JPS6326196A - Digital signal relay and exchange system - Google Patents

Abstract

PURPOSE:To prevent the deterioration in quality of a voice signal by compressing processing by allowing an input-side digital multiplexer to give a compression signal of a relay call to an exchange without decoding and allowing an output-side multiplexer to send a signal given from an exchange as a signal already compressed while multiplexing it as it is. CONSTITUTION:Compression switching control sections 32, 35 send a switching signal to corresponding decoding processing section 33 and compression processing section 34 to a notified line number to control them to bypass the decoding and compression processing. The decoding processing section 33 and the compression processing 34 have similar decoding and compression functions to that of conventional circuits, but do not execute decoding/compression reserving the switching signal, transmit/receive the compression signal to/from an exchange 20 in a way that the compression signal received from a relay line is sent to the outgoing relay line as it is with multiplexing by the bypassing of the sections. Since no decoding and re-compression is applied with respect to the relay call, the deterioration the quality of the voice signal based on the compression in the, multi-stage relaying is prevented.

Description

[Detailed Description of the Invention] [Summary] This is a switching system for preventing voice quality deterioration in a switching system that processes voice signals that are compressed, multiplexed, and relayed.

When the switch identifies whether it is a relay call or an incoming or outgoing call and notifies the digital multiplexer, the digital multiplexer on the input side passes the compressed signal of the relay call to the switch without decoding, and the multiplexer on the output side receives the compressed signal from the switch. The passed signals are multiplexed and sent out as compressed signals.

This method eliminates the repetition of compression/decoding for each multi-stage relay, so it is possible to prevent audio signal quality from deteriorating due to compression processing.

[Industrial application field]

The present invention relates to a relay switching system for an exchange that processes calls using voice signals that are compressed and multiplexed by a digital multiplexer and then relayed.

As is well known, digital audio signals normally occupy a signal band of 64 kilobits per second (Kbps), but in order to effectively utilize the transmission capacity of communication lines in their transmission,
A method is used in which the required transmission band of an audio signal is compressed using various methods, and a plurality of such compressed signals are multiplexed and transmitted over a single line.

On the other hand, a digital exchange that processes digital audio signals is configured to decode the compressed signal into an original audio 64 Kbps signal and perform exchange processing.

[Conventional technology]

FIG. 2 is a block diagram showing an example of the configuration of an exchange system.

The exchange 1 has, for example, a 64Kbps large line 2 and an exit line 3.
The switch section 4 can configure the required connections between the lines 2 and 3.

For this purpose, the control unit 5 receives the dial signal of the call occurring on each main line 2, identifies the destination, selects one vacant line of the outgoing line 3 determined by the destination, and connects the call requested by the call. The switch section 4 is controlled to configure the following.

Calls include relay calls that connect relay lines 6 and 7, etc., and calls that originate and receive calls to telephone lines 8, etc. in the area of this exchange 1, and the control unit 5 performs necessary dialing according to their destinations. Control is performed to send the signal to the outgoing line 3.

The relay line 6.7 is the multiplex receiving section 1 of the digital multiplexer.
0, connects to the exchange 1 via the multiplex transmitter 11.

The signal on the trunk line 6.7 is a digital audio signal of 64 Kbps per channel compressed to 16 Kbps, for example.
For example, it is a signal in which 32 channels are multiplexed, and the multiplex receiving unit 10 receives such a multiplexed signal, the multiplex control unit 12 divides it into each channel, and the decoding processing unit 13 converts each compressed signal into 64Kbps. is decoded into a voice signal and output to the main line 2 to the exchange 1.

In the multiplexing transmission section 11, the compression processing section 14 converts the 64 Kbps signal from each exit line 3 of the exchange 1 into a predetermined 16 Kbps compressed signal, the multiplexing control section 15 multiplexes the signal, and transmits the signal to the trunk line 7.

[Problem that the invention seeks to solve]

According to the above-mentioned switching system, when relaying through exchanges is performed in multiple stages, such as at an exchange similar to the exchange 1 at the other end of the trunk line 7, and then relayed to the next exchange, , the decoding and compression of the audio signal is repeated for each relay.

As is well known, in many compression methods, when approximating an audio signal through compression processing, some information of the original audio is omitted, so the audio signal decoded from it is somewhat different from the original audio signal, and such When compression/decoding is repeated,
The difference between the two signals becomes large, resulting in a deterioration of the audio signal quality in this sense.

For this reason, when the number of relays by the exchange increases as described above, there is a problem in that the call quality deteriorates.

[Means for solving problems]

FIG. 1 is a block diagram showing the configuration of the present invention.

The figure shows the configuration of the switching system, where 20 is an exchange, 25 is a control unit of the exchange 20, 30 and 31 are a multiplex receiving unit and a multiplex transmitting unit, respectively, of a digital multiplexer. 33 is a compression switching control section, 33 is a decoding processing section, 35 of the multiplexing and transmitting section 31 is a compression switching control section, and 33 is a compression processing section.

[For production]

The control unit 25 of the exchange 20 performs the same switching processing as in the past, but also refers to the combination of the incoming and outgoing lines of the call to distinguish between relay calls that connect the relay lines and other calls. , to the compression switching control units 32 and 35 in the case of a relay call;
The corresponding incoming line number and outgoing line number, and if necessary, notification that the call is a relay call.

The compression switching control units 32 and 35 send switching signals to the decoding processing unit 33 and compression processing unit 34 corresponding to the notified line number, and control them to bypass the decoding and compression processing, respectively.

