream electrical signal converted by the optical receiver, and the distortion with respect to the level of the frequency band component detected by the test signal level detector A level determination unit that determines whether or not the level of harmonic distortion detected by the level detection unit is equal to or higher than a certain level. Te, if the harmonic distortion level is determined to be a predetermined level or more on the level of the frequency band component of the test signal, stops the transmission of the downstream optical signal.
Thereby, the control apparatus can stop transmission of a radio signal whose harmonic distortion has increased and quality has deteriorated. Moreover, since the level of a specific frequency should just be detected, the structure of a radio | wireless communications system can be simplified.

  The wireless signal may be a signal used in a wireless LAN, or may be a broadcast wave signal.

  Preferably, the optical connectors for connecting the optical transmission lines are all slant polishing connectors. Thereby, compared with the case where other optical connectors are used, light reflection and multiple reflection to the light emitting element can be prevented even when the optical connector is in a loose state. Therefore, it is possible to prevent deterioration of the quality of the optical signal.

  ADVANTAGE OF THE INVENTION According to this invention, the radio | wireless communications system which can stop transmission of the radio signal with which quality deteriorated will be provided.

(First embodiment)
FIG. 1 is a block diagram showing a configuration of a radio communication system according to the first embodiment of the present invention.

  In FIG. 1, the wireless communication system includes a control device 10, relay devices 20-1 to 20-n (n: a natural number of 1 or more), and wireless communication terminals 30-1 to 30-n. The control device 10 and the relay devices 20-1 to 20-n are connected via optical transmission lines 40-1 to 40-n, respectively. The relay devices 20-1 to 20-n and the wireless communication terminals 30-1 to 30-n are connected to each other via wireless communication. The optical transmission line is, for example, an optical fiber.

  The control device 10 and an external network (not shown) are connected via an Ethernet (registered trademark) cable 60. The control device 10 and the external network may be connected via a cable other than the Ethernet (registered trademark) cable 60 (for example, a telephone line, a coaxial cable, or an optical fiber).

  Hereinafter, when it is not particularly necessary to distinguish, relay apparatuses 20-1 to 20-n (n: a natural number of 1 or more), wireless communication terminals 30-1 to 30-m (m: a natural number of 1 or more), an optical transmission line 40-1 to 40-n are collectively referred to as the relay device 20, the wireless communication terminal 30, and the optical transmission line 40.

  The relay device 20 converts the radio signal transmitted by the radio communication terminal 30 into an upstream optical signal, and transmits it to the control device 10 via the optical transmission path 40. The control device 10 converts the upstream optical signal transmitted from the relay device 20 via the optical transmission path 40 into an upstream electrical signal, demodulates it, and transmits it to the external network via the Ethernet (registered trademark) cable 60. .

  On the other hand, the control device 10 converts signals to be transmitted to the wireless communication terminals 30-1 to 30-m into downstream optical signals, and repeaters 20-1 to 20-20 via the optical transmission lines 40-1 to 40-n. -Send to n. The relay apparatuses 20-1 to 20-n convert the received downstream optical signals into radio signals and transmit the radio signals to the radio communication terminals 30-1 to 30-m.

  FIG. 2 is a block diagram showing a detailed configuration of the control device 10 shown in FIG. 2, the control device 10 includes a transmission signal processing unit 101, an optical transmission unit 102, an optical distribution unit 103, optical reception units 104-1 to 104-n, and a reception signal processing unit 105.

  The transmission signal processing unit 101 modulates a signal transmitted from the external network via the Ethernet (registered trademark) cable 60 and outputs the modulated signal to the optical transmission unit 102.

  The optical transmission unit 102 converts the signal modulated by the transmission signal processing unit 101 into a downstream optical signal and outputs it to the optical distribution unit 103.

  The optical distribution unit 103 branches the optical signal converted by the optical transmission unit 102 into n downstream optical signals and sends them to the optical transmission lines 40-1 to 40-n.

  When the optical receiving units 104-1 to 104-n receive the upstream optical signals transmitted from the relay apparatuses 20-1 to 20-n via the optical transmission lines 40-1 to 40-n, Convert optical signals into electrical signals.

  The reception signal processing unit 105 demodulates the electrical signal converted by the optical reception units 104-1 to 104-n. The received signal processing unit 105 transmits the demodulated signal to the external network via the Ethernet (registered trademark) cable 60. Note that the reception signal processing unit 105 may perform signal processing other than signal demodulation. The signal processing includes, for example, simple addition, diversity reception, RAKE reception, amplitude adjustment, signal selection, and the like.

  FIG. 3 is a block diagram illustrating a configuration of the relay apparatus 20 included in the wireless communication system illustrated in FIG. In FIG. 3, the relay device 20 includes an optical reception unit 201, a wireless transmission unit 202, a separation unit 203, a transmission / reception antenna unit 204, a wireless reception unit 205, an optical transmission unit 206, and a quality evaluation unit 290. Including.

  When receiving the downstream optical signal transmitted from the control device 10 via the optical transmission path 40, the optical receiving unit 201 converts the received downstream optical signal into a downstream electrical signal and outputs it to the wireless transmission unit 202.

  The wireless transmission unit 202 performs processing such as amplification on the downlink electrical signal converted by the optical reception unit 201 and outputs the processed signal to the separation unit 203.

  The separation unit 203 outputs the downlink electrical signal output from the wireless transmission unit 202 to the transmission / reception antenna unit 204. Separation section 203 outputs the electrical signal received by transmission / reception antenna section 204 to radio reception section 205.

  The wireless reception unit 205 performs processing such as amplification on the uplink electrical signal output from the separation unit 203 and outputs the processed signal to the optical transmission unit 206.

  The optical transmission unit 206 converts the upstream electrical signal output from the wireless reception unit 205 into an upstream optical signal, and outputs the upstream optical signal to the optical coupler unit 207 described later.

  The transmission / reception antenna unit 204 sends the downstream electrical signal output from the separation unit 203 into the air as a radio signal. The transmission / reception antenna unit 204 also receives a radio signal transmitted from the radio communication terminal 30.

