JPH0449742A - Communication system - Google Patents

Abstract

PURPOSE:To establish inter-terminal communication at the prescribed speed of a terminal by detecting the number of bit errors of a training signal, and outputting the training signal without an error or the training signal on which the error is attached corresponding to a detection result. CONSTITUTION:A controller 23 starts the counting of an error bit outputted from an error detector 26. Thence, when a communication processing means 24 detects the completion of the training signal (TCF signal), it is informed to the controller 23 by using a control line 25. The controller 23 outputs an error-free TCF signal outputted from a TCF signal generator 27 without attaching the error when the count value of the error bit goes less than a certain threshold value. Meanwhile, when the count value of the error bit exceeds the certain threshold value, the error is attached on the TCF signal, and the signal is outputted to the communication processing means 24.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is suitable for use in a communication processing device for a mobile communication system. In particular, the present invention relates to a communication network, a communication processing device disposed between the communication network and the terminal device, or in the terminal device in order to establish communication between terminals at a predetermined communication speed of the communication terminals.

In particular, when performing terminal-to-terminal communication such as G3 facsimile through a communication network with relatively poor transmission quality such as mobile communication,
This relates to a method for communicating without reducing the connection rate.

[Conventional technology]

With the advancement of mobile communication services such as car telephones, there is a growing demand for not only conventional voice telephones but also non-telephone services such as facsimile IIJ.

For example, buyers are already using facsimile IJ to differentiate themselves from other companies.

Conventional communication systems have far inferior transmission characteristics compared to normal telephone lines due to their unique fading, so it is not possible to obtain sufficient reliability by transmitting non-telephone signals as they are. However, good reliability can be ensured by wirelessly transmitting the non-telephone signal after error correction coding. For this purpose, it is conceivable to provide a communication processing device between the terminal device and the wireless transmission system and perform the necessary signal processing there.

FIG. 7 is a block diagram of a conventional communication system. FIG. 8 is a sequence showing the operation of a conventional communication system. In FIGS. 7 and 8, a mobile device 2 and a base station 3 in a mobile communication network 1 are provided with a communication processing device 4.5. The communication processing unit 4.5 captures communication signals between terminals, decodes them, monitors the progress of the communication protocol between terminals, switches the modem used for communication, and also applies error correction codes to signals sent and received via the wireless section. It has means for encoding and decoding. The communication processing device 4 once modulates the analog signal from the terminal 6 using a modem to convert it into a baseband data signal, and subjects it to error correction coding. The mobile device 2 modulates this error correction encoded signal into a signal for radio section transmission and transmits it. In addition, the base station 3 decodes the received signal, performs error correction decoding in the communication processing device 5, converts it into an analog signal in the same format as the signal from the terminal 6 using a modem, and then transmits the signal via the telephone network 8. It is transmitted to terminal 7.

In G3 facsimile communication, before transmitting the image signal, a TCP signal (training signal) is transmitted at the same transmission speed as the image signal.
and check the status of the transmission path. When even one bit of error is detected in the TCP signal, the facsimile on the image sending side lowers the transmission speed to reduce the probability of error occurrence (fall pack).

In addition, when performing G3 facsimile communication, by lowering the transmission speed, it is possible to further increase the redundancy of the error correction code applied to the wireless section, and it is possible to apply an error correction code with strong correction ability. becomes possible.

FIG. 8 shows a normal sequence up to image signal reception when fall pack is performed in G3 facsimile communication. When transmitting an image signal from the facsimile 9 to the facsimile 10 via the mobile communication network 1, the facsimile 10 first transmits a DIS signal 11 indicating a standard function of the receiving facsimile.

During the call, the facsimile 9 transmits DC3C3I2 indicating the setting of the function for the DIS signal, and subsequently transmits the TCP signal 13. If there is even one bit error in the TCP signal 13, the FT indicates a request for retraining.
A T signal 14 is transmitted. The facsimile machine 9 that has received the FTT signal 14 recognizes that it is difficult to ensure sufficient image quality at the current image signal communication speed, and that it is necessary to communicate at a lower speed than the current speed. For this,
The facsimile 9 transmits DC3C3I5 including information on the image signal communication speed at the time of fall pack, and subsequently transmits the TCP signal 16 at this image signal communication speed. TCF signal 16
If there is no bit error, the facsimile 10 transmits a CFR signal 17 indicating completion of reception preparation. C
After receiving the FR signal 17, the facsimile 9 transmits an image signal 18.

[Problem to be solved by the invention]

However, with conventional communication systems like this, the reception level decreases as the density, height, and width of buildings lining the road increases, so even if error correction coding is applied, the reception level will not be received by the terminal. It is difficult to make the signal error-free, and it is normal to tolerate some bit errors. (It is possible to avoid suspension.) Therefore, the lowest communication speed for G3 facsimile image signal communication is 2 or 4 bits/bit/
Errors may occur in the second TCF signal. The lowest communication speed is 2,4 bits/second TCF signal 16
If even one bit error is detected during the transmission, the G3 facsimile disconnects the line because there is no fallback speed. For this reason, when it is desired to transmit image information even if some errors remain in the received image, there is a drawback that the connection rate deteriorates.

An object of the present invention is to provide a communication method that can establish communication between terminals at a predetermined communication speed of the terminals.

[Means to solve the problem]

In the present invention, a plurality of terminals are connected through a communication network, and each terminal has means for selecting one of a plurality of communication speeds according to the state of a transmission path, and a means for selecting one of a plurality of communication speeds based on a training procedure. A communication method comprising: a means for checking whether communication is possible; an error detection device for detecting the number of bit errors in an incoming training signal based on the training procedure; A communication processing device includes a training signal generating means for generating a training signal without an error when the detection result of the error detection device is below a threshold value, and generating a training signal with an error added when the detection result exceeds the threshold value. It is characterized by being equipped.

Further, in the present invention, the communication processing device may be provided within the communication network.

Furthermore, in the present invention, the communication processing device may be provided between the communication network and each of the terminals.

Further, in the present invention, the communication processing device may be provided in each of the terminals.

[Effect]

The communication processing device uses an error detection device to detect the number of bit errors in the training signal transmitted from the other party's terminal based on the training means. The training means generates an error-free training signal when the selected communication speed is the lowest and the detection result of the error detection device is below a threshold;
When the value is below this threshold, a training signal with added errors is generated. Through the above operations, communication between terminals can be established at the predetermined communication speed of the terminals.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings. 1st
The figure is a block configuration diagram of a communication processing device of a communication system according to a first embodiment of the present invention. FIG. 2 is a sequence showing the operation of the communication system of the present invention. In FIGS. 1 and 2, the communication system is such that a plurality of terminals are connected by a mobile communication network 1 and a telephone network 8 as a communication network, and each terminal's facsimile machine 9.10 is connected to a plurality of It includes means for selecting one of the communication speeds, and means for checking whether communication is possible at the selected communication speed based on a training procedure.

Here, the features of the present invention include an error detection device 26 that detects the number of bit errors in an incoming training signal based on the above-mentioned training procedure; The controller 23 and the TCP signal generator 27 are used as a training signal generating means that generates an error-free training signal when the detection result is below a threshold value, and generates an error-added training signal when the detection result exceeds the threshold value. The communication processing device 19 and 20 including the communication processing device 19 and 20 are provided.

The communication processing devices 19 and 20 also include a communication processing means 24 that monitors the conventional terminal-to-terminal communication protocol and decodes the signal within the mobile communication network 1 with a correction code.

The operation of the communication system having such a configuration will be explained.

In FIG. 2, when an image signal is transmitted from a facsimile 9 to a facsimile 10 via a mobile communication network 1 having communication processing devices 19 and 20, the facsimile 10 first transmits a DIS signal 11 indicating a standard function of a receiving facsimile. Send. The facsimile 9 that received the DIS signal 11 transmits DC3C3I2, and then transmits the TCP signal 13.
Send. Communication processing unit E: 20 is the receiving DC3C3
When the image signal communication speed information in I2 is other than the lowest communication speed of 63, 2 or 4 bits/sec, the facsimile 1O transmits the TCP signal 13 to the facsimile 10 as usual. If a bit error is detected, an FTT signal 14 indicating a request for retraining is transmitted.

