WO2014045488A1

WO2014045488A1 - Radio transmitting apparatus, standing wave ratio measuring device and standing wave ratio measuring method

Info

Publication number: WO2014045488A1
Application number: PCT/JP2013/002826
Authority: WO
Inventors: 拓志望月
Original assignee: 日本電気株式会社
Priority date: 2012-09-18
Filing date: 2013-04-25
Publication date: 2014-03-27
Also published as: JPWO2014045488A1; JP5888424B2

Abstract

A radio transmitting apparatus is provided with a transmission signal generating device, a detection circuit, and a standing wave ratio measuring circuit. The detection circuit detects traveling wave detection voltage and reflected wave detection voltage that correspond to a transmission signal. The standing wave ratio measuring circuit measures the voltage standing wave ratio on the basis of the traveling wave detection voltage and the reflected wave detection voltage. The detection circuit comprises a detection unit and a time constant circuit. The detection circuit detects the traveling wave detection voltage and the reflected wave detection voltage. The time constant circuit averages the respective temporal variations of the traveling wave detection voltage and the reflected wave detection voltage that have been detected by the detection unit. In the time constant circuit, the time constant is set shorter in the state where the transmission signal rises than in the state where the transmission signal falls.

Description

Wireless transmission device, standing wave ratio measuring device, and standing wave ratio measuring method

The present invention relates to a wireless transmission device, a standing wave ratio measuring device, and a standing wave ratio measuring method.

In the wireless transmission device, measuring VSWR (Voltage Standing Wave Ratio) is important for grasping the characteristics of the wireless transmission device. Patent Documents 1 to 9 disclose techniques relating to VSWR measurement. As a related technique, Patent Document 10 discloses an antenna monitoring device that can detect an incident wave and a reflected wave even if the temperature changes. Patent Document 11 discloses a monitoring device that can eliminate erroneous detection due to wraparound from an antenna of another system and can correctly monitor the antenna and the antenna feeding system.

FIG. 5A is a configuration diagram showing a VSWR detection circuit according to Patent Document 1. The power amplifier 101 amplifies the input signal, and the directional coupler 102 monitors the output level. The directional coupler 103 performs level monitoring of the reflected wave power reflected from the load circuit connected to one end of the transmission line 110. The phase shifter 104 is provided between the

directional couplers

102 and 103 and applies phase rotation to the traveling wave and the reflected wave. The

detectors

105 and 106 detect traveling wave power and reflected wave power, respectively. The arithmetic unit 107 calculates VSWR from the detection voltage output from the

detectors

105 and 106. From the above, the VSWR detection circuit calculates VSWR.

FIG. 5B is a configuration diagram showing a VSWR measurement circuit according to Patent Document 2. The VSWR measurement circuit gives a microwave signal (sin θ) to the device under test 201 from the signal generator 203 through the directional coupler 202. The VSWR measurement circuit is reflected by the DUT 201 and reflected from the output end 222 of the directional coupler 202 (msinθ), and the signal generator 203 outputs the input 221 of the directional coupler 202. The leakage wave (Asin θ) is synthesized. Then, the VSWR measurement circuit measures the standing wave ratio of the DUT 201 while displaying the DC voltage obtained by detecting the synthesized signal with the detector 204 on the display 205.

FIG. 5C is a configuration diagram showing a VSWR monitor circuit according to Patent Document 3. A high frequency transmission signal is input to the input terminal 301. The traveling wave (transmission signal traveling wave) 321 of the high-frequency transmission signal amplified by the amplifier 303 via the first directional coupler 302 is output to the output terminal 317 via the second directional coupler 304. . The transmission signal reflected wave 322 travels in the opposite direction to the transmission signal traveling wave 321 and is observed as a standing wave between the transmission lines with the amplifier 303.

The branch signal of the transmission signal traveling wave 321 is output to one branch port A of the second directional coupler 304, and the branch signal of the transmission signal reflected wave 322 is mainly output to the other port B. At this time, a part of the strong transmitted signal traveling wave 321 is output as leakage power to the other port B of the second directional coupler 304. Note that the amount of power may reach the same level as the branch signal of the transmission signal reflected wave 322, which is usually weak. In this manner, the other port B has a leakage power of a part of the transmission signal traveling wave 321 with respect to the power of the branch signal of the transmission signal reflected wave 322 (in the same direction as the branch signal of the transmission signal reflected wave 322). Power with different phases) is superimposed.

The branch signal of the transmission signal traveling wave 321 is output to one branch port A of the second directional coupler 304, but part of the branch signal of the transmission signal reflected wave 322 is also output as leakage power. Although the amount of power is almost negligible because it is output from the ISO (suppression) port of the transmission signal reflected wave 322, one branch port A has power relative to the power of the branch signal of the transmission signal traveling wave 321. The leakage power of the transmission signal reflected wave 322 is superimposed. In other words, in one branch port A, a small amount of power having a phase different from that of the branch signal of the transmission signal traveling wave 321 is superimposed on the power of the branch signal of the transmission signal traveling wave 321.

The transmitted signal traveling wave before amplification branched by the first directional coupler 302 is further branched by the first distributor 306 via the first vector adjuster 305. The branched transmission signal traveling wave 321 is combined with the branched signal output from the second directional coupler 304 by the first coupler 307.

Next, the output of the first coupler 307 is DC detected by the detector 310, and the detected information is digitized by the A / D converter 312 and sent to the vector controller 314. The vector controller 314 adjusts the first vector adjuster 305 corresponding to the input detection voltage. The vector controller 314 automatically controls the first vector adjuster 305 so that the output of the first coupler 307 is minimized, that is, the detection voltage of the detector 310 is minimized. The control voltage of the vector controller 314 is a digital signal because it is processed by a CPU (Central （Processing Unit), but the first vector adjuster 305 operates with an analog signal. Therefore, the control voltage is sent out in an analog state via the D / A converter 315.

As described above, the branch signal output from the branch port B of the second directional coupler 304 is a signal in which the transmission signal reflected wave 322 and the leakage power of the transmission signal traveling wave 321 are superimposed. Of the transmission signal traveling waves 321 before amplification that are branched by the first distributor 306, those that are not input to the first combiner 307 are sent to the second combiner 309 via the second vector adjuster 308. Is output. This signal and the branch signal output from the branch port B are coupled by the second coupler 309.

