JPS6022837A - Picture data transmission system for mobile communication - Google Patents

Abstract

PURPOSE:To attain the mobile communication picture data service through the use of an existing picture data teminal device by providing a special adaptor to mobile terminal devices and an exchange and allowing the adaptors to transmit a signal in a special signal form among them. CONSTITUTION:The adaptor 3 is provided to the mobile terminals and the adaptor 8 is provided also to the exchange. Picture data information is transmitted between a facsimile terminal device 2 and the adaptor 3 and between the adaptor 8 and a facsimile terminal device 13 by the signal form decided for picture data communication terminal devices. A signal is transmitted between the adaptors 3 and 8 by performing processing such as addition of an error correction code, change of the order of information transmission by means of the interleaving system and signal retransmission by means of the re-transmission system.

Description

[Detailed Description of the Invention] Technical Field of the Invention The present invention relates to image data communication services such as facsimile services used in landline telephones in public mobile communications such as marine telephones and car telephones. The present invention relates to an image data transmission method for mobile communication using a terminal device as is.

Background of the Technology In mobile communication services, the signal error rate is poor due to factors such as fading of wireless lines, so it is extremely difficult to use facsimile terminals used in landline telephones continuously.

Prior Art and Problems In image data communication services in conventional mobile communication services, it is necessary to stop a mobile object at a location with good radio waves to perform facsimile services. In the case of domestic ship telephones, facsimile signals interfered with the control signals of the ship telephone, making them completely unusable.

Purpose of the Invention In order to solve these drawbacks, the present invention aims to develop a new signal for wireless lines that is resistant to signal errors and does not interfere with signals already used for control in mobile communications. It is designed to use the method,
The drawings will be explained in detail below.

Embodiments of the Invention In the following embodiments, a facsimile terminal will be described as an image data terminal.

FIG. 1 shows an embodiment of the present invention, in which 1 is a telephone on the mobile terminal side, 2 is a facsimile terminal, 6 is a adding device, 4 is a mobile terminal, 5 is a wireless base station, 6 is a bidirectional trunk, and 7 is a A mobile communications exchange, 8 an additional device, 9 an outgoing trunk, 10 an additional device, 11 a general telephone network relay exchange, 12 a subscriber line exchange, 15 a facsimile terminal, and 14 a telephone set.

Figure 2 is an existing facsimile! This is a signal sequence assuming one JG aircraft. A case will be described in which an image is transmitted from the facsimile terminal 2 on the mobile terminal side to the facsimile terminal 15 on the fixed telephone network.

In FIG. 1, when the telephone number of the fixed telephone 14 is dialed from the telephone 1, the mobile terminal 4. Source trunk 9
．． Trunk exchange 11. A telephone line is set up via the subscriber line exchange 12 to the telephone set 14 in the usual manner. telephone 1
In order to perform facsimile service after communication is possible with 14 and 14, the telephone 1 performs litzking, and the softening signal is detected by the mobile communication exchange 7, and the mobile communication exchange 7 connects the two-way trunk 6 and the additional equipment. 8. A connection is made to the route of the outgoing trunk 9, and a line via the access device 8 is set up. Next, when the document is inserted into the facsimile terminal 2 and the communication button of the facsimile terminal 2 is pressed, the additional device 5 disconnects the telephone 1 and connects only to the facsimile terminal 2. On the other hand, when the communication button on the facsimile terminal 16 is pressed, the telephone 14 is disconnected, the facsimile terminal 16 is connected, and the facsimile mode is set.

