JP2001197279A - Real-time Internet facsimile machine - Google Patents

Abstract

(57) [Problem] To provide a real-time type Internet facsimile apparatus in which the number of redundant packets to be added can be set to perform highly reliable communication. SOLUTION: UD is used as a network transport.
The number of redundant packets to be transmitted when using P can be arbitrarily changed during communication so that highly reliable communication can be performed. For example, the number of redundant packets in the image information transmission phase and the number of redundant packets in phases other than the image information transmission phase are set to different numbers, and the number of redundant packets in phases other than the image information transmission phase is set to zero.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a UDP (User Datagram Protocol) in a packet communication network.
The present invention relates to a real-time type Internet facsimile apparatus for transmitting and receiving fax information using l).

[0002]

2. Description of the Related Art In recent years, a communication system for communicating facsimile image information using electronic mail exchanged on the Internet (hereinafter, referred to as a "mail-type Internet facsimile communication system") has come into practical use. .

For such a communication system, IE
TF (Internet Engineering T
Ask Force), an RFC issued by an organization that summarizes technical content related to the Internet.
(Request For Comments) 230
The technical contents are defined by 1-2306.

However, in this mail-type Internet facsimile communication system, since the transmitting facsimile apparatus and the receiving facsimile apparatus do not directly communicate with each other, it is not possible to immediately confirm the communication capability between the facsimile apparatuses. Then, a situation arises in which image information communication using various functions (resolution, image processing capability, etc.) of the facsimile apparatus cannot be performed.

[0005] Further, since the notification of the communication result cannot be performed immediately, it takes time until the communication result is notified to the transmitting user, and the situation where the necessity of retransmission or the like arises is delayed. .

Therefore, as a facsimile communication system using the Internet, a real-time type Internet facsimile communication system for realizing facsimile communication via the Internet in real time has been proposed.

Details of the proposal of such a real-time type Internet facsimile communication system are described in ITU-T Recommendation T. 38 and have been published.

In such a real-time type Internet facsimile communication system, the transmitting real-time Internet facsimile apparatus can perform facsimile communication with a high real-time property with the receiving-side real-time Internet facsimile apparatus. The real-time Internet facsimile device on the sending side can transmit image information according to the communication capability of the real-time facsimile device on the receiving side, and can immediately obtain the communication result. Can be done quickly.

[0009]

The real-time Internet facsimile is a device for transmitting a document similar to a conventional facsimile by IP packet communication on the Internet, and supports both TCP / UDP as a transport. In addition, a procedure for transmitting a redundant packet and performing error recovery when using UDP is defined.

[0010] However, the method of using the redundant packet is not properly defined, causing a communication problem (communication disconnection).

For example, FIG. 6 shows the structure of a UDP packet when the number of redundant packets is four.
The main message having the header is set first, and then up to four transmission packets are attached as redundant packets, and error recovery during image information transmission is performed as shown in FIG.

In FIG. 7, the tenth and twelfth UDP packets are discarded on the network, and the serial number 1 at that time is discarded.
Although the main messages 0 and 12 became errors (they did not reach the partner terminal), the error was recovered by the arrival of the next eleventh and thirteenth packets.

However, simply transmitting the packet with the previous packet added as described above causes a problem of confusion in the protocol as described below.

FIG. 38 shows an example of a communication protocol specified by 38. According to this, if the TSI / DCS packet is lost on the network, the receiving RTifax will retransmit the DIS packet, and the redundant packet will also have the DIS information.

If the CFR packet from the receiving side is lost, the transmitting side retransmits the DCS packet. If the packet is lost, the receiving side retransmits the CFR packet.

However, the redundant packet sometimes has DIS information (which is already unnecessary in phase).
Also, after receiving the EOP packet, the received RTifax is MC
F packet is transmitted, and the content of the redundant packet is CF
May have R or DIS packets.

As described above, error recovery using a redundant packet not only retransmits an extremely meaningless information element, but also has a risk that the entire protocol may be broken.

In addition, the above-mentioned problem is particularly caused by the use of a redundant packet in Recommendation T.30. It becomes noticeable when applied to 30 command sequence parts, and the solution of this part is particularly important.

In the image information transmission / reception phase,
If the UDP packet is discarded in the network, the image information is degraded. If the discarding occurs frequently, there is a problem in that the communication is disconnected.

Although there is no apparent problem when the communication is proceeding normally, from the viewpoint of the load on the entire network,
There is a possibility that unnecessary redundant packets are being transmitted, and the number of redundant packets needs to be optimized.

It is an object of the present invention to provide a real-time Internet facsimile apparatus in which the number of redundant packets to be added can be set so that highly reliable communication can be performed.

[0022]

According to an aspect of the present invention, there is provided a real-time Internet facsimile apparatus which is connected to a computer network and transmits facsimile images by packet communication.
It is characterized in that the number of redundant packets to be transmitted when using P can be arbitrarily changed during communication so that highly reliable communication can be performed.

According to a second aspect of the present invention, the number of redundant packets in the image information transmission phase and the number of redundant packets in phases other than the image information transmission phase are set to different numbers, and the number of redundant packets in the phases other than the image information transmission phase is different. Assuming that the number is zero, Recommendation T. By adding a redundant packet only to the phase C part of No. 30, the risk of protocol breakdown and retransmission of meaningless information is prevented.

According to a third aspect of the present invention, the receiving side transmits the RT
When the N signal is transmitted, the number of redundant packets is increased, and when an error frequently occurs on the receiving side, the number of redundant packets is increased to enhance the error recovery function, thereby enabling good communication. It is characterized by doing so.

The invention according to claim 4 is characterized in that the receiving side receives the MC
When the signal of F is transmitted, the number of redundant packets is reduced, and when no error occurs on the receiving side, the transmission packet is reduced to reduce the load on the entire network. .

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. In the form of real-time type Internet facsimile communication, as shown in FIG.
A so-called gateway type, in which three faxes are connected and communicates directly with the public network (PSTN) via the Internet, and FIG. 2 except for the G3 fax at both ends from FIG.
, Two devices communicate only via the Internet.

1 and 2, the communication protocol on the Internet is the same, and ITU-T Recommendation T. In the communication of the form shown in FIG. 1, various protocols (recommendation T.30) are used to maintain G3 communication at both ends.
The above ingenuity is required.

Therefore, it is first added that the present invention is configured so as to be applicable to any of the embodiments shown in FIGS.

FIG. 3 shows an example of the configuration of an apparatus in which the communication function (direct communication via the Internet) of FIG. 2 is added to a normal G3 fax.

In FIG. 1, a CPU 1 for controlling the entire system, a ROM 2 storing a program of the CPU 1, a RAM 3 serving as a work area and a temporary storage area necessary for the operation of the program, a backup made by a battery, etc. It has an SRAM 4 for storing information to be guaranteed against power interruption, a timer control 5 for managing time of timer control (interrupt) used in the entire system, and the like.

The compression and reproduction of image information is performed by CODEC.
The facsimile uses MH / MR / MMR or the like.

Normally, image information is stored in a hard disk HD8, which is controlled by a hard disk controller HDC7.

In executing the program,
The software interface and the hardware interface with the operation unit are performed by the operation unit i / f9, and the user actually performs operations such as transmission and registration on the operation unit 10.

The image information is read by the scanner 12, and when reading the image information, the software interface and the hardware interface with the scanner 12 are performed by the scanner i / f11.

The printing of the image information is performed by the plotter 14, and when printing the image information, the software and hardware interface with the plotter 14 is performed by the plotter i / f13.

The G3 communication control unit 15 includes a normal CPU / R
OM / RAM etc. are mounted on the main board (1
7) to exchange image information, etc., using a hardware and software interface. Control the protocol according to the 30 procedures.

The network controller 16 has an electrical interface with the PSTN, and the G3 communication controller 15
Communication with the other party's G3 FAX via TN is enabled.

The LAN communication control unit 17 has a normal CPU / R
OM / RAM etc. are mounted on the main board (1
7) to exchange image information, etc., using a hardware and software interface. Control the protocol according to 38 procedures.

Here, a protocol control for Internet access called TCP / UDP / IP protocol is also performed.

The LAN controller 18 has an electrical interface with the LAN, and the LAN communication controller 17 has an LA interface.
N enables communication with the other party's real-time Internet facsimile.

FIG. 38 is an example of a communication protocol specified in 38. The facsimile of FIG.
It is described as fax.

First, the transmission side RTifax is set to the reception side RT
A connection request packet is transmitted to ifax to request a connection, whereby the receiving RTifax transmits a connection confirmation packet to the transmitting RTifax to confirm the call connection.

As a result, a communication path is established between the transmission-side RTifax and the reception-side RTifax, so that the reception-side RTifax complies with the ITU-T Recommendation T.3. 30 (T3) corresponding to 30 predetermined tone signals CED (called station identification signal).
0IND: CED) to the transmitting side RTifax, and a signal (T30IND: F) corresponding to the flag signal.
lag), a group 3 facsimile transmission procedure signal, a signal NSF for notifying an optional transmission function of the own terminal, a signal CSI for notifying an identification signal of the own terminal, and a standard signal of the own terminal. (V21H) corresponding to the signal DIS for notifying the transmission function
DLC: NSF / CSI / DIS) on the transmitting side RTif
ax.

As a result, the transmitting RTifax knows the identification signal and the transmission function of the receiving RTifax.
Based on the notified transmission function, the transmission function and the modem speed to be used at that time are set.

Next, the transmission side RTifax is a group 3 facsimile transmission procedure signal following the signal (T30IND: Flags) corresponding to the flag signal, and uses the signal TSI for notifying the identification signal of its own terminal, and uses it. A signal (V21HDLC: TSI / DCS) corresponding to the signal DCS for notifying the transmission function is transmitted to the receiving RTifax.

When receiving the signal (V21HDLC: TSI / DCS), the receiving RTifax acquires the identification information of the partner terminal (transmitting RTifax) and the transmission function used at that time.

The receiving side RTifax is a group 3 facsimile transmission procedure signal following the signal (T30IND: Flags) corresponding to the flag signal, and a signal corresponding to the signal CFR for notifying that the reception preparation is completed. (V21HDLC: CFR) on the transmission side RTifa
Send to x.

When the preparation for transmitting the image information is completed in this way, the transmission-side RTifax transmits a signal (T30IND: Speed) corresponding to a training (Training) signal for retraining the modem to the reception-side RTif.
ax, and then divides the image data of the transmission image information into a plurality of pieces, and divides each of the divided image information into packet data (in the figure, “V.17 non ECM: Imag”).
e data "is displayed. ) As the receiving RTifax
Send to

When the transmission of the image information is completed, a signal (T30IND: Flags) corresponding to the flag signal is transmitted to the receiving side RTifax, and a signal indicating a group 3 facsimile procedure signal indicating the end of the image information transmission. EOP compatible signals (V21HDLC: E
OP) to the receiving RTifax.

On the other hand, the receiving RTifax receives the signal (T3
0IND: Speed), the process shifts to preparation for receiving image information. When a packet carrying image information is received, divided image information included in the packet is sequentially extracted, combined image information is created, and the image information is created. Are stored in the image storage device 9. In this case, since a signal (V21 HDLC: EOP) is received as a post-transmission signal after receiving the image information, it is confirmed that the image information reception ends.

If the reception result of the image information at that time is good, the reception side RTifax is a group 3 facsimile procedure signal following the signal (T30IND: Flags) corresponding to the flag signal and receives the image information. (V) corresponding to the signal MCF indicating that the
21 HDLC: EOP) to the transmitting side RTifax.