Between the first distributor 306 and the second coupler 309, a second vector adjuster 308 for adjusting the phase amount and the attenuation amount is installed. The branch signal (reflected wave) of the transmission signal reflected wave 322 is digitized by the detector 311 and the A / D converter 313 and sent to the VSWR monitor 316 as reflected wave information. The VSWR monitor 316 outputs detection information of the transmission signal reflected wave to the processing circuit of the high frequency transmission device via the internal interface terminal 318.

FIG. 5D is a configuration diagram showing an antenna port monitoring system according to Patent Document 4. The antenna port monitoring system includes a transmission amplifier 401, a reflected power detection circuit 402, an A / D converter 403, a transmission power detection circuit 404, an A / D converter 405, a normal value sampling circuit 408, an abnormal value sampling circuit 409, A value sampling circuit 410, a write instruction circuit 412, a reflected wave characteristic storage circuit 411, a threshold determination circuit 413, an ALM determination circuit 414, a test signal generation circuit 407, a signal selection circuit 406, and a CPU 415 are provided.

The transmission amplification unit 401 amplifies the transmission signal of the wireless communication device. The reflected power detection circuit 402 measures the reflected power. The A / D converter 403 converts the detected reflected power value into a digital value. The transmission power detection circuit 404 measures transmission power. The A / D converter 405 converts the detected transmission power value into a digital value. The normal value sampling circuit 408 temporarily holds the transmission power value and the reflected power value at the normal time. The abnormal value sampling circuit 409 temporarily holds the transmission power value and the reflected power value at the time of abnormality. The current value sampling circuit 410 temporarily holds the current transmission power value and reflected power value. The write instruction circuit 412 instructs these holding timings. The reflected wave characteristic storage circuit 411 stores these temporarily held values. The threshold determination circuit 413 determines a threshold value based on the value read from the reflected wave characteristic storage circuit 411 and information set by the CPU 415. The ALM determination circuit 414 finally determines the VSWR alarm based on these values. The test signal generation circuit 407 generates a test signal. The signal selection circuit 406 selects whether to transmit a test signal or an operation signal. The CPU 415 controls the whole. In this way, the wireless communication device can generate a VSWR alarm.

FIG. 6 is a configuration diagram illustrating an example of a related wireless transmission device. The wireless transmission device 500 includes a MAC (Media Access Controller) 501, a baseband signal generator (BB signal generator) 502, a modulator 503, a local oscillator 504, a high output amplifier 505, a filter 506, a directional coupler 507, an antenna. 508, a VSWR measurement circuit 509, and a VSWR display unit 517. The VSWR measurement circuit 509 includes a traveling wave detector 510, a reflected wave detector 511, a fixed time constant circuit 512, a fixed time constant circuit 513, a difference detector 514, a VSWR calculator 515, and a VSWR averager 516.

The data signal generated by the MAC 501 is modulated by the baseband signal generator 502 into an I / Q axis signal that is a modulated baseband signal. That is, the baseband signal generator 502 performs I / Q modulation.

The I / Q axis signal is converted into an RF (Radio Frequency) band modulated downlink signal by the modulator 503 and the local oscillator 504. The power of the RF band modulation downlink signal is raised to a predetermined transmission power by the high power amplifier 505. The RF band modulation downlink signal output from the high power amplifier 505 is output to the antenna 508 via the filter 506 for reducing transmission spurious. The antenna 508 radiates an RF band modulation downlink signal as a radio signal to space.

Note that in the wireless transmission device, the VSWR measurement circuit 509 is provided in front of the antenna 508. This is because the VSWR measurement circuit 509 measures the VSWR considering the influence of the antenna 508 to confirm that the spatial radiation from the antenna is performed without any problem.

Between the filter 506 and the antenna 508, a directional coupler 507 for detecting a traveling wave and a reflected wave is inserted for VSWR measurement. In other words, the directional coupler 507 is inserted before the antenna 508. The traveling wave detector 510 detects the traveling wave voltage output in the direction of the antenna 508 in the wireless transmission device 500 by the directional coupler 507. Similarly, the reflected wave voltage output in the opposite direction to the antenna 508 is detected by the reflected wave detector 511.

In order to average the temporal fluctuation of the instantaneous value of the detection voltage of the traveling wave, the voltage detected by the traveling wave detector 510 is output to the difference detector 514 via the fixed time constant circuit 512 having a fixed time constant. Is done. Similarly, in order to average the temporal fluctuation of the detection voltage instantaneous value of the reflected wave, the voltage detected by the reflected wave detector 511 is detected by a differential detector via a fixed time constant circuit 513 having a fixed time constant. It is output to 514.

FIG. 7 is a configuration diagram showing an example of a fixed time constant circuit 512 (integration circuit). The fixed time constant circuit 512 includes a resistor 518 and a capacitor 519. The resistor 518 has one end connected to the traveling wave detector 510 side and the other end connected to the difference detector 514 side. One end of the capacitor 519 is connected between the resistor 518 and the difference detector 514, and the other end is grounded.

When the resistance value of the resistor 518 is R and the capacitance value of the capacitor 519 is C, the fixed time constant τ in the fixed time constant circuit 512 is τ = RC. Here, in order to sufficiently smooth the detection voltage that normally changes for each Symbol, τ is set to a relatively long time of several times to about 10 times the Symbol length.

The fixed time constant circuit 513 has the same configuration as the fixed time constant circuit 512.

Returning to FIG. 6, the description of the wireless communication device will be continued. The difference detector 514 detects the difference between the traveling wave voltage output from the fixed time constant circuit 512 and the reflected wave voltage output from the fixed time constant circuit 513. Based on the difference detection voltage detected by the difference detector 514, the VSWR calculator 515 calculates the VSWR of the wireless transmission device 500. The VSWR measured by the VSWR calculator 515 is smoothed by the VSWR averager 516. The wireless transmission device 500 outputs and displays the VSWR smoothed by the VSWR averager 516 as it is on the VSWR display unit 517 as the final report value. As described above, the wireless transmission device 500 measures the VSWR.

In particular, Patent Documents 5 to 10 disclose wireless transmission devices that can eliminate VSWR measurement errors.