The following signal transmission and reception will be explained based on the signal sequence of the G11l group shown in FIG. Assuming that the facsimile terminal 2 is on the sending side and a document is set, the facsimile terminal 16 sends out a group identification signal. When this group identification signal is received by the additional device 8, the additional device 8 sends the group identification signal to the additional device 6 in a signaling format (in this case, for example, a digital signal) that is different from the signaling method used in facsimile. Send. When the additional device 3 receives the group identification signal, it converts it back into the signal format used by the facsimile terminal and sends it to the facsimile terminal 2. (The original signal and the converted signal are each indicated by a solid 9-dot line.) When the Buaximi 9 terminal 2 receives the converted signal, it sends out a group command signal. This group command signal, like the group identification signal, is converted by the additional device 3 into, for example, a digital signal and sent to the additional device. The additional device 8 converts the signal again into the signal format used by the facsimile terminal and sends it to the facsimile terminal 1.
Send to 5. Subsequently, the phase signal and reception preparation completion confirmation signal are similarly converted by the additional devices 3 and 8 and sent and received between the facsimile terminals 2 and 16. Next, an image signal is sent from the facsimile terminal 2, and when the sending of the image signal is finished, a message end signal and a message end confirmation signal are sent and received between the facsimile terminals 2 and 15, and facsimile communication ends. Next, the image signal transmission method will be explained. FIG. 6 is a block diagram of an embodiment of the addition device 3, and FIG. 1f44 is a block diagram of an embodiment of the addition device 8. In FIG. 6, 61 is a hybrid circuit, 32 is a selector switch, 55, 54 is a modem, 35 is a percentage board, 66 is a processing unit, and 67 is a memory. In Figure 4, 41.42 is the changeover switch, 43.44 is the modem, 45 is the % port, and 4
6 is a processing device, and 41 is a memory.

When transmitting a facsimile, selector switches 32 and 4
1.42 is switched to the lower side. The signal from the facsimile terminal 2 on the mobile side is transmitted to the hybrid circuit 61 .
Modem 66, A-Boat! When the +5 signal is received by the processing device 66, it is converted into a signal format suitable for the wireless line, and the %
Boat 35. Modem 34. It is sent to the mobile terminal 4 via the changeover switch 52.

This signal is transmitted from the switch f41. of FIG. It is received by the processing device 46 via the modem 46°1A boat 45.

The received signal is again converted into a signal format suitable for the facsimile terminal and sent to the A port 45. The signal is transmitted to the general telephone network via the modem 44 degree changeover switch 42. The signal from the facsimile terminal 13 on the fixed side is as follows.

It is transmitted in the opposite direction of the flow explained above. The control signals such as the group identification signal and phase signal shown in Figure 2 are
The signal is converted and transmitted in the above procedure by the additional device shown in FIGS. The one-picture signal is sent out after being processed by a processing device in the additional device to change the information sending order using an error correction code addition interleaving method and to retransmit the signal using a retransmission method.

The contents of these processes will be explained in detail below.

Hybrid circuit 31. The image signal received by the processing device 36 via the modem 569% port 35 is first divided into sections of a certain data length (referred to as frames), and a frame number is added thereto, an error detection and correction code is attached thereto, and the image signal is stored in the memory 67. do. FIG. 5 shows the contents of an n-bit frame.

As the error detection and correction code, a BCH code, a convolutional code, etc. are used. Further, as the addition method, a method using dedicated hardware, a method of calculating and adding by a program, etc. can be applied. A collection of a certain number of frames is called a block. FIG. 6 shows an example in which one block is made up of m frames. To send this to the wireless line, as shown in Figure 7, after adding a start code if necessary, first bit 1 (F, bl) of the first frame, then bit 1 of the second frame. (F*b+) and the first bit of each frame is sent.

Next, the second bit of the first frame (FIb2),
The second bit of the second frame (F! bz) and the second bit of each frame are transmitted. That is, this is equivalent to transmitting in the vertical direction in FIG. Once all signal bits in one block have been transmitted in this manner, signals are then transmitted in a similar manner for each frame of the second block. These signals read from the memory 67 of FIG. 6 in the manner described above and sent out by the modem 34 are
Selector switch 41 in FIG. modem 462% boat 45
The data is received by the processing device 46 via the processing unit 46 and stored in the memory 47 in units of blocks. This information is reordered in processing unit 46 in a process that is the reverse of the sending process. In other words, after detecting the first bit using the start code, the first bit of the first frame is detected.
The first frame is created by combining n bits every m-th bit from the m-th bit. Next, every m bits are taken out from the second bit to form the second frame. This is the same memory processing as performed during sending. Such a method is called an interleaving method.

