JP2000078164A - Time division exchange - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a time division exchange that has an inter-ATM-station trunk by which a useless load in an ATM network is relieved. SOLUTION: The time division exchange 1 is provided with an inter-ATM- station trunk 10, a central processing unit 11 and a time division switch 12. The inter-ATM-station trunk 10 is provided with N sets of channel extract/ insertion circuits 101, N sets of communication information cell assembling/ disassembling circuits 102, a common line signal ATM cell assembling/ disassembling circuit 103, and an ATM cell multiplexer/demultiplexer circuit 104.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time-division exchange, and more particularly to a time-division exchange having a built-in ATM cell-forming function for connecting stations via an ATM (Asynchronous Transfer Mode) network.

[0002]

2. Description of the Related Art ATM technology has been developed as a new transmission / exchange technology to cope with large-scale transmission and exchange of images, LAN (local area network) data, etc. requiring high-speed wideband. However, for the time being, coexistence with the existing circuit switching network is required. For example, PBX (Private Branch Excha
nge = Private branch exchange)
A case where a TM network intervenes is conceivable. At this time,
It is effective to convert the digital trunk line including the 1.5 Mbps to 2 Mbps inter-station common channel signal channel into ATM cells in a lump to prevent the voice quality from being deteriorated due to the cell delay, and the ATM "line simulation service".
As common.

[0003] Here, when the communication traffic is low, there is a problem that the band of the vacant channel unduly occupies the band in the ATM network and becomes an unnecessary load on the ATM exchange. Conventional means for solving this problem is disclosed in JP-A-6-97.
No. 957, and shown in FIG.

This prior art relates to an ATM cell system, and includes a high-speed communication system 400, a multiplex communication channel 200 for multiplexing a plurality of communication channels for transmitting information, and a multiplex communication channel 200 accommodated in an AT network. Exchanges 300a, 3
00b. The exchange 300a includes a communication channel notification unit 301 and a cell assembling unit 302.
b or cell disassembly means 303 and used communication path notification means 30
4 is included.

[0005] The used communication path communication means 301 monitors the use state of each communication path in the multiplex communication path 200 and notifies the communication path being used. Further, the cell assembling means 302 converts only the information transmitted through the communication path notified of use from the used communication path notifying means 301 among the information transmitted through the multiplex communication path 200 to the ATM cell. And high-speed communication system 4
Send to 00.

On the other hand, the cell disassembling means 30 of the exchange 300b
Reference numeral 3 decomposes the ATM cell received from the high-speed communication system 400 to extract information, and transmits the information to the communication path notified from the used communication path notifying unit 304 that it is in use. The used communication path notifying means 304 is the same as the corresponding means 301 of the exchange 300a, and monitors a call control signal for controlling setting and release of a call for transmitting information via each communication path.
Identify the channel in use.

Therefore, the exchanges 300a, 300b
Converts only significant information arriving from an in-use communication path from information arriving from a multiplex communication path into an ATM cell, and transfers the ATM cell via the high-speed communication system 400. As a result, the cell multiplexing efficiency of the high-speed communication system is greatly improved.

[0008]

The prior art described above is
Despite having the above-mentioned effects, there are the following drawbacks or problems.

First, the first problem is that, of the information transmitted via the multiplex communication path, the information is transmitted via a communication path (hereinafter referred to as a B channel for convenience) notified from the used communication path notification means. That is, only the information to be transmitted is converted into an ATM cell. The reason is that when a plurality of B channels are collectively converted into ATM cells, a call occurs,
This is because the number of B-channels that can be dynamically converted into ATM cells at the time of disappearance cannot be changed. For this reason, once the conversion of a plurality of B-channels into ATM cells starts, the A-cells until all the B-channel calls disappear.
The conversion to TM cells must be continued. Thus, the first determined band is continuously occupied by the ATM network.

Further, the probability that a plurality of calls by a plurality of B channels occur simultaneously is extremely low.
There are few cases where channels are converted into ATM cells at once.
Practically, each B channel is converted into an ATM cell. In this case, a dynamically optimized band can be occupied in the ATM network in accordance with the occurrence and disappearance of a call. On the other hand, if the number of B channels to be converted into ATM cells is small, the delay in converting the cells into ATM cells increases, which causes a problem of deteriorating communication quality.

A second problem is that no cell assembling means for distinguishing between the B channel and the call control signal path (hereinafter referred to as D channel) is prepared. The reason is that the B channel of the multiplex communication channel is traffic occupying a fixed band, while the D channel is variable band traffic subject to the limitation of the maximum band, and is information having different characteristics. For this reason, if the D channel is converted into an ATM cell in the same manner as the B channel, meaningless information is converted into an ATM cell even when communication is not actually performed, and an unnecessary band is always occupied in the ATM network. Will be done.

