JPH09153995A - Communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication equipment in which a transmission error is corrected while the correction reflects on intention of both a transmitter side and a receiver side. SOLUTION: A transmitter side acquires a trial limit count for transmission error correction set by a receiver side in D-channel communication (T2). Furthermore, the transmitter side sets a new trial limit count based on the trial limit count set to itself and the trial limit count of the receiver to be acquired (T4). When the number of times of reception of a frame re-transmission request reaches the trial limit count for a period when transmission of one page is conducted (T7), line interrupt processing is conducted (T1).

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 transmitting information, such as a facsimile device.

[0002]

[Prior Art] ITU (International Telecommunicati
on Union) -T Recommendation defines the transmission procedures that G3 / G4 facsimile machines should follow. Recommendation T. 30 is
It defines the procedure for document facsimile transmission on the general exchange telephone network. Recommendation T. Annex C of 30 further defines a group 3 document facsimile transfer procedure on ISDN (Integrated Services Digital Network).

According to this, correction of a message transmitted from a transmitting device to a receiving device is defined as follows. That is, if the message is not properly received by the receiving device, the receiving device receives PPR (partial page request).
Send a signal to request a frame that needs to be retransmitted. Upon receiving the PPR signal, the transmitting device retransmits the requested frame. The number of attempts to correct the page is not defined and is determined by the transmitter. That is, if the transmitter is considered to have made a sufficient number of attempts, the transmitter sends a DCN (disconnect command) signal, which releases the call.

[0004]

However, in the above procedure, the transmitter side unilaterally determines the number of trials, so that the intention of the receiver side is not taken into consideration. For example,
It is considered that the number of times a frame is retransmitted increases when the line condition is poor. In such a case, if it is preferable to immediately release the line, re-establish the line connection, and perform communication in a good connection state, it is better to set the number of trials to be small. In addition, it is preferable to set a large number of trials if it is desirable to achieve complete communication as much as possible even when the line condition is poor. However, since the intention of the transmitting side and the intention of the receiving side do not necessarily match, communication may be performed in a manner that does not follow the intention of the receiving side in the above-described technique.

Therefore, an object of the present invention is to solve the above technical problems and to provide a communication device capable of performing transmission error correction reflecting the intentions of both the transmitting side and the receiving side.

[0006]

To achieve the above object, a communication apparatus of the present invention is provided with another communication apparatus in which a trial limit number for correcting a transmission error is set, through a predetermined communication line. A communication device for communication, means for obtaining the trial limit number from the other communication device, and means for determining a new trial limit number for transmission error correction based on the obtained trial limit number And a means for stopping communication with the other communication device in response to the number of trials for transmission error correction reaching the new trial limit number.

According to the above arrangement, the transmission error correction trial limit number set in the communication partner apparatus is acquired. Then, a new trial limit number can be set in consideration of the acquired trial limit number. Therefore, the trial limit number of times is set in consideration of the intentions of both the transmitting side and the receiving side.

[0008]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing the basic configuration of a facsimile apparatus which is a communication apparatus according to an embodiment of the present invention. This facsimile machine is a group 3 machine compatible with document transmission via an ISDN network, and has a main control unit 30 as a control center. The main controller 30 is composed of a microcomputer including a CPU.

The document to be transmitted is optically read by the reading unit 31 and converted into image data. This image data is subjected to predetermined image processing such as compression coding by the image processing unit 32 and converted into a transmission code. This transmission code is sent from the line 33 to the ISDN network via the network interface unit 34. When the memory transmission function is used, the image data from the reading unit 31 is temporarily stored in the image memory unit 37, and then the image processing unit 3 is used.
2 is encoded and transmitted.

On the other hand, the received code from the ISDN network is input from the line 33 to the image processing section 32 via the network interface section 34. The image processing unit 32 expands and decodes the received code to restore the original image data. The restored original image data is given to the printing unit 35 and recorded on the paper. When the memory reception function is used, the received code is temporarily stored in the image memory 37. When recording the accumulated image, the reception code is read from the image memory 37, and the reception code is subjected to the decoding process by the image processing unit 32.

The facsimile number and the like of the transmission destination can be input from the operation display unit 36. The operation display unit 36 is
A numeric keypad for inputting a facsimile number of a communication partner, a start key for instructing the start of facsimile communication, and a display unit for displaying the input facsimile number and other messages. The facsimile device further includes a D channel communication control unit 39 and a B channel communication control unit 40. The D channel communication control unit 39 performs protocol control on the D channel, which is a control channel. The B channel communication control unit 40 performs protocol control on the B channel which is an information channel.

