JP4442390B2 - Radio base station test apparatus and radio base station test method - Google Patents

Description

  The present invention relates to a radio base station test apparatus, and more particularly to a radio base station test apparatus for testing anti-jamming wave performance among reception characteristics of a radio base station sharing a transmission output terminal and a reception input terminal.

  The W-CDMA wireless standard (3GPP TS 25-101) defines a test evaluation of blocking characteristics as anti-jamming wave performance related to a wireless transceiver. This blocking characteristic test includes a test for inputting two waves of a desired wave and an interference wave within the reception frequency band, and an out-of-band blocking for inputting two waves of the desired wave and the interference wave outside the reception frequency band within the reception frequency band. There is a characteristic test.

  The influence on the reception characteristics is that when the interference wave is strong, the noise of the reception apparatus rises, and a weak reception signal is masked by the noise, so that the reception characteristics of the reception apparatus are deteriorated.

  On the other hand, this type of conventional radio base station test apparatus includes two types of signal generators for generating a designated signal and its interference wave when testing a receiving apparatus. In addition, it is configured to include a measuring instrument that inputs a synthesized signal to a device under test and measures a bit error rate or the like from a signal obtained by demodulating a signal specified by the device under test (for example, a patent) Reference 1).

  In this conventional radio base station test apparatus, the first signal generator generates a signal having a specified frequency, and the modulator performs the code modulation of a predetermined format on the signal. Generate a signal. The code-modulated signal is input as a pseudo signal wave to one input side of the directional coupler.

  The second signal generator generates a signal having a frequency different from that of the first signal generator, and outputs the signal as an interference wave to the other input side of the directional coupler. Then, the directional coupler combines these signals and outputs them to the reception input terminal of the receiving device that is the device under test.

  The receiving apparatus receives the synthesized wave, demodulates the pseudo signal wave, and outputs it. The signal demodulated by the receiving apparatus is processed by an error rate measuring device or the like that measures the bit error rate.

  Here, the radio base station described in this prior art has an output terminal of the transmission device and an input terminal of the reception device separately, and transmits by connecting an appropriate measuring instrument to the output terminal or the input terminal. The electrical characteristics of the device or the receiving device are to be tested.

JP-A-6-291739

  In the conventional radio base station test apparatus described above, since the transmission output terminal and the reception input terminal are separated, the reception side is not affected by the transmission signal. However, unlike the prior art in which the transmission device and the reception device can be individually tested, when the transmission output terminal and the reception input terminal are shared, the transmission signal output from the device under test is set under the test device setting conditions. It is necessary to remove the influence of. That is, when used in a normal field (operational state), a radio device having a transmission / reception function has a transmission / reception signal band determined and is intended (designed) to block other frequency bands. Yes. However, the interference signal transmission signal generator used in the test apparatus has a wide transmission band specification so that an arbitrary frequency can be transmitted. Therefore, when the transmission signal output from the device under test is input, the transmission signal generator outputs a frequency signal different from the interference wave by frequency-converting it with its own transmission signal (interference wave).

  The influence of this transmission signal is equal to the fact that in a test in which two waves of a desired wave and an interference wave within the reception frequency band are input, even if the transmission signal is combined with the interference wave, it is outside the reception frequency band. On the other hand, in the out-of-band blocking characteristic test in which two waves of a desired wave within the reception frequency band and an interference wave outside the reception frequency band are input, the frequency mixing component derived based on this transmission signal is within the reception frequency band. May occur. When this derived mixed component is input within the reception band of the device under test, there is a problem that the evaluation of the out-of-band blocking characteristic test is affected.

  The purpose of the present invention is to grasp the accurate reception characteristics (out-of-band blocking characteristics) by removing the influence of the transmission signal of the device under test even when the transmission output terminal and the reception input terminal are shared. An object of the present invention is to provide a radio base station test apparatus capable of performing the above.

The radio base station test apparatus of the present invention is
Having a pseudo signal generator and a noise signal generator, synthesizing signals output from each of the pseudo signal generator and the noise signal generator;
A radio base station test apparatus for testing a reception characteristic of the device under test by inputting it to an input / output common terminal of the device under test, wherein the filter attenuates a transmission frequency band of a radio signal on the output side of the noise signal generator It is characterized by having.

  In addition, the signals output from the pseudo signal generator and the noise signal generator are combined by a directional coupler.

  The filter is characterized in that the frequency characteristic excluding the attenuation band is flat.

  Further, the filter is constituted by a pass-type band filter corresponding to the output frequency band of the noise signal generator divided into a plurality, and the remaining filters excluding the filter corresponding to the transmission frequency band are connected in parallel. It is characterized by that.

  The device under test is characterized in that reception characteristics are tested by measuring a bit error rate (BER) from a signal demodulated by the device under test.

  Further, the noise signal generator outputs a signal having a frequency excluding a reception frequency band of the device under test.