  The quality evaluation unit 290 includes an optical coupler unit 207, an optical power detection unit 208, and a power control unit 209.

  The optical coupler unit 207 sends the upstream optical signal converted by the optical transmission unit 206 to the optical transmission line 40. The optical coupler unit 207 outputs the reflected light reflected from the optical transmission path 40 to the optical power detection unit 208.

  The optical power detection unit 208 detects the level of reflected light output from the optical coupler unit 207 and determines whether or not the level of reflected light is a predetermined value or more. When an abnormality occurs in the optical transmission line 40, the level of reflected light increases when an optical signal is emitted to the optical transmission line 40. When the level of the reflected light is equal to or higher than the predetermined value, the optical power detection unit 208 determines that an abnormality has occurred in the optical transmission path. In that case, the optical power detection unit 208 instructs the power control unit 209 to stop sending the radio signal radio wave.

  The power control unit 209 controls the wireless transmission unit 202 to stop the transmission of wireless signal radio waves to the wireless communication terminal. Specifically, the power control unit 209 turns off the power of the wireless transmission unit 202 or turns off a signal path switch (not shown) in the wireless transmission unit 202.

  When an abnormality occurs in the optical transmission line 40 and the transmission quality of the optical signal decreases, the quality of the radio signal also satisfies the specified conditions for items such as spurious emission power and out-of-band radiation power defined in the Radio Law. I can't do that. The spurious emission power and the out-of-band radiation power are emission power of unnecessary waves outside the necessary frequency band. When these are fired, other communication devices may be disturbed, so it is desirable that the emission power of unnecessary waves be as small as possible. In addition, permissible values of spurious emission power and out-of-band radiation power are defined for each frequency band in the Radio Law. The relay device 20 stops the transmission of the radio signal when the transmission quality of the upstream optical signal is deteriorated.

  As described above, according to the present embodiment, when an abnormality occurs in the optical transmission line, transmission of a radio signal from the relay device can be stopped. Therefore, a radio signal that does not satisfy the official conditions is not transmitted. In addition, since the relay device only needs to detect the level of reflected light, the system configuration can be simplified.

  Even when the optical transmission line is composed of a two-core optical fiber, an optical fiber failure often affects the optical fiber in the same cable. Therefore, this method is effective. In the case of single-core bidirectional transmission, the possibility of affecting only one direction is very small, and this method is effective.

  Next, a modification of the first embodiment will be described. In the wireless communication system according to the present modification, the relay device 20a evaluates the quality of the downstream optical signal received from the control device 10.

  FIG. 4 is a block diagram illustrating a configuration of the relay device 20a included in the wireless communication system according to the present modification. In FIG. 4, the relay device 20a includes an optical receiving unit 201, a wireless transmission unit 202, a separation unit 203, a transmission / reception antenna unit 204, a wireless reception unit 205, an optical transmission unit 206a, and a quality evaluation unit 290a. Including. In addition, the same code | symbol is attached | subjected to the component similar to FIG. 3, and description is abbreviate | omitted.

  The quality evaluation unit 290a includes a power control unit 209 and a received light power detection unit 210.

  The received light power detection unit 210 detects the power of the downstream optical signal received by the optical reception unit 201, and determines whether or not the power of the downstream optical signal is greater than or equal to a predetermined value. When the power of the downstream optical signal becomes less than the predetermined value, the received light power detection unit 210 instructs the power control unit 209 to stop the transmission of the radio signal.

  The power control unit 209 stops the output of the radio signal in response to an instruction from the received light power detection unit 210. Specifically, the power control unit 209 stops the output of the wireless signal by turning off the power of the wireless transmission unit 202. Note that the power control unit 209 may stop the output of the radio signal by turning off the path of the radio transmission unit 202 with a switch.

  When an abnormality occurs in the optical transmission line 40, generally, the transmission quality of the optical signal deteriorates. Therefore, it is possible to indirectly detect the deterioration of the transmission quality by monitoring the abnormality of the optical transmission line. When an abnormality occurs in the transmission path and the transmission loss increases, the power of the optical signal detected by the received light power detection unit 210 decreases. Therefore, the transmission quality of the optical signal can be evaluated by monitoring the power of the received downstream optical signal in the relay device.

  As described above, according to the present modification, when an abnormality occurs in the optical transmission line, transmission of a radio signal from the relay device can be stopped. Therefore, a radio signal that does not satisfy the official conditions is not transmitted. In this modification, the relay device only needs to have a function of detecting the level of the optical signal transmitted from the control device via the optical transmission line, and measures spurious emission power and out-of-band radiation power. Therefore, it is not necessary to provide a complicated detection circuit.

(Second Embodiment)
The radio communication system according to the second embodiment of the present invention will be described below. In the wireless communication system according to the present embodiment, the relay device evaluates the quality of the downlink electrical signal.

  FIG. 5 is a block diagram illustrating a configuration of the relay device 20b included in the wireless communication system according to the present embodiment. In FIG. 5, the relay device 20b includes an optical reception unit 201, a wireless transmission unit 202b, a separation unit 203, a transmission / reception antenna unit 204, a wireless reception unit 205, an optical transmission unit 206b, and a quality evaluation unit 290b. Including. In addition, the same code | symbol is attached | subjected to the component similar to FIG. 3, and the description is abbreviate | omitted.

  The wireless transmission unit 202b performs processing such as amplification on the downlink electrical signal converted by the optical reception unit 201, and then outputs the signal to the separation unit 203 and an electrical signal evaluation unit 211 described later.

  The quality evaluation unit 290b includes a power control unit 209 and an electric signal evaluation unit 211.

  The electrical signal evaluation unit 211 evaluates the quality of the downstream electrical signal output from the wireless transmission unit 202b.

  FIG. 6 is a block diagram illustrating a detailed configuration of the electric signal evaluation unit 211. In FIG. 6, the electric signal evaluation unit 211 includes a bandpass filter-s (hereinafter referred to as BPF-s) 251, bandpass filters (hereinafter referred to as BPF) 252-1 to 252-n, and a level detection unit. 253-1 to 253-n + 1 and a level determination unit 254.