Accordingly, an object of the present invention is to prevent a band of a common channel signal when not being used for communication from occupying a band in an ATM network unnecessarily and becoming an unnecessary load on an ATM switch. It is an object of the present invention to provide a time-division exchange which prevents deterioration of speech quality by optimizing an ATM cell delay while dynamically minimizing the conversion of meaningless information of a communication signal into ATM cells.

[0013]

Means for Solving the Problems In order to solve the above-mentioned problems, the time division switch according to the present invention employs the following characteristic configuration.

(1) In a time division switch including an ATM inter-office trunk and a time division switch, which can be connected to each other via an ATM network, n times out of a plurality of time slots of a communication multiplex path from the time division switch. N channel extraction / insertion circuits for sequentially extracting / inserting the time slot information of N, and N pieces of communication information A for converting the n pieces of information extracted / inserted by the channel extraction / insertion circuit into ATM cells / de-cells.
A common line signal ATM cellizing / decellulating circuit for converting a common line signal for performing communication of call control information with a time division exchange of the opposite side to an ATM cell / decelling by a TM celling / decelling circuit and a central processing unit. Multiplexing the ATM cells into ATM cells by the communication information ATM celling / decellifying circuit and the common line signal ATM celling / decellifying circuit;
An ATM cell multiplexing / demultiplexing circuit for separating the cell-multiplexed ATM cells.

(2) The time division exchange according to (1), wherein the communication information ATM cell / decell circuit converts the communication information into ATM cell / decell as fixed storage information.

(3) The time-division exchange according to the above (1) or (2), wherein the common line signal ATM cell / de-celling circuit converts the common line signal information into an ATM cell / de-cell as variable band information. .

(4) The communication information ATM cell / decell circuit does not perform the ATM cell / decell operation when all of the n pieces of communication information are not significant.
Or the time-division exchange according to (3).

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a time division exchange of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the configuration of a preferred embodiment of the time division exchange of the present invention. The time division switch 1 of the present invention is connected between a subscriber line 4 and an ATM line 3. The ATM line 3 is further connected to the ATM network 2.

The time-division (electronic) exchange 1 includes a trunk 10 between ATM stations, a central processing unit (CPU) 11, a time-division switch 12, and a subscriber circuit 13 connected to the subscriber line 4.
Contains. The time division switch 12 and the inter-ATM trunk 10 are connected by a communication multiplex path 14. Further, the central processing unit 11 and the trunk 10 between the ATM stations
And the time division switch 12 are connected by a control path 15.

Next, the ATM inter-office trunk 10 comprises N channel extraction / insertion circuits 101 and N communication information ATs.
M cell / decell circuit 102, common line signal ATM cell / decell circuit 103, ATM cell demultiplexing, AT
M line interface 104 is included. This ATM
The cell demultiplexing / ATM line interface 104
It is connected to the ATM network 2 via the TM line 3.

The operation of the time division exchange 1 shown in FIG. 1 will be described.
When a call is received from a subscriber accommodated in the subscriber circuit 13 to the game, the central processing unit 11 selects the ATM inter-office trunk 10 for the game as this route. Then, the central processing unit 11 performs call control via a common line between the station and the opposite station. This information is transmitted as a common line signal to the common line signal ATM cell / decellularization circuit 103 in the trunk 10 between ATM stations via the control bus 15. Here, the common line signal information is an ATM for a variable band.
Cell, and further, ATM cell demultiplexing, AT
The data is transmitted to the ATM line 3 and the ATM network 2 via the M line interface circuit 104.

The ATM cell is transmitted to the ATM line of the opposite station via the ATM network 2, and reaches the ATM line demultiplexer and ATM line interface circuit of the opposite station. Here, the signal is separated as a common line signal ATM cell and reaches the common line signal ATM cell / decellularization circuit 103. In the common line signal ATM cell / decellation circuit, the ATM cell is decellularized and returned to common line signal information, and the control bus 1
5 to the central processing unit of the opposite station.

As a result of the call processing control by the inter-office common line signal, when this setting becomes possible, the central processing unit 11 sends the relevant channel of the subscriber's circuit 13 and the ATM inter-office trunk 1
0 corresponding channels are connected by the time division switch 12. In this case, the central processing unit 11 communicates with the communication
4. Select the unused time slot with the lowest number of 4,
It is controlled to use it as a channel for the TM inter-station trunk 10. As a result, the communication channel of the phase call is
The youngest side of the time slot of the communication multiplex path 14 is always used preferentially.

