JPH09200375A - Communication equipment for ISDN - Google Patents

Abstract

(57) Abstract: When communication is performed by synchronizing reception data of two B channels of ISDN, throughput is improved in half-duplex data communication, and a small capacity and inexpensive buffer is used. A communication device capable of performing the above is provided. SOLUTION: The reception device has a reception means for receiving data of B1 channel and B2 channel which are divided and transmitted from a partner terminal via ISDN, and for synthesizing in synchronization with each other.
The receiving means includes a delay difference detecting section for detecting a delay difference between the B1 channel and the B2 channel from the respective synchronization signals, and a delay limiter circuit for detecting whether or not the delay difference between the two channels is within a predetermined allowable value. When the delay limiter circuit determines that the delay difference between both channels exceeds a predetermined allowable value, the delay limiter circuit includes a control unit for instructing the ISDN interface unit to disconnect and reconnect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device for ISDN used for communication via ISDN (Integrated Services Digital Communication Network), and in particular, by bundling two B channels constituting a basic interface of ISDN. The present invention relates to an ISDN communication device suitable for performing communication.

[0002]

2. Description of the Related Art The basic ISDN interface is 2B.
It is defined as + D. That is, the B channel which is an information channel is two channels, and the D channel which is a control channel is one channel. The transmission speed is 64 Kbps for the B channel and 16 Kbps for the D channel.

The two B channels are defined as B1 channel and B2 channel as independent channels, respectively. When both channels are used at the same time, there is no guarantee that the start times will match. Therefore, when the stereo audio L channel and R channel are sent as the B1 channel and the B2 channel, respectively, a phase shift may occur.

FIG. 3 shows a conventional ISDN compound terminal device proposed to eliminate such inconvenience.
FIG. 7 is a block diagram of No. 7952). In FIG.
Two composite terminal devices 3 connected to both ends of the SDN 30
Reference numerals 1 and 31 transmit and receive data to and from each other through the ISDN 30, and both have the same configuration.

This composite terminal device 31 is provided with a layer 1 interface section 32 for matching electrical and physical conditions in order to connect with the ISDN 30, and this interface section 32 has a D channel (Dch) interface section 33, B. A channel (Bch) data transmission unit 34 and a Bch data reception unit 35 are connected to each other.

In addition, the Bch data transmission unit 34 has a Bch
The synchronization data generation unit 36 is connected, and the Bch data reception unit 35 is connected to the Bch data synchronization unit 37. B
The ch synchronization data generation unit 36 uses the B1 channel and the B2 channel.
B channel synchronization data for synchronizing the respective data strings of the channel is generated, and the Bch data synchronization unit 37 corrects the received data string.

The respective units 32 to 37 are connected to each other via a common bus 38.
Further, the control unit 39 and the synchronization algorithm storage unit 40 are connected. The control unit 39 controls the composite terminal device 31 as a whole, and includes a synchronization algorithm storage unit 40.
Stores a synchronization algorithm for modifying the data strings in order to synchronize the data strings of the B1 channel and the B2 channel.

In this structure, the terminal device 31 on the transmitting side
When transmission data is sent from the ISDN 30 to the terminal device 31 on the receiving side, the layer 1 interface unit 32
Check the order of the data sequence received in B1 channel and B
Correct the data sequence of 2 channels. Specifically, Bch
The data synchronization unit 37 obtains correction data by delaying each data of the previously received channel by n data, and stores the delayed data in the Bch data storage unit 37a in the Bch data synchronization unit 37.

In order to correct this data string, a synchronization algorithm is stored in the synchronization algorithm storage unit 40, and the Bch data synchronization unit 37 uses this synchronization algorithm to synchronize the data strings of the subsequent B1 channel and B2 channel. I take the. The Bch data storage unit 37a is B
In order to correct the delay difference between channel 1 and channel B2, a data storage capacity that can absorb all the delay differences is secured, and it operates so as to reliably connect to the connected call.

[0010]

However, in this prior art, since it is necessary to delay the data of the channel received first and synchronize it with the data of the channel received late, if the delay difference is large, half duplex will occur. When data communication is performed, there is an inconvenience that throughput deteriorates, and B
Since the amount of data accumulated in the ch data accumulating unit 37a is large, a buffer having a large capacity is required, which causes an inconvenience of high cost.