  The BPF-s 251 and the BPFs 252-1 to 252-n pass the frequency according to the spectrum mask. The BPF-s 251 passes a radio signal in a frequency band that should be originally transmitted, and removes an out-of-band frequency of the radio signal. The BPF-s 251 outputs the frequency component of the passed signal to the level detection unit 253-1. The level detection unit 253-1 detects the level of the signal output from the BPF-s 251 and outputs it to the level determination unit 254.

  The BPFs 252-1 to 252-n pass the out-of-band frequency component of the radio signal and output it to the level detection units 252-2 to 253-n + 1. The BPFs 252-1 to 252-n pass different frequencies.

  The level determination unit 254 determines whether or not the level of the out-of-band frequency detected by the level detection units 253-2 to 253-n + 1 is equal to or higher than a certain level with respect to the frequency level detected by the level detection unit 253-1. Determine whether. When the quality of the radio signal is lowered, the level of the out-of-band frequency of the radio signal, that is, the level of unnecessary radiation power is increased. When the level of the unnecessary radiant power with respect to the level of the radio signal becomes equal to or higher than a certain level, the level determination unit 254 instructs the power control unit 209 to stop transmission of the radio signal.

  The power control unit 209 stops the output of the radio signal in response to an instruction from the electric signal evaluation unit 211. The specific operation of the power control unit 209 is the same as that of the power control unit 209 shown in FIG.

  As described above, in the present embodiment, the relay device determines that the level of unnecessary radiant power with respect to the level of the radio signal is equal to or higher than a certain level, and the quality of the radio signal can no longer satisfy the public condition. Stop transmitting wireless signals. Therefore, a radio signal that does not satisfy the official conditions is not transmitted.

  Next, a modification of the second embodiment will be described. In the wireless communication system according to the present modification, the control device converts the downstream electrical signal on which the test signal is superimposed into a downstream optical signal and transmits the downstream optical signal to the relay device. The relay device evaluates the quality of the test signal received from the control device.

  Specifically, the relay apparatus evaluates the intermodulation distortion of the test signal. The intermodulation distortion is a signal generated when a plurality of signals having different frequencies are converted into downstream optical signals in the control device. Intermodulation distortion occurs due to nonlinearity in the IL characteristics of the light emitting element. In general, when two different signals are input to a light emitting device, an amplifier, etc., in addition to the frequency of each fundamental wave, the harmonic components, the sum and difference of the frequencies of the two fundamental waves, the frequency of the fundamental wave Components such as the sum and difference of the two harmonic frequencies and the sum and difference of the two harmonic frequencies appear. As described above, a frequency component (a component other than harmonics) generated from the correlation between a plurality of frequencies is referred to as intermodulation distortion. For example, when two waves of frequency a and frequency b are input to a light emitting element or an amplifier, a frequency 2a-b or the like is generated as intermodulation distortion. Since the frequency 2a-b approaches the frequency of the main signal, the main signal may be disturbed.

  FIG. 7 is a block diagram illustrating a configuration of the control device 10a included in the wireless communication system according to the present modification. In FIG. 7, the control device 10a includes a transmission signal processing unit 101, an optical transmission unit 102a, an optical distribution unit 103, optical reception units 104-1 to 104-n, a reception signal processing unit 105, and a test signal transmission. Part 106. In addition, the same code | symbol is attached | subjected to the component similar to FIG. 2, and description is abbreviate | omitted.

  The test signal transmission unit 106 generates a test signal to be superimposed on the downlink electrical signal and outputs the test signal to the optical transmission unit 102a. The test signal transmission unit 106 includes an oscillator SG-a and an oscillator SG-b.

  The oscillator SG-a generates a test signal a and outputs it to the optical transmitter 102a. Let a be the frequency of the test signal a. The oscillator SG-b generates a test signal b and outputs it to the optical transmitter 102a. Let the frequency of the test signal b be b.

  The optical transmission unit 102a superimposes the test signals a and b output from the test signal transmission unit 106 on the downlink electrical signal output from the transmission signal processing unit 101, and converts the signal into a downlink optical signal.

  Next, a relay device that evaluates a test signal transmitted from the control device 10a will be described. Since the configuration of the relay device according to this modification is the same as the configuration of the relay device 20b shown in FIG. 5 except for the configuration of the electrical signal evaluation unit, only the electrical signal evaluation unit will be described with the aid of FIG. To do. Further, in order to distinguish the electrical signal evaluation unit included in the relay device according to this modification from the electrical signal evaluation unit illustrated in FIG. 5, the electrical signal evaluation unit included in the relay device according to this modification is referred to as the electrical signal evaluation unit 211e. Call.

  FIG. 8 is a block diagram illustrating a detailed configuration of the electrical signal evaluation unit 211e. In FIG. 8, the electric signal evaluation unit 211e includes a bandpass filter-a (hereinafter referred to as BPF-a) 255 and a bandpass filter- (2a-b) (hereinafter referred to as BPF- (2a-b)). 256, level detection units 253-1 to 253-2, and a level determination unit 254e.

  The BPF-a 255 passes the test signal a having the frequency a and removes the out-of-band frequency of the test signal a. Then, the BPF-a 255 outputs the passed test signal a to the level detection unit 253-1. The level detection unit 253-1 detects the level of the test signal a and outputs it to the level determination unit 254.

  The BPF- (2a-b) 256 passes the frequency (2a-b) of the intermodulation distortion and outputs it to the level detection unit 253-2.

  The level determination unit 254e determines whether or not the level of the intermodulation distortion detected by the level detection unit 253-2 is equal to or higher than a certain level with respect to the level of the test signal a detected by the level detection unit 253-1. to decide. When the level of intermodulation distortion with respect to the level of the test signal a becomes equal to or higher than a certain level, the level determination unit 254e instructs the power control unit 209 to stop transmission of the radio signal.

