JPS59176940A - System for monitoring radio line - Google Patents

Abstract

PURPOSE:To attain the control of a radio line with high accuracy by estimating the quality of transmission based on the result of measurement of a High probability in a syndrome series in plural past time sections to perform stably the decision of deterioration with high accuracy. CONSTITUTION:The High probability of a time corresponding to past N-clock in the syndrome series at a terminal 21 is measured by a time rate measuring circuit 24, a data 25 is outputted and compared with a data 27 corresponding to a prescribed value at a digital comparator 26. Its output 28 is delayed by a prescribed time at a shift register 29 and outputted from an intermediate tap of the register 29, and these comparison data 30 are used to estimate the quality of sound transmission in a logical circuit 31 and its result is outputted to a terminal 32. On the other hand, a voltage R corresponding to a median of a receiving wave level at the terminal 16 of a demodulator is compared with a voltage Rr33 corresponding to the prescribed value by an analog comparator 34, and when the median R is high, a High level appears at an output 35. When an output at a terminal 32 and the output 35 reach a High level, an AND circuit 36 detects it, which is discriminated as the generation of the identical channel interference, thereby outputting the High level to a terminal 37.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radio line monitoring system for monitoring the transmission quality of a communication channel during a call in mobile communication.

<Prior art> Conventionally, in mobile communications, a method for monitoring the transmission quality of voice signals after a communication channel is set is to detect the median value of the received field strength (hereinafter referred to as received wave level) of the communication channel. method has been adopted. This voltage proportional to the received wave level is obtained by detecting the received radio waves with an envelope detector, but the accuracy becomes extremely poor at low received wave levels where voice transmission quality deteriorates, so monitoring of wireless lines is required. The drawback was that it could not be controlled with high precision.

From this point of view, Japanese Patent Application No. 57-217024 ``Radio Channel Monitoring Control System'' transmits a digital signal encoded with error correction code superimposed outside the voice band, and then detects the error signal from the received digital signal. We proposed a method for estimating audio signal quality by continuously measuring the "High" probability of syndrome sequences used for detection and correction. This method cannot keep up with rapid fluctuations in the received wave level; for example, even if the received wave level recovers in response to a short-term temporary drop in the electric field (such as when a mobile station passes through a tunnel), First, it has the disadvantage that it continues to judge quality deterioration.

In the conventional method of monitoring audio transmission quality based on the received wave level, when co-channel interference occurs in IjA, the received wave level is detected as being equal to or higher than a predetermined value. Unfortunately, this method had the disadvantage that deterioration in audio transmission quality due to co-channel interference could not be detected.

Ma/ζ, in the specification of 4-11' Application No. 57-217024, the continuous 11111 constant of the "High" i rate of the syndrome sequence generated from the received error correction encoded digital signal and the received wave level A method has been proposed in which the occurrence of co-channel interference is detected when the syndrome "'High" hj rate is high even though the received wave level is above a predetermined value. This method cannot keep up with sudden fluctuations in the desired wave power to interference wave power ratio (hereinafter referred to as Despite the recovery of the I)/U ratio, the problem was that deterioration in quality continued to be detected (such as when carrying a mobile radio on the top).

<Summary of the Invention> In order to eliminate these drawbacks, the present invention measures the probability of "nigh" of the syndrome sequence on the received digital signal of the error correction code in a plurality of past time intervals, and calculates the result. It is designed to estimate the transmission quality of a band signal such as a voice signal as it is transmitted based on this, and its purpose is to perform highly accurate wireless line monitoring without being affected by temporary deterioration.

<Embodiment> Overall configuration FIG. 1 shows an embodiment of the present invention. For example, when an audio signal is transmitted as a band signal, errors and correction codes are detected in the lower band (0-0.3kHz) of the audio signal. turned Te1
FIG. 2 is a configuration diagram of a system that superimposes digital signals and monitors syndrome sequences generated during error detection and correction of received digital signals.

On the transmitting side A, the audio signal (2) applied to the audio input terminal 1 is filtered by a bandpass filter 2 to extract a 0.3 to 3 kt (z component) and input to the instantaneous amplitude limiter 3. is the preset maximum yen V number: 1in
The modulator's manual force corresponding to the shift clips the pressure waveform of 111 or more, and the harmonic components caused by its non-7131+ type operation are removed by the splatter filter 4.

The output of the filter 4 is superimposed on a digital signal, which will be described later, by an analog adder 5. On the receiving side B, on the receiving side B, the radio waves received by the receiving antenna 12 are sent to the demodulator 1.
3, the audio signal component V is extracted by the bandpass filter 14, and is output to the audio output terminal 15.

