JPH09116546A - Data transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate pulling out of synchronism in the case of transmission of two different data signals (voice signal data and signal line data or the like) by configuring a couple of data transmitters so as to store the two different data signals in a cell of a prescribed format for transmission and reception. SOLUTION: Data transmitters 2, 3 are provided between a PBX1 and a PBX2. An interface specific point A is provided between the PBX1 and the data transmitter 2 and between the data transmitter 3 and the PBX4 and an interface specific point B is provided between the data transmitters 2, 3. Then data sent from the PBX1 are processed into cells for each reference time, e.g. when voice signal data is 64kbps, the data are processed into cells for each 5ms, and individual signal line data processed into cells within the same time when the voice signal data processed into cells are multiplexed and sent from the transmitter 2 to the transmitter 3 by a prescribed cell format.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission system, and more particularly to a structure of an apparatus for transmitting data by ATM (asynchronous transfer mode).

[0002]

2. Description of the Related Art For example, a PBX (Private Branch Excha)
When building a LAN such as a corporate network using a private branch exchange (Tungsten Exchange), a TDM (Time Divisoion Multiplexe) is generally used between PBX and PBX.
r; time division multiplex device) is used to connect by a high-speed digital leased line. In this case, the audio signal data and the signal line data (individual signal line data) are usually multiplexed and transmitted in different transmission bands. Note that the signal line data means data used for controlling outgoing / incoming calls and transmitting dial signals.

[0003]

By the way, in a network such as a LAN formed by TDM, it has been proposed to replace it with a network using an ATM node in order to improve the data transmission efficiency.

In this conventional network composed of TDM, a transmission band for voice signal data and a transmission band for signal line data are separately secured, and the voice signal data and the signal line data are provided separately. Since the amount of data is different, the time that can be stored per cell in ATM changes.

Here, in a network constituted by TDM, generally, voice signal data is 64 kbps without compression, and signal line data is 1 k.
Each data transmission is performed at bps.

For example, voice signal data is transmitted in one cell 48.
When storing in a byte payload, data of (48 bytes × 8 bits) / 64 kbps = 6 ms, and when storing signal line data in this payload, (4
Data of 8 bytes × 8 bits / 1 kbps = 384 ms can be stored respectively. In addition, the audio signal data is 1
When compressed to 6k, (48 bytes x 8 bits) /
16 kbps = 24 ms.

When the audio signal data is not compressed, the audio signal data and the signal line data are 64 times different in data amount per unit time. Therefore, the signal line data cell is 6 of the voice signal data cell.
The data will be stored four times as long. Therefore, the signal line data greatly differs from the voice signal data in the delay time for cell formation and the cell fluctuation delay time. As a result, the synchronization shift with the audio signal data becomes large on the receiving side.

Particularly, in the case of signal line data, since it is used for outgoing / incoming call control, dial signal transmission, etc., when the synchronization deviation is large, new incoming / outgoing control or operation error occurs on the receiving side, and delay time There is a problem that

An object of the present invention is to provide a data transmission system capable of eliminating a synchronization deviation when transmitting two different data signals (voice signal data, signal line data, etc.) as described above.

[0010]

A data transmission system of the present invention which solves the above-mentioned problems is provided between a data transmission device which performs data communication of two different data signals at different data transmission rates by the first communication system. In the data transmission method for transmitting and receiving the two different data signals between the pair of data transmission devices, a pair of data transmission devices for performing data communication according to a second communication system different from the first communication system are provided. The data transmission device is characterized in that the two different data signals are stored in a cell having a predetermined format and transmitted and received.

In a preferred embodiment, the two different types of data signals are a voice signal data signal and a signal line data signal, and the second communication method is ATM communication.

In the data transmission system of the present invention having the above-mentioned configuration, between the pair of data transmission devices, the audio signal data and the signal line data of the same time are taken out at a certain reference time, multiplexed and stored in the same cell. That is, the audio signal data and the signal line data for each fixed time form one cell and are transmitted. As a result, the delay time for making cells and the delay time for cell fluctuations become the same, and there is no synchronization deviation on the receiving side.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, PBX1 and PBX
A pair of data transmission devices 2 and 3 (abbreviated as devices in the drawing) are provided between the data transmission device 4 and the data transmission device 4. Between the PBX 1 and the data transmission device 2, and between the data transmission device 3 and the PBX
4, an interface defining point A is provided between the data transmitting device 2 and the data transmitting device 3, and an interface defining point B is provided between the data transmitting device 2 and the data transmitting device 3.

The interface defining point A is the conventional PB.
Similar to the X-TDM interface, the standard interface defined by TTC is used for connection. The interface defining point B is connected by the ATM cell format according to the present invention.

An example of an ATM cell format is shown in FIG. This cell format is composed of a cell header 51 and a payload 52. In this embodiment, two different signal data, for example, audio signal data and signal line data (individual signal line data) are stored in the payload 52. That is, in the present embodiment, this cell format includes the cell header 61, the audio signal data 62, and the individual signal line data 63, as shown in FIG. With this configuration, the voice signal data and the signal line data can be transmitted in the same cell.

In the data transmission system of the embodiment configured as described above, the data sent from the PBX 1 is transmitted for each reference time, for example, when the audio signal data is 64 kbps, about 5 ms as shown in FIG. Make cells for each. Then, the voice signal data thus cellized and the signal line data (individual signal line data) cellized within the same time are multiplexed, and the data transmission device 2 to the data transmission device have the cell format of FIG. 3 is transmitted.

FIG. 5 shows a case where the audio signal data is compressed 16
It shows an example of cell formation in the case of kbps. In this case, the compressed voice signal data and the signal line data (individual signal line data) are converted into cells every 20 ms and multiplexed, and similarly, the data transmission device 2 in the format of FIG.
Is transmitted to the data transmission device 3.

[0018]

As is apparent from the above description, according to the present invention, there is provided a data transmission system capable of eliminating a synchronization deviation when transmitting two different signals such as signal line data and audio signal data. Can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an interface between data transmission devices to which a data transmission system according to an embodiment of the present invention is applied.

FIG. 2 is an explanatory diagram showing an ATM cell format.

FIG. 3 is an explanatory diagram showing an example of a cell format in the data transmission system according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram showing an example of cell formation when audio signal data is 64 kbps.

FIG. 5 is an explanatory diagram showing an example of cell formation when audio signal data is 16 kbps.

[Explanation of symbols]

 1,4 PBX 2,3 Data transmission device 51,61 Cell header 52 Payload 62 Voice data

Claims (3)

[Claims] 1. Data communication according to a second communication method different from the first communication method is performed between data transmission devices that perform data communication of two different data signals at different data transmission rates by the first communication method. In a data transmission method in which a pair of data transmission devices is provided and the two different data signals are transmitted and received between the pair of data transmission devices, the pair of data transmission devices each transmit the two different data signals in a predetermined format. A data transmission method characterized by being stored in a cell and configured to perform transmission / reception. 2. The two different types of data signals are:
The data transmission method according to claim 1, wherein the data transmission method is an audio signal data signal and a signal line data signal. 3. The data transmission system according to claim 1, wherein the second communication system is ATM communication.