JP2008306456A - Radio transmission apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio transmission apparatus for efficiently monitoring an operating state of an analogue transmitting section, with a simple structure. <P>SOLUTION: The radio transmission apparatus is provided with the analogue transmitting section for converting a D/A converted transmission signal into an intermediate-frequency signal and a radio frequency signal and amplifying them, a monitor signal extracting section for extracting the amplified radio frequency signal and converting it to the intermediate frequency signal to form a monitor signal, and a determining section for determining whether or not the analogue transmitting section is abnormal by comparing a frequency component of the monitor signal with an expectation value preliminarily set to the frequency component. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a radio transmission apparatus, and is preferably applied to, for example, a downlink transmission unit of a base station in a mobile communication system.

  In a mobile communication system, if there is an abnormality in the downlink transmission unit of a base station, it has a great influence on mobile terminals in the service area, so it is necessary to quickly detect and repair the failure. In general, abnormalities in the base station transmission unit can be known indirectly through reception malfunctions of mobile terminals located in the area, but there may be cases where the wireless environment is bad. Failure determination cannot be performed unless it is returned and checked with a dedicated test facility. Furthermore, even if it is known that a failure has occurred, it is difficult to identify which part is the failure, and it takes time to recover the abnormality.

  In this regard, conventionally, there is known a digital modulation wave monitoring method for detecting an abnormal operation of a digital modulation circuit by monitoring spectrum distortion of the digital modulation wave (Patent Document 1).

Conventionally, there is known a transmission apparatus that compares the detection output of the amplifier input with the detection output of the amplifier to calculate the gain of the amplifier and can determine the normality / abnormality of the amplifier from the fluctuation amount of the gain. (Patent Document 2).
JP-A-7-87142 JP-A-2005-223827

  However, in general, the downlink transmission unit of the base station includes various analog circuits such as filters, mixers (frequency converters), power amplifiers, etc., and monitors each specific part (digital modulation circuit, power amplifier, etc.). When the circuit is provided, the entire downstream transmission unit becomes complicated and the cost is greatly increased.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a wireless transmission device capable of efficiently monitoring the operation state of an analog transmission unit with a simple configuration.

  The radio transmission apparatus according to the first aspect of the present invention extracts an analog transmission unit that converts and amplifies a D / A converted transmission signal into an intermediate frequency signal and a radio frequency signal, and extracts the amplified radio frequency signal. A monitor signal extraction unit that converts the signal into an intermediate frequency signal and then performs A / D conversion to form a monitor signal, and compares the frequency component of the monitor signal with an expected value set in advance for the frequency component. A determination unit that determines whether the analog transmission unit is abnormal.

  According to the present invention, the relationship over the entire band of the analog transmission unit is achieved by a simple configuration that compares the frequency component of the monitor signal formed for the amplified radio frequency signal with the expected value preset for the frequency component. It is possible to efficiently determine the abnormal operation of each part.

In the second aspect of the present invention, the monitor signal extraction unit extracts a signal from a plurality of monitoring points of the analog transmission unit to form a monitor signal, and the determination unit receives the monitor signal from each of the monitoring points. Is compared with an expected value set in advance for the frequency component to identify an abnormal portion of the analog transmission unit.

  In the present invention, a signal is extracted from a plurality of monitoring points of the analog transmission unit to form a monitor signal, and the frequency components are compared with each expected value by a common comparison unit, so that the abnormal operation of each unit is detected. Can be judged efficiently. Further, by comprehensively analyzing the comparison results for a plurality of monitoring points, it is possible to reliably isolate (specify) a failure location.

  In the third aspect of the present invention, the expected value is a frequency component of the monitor signal acquired during normal operation of the analog transmission unit. According to the present invention, it is easy to obtain and manage the correct expected value because the correct expected value of each device can be easily obtained simply by correctly adjusting each device during the normal shipping process.

  In the fourth aspect of the present invention, when the monitor signal at each monitoring point has a predetermined bandwidth, the determination unit includes a plurality of frequency components within the bandwidth and a plurality of frequency components preset for the frequency components. Compare the expected value of. Therefore, detailed evaluation and abnormality determination of the circuit characteristics of the entire analog transmission unit are possible.

  In the fifth aspect of the present invention, the determination unit normally compares the frequency component of the monitor signal from the monitoring point at the final stage of the analog transmission unit with its expected value, and if a comparison abnormality is detected, The frequency component of the monitor signal from the monitoring point in the previous stage is compared with the expected value. Accordingly, the inspection burden during normal operation of the analog transmission unit is reduced, and when an abnormality is detected, the abnormal part can be quickly identified.

  As described above, according to the present invention, the operation state of the analog transmitter can be efficiently monitored with a simple configuration.

  Hereinafter, a plurality of preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the same reference numerals denote the same or corresponding parts throughout the drawings.