FIG. 8A is a configuration diagram showing an example of an antenna communication device according to Patent Document 6. The antenna communication device includes transmitters Tx1 to Txn, a combiner 611, an antenna monitoring device 601, an antenna filter F0, and an antenna 613. The combiner 611 includes isolators I1 to In and band pass filters F1 to Fn. The antenna monitoring device 601 includes a directional coupler 612, band pass filters 621 and 622,

detection circuits

614 and 615, an arithmetic circuit 616 and a display device 617. The antenna monitoring apparatus 601 measures VSWR with the above configuration.

The directional coupler 612 is inserted between an antenna filter F0 (bandpass filter) connected to an antenna and a transmitter in order to detect traveling waves and reflected waves. By providing the directional coupler 612 in this way, it can be expected that the reflected wave outside the band is attenuated by the antenna filter F0.

A transmission line is branched from the directional coupler 612. A band-pass filter 621 is inserted in the transmission line between the directional coupler 612 and the traveling wave detection circuit 614. A band pass filter 622 is inserted in the transmission line between the directional coupler 612 and the detection circuit 615 for reflected waves. The bandpass filters 621 and 622 can sufficiently suppress out-of-band interference waves and jamming waves before detection. As described above, the antenna communication apparatus according to FIG. 8A can eliminate the measurement error of VSWR.

FIG. 8B is a configuration diagram showing an example of another antenna communication device according to Patent Document 6. The antenna communication device includes transmitters Tx1 to Txn, a combiner 711, an antenna monitoring device 701, an antenna filter F0, and an antenna 713. The combiner 711 includes isolators I1 to In and band pass filters F1 to Fn. The antenna monitoring device 701 includes a directional coupler 712, a local oscillation circuit 723a,

mixer circuits

724 and 725, band pass filters 726 and 727, intermediate frequency filters 728 and 729, detection circuits 714 and 715, an arithmetic circuit 716, and a display device 717. Have The antenna monitoring apparatus 701 measures VSWR with the above configuration.

The local oscillation circuit 723a and the mixer circuit 724, and the local oscillation circuit 723a and the mixer circuit 725 each constitute a down converter. Each of the traveling wave path and the reflected wave path branched by the directional coupler 712 is provided with the down converter. The local oscillation circuit 723a changes the local oscillator frequency, thereby changing the pass band targeted by the down converter.

After the signal output from the directional coupler 712 is down-converted, it passes through a narrower band filter than a down-converter in which a baseband or IF (Intermediate Frequency) frequency is set. As a result, the antenna communication apparatus can more rapidly attenuate the external out-of-band interference wave or jamming wave, and reduce the error in the VSWR measurement value due to these interference wave / jamming wave.

JP 2005-092331 A Japanese Patent Laid-Open No. 03-051772 JP 2004-286632 A JP 2004-096689 A Japanese Patent Laid-Open No. 05-157781 Japanese Patent Laid-Open No. 04-357471 Japanese Patent Laid-Open No. 04-310872 Japanese Patent Laying-Open No. 2005-0117138 JP 2002-043957 A Japanese Utility Model Publication No. 05-073576 Japanese Patent Laid-Open No. 05-172879

6 has a large error in the VSWR measurement under the following environment.

FIG. 9A is a schematic diagram illustrating a state where the wireless transmission device 500 is applied. FIG. 9A shows a state in which the base station wireless transmitter of its own system and the base station wireless transmitter of another system are coupled. Here, the two wireless transmission devices communicate using an OFDM (Orthogonal-Frequency-Division-Multiplexing) method such as LTE (Long-Term Evolution) using a shared antenna.

FIG. 9A shows that an interference wave from a wireless transmission device of another system is input to the wireless transmission device of the own system. Here, own system base station transmission section 800 outputs the signal of A [dBm] to antenna 802 via antenna duplexer 801. Other system base station transmission section 803 outputs the signal of B [dBm] to antenna 802 via antenna duplexer 801. At this time, among the transmission signals output from other system base station transmission section 803, the transmission signal of BX [dBm] is output to own system base station transmission section 800 via antenna duplexer 801. X [dBm] is the isolation amount of the antenna duplexer 801.

FIG. 9B is a diagram showing a signal level between the own system base station transmission unit 800 and the antenna duplexer 801. The horizontal axis in FIG. 9B indicates the frequency f. The signal (transmission signal 1) output from the own system base station transmission unit 800 has the strength of A [dBm], and the signal (transmission signal 2) output from the other system base station transmission unit 803 is AX It has a strength of [dBm]. Here, the signal originally output from the other system base station transmission section 803 is A [dBm], and A = B. IM (Inter Modulation) 1 and IM2 are intermodulation distortions caused by the backflow waves of the transmission base station transmission signal and the transmission base station transmission signal of the other system.

FIG. 10 is a diagram showing a time waveform of the LTE downlink signal. E-TM1.1 in FIG. 10 is a test signal, and is a signal mainly communicated by QPSK (Quadrature Phase Shift Keying) -OFDMA (Orthogonal Frequency Division Multiple Access) system. E-TM2 is a test signal, and is a signal communicated in a 64QAM (Quadrature amplitude modulation) Single RB (Resource Block) system. These E-TM1.1 and E-TM2 are normal data signals in which signals exist densely on the time axis. That is, E-TM1.1 and E-TM2 are signals having a long output period. In FIG. 10, the vertical axis represents dB (relative ratio of various signals), and the horizontal axis represents time.

The control channel signal in FIG. 10 is the sparsest signal among the actual operation signals in a state where there is no link between the own system base station transmission unit 800 and the mobile terminal. The control channel signal includes broadcast information (Broadcast information) and a reference signal (reference signal).

Here, the control channel signal is a control signal that is transmitted to the mobile terminal through the control channel and is necessary for connection control by the mobile terminal. The broadcast information is a signal including a location number, neighboring cell information, information for performing transmission restriction control, and the like necessary for determining whether or not location registration is necessary in the mobile terminal. The reference signal is a training signal on the terminal side, and is a signal having a pattern determined in advance on the base station side and the mobile terminal side. On the portable terminal side, processing such as estimation of the channel (attenuation amount and phase rotation amount) is executed from the reference signal.

In one frame in FIG. 10 (= 10 subframes · 10 msec), the output period of each signal is shorter than that of a normal data signal, and the output period of each signal is further longer than that of the notification information. A short reference signal exists sparsely on the time axis.

Hereinafter, a problem when VSWR is measured under various environments when the wireless transmission device 500 shown in FIG. 6 is used as the own system base station transmission unit 800 shown in FIG. 9A will be described.

