JP3201314B2 - ATM exchange method and apparatus - 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 (Asynchronous Transfer Mode) transmission network for accommodating a conventional narrow-band signal,
The present invention relates to an ATM switching system for performing cross connection of a narrow band line by a TM exchange.

[0002]

2. Description of the Related Art In a broadband communication network using ATM, ATM is used.
By using cells, it is possible to transmit signals of various media, and even in the case of a conventional circuit-switched narrowband signal, it is possible to transmit it through an ATM switching network by converting it into an ATM cell and transmitting it. is there.

[0003] In such a broadband communication apparatus, an ATM is used.
Attempts to handle cells and narrowband signal lines have been made in the past. For example, Japanese Unexamined Patent Publication No. Hei 7-30558 discloses a method and apparatus for transmitting information supplied / restored in a narrow-band line mode in a cell mode, in which a line mode signal is converted into a cell in the apparatus, and a cell switch is used for other operations. A method for connecting to a line module is described. In this method, the input line signal and the output line signal of the device are the same and only provide a transmission path within the device.

[0004] Considering the case where narrowband line signals are communicated over an ATM network, 1.544 Mbps or 2.048 Mbps is considered.
An example is a method in which an input line signal having a standard basic transmission rate such as s is converted into a cell in the unit.
The exchange unit that can be provided on the line is the transmission speed when cellized (in this case, 1.544 Mbps or 2.048 Mbps)
And a smaller unit (an integer multiple of 64 kbps)
Cannot be provided by the ATM network.

[0005] In order to convert the line of such a 64 kbps line, it is necessary to return the line signal from the ATM cell once and then process the line signal using a digital cross-connect device. As another method for converting the route of a line in units of 64 kbps, all input lines are 64 kbps.
After decomposing into s-unit line signals, each is converted to a cell,
There is also a method of assigning a virtual path.

[0006]

In the prior art, when a narrow band device is incorporated in a wide band device, only a transmission path is provided so as to keep the state of an input / output line the same, and a line signal included therein is provided. Since there is no device that provides route conversion, there is a problem that a digital cross-connect device is required as a component of the network when the route conversion of a line is performed, and the cost of the network increases.

[0007] When an ATM cell is formed every 64 kbps, the number of circuit blocks required for cell formation increases, and the time required to form one cell requires about 6 ms, and the transmission delay time increases. In order to convert the route of a 64 kbps line signal, the circuit scale and transmission delay increase.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ATM for a narrow band line signal.
By allocating the cell method to each rough route, it is possible to simplify the device configuration in the network,
An object of the present invention is to allow a narrow band network to be accommodated in an ATM network at a lower cost.

[0009]

SUMMARY OF THE INVENTION The present invention is characterized in that it comprises a terminal device and an ATM switch which extract predetermined time slot signals from narrowband signals, group the signals into ATM cells and group them. And The terminal equipment separates the input narrowband signal into 64 kbps channel units, multiplexes them in groups having the same route, converts them into ATM cells, and assigns different virtual channel identifiers (VCIs) to the ATM cells. Further A
After switching the different virtual channels (VCs), the TM switch returns to the line signal, and after multiplexing, switches to 1.54.
A 4 Mbps, 2.048 Mbps signal is formed and output to an external line.

According to the present invention, by providing a rough cross-connect function in the ATM layer, a cross-connect device for a narrow band line can be omitted from the network. In addition, since the method of expanding to the minimum unit of 64 kbps and converting each to an ATM cell is not adopted, the time required for assembling the ATM cell from the input line signal can be reduced, and therefore the delay time in signal transmission is reduced. can do.

[0011]

FIG. 1 is a block diagram showing an embodiment of an ATM switching system according to the present invention. A network configuration using this method is placed on the subscriber side,
An ATM terminal device 200 for converting a narrow band line input signal 201 such as Mbps / 2.048 Mbps into ATM cells and multiplexing with other ATM signals 202, an ATM signal 101 from a plurality of ATM terminal devices 200, and other ATM signals It is composed of a signal 103 to and from the network, an ATM switch 100 accommodating the narrow band signal 102 from the narrow band circuit switch 300, and a plurality of narrow band circuit switches 300 such as an intra-office switch and a private branch exchange for the narrow band line signal. .

As shown in FIG. 2, the ATM terminal device 200 has a 1.544 Mbps signal or a 2.048 Mbps signal.
The signal 201 is input and converted into an ATM cell by the ATM cell generation / separation unit 210. The ATM cell generated here is
The ATM cell multiplexing / demultiplexing section 230 multiplexes the signal with another signal after the reception processing of the ATM input signal 202, and outputs it as the ATM transmission signal 101 by the ATM cell transmitting / receiving section 240.