  FIG. 1 is a diagram for explaining a radio transmission apparatus according to the first embodiment and shows an application example of the present invention to a base station downlink transmission apparatus. In the figure, 11 is a baseband (BB) processing unit that performs spreading, multiplexing, digital modulation, etc. of transmission data, 12 is a D / A converter, 17 is a local (LO) signal oscillator according to the PLL system, and 13 is a D / A. A mixer that up-converts the converted intermediate frequency (IF) signal into a radio (RF) signal using an LO signal, 14 is a power amplifier (AMP) that amplifies the power of the RF signal, and 16 is a partial RF signal output from the AMP 14. A directional coupler (coupler) for extraction, 18 is a mixer for down-converting the extracted RF signal into an IF signal using an LO signal, and 19 is an A / D for sampling the IF signal after down-conversion and converting it into a monitor digital signal. A converter 23 is a detection unit that extracts a number of monitor data necessary for monitoring circuit operation, and 21 is acquired in advance at the time of factory shipment or repair of the apparatus. A memory (MEM) 22 that stores an expected value (for example, a frequency component obtained by frequency analysis of monitor data during normal operation of the apparatus), 22 is a frequency component of the monitor data extracted by the detection unit 23 and an expected value A determination unit that determines whether or not there is an abnormality by comparing the two, and 24 is a control unit that controls the inspection of the wireless transmission circuit.

In the present embodiment, the analog transmission circuit section on the output side of the D / A converter 12 is the inspection target, and a part of the AMP 14 output RF signal is extracted, down-converted to an IF signal, and A / D converted. Monitor signal data. The monitor signal data is input to a distortion correction circuit (not shown) to check the presence / absence of an outer component (distortion component) of the main signal band (for example, 20 MHz) and a part (predetermined under the control of the control unit 24). Signal data) is read into the detector 23. In the detection unit 23, the signal data is subjected to Fourier transform by, for example, FFT (Fast Fourier Transform) to obtain a frequency component (spectrum) of the signal power. This frequency component is obtained at least at two or more locations in the main signal band. When the main signal band is divided into a plurality of sub-bands (for example, 5 MHz) and operated, at least two abnormal frequency components are obtained for each sub-band. As a result, detailed comparison / determination including the slope of the frequency component can be performed.

  The determination unit 22 compares the obtained frequency component with a frequency component (expected value) during normal operation stored in the memory 21, and the obtained frequency component falls within a predetermined range based on the expected value. If it is determined that the operation is normal, it is determined that the operation is abnormal. Since such an inspection can be performed without affecting the transmission circuit in the operating state, it is possible to always perform the inspection. In addition, by providing the coupler 16 in the vicinity of the antenna (not shown), it is possible to extract a signal that has passed through the entire analog transmission unit, thereby efficiently monitoring the operation of the entire analog transmission unit.

  FIG. 2 is a diagram for explaining a radio transmission apparatus according to the second embodiment, and shows a case where a failure point in an analog transmission unit can be automatically identified. In the figure, 15 is a directional coupler (coupler) that extracts a part of the RF signal input to the AMP 14, and SW 1 and SW 2 are high-frequency switches that switch the detection route of the monitor signal. Further, the memory 21 in this example stores the expected values acquired in advance during normal operation according to a plurality of inspection locations. In addition, the control unit 24 generates control signals S1 and S2 for performing switching control of the switches SW1 and SW2.

  Inset (a) shows a circuit example of the high-frequency switch SW2. The cathodes of the PIN diodes D1 and D2 are connected to a common output terminal, the anode of D1 is biased with a switch control signal S2 through a high frequency cutoff coil L1, and the anode of D2 is switched with a switch control signal through a coil L2. Biased by S2 / (inverted signal of S2). As a result, when the switch control signal S2 is logic 1 (high level), the monitoring route b side is conducted and the monitoring route a side is cut off. When the switch control signal S2 is logic 0 (low level), the monitoring is performed. The route b side is blocked and the monitoring route a side is conducted. In addition, you may use the relay switch etc. which a contact switches mechanically. Other configurations may be the same as those described in FIG.

  3 and 4 are flowcharts (1) and (2) of the failure inspection process according to the embodiment, and show a case where the failure location can be automatically specified using the transmission circuit unit of FIG. This inspection process is executed by the control unit 24 of FIG. FIG. 3 shows the main process, and this process is executed along with the operation of the communication apparatus. In step S11, the selector switches SW1 and SW2 are both turned OFF so that the monitor signal of the monitoring route a can be monitored. In step S12, the failure inspection process of FIG. 4 is executed (CALL) with the inspection parameter a.

  Here, the failure inspection process (subroutine) in FIG. 4 will be described. In step S31, the inspection parameter designated by the execution source of this process (inspection parameter indicating the inspection of the monitoring route a, b, or c) is acquired. In step S32, monitor data for a predetermined time is acquired. In step S33, the acquired monitor data is subjected to Fourier transform (FFT) to extract the frequency component of the transmission signal. In step S34, the obtained frequency component is compared with the expected value a, b, or c read from the memory 21 according to the inspection parameter a, b, or c, and in step S35, the presence or absence of a failure (abnormality) is determined.