The facsimile number and the like of its own station are stored in the system memory 38. In the system memory 38,
Further, the transmission error correction trial limit number N is a partial area 3
8a. Further, a retransmission counter area 38b for counting the number of transmission error correction attempts (retransmission count value) C is provided. In the following description, the transmission error correction trial limit number set in the transmission side facsimile apparatus is represented as N (T), and the transmission error correction trial limit number set in the reception side facsimile apparatus is N (T). R).

FIG. 2 is a flow chart for explaining the operation of the facsimile apparatus when transmitting an image. When the original is set in the reading unit 31, the facsimile number of the communication destination is input, and the start key of the operation display unit 36 is operated, the main control unit 30 first sets the retransmission count value C to “0”. (Step T1). Then, the D channel communication control unit 39 performs D channel protocol control (step T2). At this time, the D channel communication control unit 39 transmits a call setting message SETUP. The call setup message SETUP may include user / user information UUI, which is arbitrary information to be transmitted to the communication destination. Therefore, the main control unit 30 controls the D channel communication control unit 39 so that the UUI includes a command for requesting the transmission of the transmission error correction trial limit number N (R) set in the receiving side device. Control.

Upon receiving the SETUP including the transmission request command of the trial limit number N (R), the receiving side facsimile machine reads the trial limit number N (R) from the area 38a in the system memory 38, and then, through the ISDN network. Send to the sending device. In this case, the receiving side apparatus gives the trial limit number N (R) to the transmitting side by setting the content of UUI that can be included in the connect signal CONN as the trial limit number N (R).

Following the communication of the B-channel control information (step T3), the transmitting-side facsimile device continues the trial limit N (R) of the receiving-side facsimile device acquired by the D-channel communication and its own system memory 38. A new trial limit number NS is defined based on the trial limit number N (T) stored in the area 38a (step T
4).

Specifically, for example, the smaller value of the trial limit times N (T) and N (R) of the transmitting side and the receiving side may be set as the new trial limit number NS. In this way, when the line condition is bad, the line can be released promptly. Also, the number of trials N (T) and N
The larger value of (R) is set as the new trial limit number NS
It may be. In this way, since the transmission error can be corrected as much as possible without releasing the line, the possibility of complete communication is increased even when the line state is bad.

Furthermore, each trial limit number of times N (T) and N
The average value of (R) may be set as the new trial limit number NS. When the new trial limit number NS is determined in this way, the image data is transmitted for each partial page (step T5). In the case of full-duplex communication, a plurality of partial pages forming a page are transmitted.

When there is an error in the received partial page, the receiving side facsimile device specifies the frame number and sends a partial page request signal PPR. Therefore, the transmitting side determines whether or not the partial page request has been received (step T6). If there is no partial page request, it is determined whether there is untransmitted image data (step T10). If there is untransmitted image data, the process from step T5 is repeated. When there is a partial page request, it is further determined whether or not the retransmission count value C is smaller than the new error correction trial limit number NS (step T7). When the retransmission count value C is less than the error correction trial limit number N, the designated frame of the partial page for which a retransmission request is made is retransmitted (step T8), and the retransmission count value C is incremented by +1 (step T9). ). Then, if there is untransmitted image data, the process returns to step T5.

When there is no untransmitted image data, it is judged again whether or not there is image data that needs to be retransmitted (step T11). If retransmission is necessary, the process returns to step T8. This makes it possible to further retransmit the partial page in which a transmission error has occurred due to the retransmission in step T8. If there is no image data that needs to be retransmitted, line disconnection processing is performed (step T12), and the transmission processing ends.

When the retransmission count value C reaches the newly set trial limit number NS (step T7), the line disconnection process (step T12) is immediately performed to release the line. It should be noted that the retransmission count value C is preferably initialized to “0”, for example, every time transmission of an image of one page is completed. In this case, the trial limit number NS defines the allowable number of retransmissions during the transmission of the image of one page.

As described above, according to this embodiment, the transmission error correction trial limit number N (R) set on the receiving side is acquired by the D channel communication. Then, on the transmitting side, the trial limit number N (T) set in the local station and the acquired trial limit number N (R) on the receiving side are acquired.
Based on and, a new trial limit number of times NS is determined. Therefore, this new trial limit number NS has a value reflecting the intention of the receiving side. Therefore, in the operation of correcting the transmission error, the intentions of both the transmitting side and the receiving side can be reflected.

FIG. 3 is a flow chart for explaining the second embodiment of the present invention. In the description of this embodiment, FIG. 1 described above will be referred to again. Since the present embodiment is mainly characterized in the operation on the receiving side, FIG. 3 shows the operation of the facsimile apparatus at the time of reception. Specifically, in the present embodiment, the receiving-side facsimile device determines the transmission error correction trial limit number NS.

