JPH08307644A - Radio data communication method and device therefor - Google Patents

Abstract

PURPOSE: To provide a radio data communication method and device in which frequent occurrence of missing data, re-transmission of useless data, interruption of communication or redialing is prevented in the radio data communication and stable radio data communication is implemented. CONSTITUTION: Upon the receipt of a notice representing the arrival of a channel switching signal from a channel switching request detection means 3, an image information transmission control means 2 of a transmitter interrupts the transmission of the image information during the transmission and sends dummy data or a flag. Upon the receipt of a signal representing the end of channel changeover from a T timer 4, the control means 2 restarts the transmission of interrupted image information. As a result, all the image information is sent without causing missing of image information due to channel changeover.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless data communication method and apparatus, and more particularly to preventing frequent occurrence of data loss or retransmission, communication interruption or redial, etc. due to channel switching during wireless data communication. The present invention relates to a wireless data communication method and device capable of performing wireless communication.

[0002]

2. Description of the Related Art Conventionally, in wireless communication such as mobile phones, car phones and in-car phones such as trains, a channel switching request generated from a base station when a communication person moves from a current communication zone to another communication zone. Communication is often interrupted temporarily. Further, in a place where radio waves do not reach or are hard to reach such as in the shadow of a tunnel or a building, the reception level of the communication signal may be rapidly attenuated and the communication may be interrupted. In the case as described above, the voice call was not so affected because the user could sufficiently judge the communication contents even if the communication was interrupted during communication. The communication interruption time due to the channel switching request is usually 0.7 in the case of the analog system.
It is about 0.8 seconds.

Next, a specific example of the operation of the conventional device will be described with reference to the drawings. FIG. 8 is a timing chart showing the exchange of signals between the own device (transmitter), the other device (receiver) and the base station.

First, when the own device and the other device are connected, image information is transmitted from the own device to the other device via the base station. Next, as shown in the figure, when receiving the channel switching signal from the base station during the transmission of the image information, the own device establishes a connection of 0.7 with the base station in order to switch the channel.
It is interrupted for about 0.8 seconds (time T). When the transmission of the image information is completed, the own device sends an EOP (end of procedure) command, and the other device sends an RTN (retraining negative) command thereto. Next, the own device transmits a DCN (disconnect command) command in response to the RTN command, and ends the transmission of a series of image information.

In the conventional device as described above, there is a problem that the image information from the own device does not reach the other device during the time T and the image information is lost, and the transmission speed of the image information is high. The higher the probability, the greater the damage caused by the loss of image information. For example, when the transmission rate is 14400 (bits / second), the amount of image information missing due to the interruption is about 1.
It becomes 4 Kbytes, and a considerable amount of data is lost.

[0006] Further, in the conventional device, there is a device which retransmits the image information when its own device receives the RTN command. In this case, however, the communication time becomes longer and the call charge becomes higher because the image information is retransmitted. There is a problem that the line is occupied more than necessary.

Further, in recent years, the wireless data communication has spread in various fields and is often used for data communication such as facsimile communication. Therefore, it is a big problem that appropriate wireless data communication cannot be performed due to frequent data loss, frequent communication errors and interruptions, and repeated data resending and redial processing. Has become.

To solve these problems, Japanese Unexamined Patent Application Publication No.
In Japanese Patent Laid-Open No. 114759 (hereinafter, referred to as known document 1), when image information is received line by line in wireless data communication, the reception level is read and the presence or absence of a transmission error of the image information is detected. A technique is disclosed in which information based on a reception level is recorded at a line end portion of image information having a transmission error and the operator is notified of the information so that the operator can take appropriate measures.

Further, Japanese Patent Publication No. 60-57262 (hereinafter referred to as known document 2) and Japanese Patent Laid-Open No. 2-27866 (hereinafter referred to as known document 3) describe that when facsimile communication is started, A technique is disclosed in which a request for prohibiting channel switching is sent to a line control station (base station), and channel switching is not performed during communication.