The interleaving method works to improve the effectiveness of error detection and correction codes by converting burst errors into random errors. Figures 8a, b, and e show the effects of the interleaving method for each code of n-pi)m frames. That is, Figure 8a
is the frame format, b is the transmission order, C is the decoding order, and the transmission order is 11.21. ...12, 22,...
. . 1n, 2n, . . . mn are extracted and sent in the vertical direction of the figure, and suppose that 4 consecutive bits are incorrect. That is, ml.

12.22.32 is erroneous (Er), upon decoding, the errors are arranged randomly in each frame and the burst errors are randomized. That is, in this example, without interleaving, errors could not be corrected without a 4-bit burst error correction code, but with interleaving west, column correction is possible with a 1-bit error correction code.

Next, we will discuss the playback method. When the order of the signals received using the interleaving method is changed and each frame is returned to its original state, the error detection and correction code added to each frame is decoded and errors are corrected.

For frames whose errors cannot be corrected, the processing unit 4
6 is a boat 45. The modem 46 is activated and a retransmission request signal is sent to the additional device B. Error-free or corrected frames are stored in memory 47 in blocks. This retransmission request signal includes the frame number of the erroneous frame, an error correction code, and the like. It is desirable to send the retransmission request signal repeatedly to increase reliability. This retransmission request signal passes through the modem 34 e x A) boat 35 in FIG. 3, and when it is received and decoded by the processing device 66, the frame with the incorrect frame number is combined with each other frame of the image signal to be transmitted. The signals are combined and sent to the additional device 8 again using the interleave method. The additional device 8 restores the incremented block of signals received by the processing device 46 and performs error correction for each frame. The retransmitted signal is identified by the frame number and stored in the correct frame position in the block in memory 47 to which it was previously transmitted.

In this way, each block consists of all correct frames and is stored in the memory 47.

In the above retransmission procedure, if the retransmission requested frame is incorrect many times, it will take time to construct a correct block, so it is also necessary to terminate the retransmission request after an appropriate number of times. There may also be cases where signals are not transmitted in blocks due to extremely long line interruptions, such as in tunnels. In such a case, add a block number and
It is also necessary to consider retransmission in block units.

When the image signal is stored in block units in the memory 47 in this manner, the processing device 46 sends the image signal to the facsimile terminal 14 based on the signal system defined by the facsimile terminal. When the sending of the image signal from the facsimile terminal 2 is completed, a message end confirmation signal shown in FIG. 2 is sent. This is taken out. When the additional device 8 finishes sending the image signal to the facsimile terminal 16, it sends a message end signal. Then, the facsimile terminal 13 sends out a message completion confirmation signal, which converts the signal in the additional device 8. The additional device converts it again into an existing facsimile signal and sends it to the facsimile terminal 2, completing the facsimile signal transmission. .

In the above explanation of FIG. 2, the sequence is proceeding while checking end-to-end with the PuAxismi 9 terminals 2 and 16. That is, the facsimile terminal 2 receives the group identification signal from the facsimile terminal 13 and then sends out the group command signal. However, depending on the condition of the wireless line, for example, when passing through a tunnel, these signals may disappear and be retransmitted between the additional devices 5 and 8, and may not arrive for a long time. may be exceeded.

Furthermore, a long waiting time on the receiving side is undesirable in terms of service. As a countermeasure for such a case, there is a method in which the additional device 3 creates a signal that would come from the facsimile terminal 16 and sends it to the facsimile terminal 2 in order to proceed with the sequence even if the signal from the facsimile terminal 16 does not come. Conceivable.

