JP2631801B2 - Asynchronous transfer mode subscriber circuit for analog lines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to an asynchronous transfer mode exchange accommodating an analog subscriber line. A cellularization function is provided for analog subscriber lines, and is used for an asynchronous transfer mode switch that accommodates a subscriber line in an asynchronous transfer mode. A conventional subscriber exchange is used for a renewed asynchronous transfer mode exchange.

[0002]

2. Description of the Related Art Asynchronous transfer mode (ATM) transmits all information in units of fixed-length packets called cells.
ISD is a method that can efficiently realize high-speed communication with various speeds and various media by the exchange method.
N (Integrated Services Dig)
It is a basic technology for building an IT network. B-ISDN (Bro
adband ISDN), the existing S
TM (Synchronous Transfer M)
mode) or a function of directly connecting an existing STM system terminal or existing subscriber line to the ATM network. In particular, this is an essential function in the process of efficiently accommodating an existing network in an ATM-based integrated network.

[0003] As a method of converting an existing network into an ATM, an inter-network adapter is used to connect the existing network and the ATM network, or an ST is used.
A method of performing ATM conversion from a trunk line by adding a cell assembling / disassembling function to a trunk outgoing line of an M exchange, and a subscriber line by multiplexing outgoing lines of a subscriber exchange or a cell-forming function corresponding to a subscriber line. From ATM to ATM, and ATM terminal on the terminal side to directly connect existing terminal to ATM
A method of making it possible to accommodate in a net is conceivable.

[0004]

However, in the prior art, the methods are only classified into the rough methods as described above, and the respective realizing methods are not yet established.

The present invention has been made in view of such a background. An ATM can be converted from an analog subscriber line to connect an existing network to an ATM network, and a conventional subscriber exchange is replaced with an ATM exchange. In this case, it is an object of the present invention to provide an asynchronous transfer mode subscriber circuit for an analog line which can efficiently and economically accommodate an existing analog subscriber line in an ATM exchange with exactly the same interface as before.

[0006]

SUMMARY OF THE INVENTION The present invention relates to an asynchronous transfer mode subscriber circuit for an analog line provided with an analog subscriber circuit (2) for accommodating an analog subscriber line, wherein a level signal from the analog subscriber circuit is provided. Means (5) for converting into a message in accordance with a specified format, and performing layer 2 processing including a link access procedure for a D channel on the output of the conversion means to perform asynchronous transfer mode adaptation layer processing type 3 and type First processing means (6, 7) for forming a cell by four processing
Second processing means (14) for converting the pulse code modulation information from the analog subscriber circuit (2) into cells by type 1 processing of asynchronous transfer mode adaptation layer processing;
A multiplexing / branching unit (8) for demultiplexing a signal between the first processing unit and the second processing unit and an interface line and transmitting / receiving the signal in the form of an asynchronous transfer mode cell, wherein the first processing unit (6, 7) includes means for decomposing the output of the multiplexing / branching means into a message and providing the message to the converting means (5). The second processing means (14) decomposes the output of the multiplexing / branching means into pulse code information. Means for providing to the analog subscriber circuit (2), wherein the conversion means (5) converts the signal to a level signal in the case of a level signal based on a message from the first processing means, and converts the signal to a level signal. In the case of one of the tone designation and the push button signal receiving instruction, means for outputting the one and the selection signal is provided.

The present invention also provides a receiving circuit (11) for receiving a push button signal in response to the push button signal receiving instruction, a transmitting circuit (12) for transmitting a tone specified by the tone specification, A switch (10) for selecting and connecting the analog subscriber circuit to one of the reception circuit, the transmission circuit, and the second processing means, and a switch (10) between the analog subscriber circuit and the third processing means. An echo canceller (13) interposed therebetween, and the converting means (5) may include means for converting an output of the receiving circuit into a message and providing the message to the first processing means.

[0008]

[Operation] PCM information is converted to ATM cells and converted to ATM cells.
It transmits and receives to and from the exchange body, converts the level signal into a message, converts it into an ATM cell, and transmits and receives to and from the ATM body, and furthermore, when the message from the ATM body is a tone designation signal, Transmits the designated tone to the analog subscriber circuit, and in the case of a push button signal reception instruction signal, receives the push button signal from the analog subscriber circuit, converts it into a message, and
By converting the cells into M cells and transmitting them to the ATM exchange, the existing line can be converted from the subscriber line to the ATM network by connecting the existing network to the ATM network. Can be efficiently and economically accommodated in the ATM switch with the same interface as before.

To accommodate an STM line in an ATM network, C
The function of assembling and disassembling into ATM cells, which is defined by CITT (International Telegraph and Telephone Consultative Committee), that is, an ATM adaptation layer process (ALL process) is essential. A method of where and how to perform the ALL processing can be considered. One of the methods is to connect an STM line to a conventional ATM.
It is conceivable to accommodate in a switchboard and to provide an ALL function at the entrance to the multiple trunk line. Although this method is relatively easy to introduce, even if the ATM is advanced, an ATM exchange will eventually remain, and cannot be said to be an ATM integrated network.

In addition, since local calls are not converted to ATM,
The benefits of ATM conversion cannot be used for local calls. In view of the above, the present invention provides a local exchange which performs an ALL process for each subscriber line, thereby achieving A
This is a method that enables TM conversion. In order to accommodate analog subscriber lines, a subscriber circuit, ie, a BOR
A SCHT circuit is required, and it is the idea of the present invention to add an ALL function to the BOSCHHT function.
LSI with ALL function integrated with BORSCHT function
(Large Scale Integrated C
irquity, there is a possibility that the economy can be sufficiently achieved in the future.

Here, when an analog subscriber line is accommodated in an ATM network, not only the user information is converted into ATM cells, but also the signal system based on the analog subscriber line is A.
It must be processed by the TM exchange. The type of the signal is an in-channel PC such as a PB signal or a tone signal.
There are M signal and level signal like on-hook detection,
The former requires a signal processing circuit such as a PB signal receiving circuit (PBR). A method often used in conventional exchanges is a method in which a PB receiving circuit or the like is installed so as to be commonly used as a trunk, and is connected by a switch whenever necessary. If this method is applied as it is, AT
A time switch is required in addition to the M switch, and the interface between the subscriber line corresponding unit and the main unit also has both the ATM and the STM, which complicates the configuration of the exchange.
Also, a line for interfacing the level signal is required.

One method for this purpose is to convert not only user information but also all signals into type 1 cells in the subscriber line corresponding section, and to add an ALL processing function to a signal device trunk such as a PB receiving circuit, and to provide This is a method of unifying with the ATM cell interface. Since this method does not require the STM switching function, the AT
The complexity of the configuration resulting from having both M and STM switches can be avoided. However, from the viewpoint of adding a function for accommodating an existing analog subscriber line to the ATM exchange, not only the subscriber line corresponding unit but also the exchange itself has an analog subscriber line signal system such as a PB receiving circuit. Specific equipment needs to be added. Therefore, in the present invention, a signal circuit such as a PB receiving circuit is also installed corresponding to the line, and the reception result and the detection result of the physical change due to the level signal are edited as a message, and the message is converted to an A signal.
We devised a method to interface with the exchange body by using TM cells. As a result, signal processing specific to the analog subscriber line signal system is terminated at the subscriber line corresponding unit and all signals are transmitted and received in the form of messages, so that it can be realized without adding any special hardware to the exchange body. That is, layer 2 and layer 1 for transmitting and receiving messages are ATM
If it is used in common with the signal equipment of the subscriber line, it is only necessary to add software for performing layer 3. ATM in this way
The existing analog subscriber line can be accommodated in the ATM network simply by replacing the line corresponding part of the exchange with the line corresponding part accommodating the analog subscriber line.

[0013]

Embodiments of the present invention will be described with reference to the drawings.

In FIG. 1, the analog line asynchronous transfer mode subscriber circuit includes an analog subscriber circuit 2 accommodating an analog subscriber line 1.