The decoding processing section 33 and the compression processing section 34 have the same decoding and compression functions as conventional ones, but upon receiving a switching signal, they send and receive the compressed signal to and from the exchange 20 without executing decoding/compression, and by bypassing the two, A compressed signal received from a trunk line is multiplexed and sent as is to an outgoing trunk line.

According to the above method, since decoding and recompression are not performed on a relay call, deterioration in the quality of the audio signal due to compression during multi-stage relay can be prevented.

〔Example〕

In Figure 1, parts with the same symbols as in Figure 2 are:
It has the same functions as in the conventional exchange system.

The exchange 20 has the same switching function as the conventional exchange 1, and the control section 25 performs the same switching processing as the conventional one, and controls the required connection between the main line 2 and the outgoing line 3 by the switch section 4. .

In addition, in the process of the above-mentioned exchange process, when the control unit 25 identifies the destination using the dial signal from the main line 2, it refers to the combination of the incoming and outgoing lines that make up the connection and converts the compressed multiplexed signal. The relay calls that connect the relay lines 6 and 7 that transmit the information, and the incoming and outgoing calls that connect the other relay lines 6 and 7 and the telephone line 8, etc. are identified.

As a result, if the call to be processed is a relay call, the compression switching control unit 32 of the multiplexing receiving unit 30 connected to the main line 2 of the call, and the multiplexing control unit 32 connected to the outgoing line 3 connecting the call, The compression switching control unit 35 of the transmitting unit 31 is notified of the incoming line number and outgoing line number, respectively.

The compression switching control units 32 and 35 send switching signals to the decoding processing unit 33 and compression processing unit 34 corresponding to the notified line number, and control the processing to be switched until the call ends.

The decoding processing section 33 uses its decoding section 36 to receive and receive one signal from the multiplexing control section 12, similarly to the conventional decoding processing section 13.
It has the function of decoding the compressed signal of the channel and transmitting it to the main line 2 of the exchange.

However, upon receiving the switching signal from the compression switching control section 32,
Processing is switched from the decoding unit 36 to the bypass unit 37.

The bypass unit 37 configures the one-channel compressed signal received and received from the multiplexing control unit 12 into a 64 Kbps signal in a predetermined format by adding control bits, etc., if necessary, to the main line 2. Send.

The compression processing section 34 of the multiplexing transmission section 31 on the output side receives this signal via the switch section 4 and the output line 3, and processes it as follows.

The compression processing section 34 uses its compression section 38 to extract the received signal from the outgoing line 3 of the exchange, similar to the conventional compression processing section 14.
It has a function of compressing the audio signal of the channel and outputting it to the multiplexing control section 15.

However, upon receiving the switching signal from the compression switching control section 35,
Processing is switched from the compression section 38 to the bypass section 39.

When the bypass section 39 receives the compressed signal transferred as a 64 Kbps signal from the incoming bypass section 37 as described above, it extracts the audio compressed signal part from the signal and outputs it from the compression section 38. The compressed signal is passed to the multiplexing control unit 15 in the same way as in the case.

The recovery control of each decoding processing unit 33 and compression processing unit 34 from the state in which they have switched to the bypass processing to the state in which decoding/compression is executed is performed, for example, when the control unit 25 of the exchange detects the end of a call and restarts the state. This is done by notifying the compression switching control section 32,35.

With the above method, decoding and recompression are not performed on relay calls, and the compressed signal is passed through as is, thereby preventing deterioration in voice signal quality due to multiple compression/decoding during multi-stage relay. can do.

Decoding processing unit 33 and compression processing unit 34 that do not receive the switching signal
Since the decoding/compression process is executed in the same manner as in the conventional case, under the control of the control unit 25, the switching process is performed in the same manner as in the conventional case for calls other than relay calls.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, deterioration in signal quality due to multi-stage relay is prevented in a digital switching system having a switch that accommodates a relay line that transmits a compressed multiplexed signal of an audio signal. This has a significant industrial effect, especially in improving the call quality of wide-area switching systems.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, and FIG. 2 is a block diagram of an example of a conventional configuration. In the diagram, 1.20 is the exchange, 2 is the incoming line, 3 is the outgoing line,
4 is a switch section, 5.25 is a control section,
6.7 is a trunk line, 8 is a telephone line, 10.
30 is a multiplex receiver, 11.31 is a multiplex transmitter, 12
．． 15 is a multiplexing control unit, 13.33 is a decoding processing unit, 1
4.34 is a compression processing unit, 32.35 is a compression switching control unit, 36 is a decoding unit, 37.39 is a bypass unit, 3
8 is a block diagram showing the configuration of the compression section of the present invention. FIG. 1 is a block diagram showing an example of a conventional configuration. FIG.

Claims (1)

[Claims] A digital audio signal is converted into a predetermined compressed signal, a plurality of the compressed signals are multiplexed and transmitted to a relay line, and the multiplexed compressed signal input from the relay line is decoded into a digital audio signal. a digital multiplexing device (30, 31) having functions, and a switching device connected to the digital multiplexing device and performing switching processing for relay calls between the trunk lines and incoming and outgoing calls between the trunk lines and the voice line. (20), the exchange (20) has means for identifying the exchange destination of the call and notifying the digital multiplexer (30, 31) whether the call is a relay call or not. However, if the call is a relay call, the digital multiplexing device includes switching means (32, 33, 34, 35, 37, 39) that relays the signal of the call without decoding or compressing it. ) A digital signal relay exchange system characterized by having: