JPH0443758A - Facsimile signal repeater method in mobile communication - Google Patents

Abstract

PURPOSE:To attain repeater of a normal picture signal even when a picture signal data is going to be intermitted to a receiver facsimile equipment by providing a means inserting all '0' signals between a data and its succeeding line termination code. CONSTITUTION:When remaining data in a reception buffer are less, an all '0' signal FILL 10 whose transmission time per scanning line is not in excess of 5sec is inserted between a DATA 9 and its succeeding line termination code EOL 8 and a picture signal is repeated to a facsimile equipment. Thus, even when a picture signal data to a receiver facsimile equipment is going to be interrupted from a receiver side station by re-transmission control of a facsimile picture signal against a signal error of a radio block between a radio base station and a mobile station, while the operation of the receiver side facsimile equipment is continued, the picture signal data is sent to the facsimile equip ment. Thus, repeater of a normal picture signal is attained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a facsimile signal transmission system in mobile communication, and in particular to a mobile station and a radio base station for realizing facsimile communication without image signal deterioration. This invention relates to a facsimile signal relay method.

[Prior Art] With the development of mobile communication services such as car telephones, there is an increasing demand for not only conventional voice telephone calls (but also non-telephone services such as facsimile).

Even in the currently available car phone services,
Fax is available. Facsimile signals are originally digital signals, but currently commercially available GI [
The I-facsimile device is designed to convert this digital signal into an analog signal within the voice band using a built-in modem so that it can be used over public telephone lines.

Facsimile communication of car telephones currently in service uses facsimile signals converted to analog signals instead of voice for transmission and reception.

FIG. 5 shows how a conventional facsimile is used.

In the figure, on the mobile side, a handset 53 and a facsimile terminal 54 are connected to a mobile device 51 via a switch 52.

On the fixed side, there is a wireless base station 55 for mobile communication, a public telephone network 56, and a handset 53 connected to these via a switch 52.
and a facsimile terminal 54. Mobile device 51 and wireless base station 55 are connected via a wireless line. This wireless section 57 is a line with a band capable of transmitting audio signals, and uses analog FM signals.

The mobile side and the fixed side perform both phone calls using the handset 53 and communication using the facsimile terminal 54, but the signal from the facsimile terminal 54 is also converted by the built-in modem into an analog signal that can be transmitted within the same band as the voice signal. Therefore, it is possible to transmit facsimile signals without being aware of them in the wireless section.

In the conventional method described above, the facsimile signal is transmitted as an analog signal over the radio section, so even if an error occurs in the radio section due to fading or shadowing that is characteristic of mobile communications, it is not possible to correct the error. Zu, m
1. There was a problem in that quality deterioration was unavoidable.

As a means to improve this deterioration in image quality, it is conceivable to transmit the facsimile signal as a digital signal over a wireless section. Using the same facsimile terminal as in Figure 5,
An example of digital transmission is shown in FIG. 6. In the system shown in FIG. The facsimile terminal 64 demodulates the facsimile signal (signal from the facsimile terminal 64) and transmits the facsimile signal as a digital signal over the radio section 68.

In this example, the quality of the facsimile image signal can be expected to be improved compared to the conventional example described in FIG. 5 by increasing the signal transmission rate using an error correction code, but it is not possible to prevent deterioration of the image quality.

Figure 7 shows an example of facsimile signal transmission characteristics in conventional mobile communications.It can be seen that as the bit error rate worsens, the evaluation of facsimile images worsens.0To eliminate the deterioration of image quality In addition to digitizing the radio section, it is necessary to perform retransmission control using error detection between the mobile device 61 and the radio base station 650.

[Problem to be solved by the invention]

The facsimile signals include a binary control signal and an image signal, and the binary control signal has a retransmission function unique to the facsimile if the signal is erroneous in a relay section such as a wireless section. However, facsimile image signals do not have a retransmission function, so in order to relay signals without deteriorating image quality, it is necessary to add a retransmission protocol unique to the wireless section.