FIG. 11 shows a DL signal level between two frames (20 msec), a DL reflected wave signal level, and a VSWR when a dense test signal E-TM2 is transmitted as a DL (downlink) signal from the wireless transmission device 500. It is the figure which showed the measured value. Here, the DL reflected wave assumes a reflection state when RL (Return Loss) is 15 dB (the same applies to FIGS. 12 and 13). 11 indicates the dynamic range of the detector (the same applies to FIGS. 12 and 13).

In FIG. 11, the DL signal level varies, but the variation is within the dynamic range of the detector. In addition, the fixed time

constant circuits

512 and 513 sufficiently smooth the fluctuation. Therefore, the VSWR measurement value always shows a correct value (1.5 in this case).

FIG. 12 shows increase / decrease in DL signal level, DL reflected wave signal level, and VSWR measurement value during two frames (20 msec) when a sparse control channel during operation is transmitted as a DL signal from the wireless transmission device 500. FIG.

In this case, the period of the reference signal as a DL signal that frequently repeats ON / OFF is too short compared to the time constant τ of the fixed time

constant circuits

512 and 513.

Therefore, both the traveling wave signal and the reflected wave signal fall before the detection voltage does not fully rise and falls within the dynamic range. Therefore, the accuracy of the VSWR measurement value is deteriorated. However, only in the period in which the notification information is output (the area circled in FIG. 12), the signal density becomes high (a signal with a long output period of each signal is output), so the VSWR measurement value is correct. Indicates the value.

FIG. 13 shows a case where a sparse control channel during operation is transmitted as a DL signal from the wireless transmission device 500, and a continuously disturbing wave from another system flows backward and is input to the wireless transmission device 500. It is the figure which showed increase / decrease in the DL signal level between 2 frames (20msec), the signal level of DL reflected wave, and the VSWR measured value.

At this time, the reflected wave detector 511 detects the interference wave as a reflected wave. The interference wave is detected as a signal level in the vicinity of −30 dB in FIG. The output period of the interference wave is sufficiently longer than the time constant τ of the fixed time constant circuit 512. Therefore, the fixed time constant circuit 512 outputs a detection voltage for the interference wave. In other words, in the measurement circuit 509, the detection voltage due to the disturbing wave is mistakenly detected as the detection voltage due to the reflected wave and is measured. The detection voltage due to the interference wave is stabilized at a higher signal level. For this reason, the error in the detection voltage of the reflected wave greatly increases. The same applies to the fixed time constant circuit 513.

On the other hand, the traveling wave falls before the detection voltage rises. This is because the period of the reference signal is too short compared to the time constant τ of the fixed time constant circuit.

As a result, the detection voltage of the traveling wave is measured low, whereas the detection voltage of the reflected wave is measured high. For this reason, the accuracy of the VSWR to be measured is further deteriorated. Depending on the level of the interference wave, the accuracy of the VSWR is fixed to the worst. However, only in the period in which the notification information is output (the area circled in FIG. 13), the signal density becomes high, and the VSWR measurement value shows a correct value.

As described above, in a real environment, when the output signal density is sparse, the VSWR measurement value deteriorates. Furthermore, if there is a backflow of interference from other systems coupled by a shared antenna, the VSWR report value will be further deteriorated. In such a case, a report misunderstood as a total reflection aspect is made as a VSWR report when the antenna is expected, and an error alarm or the like is activated at the monitoring station, so that the own system is stopped. There was concern that it would.

The wireless transmitters according to Patent Documents 1 to 4 do not disclose any circuit configuration for eliminating the VSWR measurement error, and thus the above-described problem occurs.

In the wireless transmission devices according to Patent Documents 5 to 10, although the circuit configuration for eliminating the measurement error of VSWR is taken, the above-described problems cannot be solved. The same applies to Patent Document 11. Therefore, the above-mentioned problem occurs again.

The present invention has been made to solve such a problem, and provides a wireless transmission device, a standing wave ratio measuring device, and a standing wave ratio measuring method capable of suppressing a measurement error of a voltage standing wave ratio. The purpose is to provide.

The first aspect of the present invention includes a wireless transmission device. The wireless transmission device includes a transmission signal generation device, a detection circuit, and a standing wave ratio measurement circuit. The transmission signal generating device generates and outputs a transmission signal. The detection circuit is provided between transmission lines of the transmission signal generation device and the antenna, and detects a detection voltage of a traveling wave and a detection voltage of a reflected wave corresponding to the transmission signal. The standing wave ratio measuring circuit measures the voltage standing wave ratio based on the detection voltage of the traveling wave and the detection voltage of the reflected wave detected by the detection circuit. The detection circuit includes a detection unit and a time constant circuit. The detection unit detects the detection voltage of the traveling wave and the detection voltage of the reflected wave. The time constant circuit averages temporal variations with respect to each of the traveling wave detection voltage detected by the detection unit and the reflected wave detection voltage. Here, in the time constant circuit, the time constant is set shorter in the state where the transmission signal rises than in the state where the transmission signal falls.

The second aspect of the present invention includes a standing wave ratio measuring device. The standing wave ratio measuring device is provided in a wireless transmission device that generates and outputs a transmission signal. The standing wave ratio measuring device includes a detection circuit and a standing wave ratio measurement circuit. The detection circuit is provided between a transmission line between the generation device that generates the transmission signal and the antenna, and detects a detection voltage of a traveling wave and a detection voltage of a reflected wave corresponding to the transmission signal. The standing wave ratio measuring circuit measures the voltage standing wave ratio based on the detection voltage of the traveling wave and the detection voltage of the reflected wave detected by the detection circuit. The detection circuit includes a detection unit and a time constant circuit. The detection unit detects the detection voltage of the traveling wave and the detection voltage of the reflected wave. The time constant circuit averages temporal variations with respect to each of the traveling wave detection voltage detected by the detection unit and the reflected wave detection voltage. Here, in the time constant circuit, the time constant is set shorter in the state where the transmission signal rises than in the state where the transmission signal falls.

