JP3144463B2 - ATM transfer error correction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM transfer error correction device which is installed in an arbitrary 4-wire section of a communication system and automatically and efficiently corrects an ATM transfer error.

[0002]

2. Description of the Related Art Information from various sources can be transmitted at high speed, flexibly,
In a multimedia communication system for efficient and efficient transmission, an asynchronous transfer mode (ATM) is used in addition to a conventional synchronous transfer mode (STM). In this ATM, an information transfer error (ATM transfer error) occurs. Conventionally, as a means for correcting the missing voice due to the ATM transfer error, a method of performing pattern matching by autocorrelation on multi-valued information by A / D conversion and determining and correcting a reproduction position has been proposed (IEEE Trans. -
actions on Acoustics, Speech, and Signal Processin
g, Vol. ASSP-34, No. 6, 1986, pp. 1440-1448).

FIG. 2 shows a configuration example of a conventional ATM transfer error correction device. In the figure, the received signal storage means 5
The received signals r are input and sequentially stored until a predetermined number m is reached. When the number of stored received signals becomes m, the oldest one is overwritten sequentially so that the latest m received signals are always stored.

The multi-value pattern matching means 7 is an ATM
Activated by the input of the transfer error detection signal d, the storage position pe of the immediately preceding reception signal r is changed to the reception signal reading position a2
And sequentially reads out a predetermined number pm of the latest received signals. Next, read pm
The autocorrelation ac is calculated using a predetermined number pt of the latest received signals among the received signals rr as templates. Further, a position ps at which the autocorrelation ac is maximized is calculated, and the ps and pe are transmitted to the reproducing means 6 as a reproduction position pi. The multi-value pattern matching means 7
Operates once each time it is activated, and does not operate otherwise.

The reproducing means 6 is activated by the input of the ATM transfer error detection signal d, and when the reproducing position pi is inputted from the multi-value pattern matching means 7, the position pe to the position pe is set as the received signal reading position a2. The received signals stored in the received signal storage means 5 are sequentially read. Next, the read reception signal rr is output as a reproduction signal rp instead of the original reception signal r. At this time, the reading of the received signal from the position ps to the position pe is performed cyclically while the reproducing unit 6 is activated. When not activated, the reproducing means 6 outputs the received signal r as it is as the reproduced signal rp.

As described above, the conventional ATM transfer error correction apparatus performs pattern matching using the autocorrelation of the original received signal while maintaining the multi-value, and determines the reproduction position to determine the reproduction position.
The configuration is such that a TM transfer error is corrected. The calculation of the autocorrelation at this time had to be performed within one cycle of the received signal.

[0007]

By the way, in a digital signal processor (DSP) having a normal calculation capability,
It takes a long time to calculate an autocorrelation requiring a huge amount of calculation, and it is difficult to complete the calculation within one cycle of a received signal. On the other hand, if an attempt is made to reduce the calculation amount of the autocorrelation, the pattern matching itself becomes more complicated, so that the total calculation amount is not necessarily reduced. Therefore, the conventional ATM transfer error correction device requires an expensive DSP having a large calculation capability, and it has been difficult to construct the device economically.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ATM transfer error correction device which enables pattern matching with a small amount of calculation and can be economically configured using a normal DSP.

[0009]

A problem of the conventional ATM transfer error correction apparatus is that pattern matching is performed on the original received signal by using autocorrelation with multi-values. Accordingly, the ATM transfer error correction apparatus of the present invention simplifies a multi-valued received signal into three values, further patterns the three-valued received signal, reduces the amount of data to be processed, and executes with a small amount of calculation. Perform a possible proportional pattern matching to determine the playback position. As a result, there is no need to handle a complicated multi-valued received signal as it is, and there is no need to perform multi-value pattern matching by autocorrelation that requires a huge amount of calculation. The reproducing means reads out the received signal stored in the received signal storing means in accordance with the reproducing position obtained by the ternary pattern matching means, and transmits this received signal instead of the received signal having an ATM transfer error.

[0010]

FIG. 1 shows an embodiment of an ATM transfer error correction device according to the present invention. In the figure, a received signal storage unit 5 and a reproducing unit 6 are the same as those of the conventional configuration. The apparatus of the present invention further includes a ternary threshold value determining unit 1, a ternary patterning unit 2, and a ternary pattern storage unit 3, and a ternary pattern matching unit 4 is provided instead of the conventional multi-value pattern matching unit 7. It is characterized by having.

The ternarization threshold value determining means 1 receives the received signal r and obtains a section maximum value m1 and a section minimum value m2 in a predetermined section dm. The section maximum value m1 and the section minimum value m2 are multiplied by predetermined ratios r1 and r2, respectively, to obtain a positive threshold tp (= m1 × r1) and a negative threshold tm.
(= M2 × r2), and sends them to the ternary patterning means 2 as a ternary threshold value t.

The ternary patterning means 2 uses the input ternary threshold value t (tp, tm) to convert the input received signal r according to the condition r> tp, tp ≧ r ≧ tm, tm> r. Are ternarized to predetermined values a, b, and c, respectively. Next, for each of the ternary values v3, the continuous time vt or the number vn thereof is obtained, and (v3, vt) or (v
3, vn) to form a pair as a ternary pattern p
It is sent to the value pattern storage means 3.

For example, in the case where a time in which ternarized values are continuous is used, when a ternary value a continues for a time ta, a pair (a, ta) is defined as a ternary pattern p. It is sent to the value pattern storage means 3. When the number of successive ternary values is used, the ternary value a
Are transmitted to the ternary pattern storage means 3 as a ternary pattern p when (n, n) are consecutive.