However, when retransmission control is added to the relay of the image signal, if there is fading or shadowing in the wireless section and an error occurs in the transmitted image signal, the signal transmission time in the wired section can be reduced by retransmitting the image signal. In comparison, the signal transmission time in the wireless section is longer, and there is a possibility that the data relayed from the facsimile signal relay section of the mobile device or wireless base station to the receiving facsimile may be interrupted even though the relay of the image signal has not finished. There is. If the data is interrupted, depending on the subsequent processing, the receiving facsimile may shift to a disconnection operation, or even if no disconnection occurs, the image signal will be disrupted, making it impossible to achieve the purpose of retransmission control, which is to eliminate image signal errors. .

The present invention is intended to solve this problem, and relates to a method for processing image signals on the receiving side when retransmission control is added to the relay of image signals. The object is to provide a control method that allows a facsimile on the receiving side to operate normally even if the signal transmission time in the section is longer than the signal transmission time in the wired section.

[Means to solve the problem]

According to the invention, the above objects are achieved by the means specified in the claims.

That is, the present invention provides means for controlling the retransmission of a facsimile image signal when detecting a signal error in the radio section between the radio base station and the mobile station at the radio base station and the mobile station, and means for controlling the retransmission of the facsimile image signal from the radio section at the receiving side. A means for detecting the usage status of a buffer memory for receiving image signal data, and a means for detecting a line end code in a facsimile image signal, and detecting a line end code in a facsimile image signal to detect all "0" signal (FILL), and when the data in the receiving side buffer falls below a predetermined capacity due to retransmission control due to a data error during facsimile image signal relay, All “0” within a predetermined time between the scanning line unit data of the image signal in the receiving side buffer and the following line end code
This is a facsimile signal relay method in which an image signal is transmitted to a receiving facsimile machine while inserting a signal (FILL).

[For production]

In the means recited in the claims, by controlling the retransmission of facsimile image signals in response to signal errors in the radio section between the radio base station and the mobile station, the receiving station transmits the image signals for the receiving facsimile. Even if the data is about to be interrupted, the image signal data can be transmitted to the facsimile while the facsimile on the receiving side continues to operate, so that the image signal can be relayed normally. This principle will be explained using FIG. 1.

FIG. 1 shows the signal structure of a facsimile image signal. There are two types of image signal encoding methods recommended by CCITT for the G2 sofa system: a one-dimensional encoding method and a two-dimensional encoding method. Here, we will explain the one-dimensional encoding method as an example (see CCITT Recommendation T, 4).

In the figure, 8 is an end-of-line code (EOL), 9 is a facsimile variable length code (DATA) in units of one scanning line, and 1
0 is a fill (FILL=all O) for adjusting the transmission time per scanning line, and 11 is a control return code composed of six EOL8s.

The variable length DATA 9 is transmitted surrounded by EOL8 as shown in the figure, and if the transmission time per scanning line is shorter than the predetermined minimum transmission time (T), the DATA
FILLIO is inserted between A 9 and the following (EOL8) to satisfy the minimum transmission time condition.What should be noted here is that FILLIO is inserted between DAT^9 and the following EOL8.
Even if LIO is inserted, the image signal will not be erroneous, and if the maximum transmission time per scanning line is set to 5 seconds or less, the facsimile will not shift to a cutting operation.

The present invention focuses on this point, and when there is little data left in the receive buffer, DATA 9 and the following <EOL
8, the image signal is relayed to the facsimile machine while inserting all zeros so that the transmission time per scanning line does not exceed 5 seconds, thereby preventing malfunction of the facsimile machine on the receiving side.

Therefore, according to the present invention, by controlling the retransmission of facsimile image signals in response to signal errors in the radio section between the wireless base station and the mobile station, the image signal data for the receiving side facsimile is likely to be interrupted at the receiving side station. Even if this happens, by inserting FILLIO between DATA 9 and EOL 8 while transmitting the data, you can send the image signal data to the facsimile while the receiving facsimile continues to operate, so the image signal is normal. It becomes possible to relay

〔Example〕

FIG. 2 is a diagram showing one embodiment of the present invention. This figure shows the mobile device side as an example, but the wireless base station is similar except that the facsimile terminal is connected via the public telephone network. The composition is as follows.