Thus, the transmission-side RTifax recognizes that the image information has been normally received by the reception-side RTifax. Thereafter, the transmission-side RTifax outputs a signal (T30IND: Flags) corresponding to the flag signal, and then a signal (V21HDLC: V21HDLC:
DCN) to the receiving side RTifax.

The receiving RTifax receives the signal (T
30IND: Flags) and signal (V21HDL)
C: DCN), the image information receiving operation ends.

Finally, the transmission side RTifax is:
A disconnection notification packet requesting that the communication path be disconnected is transmitted to the receiving RTifax, and a series of communication operations is completed.

In this manner, the image information is transmitted from the transmission-side RTifax to the reception-side RTifax.

Further, FIG. FIG. 18 is a diagram showing a protocol stack when exchanging a fax image at 38.

Recommendation T. The 30 protocol realizes PSTN access via a PSTN (telephone line) network device such as a modem and a network control device.
Network access is realized via a network driver of an AN (Ethernet or the like). Recommendation H. Three
The 23 call control procedure gives the procedure of the connection request and response packet and the disconnection notification packet shown in FIG.

Then, the protocol is usually implemented as software and written in the ROM 2.

FIG. 6 shows a structure of a UDP packet including a redundant packet, and FIG. 7 schematically shows an error recovery at the time of transmitting image information performed thereby.

The number of redundant packets shown in FIGS. 6 and 7 is four, and a main message having a header with a serial number 45 (actually included in a UDP packet) is set first, and then up to four packets before. Is attached as a redundant packet.

Accordingly, the packet having the serial number 46 is set as the main message in the next UDP packet to be transmitted, and the packets 42 to 45 are attached as redundant packets.

In FIG. 7, the tenth and twelfth UDP packets are discarded on the network, and the main messages of the serial numbers 10 and 12 at that time become an error (a state in which they cannot reach the partner terminal). The error is recovered by the arrival of the thirteenth and thirteenth packets.

A case where the number of redundant packets transmitted when using UDP as a network transport in such a configuration can be arbitrarily changed during communication will be described with reference to FIG.

First, the transmission control instructing unit is activated by the user's transmission operation (step S1). Recommendation T.30 for the signal / image information generator. 30 is generated (step S2), and the redundant packet addition control unit is notified of the number of redundant packets (four in the example of FIG. 7) (step S3).

And, T. The information generated by the signal / image information generation unit is a T.30 signal / image information generation unit which forms a part of a UDP packet.
38 is sent to the main packet generation unit, and 38 (step S
4). It is sent to the 38 UDP packet generator.

Since the main packet is a redundant packet of the next UDP packet, it is also sent to the redundant packet storage unit (step S5).

And, T. To generate the final transmission packet, the 38 UDP packet generation unit queries the redundant packet addition control unit for the number of redundant packets, obtains the required number of packets from the redundant packet storage unit, adds the redundant packets, and adds the UDP packets. It is generated (step S6).

The T.C. 38 UDP
The packet is passed to the network transmission control unit and the UDP
Transmission to the network is performed under the control of the / IP protocol stack (step S7).

The number of redundant packets can be arbitrarily changed during communication by the transmission control instruction unit notifying (changing) the number of redundant packets to the redundant packet addition control unit as appropriate according to the transmission phase during the above processing. Become like

It goes without saying that not only the change during communication but also that the number of redundant packets can be set to an appropriate value, for example, by sending a Ping command before communication and measuring the time until the response message. .

As shown in FIG. 38 UDP
The packet generation unit itself analyzes the protocol phase, and makes a recommendation In cases other than the phase C (image information transfer phase) of 30, the control can be performed so as not to add the redundant packet.

FIG. 9 is a diagram showing the T.D. in FIG. 38UD
5 is a flowchart illustrating an operation of a P packet generation unit.

That is, T. When a main packet is received from the 38 main packet generator (step S11), the presence or absence of phase C information is determined (step S12).