A digital signal is transmitted in the following manner superimposed on the transmission of such an audio signal (13) That is, the data signal applied to the take input terminal 6 at the transmitting side A is corrected by an error correction encoder 7. The signal is encoded into a signal J format digital signal suitable for a modulation/demodulation system by a code converter 8. This digital signal is passed through a low-pass filter 9
supplied to The low-pass filter 9 receives the digital signal (
7) The spectrum is in the audio band (0,3~3.k H
The digital signal, which is band-limited by the low-pass filter 9, is superimposed on the audio signal by the analog adder 5. Modulator 1
0 generates an angle modulated wave corresponding to the input voltage and sends out a transmission radio wave via the transmission antenna 11.

On the receiving side B, a demodulator 13 demodulates the transmitted voltage waveform, and a low-pass filter 17 extracts digital signal components. The digital signal is supplied to a code decoder 18 and a clock recovery circuit 22. The clock regeneration circuit 22 regenerates a clock synchronized with the digital signal, and the digital signal is decoded by the code decoder 18 into an error correction encoded digital signal synchronized with the reproduced clock. , is returned to the original data signal by the error correction code decoder 19 and outputted to the data output terminal 2o, and at the same time, the syndrome sequence Si generated in the decoding process is outputted to the syndrome sequence output terminal 21. .

As the error correcting jE code used in this invention, the :/ syndrome sequence is sequentially generated, and the syndrome sequence "l
(i gh ``Convolutional code'' is suitable because it allows easy correspondence between the temporal change in the probability and the temporal change in the received wave level, intermediate value, and D/U ratio.

u[-11g h lI41'ili rate 6111 constant system Figure 2 shows the syndrome °' in a certain time interval in the past.
The configuration of a system that continuously measures the f(igh'' probability is shown below, and this example is a case where a convolutional code is used.

Since "f(high") appears in the syndrome series when an operation is performed to correct errors in the error correction code decoding process, the higher the median received wave level or the D/U ratio is, the higher the probability is The measurement of the "l(high" probability) of the syndrome series is equivalent to the measurement of the time rate in the past N clock equivalent time.Here, the time rate is the reception level less than or equal to the predetermined level for the predetermined time TO. Ratio Tx/T of time Tx.

It is. A special application was made in 1973 to measure the probability of
4-122937 can be used.

The syndrome series Sl appearing at the syndrome series output terminal 21 is determined by the time rate measuring circuit 24 to calculate the time rate of the °'High'' state (==
II High ghTl probability) is measured, and time rate measurement data (@1) 2s is output as digital data. The time rate measurement data 25 is converted to a predetermined value Xir of the probability of the syndrome
If the measured value/i is higher than the predetermined value Xir, the output 28 of the comparator 26 is
The comparator output 28 is delayed by a predetermined time by the shift register 29, and the comparison result between the "= High++" probability measurement value and the predetermined value in the past time interval is the intermediate value of the shift register 29. Output from the tap.

The comparison result data 30 is used in the logic circuit 31 to estimate the audio transmission quality, and the estimation result is output to the output terminal 32. Note that the reproduced clock from the terminal 23 is given to the time rate measuring circuit 24 and the shift register 29, and is used as a unit of time. On the other hand, the demodulator 13 in FIG.
The received wave level intermediate value appears at the output terminal -r-16.
3 and is compared by the analog comparator 34, and when the median level R of the 18 received waves is higher than the predetermined value Rr, an "H4gh" level appears at the output 35 of the comparator 34. The predetermined value Rr of the median received wave level is set to a level at which the probability that the 7-and-drome sequence S i K "High" will appear in the Trubel is lowered by the rule of -11. 3. The output of the output terminal 32 and the comparison output 35 and both “'r
(When it reaches "high" level, the AND circuit 36 detects this and determines that same channel interference has occurred, and the output terminal 37
Outputs "l (high" level) to

