JP2010283497A - Reception circuit failure detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To preliminarily detect a foresight that a reception circuit of a certain antenna branch is getting into a functional defect state. <P>SOLUTION: A base station designates a ranging code group to a terminal unit. The terminal unit selects one ranging code from among the group and transmits to the base station a signal modulated into an OFDM by using the selected ranging code. A reception circuit 200 demodulates the OFDM signal received by each antenna 100 into a data symbol. A detector 300 calculates a correlated power value between the data symbol and the ranging code, and transmits a detection result 400 to a detection number counter portion 500 when the selected ranging code is detected. The processing is performed per antenna branch, and each detection number count value is stored in a memory 503. In the presence of an antenna branch whose detection number count value is lower than that of another antenna branch by a fixed value or more, a failure detection portion 504 detects the branch as "reception gain deterioration" (failure). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a reception circuit abnormality detection device for a wireless communication unit in a wireless communication base station device.

  In the conventional reception circuit abnormality detection device, as shown in Patent Document 1, the reception level of each antenna and its reception circuit is notified to the CPU, and the CPU determines the reception level and the maximum reception level at each antenna. Detect whether the difference is within a certain range or out of range. If it is out of the range, the CPU increments the counter because there is a possibility of abnormality, and clears the counter if it is within the range. After starting communication between the mobile telephone and the base station apparatus, the CPU repeats this operation at regular intervals. As a result, when the value of the counter indicating the possibility of abnormality exceeds the specified value, the CPU detects the corresponding antenna and its receiving circuit as abnormal, and notifies the center of the abnormality detection result.

  Patent Document 2 is a technique that represents a development of Patent Document 1, and after detecting the validity of the receiving circuit with the maximum received power after counting up the number of communications, an abnormality is detected by the same method as Patent Document 1. The technology to do is disclosed.

  Patent Document 3 discloses a configuration in which a TDD (Time Division Multiplexing) system receives leakage power of a transmission signal at a reception side circuit and detects an abnormality of the reception circuit from demodulated data and a reception level. Disclosure.

  Further, Patent Document 4 describes the abnormality of a branch based on the maximum reception level of a reception signal converted by a branch comprising an antenna and its reception circuit and the number of normal communications in the reception circuit selected and diversityd by the reception signal. A configuration to detect is disclosed.

JP-A-9-83418 Japanese Patent No. 3139440 JP 2001-111463 A JP-A-11-205207

  In general, in a wireless receiver, a failure symptom associated with deterioration of electronic devices constituting a low noise amplifier and a local oscillator is a phenomenon such as a decrease in reception sensitivity, a decrease in reception gain, and a variation in local oscillation frequency. And appear.

  However, the conventional failure detection method based on the comparison of the reception level can detect the broken antenna and the complete malfunction of the receiver, but it is impossible to detect these precursors. When a person detects a failure, he / she is always forced to take an emergency response for recovery.

  Also, in order to reduce the number of such emergency responses, it is necessary to periodically replace and maintain the base station equipment at the operation site, and replace the equipment in a short period of time with respect to the average life of the equipment. Implementation of this has led to an increase in operating costs.

  The present invention has been made in view of such a technical situation, and an object of the present invention is to provide a reception circuit abnormality detection device capable of detecting a sign that a wireless reception device has malfunctioned.

  A subject of the present invention is a reception circuit abnormality detection device provided in a radio communication base station, wherein a plurality of antenna branches and a ranging code group designated by the radio communication base station for a terminal for each antenna branch A ranging code detector for detecting the number of detected ranging codes selected by the terminal among all the ranging codes included in the terminal, and the number of selected ranging codes detected for each antenna branch detected by the ranging code detector By comparing the above, an abnormality detection unit for detecting whether or not there is an antenna branch indicating a sign of malfunction in the plurality of antenna branches is provided.

  According to the subject of the present invention, in a receiving apparatus in a radio communication base station having a plurality of antenna branches, it is possible to detect in advance a sign that a receiving circuit of any antenna branch will malfunction. As a result, the subject of the present invention enables planned maintenance and operation of the receiving apparatus before malfunction, and can reduce the cost required for these.

  Hereinafter, various embodiments of the present invention will be described in detail along with the effects and advantages thereof with reference to the accompanying drawings.

It is a block diagram which shows the structure of the receiver circuit abnormality detection apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of the circuit which produces | generates the ranging code in a WiMAX system with which a terminal is provided. It is a figure which shows the correlation power value with the selected ranging code, and the correlation power value with other ranging codes. It is a block diagram which shows the structure of the receiver circuit abnormality detection apparatus which concerns on Embodiment 2 of this invention. It is a block diagram which shows the structure of the receiver circuit abnormality detection apparatus which concerns on Embodiment 3 of this invention.

(Embodiment 1)
Hereinafter, as an example, the present invention is applied to a WiMAX (abbreviation for Worldwide Interoperability for Microwave Access) base station apparatus (an example of a radio base station apparatus; hereinafter simply referred to as a “base station”). Indicates.

  FIG. 1 is a block diagram showing a configuration of a reception circuit abnormality detection device according to Embodiment 1 of the present invention. The reception circuit abnormality detection device is a device in a radio communication unit in the base station.

  In FIG. 1, each antenna 100 receives a carrier band OFDM signal transmitted from a terminal (for example, a mobile phone) and propagated. Each receiving circuit 200 down-converts the carrier band OFDM signal received by the corresponding antenna 100 and demodulates it. Hereinafter, a pair of configurations of an antenna 100 and a receiving circuit 200 connected to the antenna 100 is referred to as an “antenna branch”. A ranging code detector 300 connected to each antenna branch is included in a ranging code group including a plurality of ranging codes designated from the base station to the terminal from the OFDM demodulated data symbols, as will be described later. The correlator performs detection processing of the ranging code selected by the terminal. The detection number counting unit 500 includes, for each antenna branch, a counter that counts a pulse output when the ranging code detector 300 disposed in each antenna branch detects the ranging code selected by the terminal. ing. The memory 503 is a storage device that stores the count value of the detection number counting unit 500 (corresponding to the number of detections of the selected ranging code) for each antenna branch. The abnormality detection unit 504 is a part that detects an abnormality of the reception circuit 200 based on the result of the detection number for each antenna branch.

  The operation of the reception circuit abnormality detection device in FIG. 1 will be described below.

  First, in the WiMAX system, as an initial connection procedure between a base station and a terminal, the base station transmits a ranging code group including a plurality of ranging codes and a ranging code using broadcast information that is known information. The slot for this is notified or designated to the terminal. Here, the “slot” indicates a location where the terminal stores the ranging code, that is, a part in which a frame that can be transmitted by the terminal is divided by time and frequency. “Broadcast information” is information including the slot and the ranging code group.

  Next, the terminal selects one ranging code from a plurality of ranging codes included in the ranging code group designated by the base station. The terminal transmits a signal modulated to the carrier band OFDM by performing BPSK mapping using the ranging code selected by the terminal, to the slot designated by the base station.

  Each antenna 100 in the base station receives a carrier band OFDM signal transmitted from the terminal. Then, each receiving circuit 200 in the base station performs OFDM demodulation on the received carrier band OFDM signal to obtain data symbols. Each ranging code detector 300 calculates a correlation power value between the demodulated data symbol and all ranging codes included in the ranging code group designated by the base station, and a detection method based on the correlation power value described later Thus, when one ranging code selected by the terminal is detected, a detection result 400 that is a pulse signal indicating the detection is transmitted to the detection number counting unit 500. These processes or operations are performed for each antenna branch. Then, the detection number counting unit 500 stores the count value of the detection number for each antenna branch in a predetermined area in the memory 503 for each antenna branch.

  The abnormality detection unit 504 monitors the count value of the number of detections stored in each predetermined area of the memory 503, and if there is an antenna branch that is lower than the detection number count value of another antenna branch by a certain amount, The branch is detected as “reception gain degradation” (in other words, the antenna branch is detected as an abnormal antenna branch).

  Next, an example of a method for detecting one ranging code selected by the terminal in each ranging code detector 300 of FIG. 1 will be described.

The terminal selects one ranging code number from the ranging code group designated by the base station, and generates a ranging code. Here, FIG. 2 is a diagram illustrating a configuration of a circuit in the terminal that generates the ranging code in the WiMAX system. The ranging code generation circuit of FIG. 2 gives initial values to the shift registers 0 to 14, generates a ranging code string C _k according to the ranging code length and the ranging code number, and uses it as a ranging code. Each element of the ranging code sequence C _k is 0 or 1, and the terminal transmits a data symbol obtained by mapping the value of each element of the ranging code sequence C _k to each subcarrier of the OFDM signal by BPSK modulation to the base station. To do.

  Each antenna 100 of the base station receives a data symbol transmitted by the terminal, and each ranging code detector 300 of the base station receives each of the ranging codes included in the ranging code group designated by the base station, Calculate a correlation power value taking into account a reception delay with the demodulated data symbol. At this time, if there is a ranging code whose correlation power value exceeds a predetermined “threshold value”, each ranging code detector 300 selects one ranging code selected by the terminal. As a result, one ranging code selected by the terminal is detected.