In the figure, 1 is a mobile device, 2 is a facsimile terminal, 3 is a facsimile modem, 12 is a wireless device, 13 is a signal analysis circuit, 14 is a signal changeover switch, 15 is a control unit, 16 is a transmitting side retransmission processing circuit, and 17 is a Receiving side retransmission processing circuit, 18
19 represents a transmission buffer, 19 represents a reception buffer, 20 represents an EOL detection circuit, 21 represents a fill insertion switch, and 22 represents a control signal multiplexing circuit.

FIG. 3 shows an example of the frame structure of a signal during facsimile relay in the wireless section of the facsimile relay method according to the present invention, where 23 is a frame, and 24 is a control signal (24) for indicating whether the relayed signal is voice or facsimile. CONTI)
, 25 is a control signal (CONT
2).

Further, FIG. 4 shows an example of a Gm facsimile connection sequence according to the present invention (CCITT Recommendation T).

(Recommendation) 0 This figure shows a case where the fixed side facsimile is transmitting and the mobile side facsimile is receiving.

The operation of the embodiment will be described below with reference to FIGS. 2 to 4. As mentioned earlier, facsimile signals include binary control signals and image signals, and facsimiles are relayed using a combination of these signals. First, relaying of binary control signals will be explained.

DIS will be described as an example of a binary control signal. In Figure 4, the mobile device receives D from the receiving facsimile.
When the IS is received, it is demodulated by the facsimile modem 3, the received signal is analyzed by the signal analysis circuit 13, and the signal is relayed to the changeover switch 14.

The facsimile modem 3 and the changeover switch 14 are initially set to relay the binary control signal to the control signal multiplexing circuit 22. A frame 23 is constructed by the control signal multiplexing circuit 22 and the signal is relayed to the wireless section 12. At the wireless base station, the DIS is relayed to the sending facsimile by the reverse operation.

The binary control signals (DO3, CFR, E
OP, MCF, DCN, etc.) is basically relayed using this operation. However, since TCP is a training signal (all 0s) for the image signal relay modem, here, the transmitting side relays only DO3, and when the receiving side receives DC3, it temporarily switches the facsimile modem 3 to the image signal. This is handled by creating TCP on the receiving side by switching the fill insertion switch 21 to the ground side.

Next, the relay of the image signal will be explained.Relaying of the zero image signal is executed by changing the setting of the facsimile modem 3 and the changeover switch 14 to image signal settings when the mobile device 1 and the radio base station relay the CFR. The image signal input from the transmitting facsimile terminal to the radio base station 5 is demodulated by the facsimile modem 3, stored in the transmission buffer 18, and input to the transmitting side retransmission processing circuit 16.

The transmitting side retransmission processing circuit 16 performs signal manipulation for retransmission processing using the tlDLc method or the like, and transmits the signal to the receiving side via the changeover switch 14 or the like. On the reception side of the mobile station, the reception side retransmission processing circuit 17 receives the image signal while performing retransmission processing corresponding to the transmission side, and records the data in the reception buffer 19.

When the data in the reception buffer 19 exceeds a predetermined capacity, data transmission to the facsimile modem 3 is started.

Thereafter, when the data in the reception buffer 19 falls below a predetermined capacity due to a signal error in the wireless section, etc., the function of the present invention operates.

That is, when the control unit 15 detects that the capacity in the reception buffer 19 has fallen below a predetermined capacity based on the signal from the reception buffer, the control unit 15 uses the signal from the EOL detection circuit 20 as a trigger to output the data from the reception buffer 19. At the same time, the fill insertion switch 21 is switched to the ground side, and 0 is transmitted to the facsimile modem 7.

When the capacity of the reception buffer 19 is restored, the fill insertion switch 21 is returned to its original position.