77 drome series in past multiple time intervals -+ 1
By using the measurement data of the 17gh r' probability, it is possible to stably determine the deterioration of the voice transmission quality even when there is a sudden change in the median received wave level or the D/U ratio. That is, as shown in FIG. 3A, the median received wave level (or D/U ratio) R suddenly decreases at time t1, and accordingly, the syndrome series "f(high" probability/j) decreases as shown in FIG. 3B. Assume that the syndrome suddenly becomes high at the delayed time t2 as shown in .Since the measurement of the syndrome series "High" 6M rate is carried out over a period of time equivalent to the past N clocks, the received wave level reaches the minimum at the time t1. Assume that the probability of the syndrome series "'I(i gh"') reaches its maximum later on, and at this point the median received wave level R has become considerably large.In this case, the current time t3
If the voice transmission quality is estimated only from the measurement data/i at the immediately preceding measurement time τ1 (time interval = time length equivalent to N clocks), then the median received wave level (or D
/U ratio) Even though R has recovered, the measured value gi is higher than the predetermined value /1r, so the output 28 of the comparator 26
becomes ttHigh level as shown in Figure 3C,
The audio transmission quality deteriorates and it is determined that this is not the case. However, in this embodiment, the comparison result between the measurement data, g'i, and the predetermined value/lr at the past measurement time τ2 (time length equivalent to N clocks), which is separated by a time length equivalent to several clocks, and the current measurement data and the predetermined value. AND with the comparison result of , and detects the condition that the predetermined value K i r j is higher for both of these measurement times τl and 20, and the measured value 1 is higher, and from the logic circuit 31) J i g Output h level: By doing so, you can avoid erroneous judgments. Sweet,
As in the example in Figure 3, even if the received wave level (median value) falls temporarily and the measured value x 1 rises temporarily,
Since the measured value/1 at constant time τ2 is small, the output of the logic circuit 31 is at a low level, and the output from the terminal 32.3 is low.
11i g h level is not output from any of the 7. , sudden spikes in the median received level (or D/U)
In this example, the logic circuit 31 in FIG. 21 is composed of one AND circuit, and k=2.

Unfortunately, the comparison result at measurement time τ2 is obtained from the intermediate tap or output tap of the shift register 29. The interval between the measurement times τ1 and τ2 is preferably selected so that the correlation between rapid level fluctuations in the median received wave level R is small. In this invention, the measured values, S'i, are obtained in a relatively short time, and the transmission quality is determined from these plural measured values. By using a convolutional code in which information bits and check bits are arranged alternately as an error correction code, syndromes can be detected successively, and the transmission quality can be determined more quickly. As explained above, in the present invention, even at low received wave levels where the median received wave level is extremely degraded, and even with rapid fluctuations in the median level, the transmission quality of the signal in the band to be transmitted does not deteriorate. Judgments can be made stably and accurately 1. Similarly, even when the D/U ratio fluctuates rapidly, it is possible to stably and accurately judge the deterioration of the transmission quality of band signals as they are transmitted, such as audio signals. .

As described above, according to the present invention, it is possible to accurately and stably determine the deterioration of voice transmission quality, and highly accurate radio line control is possible.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing an example of a Hi g'''11'' probability measurement system,
FIG. 3 is a waveform diagram for detailed explanation of this invention.
, 1: t: 2f' human power drying 1 child, 2: band pass filter,; 3: 1 IRJ amplitude? 11ll limiter, 4 varnish black filters, 5: analog q amplifier, 6: data signal input terminal, 7: error agent iE encoder, 8: code converter,
9: Low pass filter, 10: FM modulator, 11: Transmitting antenna, 12: Receiving antenna, 13: FM f
atMMligL 14: Hand pass fill,
15: h voice output terminal, 16: Received wave level center 1 direct output terminal, 17 two low-pass filters, 18: Koma code decoder, 1
9: Error correction code decoding device, 20: Data signal output terminal, 21: Syndrome series output width; child, 22: Clock regeneration circuit, 23: Fi) Raw clock output terminal, 24
: Time rate measurement circuit for time equivalent to past N clocks, 2
5: Time rate Bl) constant data, 26: Digital comparator 2
7: Predetermined fil-1 of syndrome “l(igh” probability)
data corresponding to, 28: comparator output, 29: nf)・
Register, 30: Comparison result data with a predetermined value of the syndrome ", l(high"' probability) in the specified time interval, 31: Logic circuit, 32: Judgment 1L block j terminal, 33: Corresponding to a predetermined value of received wave level Voltage, 34: Analog comparator,
35: Comparison output, 36: AND circuit, 37: Judgment output terminal. Patent applicant: Nippon Telegraph and Telephone Public Corporation Representative Takuo Kusano 1 Sekio 2 Seki 3

Claims (1)

[Claims] (1) In a mobile radio system that transmits a band signal with a limited frequency band, an error correction coded digital signal is superimposed and transmitted outside the band signal, and the receiving side decodes the digital signal. Then, the "High" probability in multiple past time intervals of the syndrome series generated from the error correction is continuously measured, and the "High" probability in these multiple time intervals is calculated.
A wireless line monitoring method that estimates the signal transmission quality of the above-mentioned band signals based on the measurement results of probabilities.