A plurality of time slots of the communication multiplex path 14 are sequentially divided into N sections, starting from the smallest number, and are associated with N channel extraction / insertion circuits 101. Therefore, it is assumed that a call is generated for the first time when there is no inter-station continuous call via the ATM line 3. The first time slot of the communication multiplex path 14 is a communication channel, and the corresponding first channel extraction / insertion circuit 101 extracts communication information. The first chance extracting / inserting circuit 101 extracts information from the remaining (n-1) time slots that are not used, in addition to the first time slot used as the communication channel. The communication information for n time slots in which the significant and insignificant information are mixed is transmitted to the corresponding communication information ATM celling / decellulating circuit 102. Here, the cells are collectively formed as fixed band ATM cells.

The ATM cells further reach the ATM cell demultiplexing / ATM line interface circuit 104, are multiplexed with ATM cells for common line signals and other communication information ATM cells, and transmitted to the ATM line 3.

This ATM cell is transmitted to the ATM line of the opposite station via the ATM network 2 and reaches the ATM line interface line 104 of the opposite ATM cell.
Here, the communication information is separated as an ATM cell for communication information and reaches the corresponding communication information ATM cell / decellification circuit. In the communication information ATM cell forming / de-celling circuit, the ATM cell is de-cellulated and returned to the communication information, and further inserted into the first slot of the communication multiplex path via the corresponding channel extraction / insertion circuit 101.

Communication information ATM cell / decell circuit 10
2 is used only when at least one of the n time slots of the corresponding communication multiplexing path 14 is used as a communication channel.
An M-cell / de-cell operation is performed. If the value of n is too large, the probability of converting meaningless communication information into ATM cells increases, and if the value is too small, the delay in forming ATM cells increases,
Care must be taken that communication quality is degraded.

Referring now to FIGS. 2 and 3, multiplex communication path 14 in ATM inter-ATM trunk 10 of time division exchange 1 of the present invention and communication information ATM cell / decell circuit 102
Will be described in detail.

In FIG. 2, the ATM inter-office trunk 10
As a communication multiplex path 14 accommodating a time-division switch.
It adopts a multipath of 3248 time slots of 2,048 Mbps. It comprises a downstream communication multiplex path 14-1 from the time division switch 12 to the ATM phase trunk 10 and an upstream communication multiplex path 14-2 from the ATM inter-station trunk 10 to the time division switch direction.

Here, corresponding to the time slots 0 to 5, these 6 time slots are collectively referred to as the fixed band ATM.
AA for converting ATM (AAL1) into ATM cells
There are L-cell / de-cell circuits 0 and 102-1. Further, there is an ALL1 celling / decellulating circuit 1 (102-1) corresponding to the time slots 6 to 11. Similarly, ALL1 celling / decelling circuits 2 to 4 (102-3 to 102-5)
There is. However, the ALL1 cell / decell circuit 4 (102
Only -5) corresponds to 8 time slots.

ALL1 cell / decell circuits 0 to 4 (1
02) is bundled together with the ALL5 celling / decellulating circuit 103-1 by the ATM cell demultiplexing circuit 104 (see FIG. 3). The common line signal information is transferred to the variable band ATM cell (ALL
As 5), a buffer memory 105 for mutually transmitting common line information is provided between the central processing unit 11 and the ALL5 celling / decellulating circuit 103-1 for converting to ATM cells / cells. The ALL5 celling / decelling circuit 103-1 has an AT
The M-cell multiplexing / demultiplexing circuit 104 is bundled together with the ALL 1-cell / de-cell circuits 0 to 4 (102).

In operation, the five ALL1 celling / decellulating circuits 102-1 through 102-4 are sequentially allocated every 32 time slots of the communication multiplex path 14 from the youngest to the last 6 time slots. Only the ALL1 cell / decell circuit 4 (102-5) allocates 8 time slots. This is a measure for leaving more than two slots since the division unit of 32 time slots is set to six time slots here, and has no special meaning.

What is important in this operation is that the central processing unit 1
1 is to always select and supplement the multiplex communication time slots 14-1 and 14-2 of the inter-ATM trunk 10 used in the call processing from the youngest number. By this operation, for example, when the number of simultaneous connections is six or less, time slots 0 to 5 of the multiplex communication channel time slots 14-1 and 14-2 are used. The central processing unit 11 includes the ALL1
Control is performed so that only the cell / decell circuit 0 (102-1) functions. ALL1 celling / decelling circuit 1 (1
Nos. 02-1 to 102-5) do not perform the celling operation.

