JPS59200547A - Monitoring system for circuit quality - Google Patents

Abstract

PURPOSE:To improve the detection precision of a circuit error rate by providing a syndrome extractor to a receiving demodulation system device. CONSTITUTION:The error correcting decoder consisting of a branching circuit 20, register 21, syndrome extractor 22, error corrector 23, and an error rate detector 24 is provided to receiving demodulation system devices in a terminal device and a specific repeater which forms a digital radio transmission system. A signal 101 containing a digital multiplex signal and a clock signal is branched by the circuit 20 into signals 102 and 103, and the signal 103 is inputted to the syndrome extractor 22 to extract a syndrome from an error correction code. Whether an error occurs to the signal 101 or not is detected from the syndrome, and the syndrome 22 outputted by the detector 22 and a clock signal 105 are inputted to the detector 24 to detect an error rate corresponding to a specific time length and output it. Further, a correction pulse signal 107 for the signal 101 is outputted to the corrector 23.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a line quality monitoring system, and more particularly to a line quality monitoring system that improves the accuracy of detecting a line error rate in a digital wireless transmission system.

Conventionally, as a line quality monitoring method in a digital wireless transmission system, a method has been used in which, for example, in a receiving demodulation system device, a method is used in which a frame synchronization signal or a parity signal, etc., generated from a received and demodulated signal at the frame synchronization stage is monitored. In the identification section of the demodulator in the demodulation system device, a clock signal or a predetermined fixed pattern extracted from the received and demodulated signal is added to generate a pseudo pulse, and through this pseudo pulse, Methods of predicting line quality are known.

However, in these conventional line quality monitoring systems, for example, in the former case mentioned above, when line quality monitoring is required at an intermediate relay station device, digital processing circuits related to frame synchronization functions that are not originally required are required. However, there is a drawback that it has to be added specifically for line quality monitoring only, and yet, in the latter case mentioned above, the line quality is The disadvantage is that it is difficult to increase the accuracy of the determination. Moreover, a common drawback of these conventional line quality monitoring systems is that the accuracy of detecting the line error rate is low.

The purpose of the present invention is to eliminate the above-mentioned drawbacks, and to reduce the line error rate by monitoring the line quality based on the presence or absence of syndrome zero values extracted during error correction decoding in a receiving demodulation system. An object of the present invention is to provide a line quality monitoring method that significantly improves detection accuracy.

The line quality monitoring system of the present invention is a line quality monitoring system applied to monitor line quality in a digital wireless transmission system.
A means for detecting errors in the line by referring to the ROMB) is provided in a predetermined reception demodulation system device in the terminal equipment forming the digital radio transmission system, or a terminal station forming the digital radio transmission system. a predetermined reception demodulation system device in both the device and the predetermined relay station device;
configured in preparation for

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a block diagram showing the main parts of an example of a current system in a digital wireless transmission system to which an embodiment of the present invention is applied. In FIG. 1, the current system in the digital wireless transmission system includes code converters 1, 2, and 3, a transmission digital signal processing section 4, an error correction encoder 5, a modulator 6, a transmitter 7, and an antenna 8. A terminal device including a transmission modulation system device 9, a relay station 10, an antenna 11, a reception v), 12, a demodulator 13, an error correction decoder 14, a reception digital signal processing unit 15, and a code converter 16. , 17 and 18.
9. Generally, a terminal station device is equipped with both a transmitting modulation system device and a receiving demodulating system device, but in order to simplify the explanation, in Fig. 1, each terminal station device is equipped with both a transmitting modulation system device and a receiving demodulating system device. Only one device is shown. Furthermore, in many cases, a plurality of relay station apparatuses are generally required to correspond to a plurality of relay stations installed corresponding to the spans of a communication route. Of course, depending on the span, a relay station device may not be necessary. Further, normally, a standby system is provided in correspondence with the current system, but this is omitted as it is not necessary for the explanation of the present invention.

In FIG. 1, three channels of digital multiplexed signals input from a separately provided PCM multiplex converter are sent to corresponding code converters 1, 2 and 3 via terminals 51, 52 and 53, respectively. is input.

Code converters 1, 2, and 3 convert the codes of these digital multiplexed signals from bipolar signals to unipolar signals, and output the signals to a transmission digital signal processing section 4.

In the transmission digital signal processing section 4, the asynchronous unipolar signal is synchronized by a stuffing method through a rate conversion effect regarding the bit rate, and the transmission power spectrum is leveled at the time of transmission and the bit timing at the reception side is The signal is output as a scrambled digital multiplexed signal for the purpose of extraction, and is input to the error correction encoder 5. In the error correction encoder 5, 5- the transmission digital signal processing unit 4 performs error correction of a predetermined n (positive integer) bit in the temporal margin part in the subframe that occurs due to bit rate conversion; A code etc. is inserted. Examples of frames of the digital multiplexed signal in this state are shown in FIGS. 4(a), (b) and (C).
) is shown. This frame pattern is %64QA
This is an example of the M (abbreviation for 64-value quadrature amplitude modulation) method. FIG. 4(a) shows code converters 1 and 2 in FIG.
3 shows the frame pattern of each channel input to the transmission digital signal processing unit 4 through each of subframes 201 and 3, and the number of bits of each subframe 201 is 80 bits.

FIG. 4(b) shows the configuration within a subframe of the pb correction code and additional bits related to stuff synchronization, which are inserted into the temporal margin as described above in the transmission digital signal processing unit 4. In the figure, one subframe consists of a data frame 202 and the aforementioned insertion bit 203.
Formed in polymorphism. Of course, the number of bits of the data frame 202 is 80 bits. Figure 4(C) is Figure 4(b)
The figure shows the details of the configuration of one subframe by expanding it by 6- times on the time axis. In this example, the number of bits of the error correction code is n.
This corresponds to the case of = 3. In FIG. 4(C),
The insertion bit 203 is formed by the above-mentioned additional bit 203-1 and redundant three bits 203-2 of the error correction code.

The digital multiplexed signal output from the error correction encoder 5 is
The signal is input to a modulator 6, subjected to orthogonal amplitude modulation according to the 64QAM method, and transmitted to a relay station device 10 via a transmitter 7 and an antenna 8. This transmission signal is received by the reception demodulation system device 19 provided in the terminal device of the other party via the relay station device 10, and is received by the antenna 11 and the receiver 1.
2 to the demodulator 13, and the above-mentioned 64QAM
demodulated according to the method. This demodulated signal is inputted to the error correction decoding ratio 14 together with the clock signal, the syndrome is extracted from the 3-bit error correction code, the error rate of the digital multiplexed signal is detected, and the error correction code is detected. If there is an error, the error is corrected and sent to the received digital signal processing section 15. FIG. 2 is a conceptual block diagram of an embodiment of the error correction decoder 14, in which a branch circuit 20,
Register 21, syndrome extractor 22, error corrector 2
3 and an error rate detector 24. In FIG. 2, a signal 101 including a digital multiplexed signal and a clock signal is connected to a signal 102 and a signal 1 in a branch circuit 20.
03, and the signal 103 is sent to the syndrome extractor 2.
2, and a predetermined syndrome is extracted from the 3-bit error correction code. Through this syndrome, the presence or absence of an error in the digital multiplexed signal forming the signal 101 is detected, and if an error occurs, its location is also estimated. In general, the syndrome is defined as C, where H is the check matrix and C is the linear code.
−)]. In the syndrome extractor 22, if C-H=O, it is determined that there is no error, and C.11
If it is O, it is determined that there is an error, and if there is an error, the position of the error is also estimated and output. Regarding the working principle of the syndrome extractor 22 via syndromes, please refer to the related materials (2nd Information Theory and Its Applications Study Group materials).

(November 1979), and the explanation will be omitted. Among the signals output from the syndrome extractor 22, the syndrome 104 and the clock signal 105 are input to the slope rate detector 24, which detects and outputs the error rate corresponding to a predetermined time length.