[0010]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention In the above-mentioned publicly known documents 1 to 3, the interruption of communication in a place where radio waves cannot reach or are hard to reach such as in the shadow of a tunnel or a building is not considered, and the above-mentioned problems have been sufficiently described. I cannot solve the problem. Particularly, in the above-mentioned known document 1, the operator can only know the reception level of the information having the transmission error, and does not consider the problem that the wireless data communication is interrupted due to the attenuation of the reception level of the information. . Further, in the above-mentioned publicly known documents 2 and 3, channel switching is prohibited during a call, and if the user leaves the communication zone in which he / she is currently located, the reception level of the signal reaching the receiver side is attenuated and communication is interrupted. The problem has not been resolved.

Further, communication using a wireless communication network has a peculiar problem that data propagation is delayed. However, the above-mentioned publicly known documents 1 to 3 do not consider the above-mentioned problems at all and have not solved them.

An object of the present invention is to eliminate the above-mentioned problems of the prior art and prevent frequent occurrence of data loss, unnecessary data retransmission, communication interruption, redial, etc. during wireless data communication. The object of the present invention is to provide a wireless data communication method and device capable of performing stable wireless data communication.

[0013]

In order to achieve the above object, a first invention is a wireless data communication method for performing data communication using a wireless communication network, during transmission of image information,
When the channel switching signal is received, the step of interrupting the transmission of the image information and transmitting the dummy data, and the step of restarting the interrupted image information transmission after the channel switching is completed, and The second invention is the ECM.
When a channel switching signal is received during the transmission of image information by the control procedure, the step of interrupting the transmission of the image information and transmitting the flag data, and the step of storing the frame number of the image information whose transmission is interrupted. After the channel switching is completed, the step of reading the frame number and restarting the transmission from the head of the image information of the frame number is characterized.

A third aspect of the present invention is a wireless data communication apparatus for performing data communication using a wireless communication network, wherein a channel switching signal detecting means for detecting reception of a channel switching signal and an end of the channel switching are detected. Means for interrupting the transmission of the image information and transmitting dummy data when the channel switching signal is received during the transmission of the image information, and when the end of the channel switching is detected, the suspended image is interrupted. And a fourth aspect of the present invention, in which the dummy data is provided.
A fifth aspect of the present invention is a channel switching signal detection for detecting reception of a channel switching signal, in which white run length 0 and black run length 0 of a terminating code are alternately arranged or composed of continuous 0 data. Means, a means for detecting the end of the channel switching, and an ECM
When the channel switching signal is received during the transmission of the image information by the control procedure, the transmission of the image information transmitted in the frame unit is interrupted and the flag data is transmitted, and when the end of the channel switching is detected, It is characterized in that it further comprises image information transmission control means for restarting transmission from the beginning of the frame of image information that has been interrupted.

[0015]

According to the first aspect of the invention, the transmission of the image information is stopped during the channel switching, and the dummy data is transmitted. Then, when the channel switching is completed, the transmission of the suspended image information is restarted. Therefore, even if the channel is switched during the transmission of the image information, the image information can be transmitted without being lost. Further, according to the second aspect, when the channel switching is performed during the transmission of the image information by the ECM control procedure, the interrupted frame number is stored, and when the channel switching is completed, the beginning of the image information of the frame is stored. The transmission of image information is restarted. Therefore, the image information can be transmitted without being lost, and the communication time can be significantly shortened as compared with the conventional case.