  The power control unit 209 stops the output of the radio signal in response to an instruction from the electric signal evaluation unit 211. The specific operation of the power control unit 209 is the same as that of the power control unit 209 shown in FIG.

  As described above, according to this modification, the relay apparatus evaluates the intermodulation distortion of the test signal transmitted from the control apparatus, and the level of the intermodulation distortion with respect to the level of the test signal becomes equal to or higher than a certain level. If so, the transmission of the radio signal is stopped. Thereby, it is possible to prevent transmission of a radio signal with degraded quality.

  In general, it is difficult to directly measure spurious emission power, out-of-band radiation power, and the like, and the cost for measuring these is high. However, according to this modification, the intermodulation distortion of the test signal may be measured. In order to measure the intermodulation distortion, for example, only a preset frequency needs to be observed, which has an advantage that it can be realized with a simple circuit.

  In the above modification, the method for measuring the intermodulation distortion of the test signal has been described. However, instead of the intermodulation distortion, the transmission quality may be evaluated by measuring the harmonic distortion of the test signal. Good.

  A harmonic means a component having a frequency that is an integral multiple of the fundamental frequency. For example, when a signal a having a frequency a is input to a non-linear circuit, distortion occurs, and harmonics having the frequency 2a and the frequency 3a are output together with the frequency a. When the transmission quality of the signal decreases, the level of these harmonics increases. Therefore, transmission quality can also be evaluated by measuring harmonic distortion.

  In that case, since only one type of test signal may be transmitted from the control device to the relay device, the test signal transmission unit 106 illustrated in FIG. 7 only needs to include the oscillator SG-a. As a result, the downstream optical signal on which the test signal a is superimposed is transmitted to the relay device. In the relay device, the electric signal evaluation unit 211e shown in FIG. 8 only needs to have a bandpass filter-2a that allows the frequency 2a to pass instead of BPF- (2a-b).

  Hereinafter, an electrical signal evaluation unit for detecting harmonic distortion will be described. In order to distinguish the electrical signal evaluation unit included in the relay device that detects harmonic distortion from the electrical signal evaluation unit illustrated in FIG. 5, the electrical signal evaluation unit included in the relay device that detects harmonic distortion is referred to as the electrical signal evaluation unit 211f. Call.

  FIG. 9 is a block diagram illustrating a configuration of the electric signal evaluation unit 211f. When detecting harmonic distortion, the relay device 20b illustrated in FIG. 5 includes an electrical signal evaluation unit 211f illustrated in FIG. 9 instead of the electrical signal evaluation unit 211. In FIG. 9, the electrical signal evaluation unit 211f includes a bandpass filter-a (hereinafter referred to as BPF-a) 255, a bandpass filter-2a (hereinafter referred to as BPF-2a) 257, and a level detection unit 253-. 1 to 253-2 and a level determination unit 254f.

  The BPF-a 255 passes the test signal a having the frequency a and removes the out-of-band frequency of the test signal a. Then, the BPF-a 255 outputs the passed test signal a to the level detection unit 253-1. The level detection unit 253-1 detects the level of the test signal a and outputs it to the level determination unit 254.

  The BPF-2a257 passes the harmonic distortion frequency 2a and outputs it to the level detector 253-2.

  The level determination unit 254f determines whether or not the level of harmonic distortion detected by the level detection unit 253-2 is equal to or higher than a certain level with respect to the level of the test signal a detected by the level detection unit 253-1. to decide. When the harmonic distortion level with respect to the level of the test signal a becomes equal to or higher than a certain level, the level determination unit 254e instructs the power control unit 209 to stop the transmission of the radio signal.

  The power control unit 209d stops the output of the radio signal in response to an instruction from the electric signal evaluation unit 211. The specific operation of the power control unit 209d is the same as that of the power control unit 209 shown in FIG.

  As described above, according to this modification, the relay apparatus evaluates the harmonic distortion of the test signal transmitted from the control apparatus, and the level of the harmonic distortion with respect to the level of the test signal becomes a certain level or more. If so, the transmission of the radio signal is stopped. Thereby, it is possible to prevent transmission of a radio signal with degraded quality.

  As described above, in the first embodiment and the second embodiment, the case where the relay apparatus evaluates the quality of the radio signal or the optical signal has been described. Here, not the relay apparatus but the control apparatus may evaluate the quality of these signals. Hereinafter, a case where the control device evaluates the quality of a radio signal or an optical signal will be described.

(Third embodiment)
FIG. 10 is a block diagram illustrating a configuration of a control device 10b included in the wireless communication system according to the third embodiment. 10, the control device 10b includes a transmission signal processing unit 101, an optical transmission unit 102b, an optical distribution unit 103, optical reception units 104-1 to 104-n, a reception signal processing unit 105, and a quality evaluation unit. 290b. In addition, the same code | symbol is attached | subjected to the component similar to FIG. 2, and description is abbreviate | omitted.

  The optical transmission unit 102b converts a signal transmitted from the external network into a downstream optical signal and outputs it to the optical coupler unit 107 described later.

  The quality evaluation unit 290 b includes an optical coupler unit 107, an optical power detection unit 108, and a power control unit 109.

  The optical coupler unit 107 outputs the upstream optical signal to the optical distribution unit 103 and outputs the reflected light reflected from the optical transmission path 40 to the optical power detection unit 108.

  The optical power detection unit 108 detects the power of the reflected light output from the optical coupler unit 107, and when the power of the reflected light is equal to or higher than a predetermined value, the optical power detection unit 108 instructs the power control unit 109 to stop sending the downstream optical signal. Instruct.

  The power control unit 109 controls the optical transmission unit 102b to stop sending the downstream optical signal. Specifically, the power control unit 209 turns off the power of the optical transmission unit 102b or turns off a signal path switch (not shown) in the optical transmission unit 102b. The optical coupler unit 107, the optical power detection unit 108, and the power control unit 109 have the same functions as the optical coupler unit 207, the optical power detection unit 208, and the power control unit 209 shown in FIG. The detailed explanation is omitted.

  The relay device according to the present embodiment has a configuration in which the quality evaluation unit 290 is omitted from the relay device 20 illustrated in FIG.