In addition, the radio base station test method of the present invention,
Generate a pseudo signal and a noise signal, synthesize the pseudo signal and the noise signal after attenuation of the transmission frequency band of the radio signal, and input to the input / output common terminal of the device under test and It is characterized by testing reception characteristics.

  The pseudo signal and the noise signal are synthesized by a directional coupler.

  The device under test is characterized in that reception characteristics are tested by measuring a bit error rate (BER) from a signal demodulated by the device under test.

  According to the radio base station test apparatus of the present invention, by providing a filter for attenuating a predetermined band on the output side of the noise signal generator constituting the test apparatus, the influence of the transmission signal output from the apparatus under test is eliminated. Therefore, it is possible to accurately grasp the reception characteristics of the device under test.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a radio base station test apparatus of the present invention.

  The embodiment shown in FIG. 1 includes a pseudo terminal 1, attenuators 2 and 6, a directional coupler 3, a signal generator 4, a band rejection filter 5, and a base station device (device under test) 7. And an error rate measuring device 8.

  Next, the operation of the best mode for carrying out the present invention will be described with reference to the drawings.

  The pseudo terminal 1 modulates a carrier wave of a designated frequency by a predetermined code modulation method and outputs it as a pseudo signal wave. The pseudo terminal 1 is known to those skilled in the art as a generation tool that can easily realize a pseudo test without actually preparing an actual machine (a terminal assumed), and is not directly related to the present invention. Therefore, the detailed configuration is omitted.

  The signal generator 4 outputs a continuous wave signal (an unmodulated signal set in 1 MHz steps in the range of 1 MHz to 12.75 GHz) as an interference wave with respect to the pseudo signal wave.

  The attenuators 2 and 6 respectively receive the output of the pseudo terminal 1 and the output of the signal generator 4, adjust the levels to appropriate levels, and output them to the directional coupler 3.

  The directional coupler 3 is a broadband coupler that allows the output frequency (1 MHz to 12.75 GHz) of the signal generator 4 to pass, and synthesizes the interference wave from the signal generator 4 with the pseudo signal wave from the pseudo terminal. Output. This directional coupler 3 is connected to the antenna connection end when the base station apparatus 7 is tested.

  The band rejection filter 5 allows the interference wave output from the signal generator 4 to pass, but suppresses only the transmission frequency band of the device under test. In other words, it is desirable to have a flat frequency characteristic in which the transmission frequency band is greatly attenuated and the passage loss other than the attenuation band is small.

  The base station device 7 is a device under test, and it is assumed that a radio signal transmission output terminal and a reception input terminal are shared. As a means for sharing, for example, a duplexer is used. Further, it is assumed that the transmission frequency band and the reception frequency band used do not exceed 50% in the ratio band.

  The error rate measuring device 8 receives the signal demodulated by the base station apparatus 7, measures the bit error rate (BER) for estimating the influence degree of the interference wave, and outputs the result. The error rate measuring device 8 is well known to those skilled in the art and is not directly related to the present invention, and therefore the detailed configuration thereof is omitted.

  Next, the operation of the radio base station test apparatus of this embodiment will be specifically described. FIG. 2 is a block diagram illustrating a path in which a transmission signal becomes a problem.

  First, the pseudo terminal 1 outputs a pseudo signal wave (desired wave) within the reception frequency band, and the signal generator 4 outputs an interference wave outside the reception frequency band.

  The directional coupler 3 has a certain degree of coupling in the frequency range of 1 MHz to 12.75 GHz, and combines the desired wave output from the pseudo terminal 1 and the interference wave output from the signal generator 4 to generate the base station device 7. Output to. At this time, the attenuation amounts of the attenuators 2 and 6 are set in order to make the level of the desired wave and the interference wave input to the base station apparatus 7 appropriate.

  Base station apparatus 7 receives the desired wave and the interference wave, demodulates the desired wave within the reception frequency band, and outputs the demodulated signal to error rate measuring instrument 8. Further, the base station device 7 outputs a transmission signal within a predetermined transmission frequency band when tested as an operation state. This transmission signal is sent to a broadband directional coupler 3 directly connected to a shared terminal (antenna connection end) for testing.

  Here, in the pseudo terminal 1, the desired wave within the reception frequency band of the base station device 7 and the transmission signal output from the base station device 7 are combined by an internal transmission signal generator (including a non-linear element). However, a mixed wave multiplied by two waves does not occur in the reception frequency band. For example, when allocated in the 2 GHz band, a mixed wave in which the ratio band is 50% and the frequency of the transmission / reception signal is 1.5 GHz and 2.5 GHz is 1 GHz and 4 GHz, and the reception characteristic of the device under test is There is no effect.