The facsimile 9 that received the F T T signal 14 sends the DC3C3I5 which includes information on the image signal speed at the time of fall hacking.
, and then send a TCP signal 16 at this image signal communication speed.
Send.

The communication processing device 20 determines that the received image signal communication speed information at the time of fall hacking of the DC3C3I5 is 2.4 bits/bit/
If the TCP signal 16 that is subsequently received is not transmitted to the facsimile machine 10, the communication processing device 20 transmits the TCP signal 16
The number of bit errors in the F signal 16 is counted 2, and if the number of bit errors is less than a certain threshold value, the quality of the received image is judged to be acceptable, and the TCP signal 2 containing no errors is determined.
1 and sends a TCP signal 21 to facsimile January 0.

On the other hand, if the number of errors in this bin exceeds a certain threshold, it is determined that the quality of the received image is unacceptable, and a TCP signal containing the error is transmitted to the facsimile 10, causing the G3 facsimile to disconnect the line.

In FIG. 1, the communication processing means 24 takes in and decodes the digital input signal from the connection terminal 22 that is input through the control device 23, and this input signal is DC3C10 and the communication speed of the image signal is expressed as DC3C10 information. When realizing that the G3 facsimile E IJ's lowest image signal communication speed is 2 or 4 bits/sec, the DC5
When the TCP signal inputted next to the signal is detected, this is notified to the control device 23 using the control line 25. The control device 23 prevents the communication processing device 24 from outputting this TCP signal, and starts counting the error bits output from the error detection device 26. Next, when the communication processing means 24 detects the end of this TCP signal, the control line 2
5 to notify the control device 23 of this.

If the count value of error bits is less than a certain threshold value, the control device 23 outputs the error-free TCP signal outputted from the TCP signal generator 27 to the communication processing means 24 without adding any error, and performs communication. The processing means 24
After converting the CF signal to an analog signal that can be received by a facsimile machine, 1. Output to the connection terminal 28.

j5, when the count value of error bits exceeds a certain threshold value, T is output from the TCP signal generator 2T.
(An error is added to the TCP signal and output to the communication processing means 24, and the communication processing means 24 converts this TCP signal into an analog signal that can be received by the facsimile machine 10 and outputs it to the connection terminal 28. Furthermore, the control!iI device 23 , after the output of this TCF signal is completed, the input signal from the connection terminal 22 is output as is to the communication processing means 24. Note that the connection terminal 28
All signals inputted from the communication processing means 24 and the control device 23 are outputted to the connection terminal 22 as they are without processing other than those associated with normal functions.

FIG. 4 is a sequence showing the operation of the communication system according to the second embodiment of the present invention, and is a sequence up to image signal reception when fall bank is performed in G3 facunmile communication to which the system of the present invention is applied.

In FIG. 4, when transmitting an image signal from the facsimile 9 to the facsimile 10 via the communication processing devices 29 and 30, the facsimile 10 first transmits the DIS signal 11 indicating the standard function of the receiving facsimile IJ. The facsimile 9 that has received the DIS signal 11 transmits DC3C3I2 indicating the setting of the function for the DIS signal 11, and subsequently transmits the TCF signal 13.

The communication processing device 30 transmits the TCP signal 13 to the facsimile 10 when the image signal communication speed information in the received D'C3 signal 12 is other than 2 or 4 bits/sec, which is the lowest communication speed of the 03 facsimile. Send as usual.

Facsimile month 0 is FTT signal 1 which indicates a request for retraining when a bit error is detected in TCP signal 13.
Send 4. The facsimile machine 9 that received the FTT signal 14 sends a DC signal containing information about the image signal speed at the time of fall pack.
3C3I5 and then TC at this image signal communication speed.
P signal 16 is transmitted.

The communication processing device 30 determines that the received image signal communication speed information at the time of fallback of the DC3C3I5 is 2.4 bits/bit/
If the TCP signal 16 that is subsequently received is not sent to the facsimile 10, the communication processing device 30 transmits the TC
The number of bit errors in the F signal 16 is counted, and if the number of bit errors is less than a certain threshold, it is determined that the quality of the received image is acceptable, and a TCP signal containing no errors is generated. is sent to facsimile 10. On the other hand, when the number of bit errors exceeds a certain threshold, it is determined that the quality of the received image is unacceptable, and a TCP signal containing the error is transmitted to the facsimile IO, causing the G3 facsimile to disconnect the line.