  As described above, according to the present embodiment, transmission of an optical signal from the control device can be stopped when an abnormality occurs in the optical transmission line. Therefore, a radio signal that does not satisfy the official conditions is not transmitted from the relay device. Further, since it is only necessary to detect the reflected light in the control device, the configuration of the system can be simplified.

  Next, a modification of the third embodiment will be described. FIG. 11 is a block diagram illustrating a configuration of a control device 10c according to a modification of the third embodiment.

  11, the control device 10c includes a transmission signal processing unit 101, an optical transmission unit 102, an optical distribution unit 103c, optical reception units 104-1 to 104-n, a reception signal processing unit 105, and a quality evaluation unit. 290c. In addition, the same code | symbol is attached | subjected to the component similar to FIG. 2, and description is abbreviate | omitted.

    The optical distribution unit 103c outputs the downstream optical signal branched into n to the variable optical attenuators 121-1 to 121-n described later.

  The quality evaluation unit 290c includes a power control unit 109, received light power detection units 110-1 to 110-n, and variable optical attenuators 121-1 to 121-n.

  The received light power detectors 110-1 to 110-n detect the power of the upstream optical signal received by the optical receivers 104-1 to 104-n, and determine whether or not the power of the upstream optical signal is greater than or equal to a predetermined value. to decide. The received light power detection units 110-1 to 110-n instruct the power control unit 109 to stop transmission of the downstream optical signal when the upstream optical signal power becomes less than a predetermined value.

  The variable optical attenuators 121-1 to 121-n attenuate the power of the downstream optical signal output from the optical distribution unit 103c and send it to the optical transmission lines 40-1 to 40-n.

  The power control unit 109 stops the output of the downstream optical signal in response to an instruction from the received light power detection units 110-1 to 110-n. Specifically, the power control unit 109 controls the attenuation amount of the downstream optical signal in the variable optical attenuators 121-1 to 121-n, and stops the output of the downstream optical signal. At this time, the power control unit 109 stops transmission of the downlink signal only to the optical transmission line in which an abnormality has occurred. For example, when the power of the upstream optical signal detected by the received light power detection unit 110-2 is less than a predetermined value, the power control unit 109 controls the variable optical attenuator 121-2 to the optical transmission line 40-2. The transmission of the downstream optical signal is stopped.

  The functions of the received light power detection unit 110 and the power control unit 109 are the same as the functions of the received light power detection unit 210 and the power control unit 209 shown in FIG.

  As described above, according to the present modification, transmission of the downstream optical signal from the control device can be stopped when an abnormality occurs in the optical transmission line. Therefore, a radio signal that does not satisfy the official conditions is not transmitted from the relay device. In this modification, the control device only needs to have a function of detecting the level of the optical signal transmitted from the control device via the optical transmission path, and measures spurious emission power and out-of-band radiation power. Therefore, it is not necessary to provide a complicated detection circuit.

(Fourth embodiment)
FIG. 12 is a block diagram showing a configuration of a control device 10d according to the fourth embodiment of the present invention.

  In FIG. 12, the control device 10d includes a transmission signal processing unit 101, an optical transmission unit 102, an optical distribution unit 103, optical reception units 104-1 to 104-n, a reception signal processing unit 105d, and a quality evaluation unit. 290d. In addition, the same code | symbol is attached | subjected to the component similar to FIG. 2, and description is abbreviate | omitted.

  The reception signal processing unit 105d outputs the electrical signal converted by the optical reception units 104-1 to 104-n to the electrical signal evaluation unit 111 described later.

  The quality evaluation unit 290d includes a power control unit 109 and an electric signal evaluation unit 111.

  The electrical signal evaluation unit 111 evaluates the quality of the electrical signal output from the reception signal processing unit 105d, and stops transmission of the downstream optical signal when the quality of the electrical signal is reduced. Here, since the electrical signal evaluation unit 111 corresponds to the electrical signal evaluation unit 211 illustrated in FIG. 6, FIG. 6 is used and detailed description thereof is omitted.

  The power control unit 109 corresponds to the power control unit 209 illustrated in FIG. The power control unit 109 stops the output of the downstream optical signal from the optical transmission unit 102 in response to an instruction from the electrical signal evaluation unit 111.

  The relay device according to the present embodiment has a configuration in which the quality evaluation unit 290 is omitted from the relay device 20 illustrated in FIG.

  As described above, in the present embodiment, the control device determines whether or not the level of the unnecessary radiation power with respect to the level of the signal transmitted from the relay device is equal to or higher than a certain level. For example, when an abnormality occurs in the optical transmission line, the quality of the upstream signal is degraded. In this case, if a downstream signal is transmitted to the relay device, a wireless signal with degraded quality is transmitted. The control device stops the transmission of the downstream optical signal when the quality of the upstream signal decreases. Therefore, a radio signal that does not satisfy the official conditions is not transmitted from the relay device.

  Next, a modification of the fourth embodiment will be described. In the wireless communication system according to the present modification, the relay device converts an upstream electrical signal on which the test signal is superimposed into an upstream optical signal and transmits the upstream optical signal to the control device. The control device evaluates the quality of the test signal received from the relay device.

  FIG. 13 is a block diagram illustrating a configuration of the relay device 20c included in the wireless communication system according to the present modification. In FIG. 13, the relay device 20 c includes an optical reception unit 201, a wireless transmission unit 202, a separation unit 203, a transmission / reception antenna unit 204, a wireless reception unit 205, an optical transmission unit 206 c, and a test signal transmission unit 212. including.

  The test signal transmission unit 212 generates a test signal to be superimposed on the uplink electrical signal transmitted from the relay device 20c, and outputs the test signal to the optical transmission unit 206c. The test signal transmission unit 212 includes an oscillator SG-a and an oscillator SG-b.

  The oscillator SG-a generates a test signal a and outputs it to the optical transmitter 206c. Let a be the frequency of the test signal a. The oscillator SG-b generates a test signal b and outputs it to the optical transmitter 206c. Let the frequency of the test signal b be b. The test signal transmission unit 212 corresponds to the test signal transmission unit 106 shown in FIG.