As shown in FIG. 3, the ATM switch 100 exchanges ATM signals 101 received from a plurality of ATM terminal devices 200 by means of an ATM switch 130, and sends them to a plurality of ATM cell generating / separating units 110, respectively. ATM
The cell generation / separation unit 110 converts the narrowband signals mapped to a plurality of VCs (virtual channels) into cells /
The signal is restored by the line signal restoration unit (AAL processing unit) 113,
1.544 Mb in the line signal separation / multiplexing section 112
A ps or 2.048 Mbps signal 102 is generated. These 1.544Mbps / 2.048Mbps
The signal 102 is connected to a narrow band circuit switch 300 such as a local exchange or a private branch exchange.

In FIG. 2, an ATM cell generation / separation unit 2
10 is a line termination unit 211 and a line signal separation / multiplexing unit 21
2 and a cell / line signal restoration unit (AAL processing unit) 213 and a VCI addition unit 214. The route setting section 250 determines which time slot in the input signal is to be allocated to which AAL processing section based on information set in advance. The narrow-band signal terminated by the input unit (line terminating unit) 211 separates the 64 kbps signal contained therein and is multiplexed again for each line signal having the same destination.

For example, if there are two switches connected to a 1.544 Mbps input signal as a narrow band line, and each of them has 12 lines of 64 kbps,
The cells are converted into ATM cells in units of 768 kbps, and different virtual channel identifiers (VCIs) are added to the respective ATM cells. These two types of cell streams are multiplexed and converted into ATM signals.

As described above, the ATM terminal device 200 uses the ATM.
A signal 101 which has been converted into a cell and output to the outside as an ATM signal.
Is transmitted to the ATM switch 100 and the ATM in FIG.
By the switch unit 130, the packet is distributed to the ATM cell generation / separation unit 110 corresponding to the desired external line output. A
In the TM cell generation / separation unit 110, the ATM terminal unit 200
The signal is restored to the line signal 102 in the reverse manner to the case where the signal is generated. That is, a line signal of 64 kbps × N is restored by the AAL processing unit 113 for each ATM cell having the same virtual path identifier.

These signals are transmitted to a plurality of ATM terminal devices 20.
0, one to one, and multiplexing these plurality of restored signals, and finally 1.544 Mbps or 2.048 Mbps
And generates an interface signal with the narrow band circuit switch 300 and outputs the signal to an outside line.

Next, a case where the network configuration shown in FIG. 1 is applied to a subscriber network will be described. The ATM terminal device 200 is a device placed on the subscriber side. Here, the narrowband castle line is converted into an ATM cell and taken into the network.
In the ATM terminal device 200, when a 1.544 Mbps signal (64 kbps × 24) narrowband line signal 201 is input, a 64 kbps × 6 channel (384)
kbps) to the private branch exchange, 64 kbs × 12 channels (768 kbps) to the central office, and 64
ATM for kbps x 6 channels (384 kbps)
It is assumed that the connection is made as a signal 103 to an exchange located in another station via a network.

At this time, the ATM terminal device 200
1.544 Mbp in M cell generation / separation section 210
The s signal is separated into 64 kbps units.
The time slot is extracted, multiplexed into a 384 kbps signal, and the AAL processing unit 213 converts the cell into an ATM cell. Further, the VCI addition / ATM multiplexing section 214
The TM switch 100 adds a virtual channel identifier (VCI) corresponding to a virtual path connected to the interface to the private branch exchange 300. Similarly, a signal of 786 kbps connected to the intra-office switchboard 300 and a signal of 384 kbps transmitted on another ATM network and connected to another station are extracted from the corresponding time slot and multiplexed. The cell is further added, a VCI is added, the cell is multiplexed with other ATM signals, and output as an ATM signal 101.

By the way, in the connection form assumed by the cross-connect method of the narrow band castle line provided by the present method, ATM is used.
About two or three exchanges are connected on the exchange side. For this purpose, the route separation / A
The number of AL processing units may be two or three for one input line.

As described above, in many cases, it is not necessary to provide an AAL function for each 64 kbps signal, so that the number of AAL function blocks can be reduced, and the time required to convert a 64 kbps signal into cells is reduced. Can be done. Here, the celling time means the time required for an input line signal to form an ATM cell. In the case of a 64 kbps signal, to generate a 48-byte payload forming one ATM cell, (8) 6 ms is required due to the relationship of × 48) / 64k. 64k as in the present invention
Increasing the signal speed for cell multiplexing of a plurality of bps reduces the celling time, thereby reducing the transmission delay of the line signal.