Further, the syndrome extractor 22 outputs a correction pulse signal 107 for the digital multiplexed signal corresponding to the position where an error occurs, and is input to the error corrector 23. Note that the syndrome 104 can also generate an alarm regarding the occurrence of a line error.

On the one hand, a signal 102 including the digital multiplexed signal and a clock signal is branched in the branch circuit 20;
is input to the error corrector 23 via the register 21,
The error code is corrected by the correction pulse signal 107 inputted from the syndrome extractor 22 described above, and a signal 109 containing a normal digital multiplexed signal and a clock signal is generated.
is output as This signal 109 is input to the receiving digital signal processing unit 15 (9-) in FIG. 1, where it is descrambled, separated into three channels of digital signals, and destuffed. , 17 and 18. These code converters 16, 17 and 18 each convert the unipolar signal of each channel into a bipolar signal and output it to the PCM multiplex converter via terminals 54, 55 and 56.

FIG. 3 shows an error correction decoder provided in a reception demodulation system device # of a relay station device when the present invention is applied to monitor the listening quality in a specific relay station device in a digital wireless transmission system. FIG. 2 is a conceptual block diagram of an embodiment of the present invention. In FIG. 3, this error correction decoder includes a syndrome extractor 25 and an error detector 26, and a signal 107 containing a digital multiplexed signal and a clock signal sent from the demodulator is used for syndrome detection. vessel 25
is input, and a predetermined syndrome is extracted as in the case in FIG. 2 described above. Syndrome detector 25
The syndrome 10710- and the clock signal 108 outputted from the error detector 26 are input to the error detector 26 to detect and output the error rate corresponding to a predetermined time length.

Furthermore, the syndrome 107 generates an alarm regarding the occurrence of a line error.

What the error correction decoding ratios shown in FIGS. 2 and 3 have in common is that they both include a syndrome extractor, which extracts syndromes from the digital multiplexed signal.
It is used for line quality monitoring. The detection accuracy of this syndrome-based line error detection method is extremely high, and is significantly improved compared to conventional methods. In the above description, the present invention is applied to a digital wireless transmission system using a multilevel orthogonal amplitude modulation method, but the application of the present invention is limited to the case using the multilevel orthogonal modulation method. rather than something that
Needless to say, the present invention can also be applied to digital wireless transmission systems using other modulation systems.

As explained in detail above, one aspect of the present invention is to detect a line error by extracting a predetermined syndrome corresponding to an error correction code added to a digital multiplexed signal. This has the effect of significantly improving error rate detection accuracy.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the main parts of a digital wireless transmission system to which an embodiment of the present invention is applied, and FIG. 2 is a conceptual block diagram of an embodiment of an error correction post-transmission system provided in a terminal equipment. 3 is a conceptual block diagram of an embodiment of an error correction decoder provided in a relay station device, 41W(a), (
b) and (C) are respectively explanatory diagrams of frame-patterns of digital multiplexed signals. In the figure, 1.2, 3, 16, 17, 18... Code converter, 4... Transmission digital signal processing unit, 5...
. . . error correction encoder, 6 . . . modulator, 7.
...Transmitter, 8゜11 ...Antenna, 9
......Transmission modulation system device, 10...Relay station device, 12...Receiver, 13...Demodulator, 14...Error Correction decoding ratio, 15...
... Reception digital signal processing section, 19 ... Reception demodulation system device, 20.24 ... Branch circuit, 21.
...Register, 22゜25...Syndrome extractor, 23...Error corrector, 24, 26
...Error rate detector. 13-

Claims (1)

[Claims] In a line quality monitoring system applied to monitor line quality in a digital wireless transmission system, a means for detecting errors in the line by referring to a predetermined syndrome (SYNDROMB) is provided in the digital wireless transmission system. A line characterized in that it is provided in a predetermined reception demodulation system device in a terminal device forming the digital wireless transmission system, or a predetermined reception demodulation system device in both the terminal device and a predetermined relay station device forming the digital wireless transmission system. Quality monitoring method.