  The optical transmission unit 206c superimposes the test signals a and b output from the test signal transmission unit 212 on the upstream electrical signal output from the wireless reception unit 205, and converts it into an upstream optical signal.

  Next, a control device that evaluates a test signal transmitted from the relay device 20c will be described. Since the configuration of the control device according to this modification is the same as the configuration of the control device 10d shown in FIG. 12 except for the configuration of the electric signal evaluation unit, FIG. 12 is used and only the differences will be described. . Since the configuration of the electrical signal evaluation unit in the case of evaluating the intermodulation distortion is the same as the configuration of the electrical signal evaluation unit 211e shown in FIG. 8, FIG. 8 is cited. The electrical signal evaluation unit 211e evaluates the quality of the test signal superimposed on the upstream electrical signal output from the reception signal processing unit 105d. The electrical signal evaluation unit 211e instructs the power control unit 109 to stop the transmission of the downstream optical signal when the level of the intermodulation distortion with respect to the level of the test signal becomes a certain level or more.

  As described above, according to this modification, the control apparatus evaluates the intermodulation distortion of the test signal transmitted from the relay apparatus, and the level of the intermodulation distortion with respect to the level of the test signal becomes equal to or higher than a certain level. In this case, transmission of the downstream optical signal is stopped. Thereby, it is possible to prevent the relay apparatus from transmitting a radio signal with degraded quality.

  In this modification, the control device evaluated intermodulation distortion. Here, it is good also as evaluating a harmonic distortion similarly to the modification of 4th Embodiment. In this case, the configuration of the electrical signal evaluation unit is the same as that of the electrical signal evaluation unit 211f shown in FIG. In the output signal output from the reception signal processing unit 105d, the electrical signal evaluation unit 211f is configured to stop the transmission of the downstream optical signal when the harmonic distortion level with respect to the test signal level is equal to or higher than a certain level. The control unit 109 is instructed.

  As described above, in this modification, the control device evaluates the intermodulation distortion or the harmonic distortion of the test signal transmitted from the relay apparatus, and the level of the intermodulation distortion or the harmonic distortion with respect to the level of the test signal is determined. When the signal exceeds a certain level, the transmission of the radio signal is stopped. Thereby, it is possible to prevent transmission of a radio signal with degraded quality. In order to measure the intermodulation distortion or the harmonic distortion, for example, it is only necessary to observe a preset frequency, so that there is an advantage that it can be realized with a simple circuit.

  Moreover, in said 1st-4th embodiment, a slant polishing connector is the most suitable as an optical connector which connects optical transmission paths or optical transmission paths and an apparatus. When the connector becomes loose, reflection occurs at the end face of the connector. Therefore, in the PC connector etc., light reflection to the light emitting element occurs, or multiple reflections occur when there are multiple reflection points. Quality will deteriorate. However, by adopting the oblique polishing connector, there is an advantage that light reflection or multiple reflection to the light emitting element does not occur even when the connector is loose, and the signal quality does not deteriorate.

  In the first to fourth embodiments, the wireless communication system has been described on the assumption that communication is performed using a wireless LAN signal. Here, the wireless communication system can also be used as a retransmission system for measures against dead areas of broadcast waves. However, in a system that communicates using broadcast waves, it is generally considered that an upstream signal is unnecessary. Therefore, as described in the third embodiment and the fourth embodiment, a method of evaluating the quality of the uplink signal cannot be taken, but the other methods are described in the first to fourth embodiments. Such a wireless communication system can be used.

  As described above, the wireless communication systems according to the first to fourth embodiments are systems that can communicate with wireless signals composed of a plurality of channels in the same area, such as a commercial building network, a wireless LAN service, and the like. Useful. Moreover, the radio | wireless communications system which concerns on 1st-4th embodiment is applicable also to uses, such as a train and a network in an aircraft.

  INDUSTRIAL APPLICABILITY The present invention is useful as a wireless communication system that can stop transmission of a wireless signal with degraded quality.

The block diagram which shows the structure of the radio | wireless communications system which concerns on the 1st Embodiment of this invention. The block diagram which shows the structure of the control apparatus with which the radio | wireless communications system shown in FIG. 1 is provided. 1 is a block diagram illustrating a configuration of a relay device 20 included in the wireless communication system illustrated in FIG. The block diagram which shows the structure of the relay apparatus 20a with which the radio | wireless communications system which concerns on the modification of 1st Embodiment is provided. The block diagram which shows the structure of the relay apparatus 20b with which the radio | wireless communications system which concerns on the 2nd Embodiment of this invention is provided. The block diagram which shows the detailed structure of the electric signal evaluation part 211 The block diagram which shows the structure of the control apparatus 10a with which the radio | wireless communications system which concerns on the modification of 2nd Embodiment is provided. The block diagram which shows the detailed structure of the electric signal evaluation part 211e The block diagram which shows the detailed structure of the electrical signal evaluation part 211f The block diagram which shows the structure of the control apparatus 10b which concerns on 3rd Embodiment. The block diagram which shows the structure of the control apparatus 10c with which the radio | wireless communications system which concerns on the modification of 3rd Embodiment is provided. The block diagram which shows the structure of 10 d of control apparatuses with which the radio | wireless communications system which concerns on the 4th Embodiment of this invention is provided. The block diagram which shows the structure of the relay apparatus 20c with which the radio | wireless communications system which concerns on the modification of 4th Embodiment is provided. The figure which shows the structure of the conventional radio | wireless communications system of patent document 1

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Control apparatus 20 Relay apparatus 30 Wireless communication terminal 40 Optical transmission line 60 Ethernet (trademark) cable 101 Transmission signal processing part 102,206 Optical transmission part 103 Optical distribution part 104,201 Optical reception part 105 Reception signal processing part 106,212 Test signal transmission unit 202 Wireless transmission unit 203 Separation unit 204 Transmission / reception antenna unit 205 Wireless reception unit 107, 207 Optical coupler unit 108, 208 Optical power detection unit 109, 209 Power control unit 110, 210 Light reception power detection unit 111, 211 Electrical signal Evaluation unit 251, 252, 255-257 Band pass filter (BPF)
253 Level detection unit 254 Level determination unit 290 Quality evaluation unit