FIG. 3 is a block diagram of a communication processing device of a communication system according to a second embodiment of the present invention.

In FIG. 3, 23 is a control device, 24 is a communication processing means having means for monitoring a conventional terminal-to-terminal communication protocol and means for encoding and decoding an error correction code, 25 is a control line;
27 is a TCP signal generator, 26 is an error detection device, 32
3 is a connection terminal on the communication network side, 33 is a modem, and 34 is a connection terminal on the terminal side.

The analog human input signal from the connection terminal 32 is once demodulated into a digital signal using the modem 33, and is input to the communication processing means 24 through the control device 23. The communication processing means 24 takes in and decodes this digital input signal, and determines that this input signal is a DC3 signal and that the image signal communication speed is the lowest image signal communication speed of C3 facsimile. , 4 bits/second, and detects the TCP signal inputted next to the DC3 signal, this is notified to the control device 23 using the control line 25.

The control device 23 prevents the communication processing means 24 from outputting this TCP signal, and starts counting the error bits output from the error detection device 26.

Next, when the communication processing means 24 detects the end of this TCP signal, it notifies the control device 23 of this using the control line 25.

If the count value of error bits is less than a certain threshold value, the control device 23 outputs the error-free TCP signal outputted from the TCP signal generator 2'7 to the communication processing means 24 without adding an error. The communication processing means 24 converts this signal into an analog signal that can be received by the terminal, and then outputs it to the connection terminal 34.

On the other hand, if the count value of error bits exceeds a certain threshold, the TC output from the TCP signal generator 27 is
An error is added to the P signal and output to the communication processing means 24, which converts this signal into an analog signal that can be received by the terminal and outputs it to the connection terminal 34. Furthermore, after the output of this TCP signal is finished, the control device 23 passes the input signal from the modem 33 to the communication processing means 24 as it is.

Note that all signals input from the connection terminal 34 are output to the connection terminal 34 as they are without being processed by the communication processing means 24, the control device 23, and the modem 33 other than those associated with normal functions.

FIG. 6 is a sequence showing the operation of the communication system according to the third embodiment of the present invention, and is a sequence up to image signal reception when fall pack is performed in G3 facsimile communication to which the system of the present invention is applied.

In FIG. 6, when transmitting an image signal from facsimile 37 to facsimile 38 using facsimile machines 37 and 38 having communication processing devices 35 and 36, facsimile machine 38 first uses DIS, which indicates the standard function of a receiving facsimile machine.
Send signal 11. The facsimile 37 that has received the DIS signal 11 transmits DC3C3I2 indicating the function setting for the DIS signal 11, and then transmits the TCP signal 13.

The communication processing device 36 transmits the TCP signal 13 to the facsimile 38 when the image signal communication speed information in the received DC5 signal 12 is other than 2 or 4 bits/sec, which is the lowest communication speed of the 63 facsimile IJ. Send as per.

When the facsimile 38 detects a bit error in the TCF signal 13, it sends an FTT signal 1 indicating a request for retraining.
Send 4. The facsimile 37 that received the FTT signal 14 sends a DC signal containing information about the image signal connection room at the time of fallback.
3C3I5 and then TC at this image signal communication speed.
P signal 16 is transmitted.

The communication processing device 36 determines that the received image signal communication speed information at the time of fallback of the DC3C3I5 is 2.4 bits/bit/
If the TCP signal 16 that is subsequently received is not sent to the facsimile 38, the communication processing device 36 transmits the TC
The number of bit errors in the F signal 16 is counted, and if the number of bit errors is less than a certain threshold, it is determined that the quality of the received image is acceptable, and a TCP signal containing no errors is generated. is sent to facsimile 38. On the other hand, when the number of bit errors exceeds a certain threshold, it is determined that the quality of the received image is unacceptable, and a TCP signal containing the error is transmitted to the facsimile 38, causing the G3 facsimile to disconnect the line.