The third aspect of the present invention includes a standing wave ratio measuring method. This standing wave ratio measuring method is a standing wave ratio measuring method in which a voltage standing wave ratio is measured in a wireless transmission device that generates and outputs a transmission signal. Here, the standing wave ratio measuring method includes the following steps (a) to (d).
(A) detecting a detection voltage of a traveling wave and a detection voltage of a reflected wave corresponding to the transmission signal;
(B) detecting a detection voltage of the traveling wave and a detection voltage of the reflected wave;
(C) averaging time fluctuations for each of the traveling wave detection voltage and the reflected wave detection voltage detected by the detection unit; and (d) the transmission signal in a state where the transmission signal rises. Set the time constant of the time constant circuit short compared to the state where the signal falls.

According to the present invention, it is possible to provide a wireless transmission device, a standing wave ratio measuring device, and a standing wave ratio measuring method capable of suppressing the measurement error of the voltage standing wave ratio.

1 is a configuration diagram illustrating an example of a wireless communication device according to a first exemplary embodiment; FIG. 3 is a block diagram showing a configuration example of a detection circuit according to the first exemplary embodiment; FIG. 3 is a configuration diagram illustrating an example of a wireless communication apparatus according to a second embodiment; FIG. 6 is a configuration diagram illustrating an example of a multiple time constant circuit according to a second exemplary embodiment; It is the block diagram which showed the VSWR detection circuit concerning related technology. It is the block diagram which showed the VSWR measurement circuit concerning related technology. It is the block diagram which showed the VSWR monitor circuit concerning related technology. It is a block diagram which shows the antenna port monitoring system concerning related technology. It is the block diagram which showed the example of the radio | wireless transmission apparatus concerning related technology. It is the block diagram which showed the example of the fixed time constant circuit concerning related technology. It is the block diagram which showed the example of the antenna communication apparatus concerning related technology. It is the block diagram which showed the example of the other antenna communication apparatus concerning related technology. It is the schematic which showed the state to which the radio | wireless transmission apparatus concerning related technology is applied. In related technology, it is the figure which showed the signal level between a self-system base station transmission part and an antenna sharing device. It is a figure which shows the time waveform of the LTE downlink signal concerning related technology. In related technology, when a dense test signal is transmitted from a wireless transmission device, it is a diagram showing a DL signal level polled in two frames, a DL reflected wave signal level, and a VSWR measurement value. In related technology, when a sparse control channel during operation is transmitted from a wireless transmission device, it is a diagram illustrating a DL signal level polled in two frames, a DL reflected wave signal level, and a VSWR measurement value. In related technology, when a sparse control channel during operation is transmitted from a wireless transmission device and an interference wave from another system is added, the DL signal level polled in two frames, the signal level of the DL reflected wave, and the VSWR It is the figure which showed the measured value.

Embodiment 1
The first embodiment will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of an example of a wireless transmission device according to the first embodiment. The wireless transmission device 10 includes a transmission signal generation device 11, an antenna 12, a detection circuit 13, and a standing wave ratio measurement circuit 14.

The transmission signal generator 11 generates and outputs a transmission signal. The transmission signal generation device 11 may output one type of transmission signal, or may output a plurality of types of transmission signals having different periods.

The antenna 12 transmits the transmission signal output from the transmission signal generation device 11 as a radio signal. Here, a reflected wave of the output signal of the transmission signal generation device 11 flows from the antenna 12 to the transmission signal generation device 11.

The detection circuit 13 is provided between the transmission lines of the transmission signal generation device 11 and the antenna 12, and detects the detection voltage of the traveling wave and the detection voltage of the reflected wave corresponding to the transmission signal.

FIG. 2 is a block diagram showing a configuration example of the detection circuit 13. The detection circuit 13 includes a detection unit 15 and a time constant circuit 16.

Detecting unit 15 detects a traveling wave detection voltage and a reflected wave detection voltage. For example, the detection unit 15 detects the detection voltages of the traveling wave and the reflected wave by separating and extracting the traveling wave and the reflected wave flowing between the transmission lines.

The time constant circuit 16 averages temporal fluctuations for each of the traveling wave detection voltage and the reflected wave detection voltage detected by the detection unit 15. The time constant set in the time constant circuit 16 is a time during which the detection voltage output from the time constant circuit 16 is about 63% of the input detection voltage. That is, the time constant is a parameter indicating the speed of response of the time constant circuit 16. Here, in the time constant circuit 16, the time constant is set shorter when the transmission signal rises than when the transmission signal falls.

Here, one time constant circuit 16 may be provided for each traveling wave and reflected wave. Note that the time constants of the respective circuits may be the same or different within an error or a numerical value within an allowable range.

Returning to Fig. 1, the explanation will be continued. The standing wave ratio measuring circuit 14 measures a VSWR (voltage standing wave ratio) based on the detection voltage of the traveling wave and the detection voltage of the reflected wave detected by the detection circuit.

By configuring the wireless transmission device 10 as described above, the following effects are obtained. In the time constant circuit 16, the time constant is set shorter when the transmission signal rises than when the transmission signal falls. That is, in the state where the transmission signal rises, the rising of the detection voltage output from the time constant circuit 16 can be accelerated. Therefore, the detection voltage output from the time constant circuit 16 can sufficiently rise (response quickly) before the traveling wave and the reflected wave in the transmission signal become off-edge. This can be realized regardless of the length of the output period of each signal in the transmission signal. Therefore, the wireless transmission device 10 can suppress the measurement error of the traveling wave and the reflected wave even while the transmission signal having a short output period of each signal is output. In this way, the wireless transmission device 10 can suppress the VSWR measurement error.

The first embodiment can also be understood as an invention of a standing wave ratio measuring device including the detection circuit 13 and the standing wave ratio measuring circuit 14. The processing of the detection circuit 13 and the standing wave ratio measurement circuit 14 can also be understood as an invention of the standing wave ratio measurement method.

Embodiment 2
The second embodiment will be described below with reference to the drawings.

FIG. 3 is a configuration diagram of an example of the wireless transmission device 20 according to the second embodiment. The wireless transmission device 20 includes a MAC 21, a baseband (BB) signal generator 22, a modulator 23, a local oscillator 24, a high power amplifier 25, a filter 26, a directional coupler 27, an antenna 28, a VSWR measurement device 29, and a VSWR display. The unit 37 is provided. The MAC 21 to the local oscillator 24 and the antenna 28 correspond to the transmission signal generation device 11 and the antenna 12 according to FIG. Here, the wireless transmission device 20 uses the antenna 28 to perform communication based on an OFDM (Orthogonal Frequency Division Multiplexing) scheme such as LTE (Long Term Evolution). The wireless transmission device 20 is provided in a base station that performs wireless communication with a mobile terminal, and generates a signal for wireless communication with the mobile terminal.