Claims (20)

A wireless communication system in which an optical signal transmitted from a control device connected via an optical transmission line is converted into an electrical signal by a relay device and transmitted to a wireless communication terminal as a wireless signal,
The control device includes:
A first optical transmission unit that converts a downstream electrical signal into a downstream optical signal and transmits the downstream electrical signal to the relay device via the optical transmission path;
The relay device is
A first optical receiver that converts the downstream optical signal transmitted from the control device via the optical transmission path into the downstream electrical signal;
An antenna unit that transmits the downlink electrical signal converted by the first optical receiving unit as a radio signal to the radio communication terminal;
Quality evaluation means for evaluating the transmission quality in the optical transmission path and determining whether the transmission quality satisfies a predetermined condition;
A wireless communication system, comprising: signal transmission stopping means for stopping transmission of the wireless signal when the quality evaluation means determines that the transmission quality does not satisfy a predetermined condition. The quality evaluation unit and the signal transmission stop unit are provided in the relay device,
The quality evaluation means evaluates the quality of the downstream optical signal, determines whether the quality of the downstream optical signal satisfies a predetermined condition,
2. The radio communication according to claim 1, wherein the signal transmission stop unit stops the transmission of the radio signal when the quality evaluation unit determines that the quality of the downstream optical signal does not satisfy a predetermined condition. system. The quality evaluation unit is a light reception power detection unit that detects power of a downstream optical signal received by the relay device and determines whether the power is a predetermined value or less,
3. The radio communication system according to claim 2, wherein the signal transmission stop unit stops the transmission of the radio signal when the light reception power detection unit determines that the power of the downstream optical signal is equal to or less than a predetermined value. . The quality evaluation unit and the signal transmission stop unit are provided in the relay device,
The quality evaluation means evaluates the quality of the downlink electrical signal, determines whether the quality of the downlink electrical signal satisfies a predetermined condition,
2. The wireless communication according to claim 1, wherein the signal transmission stop unit stops transmission of the radio signal when the quality evaluation unit determines that the quality of the downlink electrical signal does not satisfy a predetermined condition. system. The quality evaluation means includes
A radio signal level detection unit that detects a level of a frequency band component of a radio signal to be transmitted from the antenna unit, from a downlink electrical signal converted by the first optical reception unit;
An unnecessary radiation level detection unit that detects a level of a component outside the frequency band of a radio signal to be transmitted from the antenna unit, from the downlink electrical signal converted by the first optical reception unit,
A level determination unit that determines whether or not the level of the component outside the frequency band detected by the unnecessary radiation level detection unit with respect to the level of the frequency band component detected by the radio signal level detection unit is equal to or higher than a certain level. Become
The signal transmission stop unit stops transmission of the radio signal when the level determination unit determines that the level of the component outside the frequency band with respect to the level of the frequency band component is equal to or higher than a certain level. 4. The wireless communication system according to 4. The control device further includes:
Including a test signal generator for generating two test signals of different frequencies;
The first optical transmission unit converts the downlink electrical signal on which the test signal generated by the test signal generation unit is superimposed into a downlink optical signal,
The quality evaluation means includes
A test signal level detector for detecting the level of the frequency band component of the test signal superimposed on the downstream electrical signal converted by the first optical receiver;
A distortion level detector for detecting the level of intermodulation distortion of the test signal superimposed on the downstream electrical signal converted by the first optical receiver;
A level determination unit that determines whether or not the level of intermodulation distortion detected by the distortion level detection unit with respect to the level of the frequency band component detected by the test signal level detection unit is equal to or higher than a certain level;
The signal transmission stop means stops the transmission of the radio signal when the level determination unit determines that the level of the intermodulation distortion with respect to the level of the frequency band component of the test signal is equal to or higher than a certain level. The wireless communication system according to claim 4. The control device further includes a test signal generation unit that generates a test signal,
The first optical transmission unit converts the downlink electrical signal on which the test signal generated by the test signal generation unit is superimposed into a downlink optical signal,
The quality evaluation means includes
A test signal level detector for detecting the level of the frequency band component of the test signal superimposed on the downstream electrical signal converted by the first optical receiver;
A distortion level detector that detects the level of harmonic distortion of the test signal superimposed on the downstream electrical signal converted by the first optical receiver;
A level determination unit that determines whether or not the level of harmonic distortion detected by the distortion level detection unit with respect to the level of the frequency band component detected by the test signal level detection unit is equal to or higher than a certain level. ,
The signal transmission stop means stops the transmission of the radio signal when the level determination unit determines that the level of the harmonic distortion with respect to the level of the frequency band component of the test signal is equal to or higher than a certain level. The wireless communication system according to claim 4. The antenna unit receives a radio signal transmitted from the radio communication terminal as an upstream electrical signal,
The relay device further includes a second optical transmission unit that converts the upstream electrical signal received by the antenna unit into an upstream optical signal and transmits the upstream optical signal to the control device via the optical transmission path,
The control device further includes a second optical receiving unit that converts the upstream optical signal transmitted from the relay device via the optical transmission path into an upstream electrical signal,
The quality evaluation unit and the signal transmission stop unit are provided in the relay device,
The quality evaluation means evaluates the quality of the upstream optical signal, determines whether the quality of the upstream optical signal satisfies a predetermined condition,
2. The radio communication according to claim 1, wherein the signal transmission stop unit stops the transmission of the radio signal when the quality evaluation unit determines that the quality of the upstream optical signal does not satisfy a predetermined condition. system. The quality evaluation means includes
An optical coupler unit that branches the upstream optical signal converted by the second optical transmission unit and the reflected light reflected from the optical transmission path;
An optical power detection unit that detects the power of the reflected light branched by the optical coupler unit and determines whether the power of the reflected light is equal to or greater than a certain value;
The wireless communication system according to claim 8, wherein the signal transmission stop unit stops transmission of the wireless signal when the optical power detection unit determines that the power of the reflected light is equal to or greater than a certain value. The quality evaluation means and the signal transmission stop means are provided in the control device,