FIG. 4 shows A in the ATM switching system of the present invention.
It is a block diagram showing a 2nd embodiment of a TM terminal unit. In the first embodiment, the ATM terminal device 20
0 is a narrow band signal (1.544 Mbps or 2.0
48 Mbps) 201 is input, and line signals included therein are grouped into ATM cells by a route, but a plurality of narrow band line signals 201 can be accommodated (three in FIG. 4). Is shown).

In this case, the line signal separation / multiplexing section 212 includes a plurality of separation blocks 215 and a multiplex block 2
16, each input signal 201 is terminated by a line termination unit 211,
The signal is separated into line signals in units of 4 kps, multiplexed by a multiplex block 216 for each line having the same route, and then converted into cells by the AAL processing unit 213. In this case, since the line speed after grouping is similar to that of the input line, the cell assembling time can be further reduced. In addition, since the entire input lines are grouped together, the AAL function is used in the first embodiment. It is sufficient to provide only the number of routes equal to the number of routes as in the embodiment.

[0024]

In the switching system according to the present invention, the capacity to be converted into cells is selected in advance for each line to be cross-connected, and the narrow band signal is converted to the channel unit (N × N).
Since cells are converted into cells in units of 64 kbps and cross-connected at the ATM layer, a cross-connect device for a narrow band line can be omitted, and the cost of the ATM device can be reduced.

The switching method according to the present invention is 64 kb.
AT after multiplexing ps line with line having the same route
By using M cells, the time required for ATM cells can be reduced.
It is possible to reduce transmission delay on a communication path.

[0026]

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an ATM switching system according to the present invention.

FIG. 2 is a block diagram showing a first embodiment of an ATM terminal device constituting the present invention;

FIG. 3 is a block diagram showing an embodiment of an ATM exchange constituting the present invention.

FIG. 4 is a block diagram showing a second embodiment of the ATM terminal device constituting the present invention;

[Explanation of symbols]

Reference Signs List 100 ATM switch 200 ATM terminal equipment 300 Narrow band line switch 101, 103, 202 ATM signal 102, 201 Narrow band line signal such as 1.544M / 2.048M 110, 210 ATM cell generation / separation unit 111, 211 Line termination Circuits 112, 212 Line signal separation / multiplexing circuit 113, 213 Cell / line signal restoration unit (AAL processing unit) 114, 214 VCI addition / ATM multiplexing unit 215 Line signal separation unit 216 Line signal multiplexing unit 120, 220, 240 ATM cell Transmission / reception unit 130 ATM switch 230 ATM cell multiplexing / demultiplexing unit 140, 250 Route setting unit

Claims (4)

(57) [Claims] In a communication path accommodating a narrow-band line signal on an ATM network, when converting the narrow-band line signal into an ATM cell, a line of an input narrow-band signal is separated, and the line is divided by a predetermined route. An ATM switching method, comprising multiplexing again to form ATM cells, and allocating the ATM cells to different virtual paths to perform cross-connection of the narrowband line signal in an ATM switch. 2. A signal between another ATM signal network and a narrow band.
ATM switching accommodating narrowband line signals from circuit switching equipment
In an ATM switching device provided with a switching device, the ATM switching device receives an input from the narrow band circuit switching device.
Separated narrowband line signals and
Multiplexed again for each route, converted to ATM cells, and
Output from the ATM switch and the ATM switch.
To generate a narrow-band line signal and
It has means for generating / separating ATM cells to be sent to the exchange.
An ATM switching device, characterized in that: 3. A method for converting an input signal of a narrow band line into an ATM cell.
Multiplexed with the ATM signal and input to the ATM exchange.
With the ATM signal from the ATM switch
ATM cell generation / separation means for generating narrowband line signals
Contractor comprising an ATM terminal device having
The ATM switching device according to claim 2 . 4. An ATM cell generating / separating means, comprising :
The narrow-band signal terminated at the
The same destination based on the information set in the road setting section
Multiplexing is performed again for each line signal
Narrowband signal restored by line signal restoration unit to narrowband line
A line signal separating / multiplexing unit connected to an exchange;
The narrowband signal remultiplexed by the demultiplexing unit is
As well as map to multiple virtual channels.
/ Line signal restoration to restore the narrow band signal
And the cell assembled into the ATM cell are connected.
When a virtual channel identifier corresponding to a virtual path
Both multiplex incoming ATM cells for each virtual channel
VCI added to output to cell / line signal restoration unit
3. An ATM / ATM multiplexing unit.
Or the ATM switching device according to 3 .