The present invention solves such a conventional problem, and provides an ISDN communication apparatus which improves throughput in half-duplex data communication and uses a small-capacity and inexpensive buffer. With the goal.

[0012]

A communication device for ISDN according to the present invention is a receiving means for receiving respective data of B1 channel and B2 channel which are divided and transmitted from a partner terminal via ISDN, and synthesize them in synchronization. With I
In the SDN communication device, the receiving means detects the delay difference between the B1 channel and the B2 channel sync signals and detects whether the delay difference between the two channels is within a predetermined allowable value. A delay limiter circuit for detecting and a control unit for instructing the ISDN interface unit to disconnect and reconnect when the delay limiter circuit determines that the delay difference between both channels exceeds a predetermined allowable value.

Therefore, according to the present invention, when a delay difference occurs between the two B channels, the data of the previously received channel is temporarily stored, and the delay difference from the delayed data string of the channel is measured, It is determined whether the delay difference is within the allowable value. If the delay difference exceeds the allowable value, the line is automatically disconnected and a reconnection (retry) operation starts. In most cases, you can connect to a line with a small delay difference,
Throughput can be improved because communication is performed by bundling channels with small delay differences. If the delay difference is within the allowable value, the data of the channel that was previously received and accumulated and the data of the channel that was received later are synchronized and combined to perform communication.

[0014]

1 is a block diagram showing a communication system using an ISDN communication apparatus according to the present invention.
B as the transmission / reception transmission line of the SDN basic interface
It shows a system in which one channel and B2 channel are used at the same time, and image information is divided into a plurality of data and transferred at a transmission rate of 128 Kbps.

In the figure, two ISDN terminal devices 2 and 2 having the same structure are connected to both ends of the ISDN 1 and are configured to transmit and receive data to and from each other through the ISDN 1. In the following explanation, IS
The terminal device 2 (2A) on the left side of the DN 1 will be described as the calling side, and the terminal device 2 (2B) on the right side will be described as the receiving side.

The ISDN terminal device 2 has a terminal adapter 3 connected to the ISDN 1, and a video monitor 5 for displaying image information via the image codec device 4 and an image information are generated on the terminal adapter 3. The video cameras 6 for doing so are respectively connected.
The image codec device 4 encodes and compresses outgoing image information and expands and decrypts incoming image information.

The terminal adapter 3 is an IS according to the present invention.
A division transmission unit that functions as a DN communication device and is activated by the image codec unit 4 and divides image information and sends it to the other party's terminal, and a division reception unit to receive divided data sent from the other party's terminal. Have
The B1 channel and the B2 channel are connected to the other party via ISDN1.

FIG. 2 is a block diagram showing an embodiment of the terminal adapter 3 as the ISDN communication device according to the present invention, and shows only the Bch data receiving means. When the synchronization establishment processing is completed, the synchronization confirmation data and the image data are divided into two pieces of channel data of the B1 channel and the B2 channel and sent out, and are combined into one channel data by this receiving means. At the time of transmission from the terminal adapter 3 on the calling side, the delay amounts in ISDN 1 often differ from each other even if the two channel data are in a predetermined order.

Therefore, first, the operation when the B2ch data received by the ISDN interface unit 11 is delayed with respect to the B1ch data will be described together with the configuration. In this case, the B1ch sync detection unit 12 detects the sync signal of the B1 channel.
The channel sync signal is not detected by the B2ch sync detector 13. Therefore, the Bch data delay difference detection unit 14
It can be detected that the 2ch data is behind the B1ch data.

Next, the Bch data delay difference detection unit 14 determines whether or not the delay difference is within an allowable value by the delay limiter circuit 14a. If the allowable value is exceeded, the control unit 1
5, a circuit disconnection instruction and a reconnection instruction are automatically issued, and the control unit 15 receives this instruction and instructs the ISDN interface unit 11 to disconnect and reconnect.

When the delay limiter circuit 14a determines that the delay difference is within the allowable value, the data storage input / output control unit 16 is activated and the Bch data storage unit 17 is controlled to store the B1ch data via the signal line La. . This makes B
The ch data storage unit 17 stores the data after receiving the synchronization signal of the B1 channel from the ISDN interface unit 11 via the signal line L1.