The quality evaluation means evaluates the quality of the downstream optical signal, determines whether the quality of the downstream optical signal satisfies a predetermined condition,
The signal transmission stop means stops the transmission of the downstream optical signal by stopping the transmission of the downstream optical signal when the quality evaluation means determines that the quality of the downstream optical signal does not satisfy a predetermined condition. The wireless communication system according to claim 1, wherein transmission of the wireless signal is stopped. The quality evaluation means includes
An optical coupler unit that branches the downstream optical signal converted by the first optical transmission unit and the reflected light reflected from the optical transmission path;
An optical power detection unit that detects the power of the reflected light branched by the optical coupler unit and determines whether the power of the reflected light is equal to or greater than a certain value;
The radio communication system according to claim 10, wherein the signal transmission stop unit stops transmission of the downstream optical signal when the optical power detection unit determines that the power of the reflected light is equal to or greater than a predetermined value. . The antenna unit receives a radio signal transmitted from the radio communication terminal as an upstream electrical signal,
The relay device further includes a second optical transmission unit that converts the upstream electrical signal received by the antenna unit into an upstream optical signal and transmits the upstream optical signal to the control device via the optical transmission path,
The control device further includes a second optical receiving unit that converts the upstream optical signal transmitted from the relay device via the optical transmission path into an upstream electrical signal,
The quality evaluation means and the signal transmission stop means are provided in the control device,
The quality evaluation means evaluates the quality of the upstream optical signal;
The signal transmission stop means stops transmission of the downstream optical signal by stopping the transmission of the downstream optical signal when the quality evaluation means determines that the quality of the upstream optical signal does not satisfy the predetermined condition. The wireless communication system according to claim 1, wherein transmission of the wireless signal is stopped. The quality evaluation means detects the power of the upstream optical signal received by the control device, and determines whether or not the power of the upstream optical signal is equal to or less than a predetermined value. Department,
The wireless communication according to claim 12, wherein the signal transmission stop unit stops transmission of the downstream optical signal when the light reception power detection unit determines that the power of the upstream optical signal is equal to or lower than a predetermined value. system. The antenna unit receives a radio signal transmitted from the radio communication terminal as an upstream electrical signal,
The relay device further includes a second optical transmission unit that converts the upstream electrical signal received by the antenna unit into an upstream optical signal and transmits the upstream optical signal to the control device via the optical transmission path,
The control device further includes a second optical receiving unit that converts the upstream optical signal transmitted from the relay device via the optical transmission path into an upstream electrical signal,
The quality evaluation means and the signal transmission stop means are provided in the control device,
The quality evaluation means evaluates the quality of the upstream electrical signal,
The signal transmission stop means stops transmission of the downstream optical signal from the repeater when the quality evaluation means determines that the quality of the upstream electrical signal does not satisfy the predetermined condition. The wireless communication system according to claim 1, wherein transmission of the wireless signal is stopped. The quality evaluation means includes
A signal level detection unit for detecting a level of a frequency band component of a radio signal to be received from the radio communication terminal from an upstream electrical signal converted by the second optical reception unit;
An unnecessary radiation level detector that detects the level of the component outside the frequency band of the radio signal to be received from the radio communication terminal, from the upstream electrical signal converted by the second optical receiver;
A level determination unit that determines whether the level of the component outside the frequency band detected by the unnecessary radiation level detection unit with respect to the level of the frequency band component detected by the signal level detection unit is equal to or higher than a certain level. ,
The signal transmission stop means stops transmission of the downstream optical signal when the level determination unit determines that the level of the out-of-frequency band component with respect to the level of the frequency band component is equal to or higher than a certain level. Item 15. The wireless communication system according to Item 14. The relay device further includes:
Including a test signal generator for generating two test signals of different frequencies;
The second optical transmission unit converts the upstream electrical signal on which the test signal generated by the test signal generation unit is superimposed into an upstream optical signal,
The quality evaluation means includes
A test signal level detector for detecting the level of the frequency band component of the test signal superimposed on the upstream electrical signal converted by the second optical receiver;
A distortion level detector that detects the level of intermodulation distortion of the test signal superimposed on the upstream electrical signal converted by the second optical receiver;
A level determination unit that determines whether or not the level of intermodulation distortion detected by the distortion level detection unit with respect to the level of the frequency band detected by the test signal level detection unit is equal to or higher than a certain level;
The signal transmission stop unit stops transmission of the downstream optical signal when the level determination unit determines that the level of the intermodulation distortion with respect to the level of the frequency band component of the test signal is equal to or higher than a certain level. The wireless communication system according to claim 14. The relay device further includes:
Including a test signal generator for generating a test signal;
The second optical transmission unit converts the upstream electrical signal on which the test signal generated by the test signal generation unit is superimposed into an upstream optical signal,
The quality evaluation means includes
A test signal level detector for detecting the level of the frequency band component of the test signal superimposed on the upstream electrical signal converted by the second optical receiver;
A distortion level detector that detects the level of harmonic distortion of the test signal superimposed on the upstream electrical signal converted by the second optical receiver;
A level determination unit that determines whether or not the level of harmonic distortion detected by the distortion level detection unit with respect to the level of the frequency band component detected by the test signal level detection unit is equal to or higher than a certain level. ,
The signal transmission stop means stops transmission of the downstream optical signal when the level determination unit determines that the level of the harmonic distortion with respect to the level of the frequency band component of the test signal is equal to or higher than a certain level. The wireless communication system according to claim 14.   The wireless communication system according to claim 1, wherein the wireless signal is a signal used in a wireless LAN.   The wireless communication system according to claim 1, wherein the wireless signal is a broadcast wave signal. 2. The wireless communication system according to claim 1, wherein all of the optical connectors for connecting the optical transmission lines are oblique polishing connectors.

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