More specifically with reference to FIG. 3,
First, the main control unit 30 initializes the retransmission count value C to "0" (step R1). Then, D channel communication is performed (step R2). At this time, the transmitting side facsimile device includes the transmission error correction trial limit number N (T) set in the transmitting side facsimile device in the UUI in the call setting message SETUP. As a result, the receiving side facsimile apparatus can acquire the trial limit number of times N (T) set on the transmitting side.

Communication of B channel control information (step R
Subsequent to 3), the main control unit 30 reads the trial limit number (R) stored in the area 38a in the system memory 38 of the receiving side facsimile device. Then, based on the read trial limit number (R) and the transmission side trial limit number N (T) acquired by the D channel communication,
A new trial limit number NS is set (step R4
A). The new trial limit number NS may be determined in the same manner as in the case of the first embodiment.

When the image data is received (step R4
B) It is determined whether or not the received partial page has an error (step R5). If there is an error, the retransmission count value C is compared with the newly set trial limit number NS (step R6). When the retransmission count value C is less than the trial limit number NS, the partial page request signal PPR is transmitted (step R7), and the transmitting side is requested to retransmit the frame of the partial page. Then, the retransmission count value C is incremented by +1 (step R8). Then, it is determined whether there is data to be received (step R9). This determination is made based on the control signal sent from the transmitting side. If there is no data to be received, the line is disconnected (step R10). If there is data to be received, step R4
Return to B.

If it is determined in step R5 that the received partial page has no error, the process proceeds to step R9. On the other hand, when it is determined in step R6 that the retransmission count value C has reached the trial limit number NS, it is determined that the line state is bad, and the line disconnection process (step R1
0) is performed. It should be noted that the retransmission count value C is preferably initialized to "0", for example, every time reception of one page is completed, as in the case of the first embodiment.

As described above, according to this embodiment, the trial limit number N (T) set on the transmitting side is transmitted to the receiving side. At the receiving side, the trial limit times N (T) and N set at the transmitting side and the receiving side, respectively.
A new trial limit number NS taking into consideration (R) is determined. Then, the number of partial page retransmission attempts is monitored in the receiving side device, and when the number of retransmission attempts exceeds the trial limit number NS, line disconnection processing is performed. With such a configuration, the same effect as in the case of the first embodiment can be obtained. Further, in the present embodiment, it is not necessary to send the trial limit number of times from the receiving side to the transmitting side, and therefore, there is also an advantage that the preprocessing of communication becomes simpler than in the first embodiment.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, in the above embodiment, the case where the information transmission is performed in full duplex is taken as an example, but the information transmission may be performed in half duplex. In this case, every time a partial page is transmitted from the transmitting side, the reception side waits for a reception confirmation or a retransmission request from the receiving side. Therefore, the error correction trial limit number may be set for the same partial page.

Further, in the above-described embodiment, the trial limit number of transmission errors is transmitted from one device to the other device using SETUP or CONN which is a D channel control signal. Information can also be transmitted using B channel signals. B channel signals that can be used for such purposes include, for example, NSC (non-standard function command signal), NSF (non-standard function identification signal) and NSS (non-standard function setting signal).

Furthermore, in the above description of the embodiment, an example in which the present invention is applied to a facsimile device has been shown, but the present invention can be applied to any communication device for data transmission. In addition, it is possible to make various design changes within the technical scope described in the claims.

[0031]

As described above, according to the present invention, a new trial limit number is determined in consideration of the trial limit number acquired from the device of the communication partner, so that the intentions of both the transmitting side and the receiving side are determined. It is possible to set the maximum number of trials that can be considered. This makes it possible to perform a transmission error correction operation that sufficiently reflects the intentions of the transmitting side and the receiving side.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of a facsimile apparatus which is a communication apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the transmission side apparatus according to the first embodiment.

FIG. 3 is a flowchart for explaining an operation of a receiving side apparatus according to the second embodiment.

[Explanation of symbols]

 30 main controller 38 system memory 38a area in which trial limit number of times is stored 38b retransmission counter area 39 D channel communication controller

Claims (1)

[Claims] 1. A communication device for communicating via a predetermined communication line with another communication device in which a trial limit number for correcting a transmission error is set, the trial limit being sent from the other communication device. A means for obtaining the number of times, a means for determining a new trial limit number for transmission error correction based on the obtained trial limit number, and a trial number for the transmission error correction reaching the above new trial limit number. And a means for terminating communication with the other communication device in response to the request.