The ternary pattern storage means 3 receives ternary patterns p and stores them sequentially until a predetermined number n is reached. When the number of stored ternary patterns becomes n,
The oldest one is sequentially overwritten so that the latest n ternary patterns are always stored. The ternary pattern matching means 4 is activated by the ATM transfer error detection signal d, and stores the storage position p3e of the immediately preceding ternary pattern p.
Is sent to the ternary pattern storage means 3 as the ternary pattern reading position a1, and a predetermined number p3m of the latest ternary patterns are sequentially read. Then, among the p3m number of ternary patterns rp3 read, a predetermined p3t number of latest ternary pattern _{(v3 1, vt 1),} (v3 2, vt 2), (v3 3, vt
₃ ),..., ( _{V3 p3t} , vt _p3t ), these are used as templates to perform _opaque proportional pattern matching. Specifically, when a predetermined ratio is set as v _min and v _max as an index of ambiguity, all i (=
, P3t), v3 _{j + i} = v3 _i
In addition, a minimum positive integer j that satisfies vt _i × v _min ≦ vt _{j + i} ≦ vt _i × v _max is obtained, and j is set to p3s. P3s obtained in this way and the previous storage location p3
e, the storage positions ps and p in the received signal storage unit 5 are determined using the relationship between the storage position and the corresponding time.
e respectively. Further, the reproduction start position ps1 of the first cycle is obtained from the time corresponding to the storage position p3e of the immediately preceding ternary pattern and the current time. These ps1, ps and pe are sent to the reproducing means 6 as the reproducing position pi. The ternary pattern matching means 4 operates once each time it is activated, and does not operate otherwise.

When the reproducing means 6 is activated by the input of the ATM transfer error detection signal d, the reproducing position pi (= ps1, p) inputted from the ternary pattern matching means 4
s, pe), the first cycle is from position ps1 to position p
The received signal stored in the received signal storage means 5 is sequentially read out with e as a received signal read position a2. From the second cycle onward, the received signals stored in the received signal storage unit 5 are sequentially read, with the position ps to the position pe being the received signal read position a2. Next, the read reception signal rr
Is output as a reproduced signal rp in place of the original received signal r. At this time, the reading of the received signal is performed cyclically while the reproducing means 6 is activated. Note that the reproduction means 6
Outputs the received signal r as it is as the reproduction signal rp when it is not activated.

As described above, the ATM transfer error correction device of the present invention can apply proportional pattern matching that can be executed with a small amount of calculation by simplifying a multilevel received signal into three values. Furthermore, a pattern is formed by pairing the ternary value and the time (or the number) in which the value is continuous,
Pattern matching is performed after reducing the amount of data to be processed. As a result, not only the success rate of the pattern matching can be increased, but also the processing can be completed within one cycle of the received signal using a DSP having a normal calculation capability.

In the embodiment described above, 3
The same applies to the case where noise reduction processing is inserted before or after ternarization in the value patterning means 2. The same applies to the case where an interpolation process such as an upsampling process or an nth-order interpolation process is performed between sampling points in the process of the reproduction process. The same applies to a configuration in which the equality is included in the magnitude determination with the threshold.

[0018]

As described above, the present invention can reduce the amount of data to be processed and apply proportional pattern matching that can be executed with a small amount of calculation. The processing can be completed within one cycle of the received signal using a DSP having the calculation capability of Thus, an economical ATM transfer error correction device can be configured, and high-quality voice transmission can be economically performed by ATM.

In addition, STM which has been widely used
A transfer error (ATM transfer error) occurring in an ATM section in an arbitrary 4-wire portion of the section or in a conventional STM communication device can be automatically corrected. Therefore, analog terminal devices that have been widely used,
High quality voice transmission via ATM can be realized using these terminal devices without making any changes to the STM terminal devices.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an ATM transfer error correction device according to the present invention.

FIG. 2 is a block diagram showing a configuration example of a conventional ATM transfer error correction device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 ternary thresholding means 2 ternary patterning means 3 ternary pattern storing means 4 ternary pattern matching means 5 received signal storing means 6 reproducing means 7 multi-value pattern matching means

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-4062 (JP, A) JP-A-5-268685 (JP, A) Mitsuhiro Yuito, Naoki Matsuo, "A new sample-interpolation method for rec overings missing speech samples in packet voice communications ", International online Conferencing on Acoustics, Speech, and Signal Processing, 1989. , ICASPSP-89, vol. 1, pp. 381-384, 23 May 1989 (58) Fields investigated (Int. Cl. ⁷ , DB name) H04L 12/28 H04L 12/56 H04L 1/00 H04Q 11/04

Claims (1)

(57) [Claims] 1. A reception signal storage means for storing a reception signal, and a reception signal activated by an input of an ATM transfer error detection signal and read from the reception signal storage means in accordance with a designated reproduction position, and read out. An ATM transfer error correction device comprising: a reproducing unit for transmitting a signal in place of a received signal having an ATM transfer error. A ternary conversion for inputting a received signal and determining a threshold for ternaryizing the received signal. Threshold value determining means, ternary patterning means for inputting a ternary threshold from the received signal and the ternary threshold value determining means, and patterning the received signal into ternary values; and receiving signals from the ternary patterning means. A ternary pattern storage means for inputting and sequentially storing the ternary patterns of the following, and activated by the input of the ATM transfer error detection signal, and ATM transfer characterized by comprising a ternary pattern matching means for reading a value pattern, performing a proportional pattern matching on the ternary pattern, determining a reproducing position, and sending the reproducing position to the reproducing means. Error correction device.