When there is phase C information,
In order to generate a transmission packet as described above, the redundant packet addition control unit is inquired about the number of redundant packets (step S13), the required number of packets are obtained from the redundant packet storage unit, the redundant packets are added, and the UDP packet is added. It is generated (step S14).

The generated T.P. The 38 UDP packet is passed to the network transmission control unit, and the UDP / I
The transmission to the network is performed under the control of the protocol stack of P (step S15).

Thus, the recommendation T. It is possible to control to add a redundant packet only to the phase C portion of the T.30, and it is possible to prevent the danger of protocol breakdown and retransmission of meaningless information.

Note that, as shown in FIG.
The number of redundant packets added when a TN (Retrain Negative) signal is sent may be increased.

FIG. 10 is a flowchart corresponding to FIG. 9, and the information on the conditional branch of the presence or absence of the RTN signal reception response in FIG. 10 is set by the transmission control instruction unit in FIG.

The RTN signal is a signal indicating that the reception of the page has failed when an error frequently occurs on the receiving side. The process returns to phase B of 30 to shift down the communication speed.

In the communication shown in FIG. 2, for example, UDP
When the line (Internet) condition at the time of using the transport is bad and the packet is frequently lost, the RTN signal is transmitted. In the example of FIG. 7, five consecutive UDs are transmitted.
If P packets are lost, one packet will not be recovered.

In the embodiment shown in FIG. 1, the RTN signal is also transmitted depending on the state of the telephone line between the receiving side Gateway and the receiving G3 FAX.

In the case of the embodiment shown in FIG. 1, the downshift of the modem communication speed is effective when the cause of the error is on the telephone line side, but when the cause of the error is on the UDP transport, the downshift is effective. It becomes meaningless.

Therefore, in such a case, in the flowchart shown in FIG. 10, as in the case shown in FIG. 9, redundant packets are not added in information transmission other than the phase C.

On the other hand, if a response is made to the RTN signal in the protocol phase, the number of redundant packets obtained from the redundant packet addition control unit is increased, the number is notified, and the redundant packet is obtained from the redundant packet storage unit. .

That is, in FIG. 38 when a main packet is received from the main packet generator (step S2).
1) The presence or absence of phase C information is determined (step S)
22).

When there is phase C information,
In order to generate a transmission packet, the redundant packet addition control unit is inquired of the number of redundant packets (step S23).
It is determined whether there is a TN signal reception response (step S2).
4).

At this time, if the RTN signal response is received, the error recovery has not been sufficiently performed, so that the redundant packet control unit is notified that the number of packets to be added is to be updated by updating (step S25).

Then, this number of redundant packets is read from the redundant packet storage unit and added to the main packet, and UDP
A packet is generated (step S26).

The T.C. The 38 UDP packet is passed to the network transmission control unit, and the UDP / I
The transmission to the network is performed under the control of the protocol stack of P (step S27).

On the other hand, if there is no response to the reception of the RTN signal in step S24, it is not necessary to change the number of redundant packets to be added.
Proceed to.

If it is determined in step S22 that the information is not the phase C information, the flow directly proceeds to step S27.

As a result, the possibility of error recovery is increased, transmission errors can be avoided, and when errors occur frequently on the receiving side, the number of redundant packets is increased to enhance the error recovery function and perform good communication. It becomes possible.

On the other hand, when the number of added redundant packets is large, as shown in FIG. 11, the number of redundant packets is reduced by the presence or absence of a reception response of an MCF (Message Confirm) signal which is a reception success signal. Is possible. FIG. 11 is a flowchart corresponding to FIG.

That is, in FIG. 38 when a main packet is received from the main packet generator (step S3).
1) The presence or absence of phase C information is determined (step S)
32).

If there is phase C information,
In order to generate a transmission packet, the redundant packet addition control unit is inquired of the number of redundant packets (step S33).
It is determined whether there is a CF signal reception response (step S3).
4).