Here, the features of the present invention are as follows: a message conversion circuit 5 as conversion means for converting a level signal from the analog subscriber circuit 1 into a message in accordance with a specified format; D channel link access procedure (LAPD, L
Ink Access Procedure onth
e D-channel) to perform layer 2 processing,
Asynchronous transfer mode adaptation layer processing (ALL
As the first processing means for converting into cells by the type 3 and type 4 processing of (processing), the layer 2 processing unit 6 and the ALL type 3 and 4 processing units 7 and the pulse code modulation information (PCM information) from the analog subscriber circuit 2 are used. ALL processing type 1
A second processing means (14) for converting into cells by processing, a layer 2 processing unit 6, an ALL type 3, a 4 processing unit 7, and an ALL
An ATM cell multiplexing / branching unit 8 as multiplexing / branching means for multiplex-decomposing a signal between the type 1 processing unit 14 and the ATM cell multiplexing line 9 as an interface line and transmitting / receiving the signal in the form of an asynchronous transfer mode cell (ATM cell); The layer 2 processing unit 6 and the ALL type 3 and 4 processing units 7 include means for decomposing the output of the ATM cell multiplexing / branching unit 8 into a message and supplying the message to the message conversion circuit 5, and the ALL type 1 processing unit 14
Includes means for decomposing the output of the ATM cell multiplexing / branching unit 8 into PCM information and providing the PCM information to the analog subscriber circuit 2. The message converting circuit 5 is based on the message from the layer 2 processing unit 6, It is characterized in that it includes means for converting the signal into a level signal and applying the signal to the analog subscriber circuit 2, and for outputting one of the tone designation and the push button signal reception instruction in the case of one of the tone designation and the push button signal reception instruction.

Further, a PB signal receiving circuit 11 as a receiving circuit for receiving a push button signal (PB signal) according to the push button signal receiving instruction, and a tone transmitting circuit 12 as a transmitting circuit for transmitting a tone specified by the tone specification. A switch 10 for selecting and connecting the analog subscriber circuit 2 to one of the PB signal receiving circuit 11, the tone transmitting circuit 12, and the ALL type 1 processing unit 14 according to the selection signal; Echo canceller 1 inserted between ALL type 1 processing unit 14
The message conversion circuit 5 includes means for converting the output of the PB signal reception circuit 11 into a message and providing the message to the layer 2 processing unit 6.

The operation of the thus-configured analog line asynchronous transfer mode subscriber circuit will be described. FIG. 2 is a diagram showing the structure and coding of the data unit of the division and assembling sublayer protocol handled by the type 1, type 3 and type 4 protocols of the asynchronous transfer mode adaptation layer of the asynchronous transfer mode subscriber circuit for analog lines of the present invention. is there. FIG. 2A shows Type 1 of the ALL process, FIG. 2B shows Type 3 of the ALL process, and FIG.
(C) shows type 4 of the ALL processing. Further, SN is a sequence number, SNP is a sequence number protection, SAR
-PDU is a subassembly sublayer protocol data unit,
ST is the segment type, Res. Is the reserved field, LI is the length, CRC is the redundancy check code and M
ID indicates a multiplexing identifier.

In FIG. 1, the analog subscriber circuit is SL
IC (Subscriber Line Interf)
ACE Circuit), which has a BORSCHT function such as power supply, two-wire to four-wire conversion, and analog-to-digital conversion, and performs analog-to-digital conversion and μlaw or information conversion of information such as voice from the analog subscriber line 1. Alaw PCM pulse code modulation and coding, output to PCM signal input / output line 3, and convert PCM signal from PCM signal input / output line 3 to analog signal such as voice by analog-to-digital conversion to analog subscriber line 1. Output.

Further, the analog subscriber circuit 2 monitors off-hook of the subscriber, that is, detects a call, and outputs a level signal change to the level signal input / output line 4 upon detection. The message conversion circuit 5 converts the level signal change into a message in a specified format. For example, a message indicating that an off-hook is detected is created, the layer 2 processing unit 6 converts the message into an LAPD frame, and the ALL type 3 and 4 processing unit 7 outputs the LA type frame.
As shown in FIG. 2B and FIG. 2C, the message is divided into cell length units. The ATM cell multiplexing / branching unit 8 sends the output of the ALL type 3 and 4 processing unit 7 to the main body of the ATM exchange via the ATM cell multiplexing line 9 in the form of cells.

When, for example, a dial tone transmission instruction and a PB reception instruction message are input in the form of cells from the ATM exchange via the ATM cell multiplex line 9, the message conversion circuit 5 outputs the respective messages based on the contents of the messages. An instruction is given to the tone transmitting circuit 12 or the PB receiving circuit 11, and a selection signal is given to the switch 10. The switch 10 has its output side from the analog subscriber circuit 2 connected to the PB signal receiving circuit 11 and the input side to the analog subscriber circuit 2 connected to the tone transmitting circuit 12 on the PCM signal input / output line 3 based on this selection signal. . A dial tone is designated as a tone in the tone transmitting circuit 12.