The MAC 21 generates a data signal to be wirelessly transmitted and outputs it to the baseband signal generator 22. The MAC 21 corresponds to a lower sublayer of the data link layer (second layer) in the OSI reference model, and is a part that defines and executes a frame (data transmission / reception unit) transmission / reception method, frame format, error detection method, and the like. In other words, the MAC 21 is a major part necessary for data generation. Here, the MAC 21 outputs a reference signal (second transmission signal) that repeats ON / OFF in a low period, in addition to a normal data signal and broadcast information (first transmission signal). The details of the data signal, the broadcast information, and the reference signal are as described above.

The baseband signal generator 22 modulates the data signal output from the MAC 21 to generate a modulated baseband signal (I / Q axis signal). This modulated baseband signal is output to the modulator 23.

The modulator 23 modulates the frequency of the input modulated baseband signal according to the frequency of the signal output from the local oscillator 24, and outputs the modulated baseband signal as an RF band modulated downlink signal.

The local oscillator 24 outputs a signal having a frequency used for frequency modulation of the modulator 23. Note that the frequency of the signal output from the local oscillator 24 may be changed according to the situation.

The high-power amplifier 25 amplifies the voltage of the RF band modulation downlink signal output from the modulator 23 and increases the signal power to a predetermined transmission power required for wireless transmission. The high output amplifier 25 outputs the amplified signal to the filter 26.

The filter 26 is a filter provided to reduce spurious transmission signals transmitted from the antenna. The filter 26 includes at least one of a low pass filter, a high pass filter, a band pass filter, and the like.

The transmission signal output from the filter 26 is radiated to the space as a radio signal by the antenna 28 via the directional coupler 27.

The directional coupler 27 is inserted in front of the antenna 28 so that the VSWR measuring device 29 detects the traveling wave and the reflected wave of the transmission signal. In other words, the directional coupler 27 is provided between the transmission lines of the signal generation device and the antenna. The directional coupler 27 outputs a signal corresponding only to traveling wave power to the traveling wave detector 30 and outputs a signal corresponding only to reflected wave power to the reflected wave detector 31.

The VSWR measuring device 29 is provided in front of the antenna 28 in order to measure the VSWR that is expected to be affected by the antenna 28 and to confirm that the spatial radiation from the antenna 28 is performed without any problem.

The VSWR measuring device 29 includes a traveling wave detector 30, a reflected wave detector 31, a plurality of time constant circuits 32, a plurality of time constant circuits 33, a difference detector 34, a VSWR calculator 35, and a VSWR averager 36.

The traveling wave detector 30 to the plurality of time constant circuits 33 correspond to the detection circuit 13 according to FIG. 1, and the difference detector 34 to the VSWR averager 36 correspond to the standing wave ratio measurement circuit 14 according to FIG. The traveling wave detector 30 and the reflected wave detector 31 correspond to the detector 15 according to FIG. 2, and the plurality of time

constant circuits

32 and 33 correspond to the time constant circuit 16 according to FIG.

The traveling wave detector 30 detects the traveling wave voltage corresponding to the transmission signal, and outputs the detected voltage to the multiple time constant circuit 32. The reflected wave detector 31 detects the voltage of the reflected wave corresponding to the transmission signal and outputs the detected voltage to the multiple time constant circuit 33.

The multiple time constant circuit 32 averages (smooths) the temporal fluctuation of the input traveling wave detection voltage and outputs it to the difference detector 34. As the time constant of the multiple time constant circuit 32, either the long time constant τL or the short time constant τS is set. The long time constant τL is set as the time constant of the multiple time constant circuit 32 during the period when the radio transmission apparatus 20 falls (does not transmit) the signal. The short time constant τS is set as the time constant of the multiple time constant circuit 32 during a period in which the wireless transmission device 20 starts up and transmits a transmission signal (normal data signal, broadcast information, reference signal, etc.).

The multiple time constant circuit 33 averages the temporal variation of the detection voltage of the input reflected wave and outputs it to the difference detector 34. As the time constant of the multiple time constant circuit 33, either the long time constant τL or the short time constant τS is set. The long time constant τL is set as the time constant of the multiple time constant circuit 33 during the period when the radio transmission apparatus 20 falls (does not transmit) the signal. The short time constant τS is set as the time constant of the multiple time constant circuit 33 during a period in which the wireless transmission device 20 starts up and transmits a transmission signal (normal data signal, broadcast information, reference signal, etc.).

FIG. 4 is a configuration diagram showing a configuration example of the multiple time constant circuit 32. The multiple time constant circuit 32 is an RC

circuit having resistors

38 and 39, a capacitor 40 and a diode 41.

The resistor (first resistor) 38 has one end connected to the traveling wave detector 30 side and the other end connected to the difference detector 34 side. The resistor (second resistor) 39 is connected in parallel with the resistor 38, one end connected to the traveling wave detector 30 side, and the other end connected to the anode of the diode 41. The resistor 38 is conductive, while the resistor 39 is a resistor capable of switching the conductive state.

The capacitor 40 has one end connected between the resistor 38 and the difference detector 34 and the other end grounded. One end of the capacitor 40 is also connected to the cathode of the diode 41. The diode 41 has an anode connected to the other end of the resistor 39 and a cathode connected between the resistor 38 and the differential detector 34. The diode 41 causes a current to flow when a predetermined voltage (forward voltage) is applied.

4, the resistance value of the resistor 38 is R1, the resistance value of the resistor 39 is R2, and the capacitance value of the capacitor 40 is C. While the diode 41 is off, the fixed time constant τL in the multiple time constant circuit 32 is τL = R1 * C. Here, in order to sufficiently smooth the detection voltage of the traveling wave that normally changes for each Symbol, τL is set to a relatively long time of several times to about 10 times the Symbol length.

While the diode 41 is on, the fixed time constant τS in the multiple time constant circuit 32 is τS = R ′ * C. R ′ is a combined resistance, and R ′ = (R1 * R2) / (R1 + R2). Here, R ′ always takes a smaller value than R1 (in other words, the combined resistance value of the time constant circuit is made smaller). Therefore, the fixed time constant τS is a time constant shorter than the fixed time constant τL. At the time of designing the multiple time constant circuit 32, the value of the fixed time constant τS can be greatly reduced from the fixed time constant τL by providing the resistor 39 having a resistance value R2 that is significantly lower than the resistance value R1.