In this state, when one connection is newly added, the central processing unit 11 sets the communication multi-path time slots 14-1 and 14-1.
The time slot 6 is newly supplemented in 4-2. At the same time, the ALL1 cell / decell circuit 0 (102-
Instruct 1) to start the celling / decelling operation.

Conversely, when all the calls disappear and the use of the communication multi-path time slots 14-1 and 14-2 is stopped, ALL is used.
1-cell / de-cell circuits 0 to 4 (102-1 to 102
In the case of -5), all the celling operations are stopped under the control of the central processing unit 11.

Next, referring to FIG. 3, when a call control procedure with the opposite station is required for the connection between the stations, the central processing unit 11
Writes the common line signal information according to a predetermined communication means into the buffer memory 105, and generates the ALL 5 cell / decell circuit 10
Instruct 3-1 to send. The ALL5 celling / decelling circuit 103-1 reads valid common line signal information from the buffer memory 105 and converts ALL5 into a cell. The generated ATM cells are sequentially sent to the ATM cell demultiplexing circuit 104 and multiplexed with the communication information cells.

Conversely, the ATM cell of the common line signal information ALL 5 separated by the ATM cell demultiplexing circuit 104 is AL
The cell is decellularized by an L5 celling / decellulating circuit 103-1.
The original common line signal information according to the predetermined communication means is restored. The restored common line signal information is written into the buffer memory 105, and notifies the central processing unit 11 of the reception of the information. In response, central processing unit 11 reads out common line signal information from buffer memory 105.

In the above, the configuration and operation of the preferred embodiment of the time division exchange of the present invention have been read. However, these are merely examples, and it is apparent that various modifications can be made without departing from the gist of the present invention.

[0040]

As will be understood from the above description, according to the time division exchange of the present invention, the ATM cell unit is minimized to such an extent that the ATM cell delay does not affect the communication quality, and the ATM cell unit is reduced. If all of the communication information is unnecessary, the ATM cell is not converted. As a result, it is possible to use A
It is possible to suppress the use of TM cells and reduce unnecessary load on the ATM network.

Further, according to the time division exchange of the present invention, the common line signal information is set as a fixed band for one time slot,
Instead of using M cells, only effective common line signal information is used as variable band information to perform ATM cell conversion. Therefore, unnecessary load on the ATM network can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of a preferred embodiment of a time-division exchange according to the present invention and associated devices.

FIG. 2 is a diagram illustrating the operation of a multiplex communication path and a communication information ATM cell / decell circuit in the trunk between ATM stations in FIG. 1;

FIG. 3 is a diagram illustrating the operation of common line signal ATM celling / decelling in the ATM aspect trunk of FIG. 1;

FIG. 4 is a block diagram showing the principle of an ATM switching system according to the prior art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Time division switch 2 ATM network 10 Trunk between ATM stations 11 Central processing unit 12 Time division switch 101 Channel extraction / insertion circuit 102 Communication information ATM cellization / decellulation circuit 103 Common line signal ATM cellization / decellulation circuit 104 ATM cell Demultiplexing circuit

Claims (4)

[Claims] An ATM which can be connected between stations via an ATM network.
In a time division switch including an interoffice trunk and a time division switch, N channel extraction / insertion circuits for sequentially extracting / inserting n time slot information among a plurality of time slots of a communication multiplex path from the time division switch. And N pieces of communication information ATM for converting the n pieces of information extracted / inserted by the channel extraction / insertion circuit into ATM cells / de-cells.
A cell line / decellularization circuit, and a central processing unit, a common line signal for performing communication of call control information with a time-division exchange of the opposite station, and a common line signal ATM cell / decellularization circuit for converting the common line signal into an ATM cell. ATM cells for multiplexing ATM cells which have been converted into ATM cells by the communication information ATM cell forming / de-celling circuit and the common line signal ATM cell forming / de-cellifying circuit, and separating the cell multiplexed ATM cells. And a demultiplexing circuit. 2. The communication information ATM cell / de-celling circuit uses the communication information as fixed storage information as an ATM cell / de-cell.
The time-division exchange according to claim 1, wherein the time-division exchange is decelerated. 3. The common line signal ATM cell / de-cell conversion circuit converts the common line signal information into variable band information by using an ATM.
3. The method according to claim 1, wherein the cell / cell is used.
The time-division exchange described in. 4. The communication information ATM cell / de-cell conversion circuit, if all of the n pieces of communication information are not significant,
4. The time-division exchange according to claim 1, wherein the cell is not converted into a TM cell / de-cell.