When the transmission and reception of the facsimile signal is completed, the switch 52 in FIG. 6 and the switches 41 and d42 in FIG. 4 are turned upward to return to the communication state.

In the above explanation, when transmitting a facsimile using a combination of error correction method, interleap method, and retransmission method, it is not necessary to use all three methods; It is also possible to use some, for example a combination of error correction and interleaving or only error correction and retransmission.

In addition, in Fig. 1, the connection method of the additional device 8 is described in which hooking is detected from the telephone 1, but instead of hooking, a special signal (for example, a tone signal or a digital signal) is sent from the additional device 5, and the connection method is bidirectional. A method may also be considered in which the trunk 6 is provided with a receiving circuit for the special signal, and the additional device 8 is connected by receiving the special signal. Furthermore, although the additional device 8 can be connected by a so-called headband connection, it is also conceivable to combine this with the outgoing trunk 9.

In addition, since the explanation was given for entering facsimile communication after a general telephone connection, hooking or other special signals are required as a signal to enter facsimile communication, but in the case of facsimile communication network services etc.
If the exchange can determine in advance that the special number is a facsimile service, the subsequent trunk switching operation can be omitted by immediately connecting to the additional device 10.

9 and 10 show flowcharts of processing operations on the image data sending side and image data receiving side of the present invention.

As described in detail of the invention, when transmitting images and data using mobile communication services, special additional equipment is installed in the mobile terminal and exchange, and error correction and incremental retransmission methods are combined between the additional equipment. By converting and transmitting to a new signal system, it has become possible to provide mobile communication image data services using existing image data terminal equipment as is.

The new signaling system uses an interpolation method to randomize burst-like errors and improve the efficiency of error correction codes.It also uses a retransmission method to provide a remedy for extreme bursts, so Error-free transmission is also possible. Furthermore, by adopting a new signal system that is different from the signal system used in existing mobile radio services, it becomes possible to create a system that does not interfere with the signals of existing mobile radio services.

[Brief explanation of the drawing]

FIG. 1 is a relay system diagram of an embodiment of the present invention, FIG. 2 is a signal sequence diagram, FIG. 6 is a block diagram of the additional device 6, and FIG.
The figure is a block diagram of the additional device 8, FIG. 5 is the frame configuration,
FIG. 6 is a bug configuration, FIG. 7 is a signal transmission diagram, FIG. 8 is an explanatory diagram of an interleaving system, and FIGS. 9 and 10 are charts of the present invention. 1...Telephone, 2...9 facsimile terminals, 3...
Additional device, 4... Mobile terminal, 5... Wireless base station, 6
... Bidirectional trunk, 7... Mobile communications exchange, 8
... Additional device, 9... Outgoing trunk, 10... Additional device, 11... Trunk exchange, 12... Subscriber line exchange, 16... Facsimile terminal, 14... Telephone,
61... Hybrid circuit, 52... Selector switch, 63... Modem, 34... Modem, 65...%
Boat, 66... Processing device, 37... Memory, 41
... Selector switch, 42... Selector switch, 43.
...modem, 44...modem, 45...% port,
46...Processing device, 47...Memory patent applicant Nippon Telegraph and Telephone Public Corporation Agent Patent attorney Gobe Tamamushi (one other person) Figure 1 Figure 3 Figure 2 Figure 5 Figure 6 Figure 8

Claims (1)

[Claims] In public mobile communications, when image data communication is performed between a mobile terminal and a fixed terminal using an image data communication terminal used in a landline telephone, a first An additional device is installed, a second additional device is installed in the switching center, and an image data communication terminal is installed between the mobile side terminal and the first additional device and between the fixed side terminal and the second additional device. The image data information is transmitted using the signal method specified in . The image data information is transmitted between the first additional device and the second additional device using a signal method different from the signal method specified for the image data communication terminal.a) Movement. Image data transmission method for communication.