When the radio transmission device 20 transmits a signal (even when outputting a transmission signal that repeats ON / OFF in a low period like a reference signal), a detection voltage higher than a predetermined voltage is applied to the diode 41 at the rising edge of the signal. Thereby, the diode 41 is turned on. That is, the current path of the resistor 39 connected in parallel with the resistor 38 is conducted by the diode 41 when the traveling wave voltage rises. Thereby, the rising of the detection voltage can be accelerated. It is desirable that the short time constant τS is set to a length of around 1 Symbol because it corresponds to the shortest 1 Symbol length period in the reference signal.

On the other hand, in order to hold the detection voltage after the OFF edge of the reference signal existing in a low period, it is necessary to set the long time constant τL to a relatively long time of several times to about 10 times the Symbol length. is there. In order to sufficiently smooth the fluctuation of the normal detection voltage in a long period when the signal is not transmitted, it is necessary to set the long time constant τL to a relatively long time of several times to 10 times the Symbol length. . When the wireless transmission device 20 causes the transmission signal to fall (not output), a detection voltage equal to or higher than a predetermined voltage does not flow to the diode 41. Therefore, the current path of the resistor 39 connected in parallel with the resistor 38 is cut off when the diode 41 is turned off, and only the resistor 38 and the capacitor 40 are connected. Therefore, the time constant of the multiple time constant circuit 32 is the long time constant τL (= RC).

The resistance values R1, R2 and the capacitance value C are determined such that the short time constant τS is set to a length around 1 Symbol and the long time constant τL is set to a length of several times to about 10 times the Symbol length. .

Since the multiple time constant circuit 33 has the same configuration as the multiple time constant circuit 32, the description thereof is omitted.

Hereinafter, returning to FIG. 3, the description of each part of the wireless transmission device 20 will be continued. The difference detector 34 detects the difference between the detection voltage of the traveling wave output from the multiple time constant circuit 32 and the detection voltage of the reflected wave output from the multiple time constant circuit 33, and outputs the difference detection voltage.

VSWR calculator (VSWR calculator) 35 calculates the VSWR of the wireless transmission device 20 based on the difference detection voltage detected by the difference detector 34.

The wireless transmission device 20 outputs and displays the VSWR smoothed by the VSWR averager 36 on the VSWR display unit 37 as a final report value. As described above, the wireless transmission device 20 measures the VSWR.

As described above, the multiple time

constant circuits

32 and 33 can suppress fluctuations in the detection voltage when the wireless transmission device 20 does not output a transmission signal (the long time constant τL is set to be equal to that of the multiple time constant circuits 32 and 33). The effect of setting the time constant). On the contrary, when the wireless transmission device 20 outputs a transmission signal (for example, when outputting a signal that repeats ON / OFF in a low period such as a reference signal), the detection voltage can be designed to rise sufficiently even in a short time. (Effect of setting the short time constant τS as the time constant of the plurality of time constant circuits 32 and 33). Therefore, no matter what signal the wireless transmission device 20 outputs, the detection voltage of both the traveling wave and the reflected wave can be set to rise immediately and with a sufficient voltage value. In other words, the wireless transmission device 20 can appropriately average temporal variations in the detection voltage even when the types of transmission signals are different. Therefore, the wireless transmission device 20 can suppress the measurement error of the voltage standing wave ratio.

Further, the wireless transmission device 20 is provided in a base station that performs wireless communication with a mobile terminal, and outputs broadcast information and a reference signal as a transmission signal. For this reason, the measurement error of the voltage standing wave ratio can be suppressed in the base station that performs wireless communication with the mobile terminal.

In particular, when the wireless transmission device 20 uses the antenna 28 in common with the other system base station transmission unit as shown in FIG. 6, the same direction as the reflected wave from the other system base station transmission unit via the antenna 28. Interference wave (interference wave) flows between the transmission lines. Even in such a case, the radio transmission apparatus 20 may prevent the true reflected wave voltage from being masked by the reflected wave voltage due to the backflow of the constant disturbance wave from the outside in the reflected wave detection voltage input to the difference detector 34. can do. In this way, since the radio transmission device 20 can improve the accuracy of traveling wave detection and reflected wave detection, adverse effects on VSWR measurement due to interference waves can be suppressed (ie, the accuracy of VSWR measurement can be improved). . In addition, since the time constant value of the time constant circuit can be switched between when the transmission signal is raised (output) and when it is lowered (not output), the wireless transmission device 20 improves the responsiveness and stability of the VSWR measurement. It is possible to achieve both safety.

In other words, the wireless transmission device 20 can accurately calculate the VSWR expecting the outside of the antenna regardless of the transmission state of the own system (transmission density shading). Note that the wireless transmission device 20 performs wireless communication by an OFDM scheme such as LTE.

For example, when a device that generates an alarm when the VSWR exceeds a predetermined value is attached to the wireless transmission device 20, a VSWR alarm or the like due to a malfunction does not occur, and a problem actually occurs in the antenna itself or in connection with the antenna. The alarm is activated only when VSWR deteriorates. For this reason, the precision of the maintenance inspection of the wireless transmitter 20 can be improved.

The wireless transmission devices disclosed in Patent Documents 5 to 7 are effective when the frequency band of the external interference wave / jamming wave is far from the desired transmission band. However, when the transmission band of the own system and the interference band from other systems are close, or when the transmission band and the interference band overlap, the interference wave / jamming wave due to the frequency selectivity of the filter It cannot be expected that sufficient filtering will be done. For this reason, these wireless transmission devices cannot eliminate the VSWR measurement error.

In the wireless transmission devices disclosed in Patent Documents 5 to 7, in order to solve the above-mentioned problem, a steeper filter characteristic is required in the filter circuit. Therefore, the design difficulty level of the wireless transmission device is significantly increased, and there is a problem that the device shape and the price increase. Although it is conceivable to configure the measurement circuit so that a fixed-band filter is inserted into the detector, since the frequency set by the filter cannot be made variable, the flexibility (general versatility) of the measurement circuit is lost. End up. However, in the wireless transmission device 20, the flexibility (general versatility) of the measurement circuit can be maintained.