Inset (a) shows a graph image of the monitor signal. The horizontal axis is the frequency f, and the vertical axis is the frequency component of the transmission power. For example, when the entire band 20 MHz is divided into 5 MHz and operated, the frequency components of the entire band are obtained so that each of the sub-bands C0 to C3 includes a plurality of frequency components. The telecommunications carrier, for example, uses the sub-band C0 as a dedicated call and C1 as a dedicated HSDPA (High Speed Downlink Packet Access). When the transmission circuit unit is operating normally, a flat frequency component can be obtained over the entire band of 20 MHz as shown by the solid line in the figure. The graph displays the magnitude of the frequency component with an envelope. However, when there is some obstacle, the amplitude of the frequency component is not uniform as shown by the dotted line in the figure. An abnormal state can be easily determined by detecting such a state.

  Returning to FIG. 3, in step S <b> 13, it is determined whether or not an abnormality is detected. If no abnormality is detected, the process returns to step S <b> 12. Thereby, normally, the whole analog communication unit can be efficiently monitored by the inspection of the monitoring route a. If an abnormality is detected in the determination in step S13, the abnormal part is specified in the processing after step S14. That is, in step S14, the inspection result a is held in the memory 21. In step S15, the switch SW2 is switched to the ON side, and in step S16, the inspection process for the monitoring route b is executed. In step S17, the inspection result b is held in the memory 21. In step S18, the switch SW1 is switched to the ON side, and in step S19, the inspection process for the monitoring route c is executed. In step S20, the inspection result c is held in the memory 21. In step S21, the failure location is identified based on the stored inspection results a to c and reported to the host system.

  For example, when the inspection result a is abnormal and the inspection result b is normal, it can be determined that the AMP 14 has a failure. Further, when the inspection results a and b are abnormal and the inspection result c is normal, it can be determined that the mixer 13 has a failure.

  In the above embodiment, the transmission circuit is inspected regardless of whether or not the base station is congested. However, the present invention is not limited to this. If the inspection is performed by detecting a vacant state of the base station (or a state in which there are few connected terminals, etc.), the processing load on the base station control unit can be reduced. Whether or not the base station is congested can be easily determined by monitoring the access status of the mobile terminal based on, for example, an RRC (Radio Resource Control) call processing signal. One of the main functions of RRC is re-establishment / maintenance / release at the time of establishment / disconnection of the RRC connection between the terminal and the base station. The processing load on the base station increases due to the establishment / re-establishment of the RRC connection, and is alleviated by releasing the RRC connection. Therefore, it is possible to easily determine whether or not the base station is idle by managing the number of mobile terminals located in the local station.

  In the above embodiment, a part of the transmission signal is extracted using the coupler. However, the present invention is not limited to this. You may comprise so that all the transmission signals may be switched and input into a test | inspection circuit. The inspection in this case is performed by detecting the idle time of the base station.

  In the above embodiment, the frequency components of the entire band are obtained by FFT calculation, but the present invention is not limited to this. The frequency component may be detected by detecting the output of the bandpass filter circuit provided for each subband.

  Moreover, although several embodiment suitable for the said invention was described, it cannot be overemphasized that the structure of each part, control, a process, and these combination can be variously changed within the range which does not deviate from this invention. .

It is a figure explaining the radio | wireless transmission apparatus by 1st Embodiment. It is a figure explaining the radio | wireless transmission apparatus by 2nd Embodiment. It is a flowchart (1) of failure inspection processing by an embodiment. It is a flowchart (2) of the failure inspection process by embodiment.

Explanation of symbols

11 Baseband (BB) processing unit 13, 18 Mixer 14 Power amplifier (AMP)
15,16 Directional coupler (coupler)
17 Local oscillator 21 Memory (MEM)
22 determination unit 23 detection unit 24 control unit

Claims (5)

An analog transmitter for converting and amplifying the transmission signal after D / A conversion into an intermediate frequency signal and a radio frequency signal;
A monitor signal extraction unit that extracts the amplified radio frequency signal and converts it to an intermediate frequency signal, and then performs A / D conversion to form a monitor signal;
A determination unit that determines whether the analog transmission unit is abnormal by comparing the frequency component of the monitor signal with an expected value set in advance for the frequency component;
A wireless transmission device comprising: The monitor signal extraction unit extracts a signal from a plurality of monitoring points of the analog transmission unit to form a monitor signal,
The determination unit identifies an abnormal portion of the analog transmission unit by comparing a frequency component of a monitor signal from each of the monitoring points with an expected value set in advance for the frequency component. Item 2. The wireless transmission device according to Item 1. The radio transmission apparatus according to claim 1, wherein the expected value is a frequency component of a monitor signal acquired during normal operation of the analog transmission unit. When the monitor signal at each monitoring point has a predetermined bandwidth, the determination unit compares a plurality of frequency components within the bandwidth with a plurality of expected values preset for the frequency components. The wireless transmission device according to claim 3, wherein: The determination unit usually compares the frequency component of the monitor signal from the monitoring point at the final stage of the analog transmission unit with its expected value, and if a comparison abnormality is detected, monitors from the monitoring point at the preceding stage. 3. The radio transmission apparatus according to claim 2, wherein the frequency component of the signal is compared with an expected value thereof.

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