At this time, if an MCF signal response is received, the error recovery has been sufficiently performed, and the redundant packet control unit is notified that the number of packets to be added is reduced and updated (step S35).

Then, this number of redundant packets is read from the redundant packet storage unit and added to the main packet, and UDP
A packet is generated (step S36).

The T.C. The 38 UDP packet is passed to the network transmission control unit, and the UDP / I
The transmission to the network is performed under the control of the protocol stack of P (step S37).

On the other hand, if there is no MCF signal reception response in step S34, there is no need to change the number of redundant packets to be added.
Proceed to.

If it is determined in step S32 that the information is not the phase C information, the flow directly proceeds to step S37.

As described above, the reduction in the number of redundant packets is based on T.264.
Int means to reduce 38 UDP packets, Int
This has the effect of reducing the network load on the entire ernet.

Although not shown, it goes without saying that the minimum number of redundant packets is "zero".

[0103]

As described above, according to the first aspect of the present invention, the number of redundant packets can be set arbitrarily during communication, so that the number of redundant packets can be optimized. Reliability is improved.

According to the invention of claim 2, the recommendation T. Three
By controlling to add a redundant packet only to the phase C portion of 0, it is possible to prevent the danger of protocol failure and retransmission of meaningless information, thereby improving communication reliability.

According to the third aspect of the present invention, when an error occurs frequently on the receiving side, the number of redundant packets is increased, so that the error recovery function is enhanced so that good communication can be performed. Therefore, communication reliability is improved.

According to the fourth aspect of the invention, when no error occurs on the receiving side, the number of redundant packets is reduced to reduce the number of transmission packets, so that the load on the entire network can be reduced. .

[Brief description of the drawings]

FIG. 1 is a diagram showing a communication mode for directly communicating with a public network via the Internet.

FIG. 2 is a diagram showing a communication mode in which two devices communicate only via the Internet.

FIG. 3 is a block diagram in FIG. 2;

FIG. FIG. 3 is a diagram showing an example of a communication protocol specified by 38.

FIG. FIG. 18 is a diagram showing a protocol stack when exchanging a fax image at 38.

FIG. 6 is a diagram showing a configuration of a UDP packet.

FIG. 7 is a diagram illustrating communication using a UDP packet.

FIG. 8 is a configuration diagram in which the number of redundant packets can be arbitrarily changed during communication.

FIG. 38 is a flowchart in a case where a 38 UDP packet generating unit itself analyzes a protocol phase and adds a redundant packet.

FIG. 10 is a flowchart in a case where the number of redundant packets added by the RTN signal is increased.

FIG. 11 is a flowchart in a case where the number of redundant packets added by the MCF signal is reduced.

[Explanation of symbols]

 1 CPU 2 ROM 3 RAM 4 SRAM 5 Timer control 6 CODEC 7 Hard disk controller HDC 8 Hard disk HD 9 Operation unit i / f 10 Operation unit 11 Scanner i / f 12 Scanner 13 Plotter i / f 14 Plotter 15 G3 Communication control unit 16 Network Control unit 17 LAN communication control unit 18 LAN control unit

Claims (4)

[Claims] 1. connected to a computer network,
A real-time Internet facsimile apparatus for transmitting a facsimile image by packet communication, wherein the number of redundant packets transmitted when using UDP as a network transport can be arbitrarily changed during communication. Facsimile machine. 2. The number of redundant packets in the image information transmission phase and the number of redundant packets in phases other than the image information transmission phase are set to different numbers, and the number of redundant packets in phases other than the image information transmission phase is set to zero. 2. The real-time Internet facsimile apparatus according to claim 1, wherein: 3. The real-time Internet facsimile apparatus according to claim 1, wherein the number of redundant packets is increased when an RTN signal is sent from a receiving side. 4. A real-time Internet facsimile apparatus wherein the number of redundant packets is reduced when an MCF signal is sent from a receiving side.