As described above, the analog subscriber circuit 2
, A dial tone is transmitted to the subscriber terminal. When the subscriber hears the dial tone and the subscriber transmits a PB signal, the PB signal receiving circuit 11 receives the PB signal, and the message conversion circuit 5 determines the reception result. Is converted into a message and transmitted to the ATM switching unit in an ATM cell.

When the communication state is established after the call control processing, the switch 10 connects the PCM signal input / output line 3 to the echo canceller 13. The AAL type 1 processing unit 14 converts the PCM signal (information such as voice) from the analog subscriber circuit 2 into cells at a fixed speed by the type 1 processing of the ALL processing as shown in FIG. 8 is ALL
An ATM header is added to the output of the type 1
It is transmitted to the TM cell multiplex line 9. The ATM cell multiplexing / branching unit 8 and the ALL type 1 processing unit 14 decompose the PCM signal from the ATM cell multiplexing line 9 and supply it to the analog subscriber circuit 2 via the echo canceller 13 and the switch 10 to provide the subscriber terminal. Communicate information. The echo canceller 13 cancels an echo generated at the time of two-wire to four-wire conversion in the analog subscriber circuit 2 as necessary.

[0023]

As described above, the present invention provides an ATM
In constructing a network, an analog subscriber line, which currently exists as a huge facility, can be accommodated in an ATM network as it is, and there is an excellent effect of contributing to rapid and economical progress of ATM conversion. In addition, LSI (Large Scale)
If economy and miniaturization can be realized by an integrated circuit, etc., existing services such as telephones can be provided more economically.

[Brief description of the drawings]

FIG. 1 is a block diagram of an asynchronous transfer mode subscriber circuit for an analog line according to an embodiment of the present invention.

FIG. 2 is a diagram showing the structure and coding of a data unit of a sub-assembly sublayer protocol handled by the type 1, type 3, and type 4 protocols of an asynchronous transfer mode adaptation layer of an asynchronous transfer mode subscriber circuit for an analog line according to the present invention. .

[Description of Signs] 1 Analog subscriber line 2 Analog subscriber circuit 3 PCM signal input / output line 4 Level signal input / output line 5 Message conversion circuit 6 Layer 2 processing unit 7 ALL type 3, 4 processing unit 8 ATM cell multiplex branching unit Reference Signs List 9 ATM cell multiplex line 10 Switch 11 PB signal receiving circuit 12 Tone transmitting circuit 13 Echo canceller 14 ALL type 1 processing unit CRC Redundancy check code LI Length indication MID Multiplexing identifier SAR-PDU Divided assembly sublayer protocol data unit SN Sequence number SNP Sequence number protection Res. Reserve field

Claims (2)

(57) [Claims] 1. An analog line asynchronous transfer mode subscriber circuit comprising an analog subscriber circuit accommodating an analog subscriber line, wherein a level signal from the analog subscriber circuit is converted into a message according to a specified format. A conversion unit (5) for performing conversion, and a layer 2 process including a link access procedure for a D channel is performed on an output of the conversion unit, and a cell is formed by a type 3 and type 4 process of an asynchronous transfer mode adaptation layer process. Processing means (6, 7)
Second processing means (14) for converting the pulse code modulation information from the analog subscriber circuit (2) into cells by type 1 processing of asynchronous transfer mode adaptation layer processing;
A multiplexing / branching unit (8) for demultiplexing a signal between the first processing unit and the second processing unit and an interface line and transmitting / receiving the signal in the form of an asynchronous transfer mode cell, wherein the first processing unit (6, 7) includes means for decomposing the output of the multiplexing / branching means into a message and providing the message to the converting means (5). The second processing means (14) decomposes the output of the multiplexing / branching means into pulse code information. Means for providing to the analog subscriber circuit (2), wherein the conversion means (5) converts the analog signal into a level signal in the case of a level signal based on a message from the first processing means, And a means for outputting one of the tone designation and the push button signal reception instruction and a selection signal. Circuit. 2. A receiving circuit (11) for receiving a push button signal according to the push button signal receiving instruction, a transmitting circuit (12) for transmitting a tone specified by the tone specification, and the analog subscription according to the selection signal. A switch for selecting and connecting a user circuit to one of the receiving circuit, the transmitting circuit and the second processing means (10)
And an echo canceller (13) inserted between the analog subscriber circuit and the third processing means. The converting means (5) converts an output of the receiving circuit into a message to convert the output into a message. 2. An asynchronous transfer mode subscriber circuit for an analog line according to claim 1, further comprising means for providing processing means.