  On the other hand, in the signal generator 4, when the interference wave to be output and the transmission signal are combined by an internal transmission signal generator (including a non-linear element), a mixed wave multiplied by two waves is generated in the reception frequency band. There is. That is, this is a case where a frequency is selected such that one of the frequency components (sum and difference) resulting from the two-wave multiplication falls within the reception band of the base station device 7. Therefore, in addition to the original frequency (interference wave), unnecessary frequency components are generated, and the reception characteristics cannot be accurately grasped.

  As a countermeasure, the radio base station test apparatus of the present embodiment uses the band rejection filter 5 shown in FIG. 2 to eliminate the influence of the transmission signal of the base station apparatus 7 and to accurately measure the reception characteristics. is there.

  Next, the configuration of the band rejection filter 5 will be described. FIG. 3 is a block diagram showing a configuration example of the band rejection filter shown in FIG. FIG. 4 is a frequency characteristic diagram showing an ideal band rejection filter. FIG. 5 is a frequency characteristic diagram according to the configuration of the band rejection filter shown in FIG.

  As shown in FIG. 3, the band rejection filter 5 includes a selector A51 and a selector B52, and a filter A501 to a filter E505.

  The selector A51 and the selector B52 operate in conjunction with each other and select a plurality of filters excluding the filter corresponding to the transmission frequency band.

  The filters A501 to E505 have respective bands obtained by appropriately dividing the frequency range of 1 MHz to 12.75 GHz, and are selected by the selector A51 and the selector B52.

  The band rejection filter 5 configured in this way blocks only a predetermined band, that is, a transmission frequency band. Ideally, as shown in FIG. 4, an attenuation sufficient to block the transmission signal is obtained, but the frequency characteristic is flat in the frequency band including the adjacent reception frequency band and excluding the stop band. desirable.

  However, the band rejection filter 5 cannot realize a steep attenuation characteristic only for the transmission frequency band while the interference wave can take a frequency range of 1 MHz to 12.75 GHz. Therefore, it is assumed that a frequency range of 1 MHz to 12.75 GHz is divided into several frequency bands, and band-pass filters that pass each frequency band are prepared and combined according to the number of frequency divisions.

  FIG. 5 shows a case where filters A501 to E505, which are bandpass filters, excluding the filter C503 corresponding to the transmission frequency band are selected by the selector A51 and the selector B52. In FIG. 5, the transmission frequency is 2140 MHz in the 2 GHz band.

  As shown in FIG. 5, it is sufficiently possible to arrange the attenuation amounts of the divided passbands within a predetermined range. Therefore, only the transmission frequency band is blocked, and the frequency of the interference wave can be arbitrarily set in the range of 1 MHz to 12.75 GHz excluding the transmission frequency band.

It is a block diagram which shows one Embodiment of the radio base station test apparatus of this invention. It is a block diagram which shows the path | route in which a transmission signal becomes a problem. FIG. 3 is a block diagram illustrating a configuration example of a band rejection filter illustrated in FIG. 2. It is a frequency characteristic figure which shows an ideal band stop filter. FIG. 4 is a frequency characteristic diagram according to the configuration of the band rejection filter shown in FIG. 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pseudo terminal 2, 6 Attenuator 3 Directional coupler 4 Signal generator 5 Band stop filter 7 Base station apparatus 8 Error rate measuring device

Claims (9)

Having a pseudo signal generator and a noise signal generator, synthesizing signals output from each of the pseudo signal generator and the noise signal generator;
A radio base station test apparatus for testing a reception characteristic of the device under test by inputting it to an input / output common terminal of the device under test, wherein the filter attenuates a transmission frequency band of a radio signal on the output side of the noise signal generator A radio base station test apparatus comprising:   The radio base station test apparatus according to claim 1, wherein signals output from the pseudo signal generator and the noise signal generator are combined by a directional coupler. The radio base station test apparatus according to claim 1, wherein the filter has a flat frequency characteristic excluding an attenuation band . The filter is composed of a pass-type band filter corresponding to the output frequency band of the noise signal generator divided into a plurality of filters, and the remaining filters except for the filter corresponding to the transmission frequency band are connected in parallel. The radio base station test apparatus according to claim 1 or 3, characterized in that: The radio base station according to claim 1, wherein the device under test is tested for reception characteristics by measuring a bit error rate (BER) from a signal demodulated by the device under test. Test equipment. 6. The radio base station test apparatus according to claim 1, wherein the noise signal generator outputs a signal having a frequency excluding a reception frequency band of the device under test. Generate a pseudo signal and a noise signal, synthesize the pseudo signal and the noise signal after attenuation of the transmission frequency band of the radio signal, and input to the input / output common terminal of the device under test and A radio base station test method characterized by testing reception characteristics . 8. The radio base station test method according to claim 7, wherein the pseudo signal and the noise signal are synthesized by a directional coupler . 8. The radio base station according to claim 7, wherein the device under test is tested for reception characteristics by measuring a bit error rate (BER) from a signal demodulated by the device under test. Test method.

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