  Here, FIG. 3 shows the ranging specified by the base station when the base station receives the data symbol transmitted from the terminal and the ranging code selected by the terminal on the subcarrier without delay. It is a figure which shows an example of the calculated value of correlation power with each of all the ranging codes contained in a code group, and the demodulated data symbol. In FIG. 3, the correlation power 600 drawn by a thin solid line is demodulated with one ranging code selected by the terminal from all the ranging codes included in the ranging code group designated by the base station. This is a calculated value of correlation power with the data symbol. Even in a radio wave propagation environment without a delay wave, a correlation power value exceeding a threshold value may be detected at each delay point, and FIG. 3 shows such an example. On the other hand, a reference numeral 601 drawn by a thick solid line indicates a remaining ranging code that is not selected by the terminal among all the ranging codes included in the designated ranging code group, and a demodulated data symbol. The maximum value among the calculated values of correlation power is shown. Since there are a plurality of ranging codes that are not selected by the terminal, the number of correlation powers to be calculated is also a plurality, and the maximum values thereof are graphed. The vertical axis in FIG. 3 is the correlation power value when all the power values of the subcarriers including the ranging code are normalized to 1, and the horizontal axis indicates the delay time in units of 1 / sampling frequency. Yes. In this example, the threshold 602 is set to 35 dB, the correlation power value 401 with one ranging code selected by the terminal exceeds the threshold 602, and the correlation power with other ranging codes is The value becomes lower than the threshold value 602, and one ranging code selected by the terminal is detected.

  Correlation power value 401 is usually a value that exceeds threshold value 602 at a plurality of delay points due to the influence of delay waves due to the radio propagation environment. Therefore, the total value of all delay points (including the case where the delay point is 0) is defined as “correlation power value” with one ranging code selected by the terminal.

  In addition, the circuit portion composed of each ranging code detector 300, the detection number counting unit 500, and the memory 503 shown in FIG. 1 is “to each ranging branch, a ranging code group designated by the wireless communication base station for the terminal. It constitutes a “ranging code detector for detecting the number of detected ranging codes selected by the terminal among all the ranging codes included”.

  From the above description, according to the present embodiment, it is possible to accurately detect a sign that the receiving device in the base station (corresponding to the receiving circuit 200 in FIG. 1) is malfunctioning. This makes it possible to maintain and operate a typical receiving apparatus and reduce the cost required for these.

(Embodiment 2)
FIG. 4 is a block diagram showing a configuration of a reception circuit abnormality detection device according to Embodiment 2 of the present invention. The reception circuit abnormality detection device is also a device in the wireless communication unit in the base station.

  In FIG. 4, the ranging code detector 300 of each antenna branch calculates the correlation power value 401 of the ranging code described in FIG. 3 of the first embodiment every time the correlation power value 401 is detected. It transmits to the electric power total part 501.

  Here, the correlation power value 401 corresponds to the signal power of the received SNR (Signal to Noise Ratio: the amount of noise with respect to the signal). When the correlation power value 401 is low, the received SNR also takes a low value. . Accordingly, when the total value of the correlation power values 401 is relatively low, it can be estimated that the reception sensitivity of the antenna branch has deteriorated.

  Therefore, the correlation power summation unit 501 sums the correlation power values 401 output from the corresponding ranging code detector 300 for each antenna branch, and stores the total value in the memory 503 as the correlation power total value. Therefore, the correlation power total value stored in the memory 503 is the correlation power total value stored and stored for each antenna branch.

  The abnormality detection unit 504 monitors the total correlation power value of each antenna branch stored in the memory 503, and the total correlation power value of the other antenna branches is lower than a certain value by a certain value. When the presence of the antenna branch is detected, the antenna branch is detected as an antenna branch of “reception sensitivity degradation”, that is, the reception circuit 200 of the antenna branch is detected as abnormal.

  In addition, the circuit portion composed of each ranging code detector 300 shown in FIG. 4, the correlation power summation unit 501, and the memory 503 has a “ranging code group designated by the radio communication base station for the terminal for each antenna branch”. It forms a ranging code detecting unit that detects a total value of correlation power values of ranging codes selected by the terminal among all the ranging codes included.

  As described above, according to the present embodiment, it is possible to detect a sign of a malfunction of the receiving circuit by comparing the total correlation power values of the antenna branches.