On the other hand, if the capacity of the receive buffer 19 does not recover and the time since the EOL of the previous transmission reaches about 4.5 seconds (an appropriate value that does not exceed 5 seconds), - temporarily switch the fill insertion switch. 21, the next EOL and facsimile scanning line data are transmitted to the facsimile modem 7, and the operation of switching the fill insertion switch 21 to the ground side is repeated.

Thereafter, when the receiving side retransmission processing section 17 detects that the reception of the image signal is completed, this function is stopped and all the data in the receiving buffer 19 is relayed to the facsimile modem 7.

At this time, when the end of the image signal relay is detected on the transmitting and receiving sides, the facsimile modem 3 and the switching switch 4 are switched to the binary control signal relay side.

Furthermore, as shown in Figure 4, if the transmission time in the wireless section becomes longer than the signal transmission time in the wired section due to an error in the wireless section, not only the facsimile on the receiving side
It is also necessary to control the operation of the facsimile machine on the sending side. Regarding this, in this embodiment, the flag signal is sent to the sending facsimile machine, ignoring the binary control signal such as EOP immediately after the image signal, and the flag signal is sent after the relay of the image signal in the wireless section is completed. This is handled by stopping the EOP and relaying the retransmitted EOP, etc. (Patent Application No. 1-24513)
(see 5).

In the above explanation of the embodiment of the facsimile signal relay method according to the present invention, the explanation has been made on the assumption that the wireless line is a digital line. This can also be achieved by providing a facsimile modem on the machine 12 side.

〔Effect of the invention〕

As described above in detail, according to the present invention, a mobile station and a wireless base station are connected via a wireless line having a function of retransmitting image signals, and communication by facsimile is possible between the mobile station and general subscribers. In a method of relaying facsimile signals in mobile communications for the purpose of This has the advantage of preventing the receiving facsimile machine from switching to a cutting operation and from disrupting the image signal due to the difference.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of the signal structure of a facsimile image signal, FIG. 2 is a diagram showing an embodiment of the present invention, and FIG. 3 is a diagram showing the frame structure of a signal during facsimile relay in a wireless section according to the present invention. FIG. 4 is a diagram showing an example of the connection sequence of the Gl facsimile according to the present invention, FIG. 5 is a diagram showing the usage pattern of the conventional facsimile, and FIG. 6 is a diagram showing the usage of the conventional facsimile. FIG. 7 is a diagram showing an example of a configuration for transmission, and FIG. 7 is a diagram showing an example of transmission characteristics of a facsimile signal. 1...mobile device, 2...facsimile terminal, 3...facsimile modem, 8...
・End of line code (EOL), 9...Facsimile variable length code (DATA) in units of one scanning line, 10...
...FILL, 11...Control return code, 12...Radio device, 13...Signal analysis circuit, 14...Signal switching switch, 15
. . . Control unit, 16 . . . Sending side retransmission processing circuit, 17 . . . Receiving side retransmission processing circuit, 18 .
...Transmission buffer, 19...Reception buffer, 20...EOL detection circuit, 21...
Fill insertion switch, 22 old control signal multiplex circuit,
23... frame, 24... control signal (C
ONTI ), 25... Control signal (CONT
2), 26... Data section. Agent Patent Attorney Sosanzu Honma

Claims (1)

[Claims] In a facsimile signal transmission system between a mobile station and a radio base station, there is provided a means for controlling the retransmission of facsimile image signals in the radio base station and the mobile station, and a means for controlling the retransmission of facsimile image signals at the receiving side. means for detecting the usage status of a buffer memory for receiving the data, and a means for detecting a line end code in a facsimile image signal to detect all "0"s between data in units of scanning lines of the facsimile image signal and the following line end code. If the data in the buffer on the receiving side falls below a predetermined capacity due to retransmission control due to a data error during facsimile image signal relay, the receiving side The image signal is transmitted to the receiving facsimile machine while inserting an all-0 signal (FILL) within a predetermined time between the scanning line unit data of the image signal in the buffer and the following line termination code. A method for relaying facsimile signals in mobile communications, characterized by transmitting facsimile signals.