Thereafter, the B2ch synchronization detector 13 outputs B2c.
When the h synchronization signal is detected, the data storage input / output control unit 1
6, the Bch data storage unit 17 is instructed to sequentially output the stored B1ch data via the signal line Lb. As a result, the B1ch data output from the Bch data storage unit 17 and the B2ch data sent from the ISDN interface unit 11 via the signal line L2 are combined by the switching unit 18.

The switching unit 18 is a data storage input / output control unit 16
Is controlled by a control signal sent from the Bch through the signal line Lc, and when the control signal is logic "1", the B1ch data sent from the Bch data storage unit 17 is selected,
When it is logic "0", it is sent from B via signal line L2.
2ch data is selected, and the image codec device 4 is selected.
To send to.

Next, a case where the B1ch data received by the ISDN interface section 11 is delayed with respect to the B2ch data will be described. In this case, the Bch data delay difference detection unit 14 detects the synchronization detection signal from the B2ch synchronization detection unit 13, but the B1ch synchronization detection unit 12 does not detect the synchronization signal due to the delay in the next cycle. Therefore, the Bch data delay difference detection unit 14
It is possible to detect that the B1ch data is behind the B2ch data.

Next, the delay limiter circuit 14a determines whether or not the delay difference is within the allowable value. If the allowable value is exceeded, a line disconnection instruction and a reconnection instruction are automatically issued to the control unit 15, and the control unit 15 receives this instruction and receives the ISD.
The N interface unit 11 is instructed to disconnect / reconnect.

If the delay difference is within the allowable value, the data storage input / output control unit 16 is activated, and the B2ch signal is sent via the signal line Lb.
The Bch data storage unit 17 is controlled so as to store data. As a result, the ISDN is stored in the Bch data storage unit 17.
Data after receiving the synchronization signal of the B2 channel from the interface unit 11 via the signal line L1 is accumulated.

After that, the B1ch synchronization detector 12 outputs B1c.
When the h synchronization signal is detected, the data storage input / output control unit 1
6 instructs the Bch data storage unit 17 to sequentially output the stored B2ch data via the signal line La. As a result, the B2ch data output from the Bch data storage unit 17 and the B1ch data sent from the ISDN interface unit 11 via the signal line L2 are combined by the switching unit 18.

The switching unit 18 is a data storage input / output control unit 16
Is controlled by a control signal sent from the Bch through the signal line Lc. When the control signal is logic "1", the B2ch data sent from the Bch data storage unit 17 is selected,
When it is logic "0", it is sent from B via signal line L2.
1ch data is selected, and the image codec device 4 is selected.
To send to.

[0029]

According to the present invention, when a transmission delay difference larger than a predetermined allowable value occurs between two received data of B1 channel and B2 channel, the line is automatically disconnected and the reconnection operation is performed. Since the delay difference is limited so as to shift to, in most cases by reconnecting the line,
It becomes possible to connect to a line with a small delay difference, and it is possible to perform communication by bundling channels with a small delay difference.

Therefore, the throughput in the case of performing half-duplex data communication can be improved, and the basic interface I
SDN can be effectively utilized. Further, since the delay difference becomes small, the buffer for temporarily storing the data can be small in capacity and inexpensive.

[Brief description of drawings]

FIG. 1 is a block diagram of a communication system using an ISDN communication device of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of an embodiment of the present invention.

FIG. 3 is a block diagram of a conventional ISDN composite terminal device.

[Explanation of symbols]

 1 ISDN 2 ISDN terminal device 3 terminal adapter (communication device for ISDN) 11 ISDN interface unit 12 B1ch synchronization detection unit 13 B2ch synchronization detection unit 14 Bch data delay difference detection unit 14a delay limiter circuit 15 control unit 16 data storage input / output control unit 17 Bch data storage unit 18 Switching unit

Claims (1)

[Claims] 1. Integrated service digital communication network (ISD)
A communication device for ISDN, comprising: receiving means for receiving and synchronously synthesizing each data of the B1 channel and B2 channel transmitted from the other terminal via N), the receiving means comprising: A delay difference detecting section for detecting a delay difference between the two channels from the respective synchronization signals of the B channel and the B2 channel; a delay limiter circuit for detecting whether or not the delay difference between the two channels is within a predetermined allowable value; and the delay limiter circuit. And a control unit for instructing the ISDN interface unit to disconnect and reconnect the line when it is determined that the delay difference between the two channels exceeds the predetermined allowable value.