FIG. 5 is a block diagram of a communication processing device of a communication system according to a third embodiment of the present invention. In FIG. 5, 23 is a control device, 24 is communication processing means having means for monitoring a conventional terminal-to-terminal communication protocol and means for performing error correction coding/decoding, and 25
27 is a control line, 27 is a TCP signal generator, 26 is an error detection device, 40 is a connection terminal on the communication network side, and 41 is a connection terminal in the terminal.

The communication processing means 24 receives and decodes the analog human input signal from the connection terminal 40, and determines that this input signal is DC3C12 and that the image signal communication speed is the lowest image signal communication speed of 63 facn mm2. , 4 bits/second, and detects the TCP signal inputted next to the DC5 signal, this is notified to the control device 23 using the control line 25. The control device 23 prevents this TCP signal from being output to the connection terminal 41, and starts counting the error focus output from the error detection device 26. Next, the communication processing means 24
When FCF3I completion is detected, this is notified to the control device 23 using the control line 25.

When the count value of error bits is less than or equal to a certain threshold value, the control device 23 outputs the error-free TCP signal outputted from the TCP signal generation device 27 to the connection terminal 41 without adding any error.

On the other hand, if the count value of error bits exceeds a certain threshold, the TC output from the TCP signal generator 27 is
An error is added to the P signal and output to the connection terminal 41. Further, after the output of this TCP signal is finished, the control device 23 allows the input signal from the communication processing means 24 to pass through the connection terminal 41 as it is. Note that all signals manually input from the connection terminal 41 are output to the connection terminal 40 as they are without being processed by the control device 23 and the communication processing means 24 other than those associated with normal functions.

In the quantum explanation, assume that the facsimile is a 63-inch model and the minimum image signal communication speed is 2.4 bits/second! ,) but (
It is clear that the present invention can be applied to facsimiles other than J3, that is, facsimiles whose minimum image signal communication speed is 2.4 bits/sec.

〔Effect of the invention〕

As described above, the present invention has an excellent effect of being able to establish communication between terminals at a predetermined communication speed of the communication terminals. Particularly, when performing terminal-to-terminal communication such as G3 facsimile through a communication network with relatively poor transmission quality such as mobile communication, there is an advantage that communication can be established without reducing the connection rate.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram of a communication processing device of a communication system according to a first embodiment of the present invention. FIG. 2 is a sequence diagram showing the operation of the communication system according to the first embodiment of the present invention. FIG. 3 is a block diagram of a communication processing device of a communication system according to a second embodiment of the present invention. FIG. 4 is a sequence diagram showing the operation of the communication system according to the second embodiment of the present invention. FIG. 5 is a block diagram of a communication processing device of a communication system according to a second embodiment of the present invention. FIG. 6 is a sequence showing the operation of the communication system according to the second embodiment of the present invention. FIG. 7 is a block diagram of a conventional communication system. FIG. 8 is a sequence showing the operation of a conventional communication system. 1...Mobile communication network, 2...Mobile device, 3.
・Base station, 4.5.19.20.29.30.35.3
6... Communication processing device, 6.7... Terminal, 8... Telephone network, 9.10.37.38... Facsimile, 11
...DIS signal, 12.15...DC3C1213
,16,21,31,39...TCFCF3I4...
- FTT signal, 17... CFR signal, 18... Image signal, 22.28.32.34.40.41... Connection terminal, 23... Control device, 24... Communication processing means, 2
5... Control line, 26... Error detection device, 27...
TCF signal generator, 33...modem. Patent Applicant Nippon Telegraph and Telephone Corporation Agent Patent Attorney Nao Takashi Ide Conventional Case Nokenosu 8 l Ryo

Claims (1)

[Claims] 1. A plurality of terminals are connected by a communication network, and each terminal has means for selecting one of the plurality of communication speeds according to the state of the transmission path, and a means for selecting one of the plurality of communication speeds based on a training procedure. a means for checking whether communication is possible at a selected communication speed; training signal generating means for generating a training signal with no errors when the detection result of the error detection device is below a threshold value and generating a training signal with added errors when the detection result exceeds the threshold value. A communication method characterized by comprising a communication processing device. 2. The communication system according to claim 1, wherein the communication processing device is provided within the communication network. 3. The communication system according to claim 1, wherein the communication processing device is provided between the communication network and each of the terminals. 4. The communication system according to claim 1, wherein the communication processing device is provided within each of the terminals.