(Embodiment 3)
FIG. 5 is a block diagram showing a configuration of a reception circuit abnormality detection device according to Embodiment 3 of the present invention. The reception circuit abnormality detection device is also a device in the wireless communication unit in the base station.

  In FIG. 5, the ranging code detector 300 of each antenna branch detects the correlation power value 401 of the ranging code exceeding the threshold value 602 described in FIG. 3 of the first embodiment. Deflection angle θ [rad] × subcarrier interval [Hz] / 2π on the IQ plane of the complex correlation value of the selected ranging code (corresponding to the correlation value in complex number format (I, Q) before obtaining the correlation power value) Is calculated to obtain the frequency offset value 402 of the received signal. Each time the ranging code detector 300 detects the correlation power value 401 of the ranging code exceeding the threshold 602, the frequency offset value 402 calculated from the complex correlation value of the selected ranging code, To 502.

  The frequency offset totaling unit 502 sums up the frequency offset values 402 transmitted from the corresponding ranging code detector 300 for each antenna branch, and stores the total value in the memory 503 as the frequency offset total value. Accordingly, the memory 503 stores and stores the total frequency offset value related to each antenna branch in a predetermined area corresponding to each antenna branch.

  The anomaly detection unit 504 monitors the total frequency offset value for each antenna branch stored in the memory 503, and there is a difference that the total frequency offset value is more than a certain value compared to the total frequency offset value of other antenna branches. When the presence of a certain antenna branch is detected, the antenna branch is detected as an antenna branch of “frequency accuracy degradation”. In other words, the abnormality detection unit 504 detects that the reception circuit 200 of the antenna branch is abnormal.

  In addition, the circuit portion comprising each ranging code detector 300, the frequency offset summing unit 502, and the memory 503 shown in FIG. 5 is “the ranging code group designated by the radio communication base station for the terminal for each antenna branch”. It forms a ranging code detecting unit that detects the total frequency offset value of the ranging code selected by the terminal among all the included ranging codes.

  As described above, according to the present embodiment, it is possible to detect a sign of a malfunction of the receiving circuit by comparing the total frequency offset value of each antenna branch.

(Appendix)
While the embodiments of the present invention have been disclosed and described in detail above, the above description exemplifies aspects to which the present invention can be applied, and the present invention is not limited thereto. In other words, various modifications and variations to the described aspects can be considered without departing from the scope of the present invention.

  The present invention is suitable for application to, for example, a receiving apparatus in a wireless system including a correlator that calculates correlation power for each antenna branch.

  100 antenna, 200 receiving circuit, 300 ranging code detector, 400 ranging code detection result, 401 correlation power value, 500 detection number counting unit, 501 correlation power totaling unit, 502 frequency offset totaling unit, 503 memory, 504 abnormality detecting unit, 600 Correlated power value of a ranging code selected by the terminal, 601 Maximum correlation power value of a ranging code other than the selected ranging code, 602 threshold.

Claims (3)

A reception circuit abnormality detection device provided in a radio communication base station,
Multiple antenna branches,
A ranging code detection unit that detects the number of detected ranging codes selected by the terminal among all the ranging codes included in the ranging code group designated by the wireless communication base station for the terminal for each antenna branch When,
Abnormality detection that detects whether there is an antenna branch indicating a sign of malfunction in the plurality of antenna branches by comparing the number of selected ranging code detections for each antenna branch detected by the ranging code detection unit And comprising a part,
Receiver circuit abnormality detection device. A reception circuit abnormality detection device provided in a radio communication base station,
Multiple antenna branches,
For each antenna branch, a total value of correlation power values of ranging codes selected by the terminal among all the ranging codes included in the ranging code group designated by the wireless communication base station for the terminal is detected. A ranging code detector;
An abnormality detection unit for detecting whether or not there is an antenna branch indicating a sign of malfunction in the plurality of antenna branches by comparing the correlation power total value for each antenna branch detected by the ranging code detection unit; Characterized by comprising,
Receiver circuit abnormality detection device. A reception circuit abnormality detection device provided in a radio communication base station,
Multiple antenna branches,
A ranging code for detecting a total frequency offset value of the ranging code selected by the terminal among all the ranging codes included in the ranging code group designated by the wireless communication base station for the terminal for each antenna branch A detection unit;
An abnormality detection unit for detecting whether or not there is an antenna branch indicating a sign of malfunction in the plurality of antenna branches by comparing the total frequency offset value detected for each antenna branch detected by the ranging code detection unit; Characterized by comprising,
Receiver circuit abnormality detection device.

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