Note that a configuration of the wireless transmission device 20 in which extraneous interference waves are attenuated by the filter 26 in FIG. 3 and the directional coupler 27 is inserted in front of the filter 26 can be considered (in FIG. Sex coupler 27 is inserted). However, when the downlink transmission band of the own system and the downlink transmission band of another system are close to each other, attenuation of the interference wave in the filter 26 cannot be expected. Even under such environmental conditions, the wireless transmission device 20 shown in FIG. 3 can suppress the deterioration of the VSWR measurement accuracy due to the interference wave.

As shown in FIG. 4, the multiple time

constant circuits

32 and 33 are connected in parallel with the resistor 38 that is conducting, and the resistor 39 that can switch the conducting state according to the rise and fall of the transmission signal. RC circuit having By switching the conduction state of the resistor 39, the value of the time constant in each time constant circuit can be changed. For this reason, the wireless transmission device 20 can change the time constant by a time constant circuit having a simple configuration.

Furthermore, the cost of the time constant circuit can be reduced by making the combined resistance value variable instead of the combined capacitance value of the time constant circuit.

The multiple time

constant circuits

32 and 33 switch the conduction state of the resistor 39 by the diode 41 according to the rising and falling edges of the transmission signal. Here, by using the diode 41, the multiple time

constant circuits

32 and 33 can be configured in a simple manner.

The present invention has been described above with reference to the embodiment, but the present invention is not limited to the above. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the invention.

In the configuration of the multiple time constant circuit shown in FIG. 4, the value of the time constant is changed by changing the conduction state of one of the two resistors. However, three or more resistors may be provided in a plurality of time constant circuits. Furthermore, the multiple time constant circuit may include a plurality of resistors that can change the conduction state. By making the conduction states of the plurality of resistors variable, three or more types of combined resistance values in the plurality of time constant circuits can be changed. Therefore, the value of the time constant in the multiple time constant circuit can be changed to three or more types. This makes it possible to set a finer time constant in the time constant circuit, and the radio communication apparatus 20 can suppress a VSWR measurement error.

Only one of the multiple time

constant circuits

32 and 33 may have the configuration shown in FIG.

The present invention is applied not only to a communication system related to LTE but also to a communication system related to a communication standard of the fourth generation or higher (for example, LTE-Advanced, IMT (International Mobile Telecommunications) -Advanced, WiMAX (Worldwide Interoperability for Microwave Access) 2). May be.

This application claims priority based on Japanese Patent Application No. 2012-204212 filed on September 18, 2012, the entire disclosure of which is incorporated herein.

The present invention can be applied to all wireless communication apparatuses, and can be applied to, for example, a transmission apparatus portion of a base station system apparatus.

DESCRIPTION OF SYMBOLS 10 Radio communication apparatus 11 Transmission signal generation apparatus 12 Antenna 13 Detection circuit 14 Standing wave ratio measurement circuit 15 Detection part 16 Time constant circuit 21 MAC
22 Baseband signal generator 23 Modulator 24 Local oscillator 25 High-power amplifier 26 Filter 27 Directional coupler 28 Antenna 29 VSWR measuring device 30 Traveling wave detector 31

Reflected wave detector

32, 33 Multiple time constant circuit 34 Difference detector 35 VSWR Calculator 36 VSWR Averager 37

VSWR Display

38, 39 Resistor 40 Capacitor 41 Diode

Claims

A transmission signal generating device that generates and outputs a transmission signal; and
A detection circuit for detecting a detection voltage of a traveling wave and a detection voltage of a reflected wave, which is provided between transmission lines of the transmission signal generation device and the antenna, and corresponding to the transmission signal;
A standing wave ratio measuring circuit for measuring a voltage standing wave ratio based on a detection voltage of a traveling wave and a detection voltage of a reflected wave detected by the detection circuit;
The detection circuit includes:
Detecting means for detecting the detection voltage of the traveling wave and the detection voltage of the reflected wave;
The time variation is averaged with respect to each of the detection voltage of the traveling wave detected by the detection means and the detection voltage of the reflected wave, and in a state where the transmission signal rises, compared to a state where the transmission signal falls. And a time constant circuit in which the time constant is set short.
The wireless transmission device is provided in a base station that performs wireless communication with a mobile terminal,
The base station further includes another wireless transmission device other than the wireless transmission device, and the wireless transmission device performs wireless transmission by sharing an antenna with the other wireless transmission device.
The wireless transmission device according to claim 1.
The wireless transmission device performs wireless transmission by an LTE OFDM scheme.
The wireless transmission device according to claim 1 or 2.
The time constant circuit includes a first resistor that is conductive, a second resistor that is connected in parallel with the first resistor, and that can switch a conductive state in response to rising and falling of the transmission signal; An RC circuit having
The wireless transmission device according to any one of claims 1 to 3.
The time constant circuit further includes a diode that switches a conduction state of the second resistor according to a rising edge and a falling edge of the transmission signal.
The wireless transmission device according to claim 4.
A standing wave ratio measuring device provided in a wireless transmission device that generates and outputs a transmission signal,
A detection circuit for detecting a detection voltage of a traveling wave, a detection voltage of a reflected wave, and a detection voltage of a traveling wave corresponding to the transmission signal, provided between a transmission line of the generation device that generates the transmission signal and an antenna;
A standing wave ratio measuring circuit for measuring a voltage standing wave ratio based on a detection voltage of a traveling wave and a detection voltage of a reflected wave detected by the detection circuit;
The detection circuit includes:
Detecting means for detecting the detection voltage of the traveling wave and the detection voltage of the reflected wave;
The time variation is averaged with respect to each of the detection voltage of the traveling wave detected by the detection means and the detection voltage of the reflected wave, and in a state where the transmission signal rises, compared to a state where the transmission signal falls. A standing wave ratio measuring device having a time constant circuit in which a time constant is set long.
A standing wave ratio measuring method for measuring a voltage standing wave ratio in a wireless transmission device that generates and outputs a transmission signal,
Detecting the detection voltage of the traveling wave corresponding to the transmission signal and the detection voltage of the reflected wave;
In the time constant circuit, the detected voltage of the traveling wave and the detected voltage of the reflected wave are averaged over time,
In the state where the transmission signal rises, the time constant of the time constant circuit is set shorter than the state where the transmission signal falls.
Standing wave ratio measurement method.