According to the third aspect of the invention, when the image information transmission control means receives a notification from the channel switching signal detecting means that the channel switching signal has been received, the transmission of the image information is stopped and the dummy data is transmitted. To do. After that, when the notification of the end of the channel switching is received, the transmission of the interrupted image information is restarted. Therefore, it is possible to transmit the image information without loss by creating dummy data using the means of the conventional device and transmitting the dummy data. Further, according to the fourth invention, when the receiver receives the data in which the white run length 0 and the black run length 0 of the terminating code are alternately arranged, or the dummy data composed of the continuous data of 0, it receives the data. I will discard it, so
The probability of a decoding error is very small, and the receiver does not cause a trouble such as releasing the line. Further, according to the fifth invention, when the image information transmission control means receives a notification from the channel switching signal detection means that the channel switching signal has been received, the transmission of the image information is interrupted,
The interrupted frame number is stored and a flag is transmitted. After that, when the notification of the end of the channel switching is received, the transmission of the image information is restarted from the head of the interrupted frame. Therefore, by using a simple means, it is possible to transmit the image information without loss. Also,
Since it is not necessary to retransmit the image information according to the ECM control procedure, it is possible to significantly reduce the communication time.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. 2 is a block diagram showing a specific example of the configuration of a data communication apparatus, for example, a facsimile apparatus, and FIG. 3 is a block diagram showing a specific example of a wireless communication apparatus for using the facsimile apparatus in a wireless communication network. In the figure, 11 is a CPU for controlling the operation of the entire apparatus, 12 is a ROM in which a control program is stored, 13 is various information related to control of the CPU 11, for example, a counter, a flag and data are temporarily or permanently stored. RAM, 14 is a clock device for indicating the current time and measuring time, 15
Is a keyboard for inputting identification signals and communication numbers, 16
Is a display that displays the status of the device, operating procedures, and the like.

Reference numeral 17 denotes a wireless device for inputting and outputting image data (image information), a protocol and the like via the antenna 24, and the antenna 24 is connected to a wireless communication network. Reference numeral 18 denotes a modulation / demodulation device that modulates image data output via the wireless device 17 or demodulates input image data, and 19 stores the image data that is modulated by the modulation / demodulation device 18 or demodulated. RAM 20 is an encoding / decoding device for encoding and decoding image data, and 21 is a RAM for storing an image read by the scanner 22 and image data recorded by the printer 23. The wired communication network is, for example, a telephone line, an ISDN network, a LAN, or the like, and the wireless communication network is, for example, a mobile phone, a car phone, an in-car phone such as a train, or the like.

FIG. 3 is a block diagram showing the configuration of a general wireless communication device (mobile device). In the figure, reference numeral 31 is a control unit that controls line connection with a base station, channel switching during a call, registration of one's position, and the like. Reference numeral 32 is a transmitter that modulates audio and image data and amplifies it to a predetermined transmission output, and includes a transmission power amplifier 40, a transmission mixer 41, and a modulator 42. Reference numeral 33 is a receiver for demodulating the received audio and image data, and the receiving mixer 43,
It is composed of an amplifier 44 and a demodulator 45. Reference numeral 34 is a frequency synthesizer which generates a large number of frequencies, and 35 is a receiver 3 which receives the audio and image data received by the antenna 24.
3, a voice transmission / reception duplexer for transmitting the voice and image data modulated and amplified by the transmitter 32 through the antenna 24, and 36 outputs the voice and image data demodulated by the receiver 33 to the output device 37. The received signal processing circuit 38 is a transmission signal processing circuit for outputting the audio or image data input by the input device 39 to the transmitter 32. The output device 37 includes a printer 23, a speaker, etc., and an input device 39.
Corresponds to the scanner 22 and the microphone, respectively.

Next, a first embodiment of the present invention will be described with reference to FIGS.
Will be described with reference to. FIG. 4 is a flow chart showing the operation of this embodiment, and FIG. 5 is a timing chart of the essential parts of this embodiment.

In step S1, the connection between the own device and the other device is successful, and the image information is transmitted. Step S
In 2, it is judged whether or not the channel switching signal is received. If the judgment is negative, the process proceeds to step S3.
In step S3, it is determined whether all the image information has been transmitted. If the determination at step S2 becomes affirmative before the determination at step S3 becomes affirmative, that is, if a channel switching signal is received during the transmission of the image information, the process proceeds to step S4 and the own device (transmitter) transmits the image information. Is stopped to switch the channel, and T time is set. This T time is a time that is equal to or longer than the TO time that is considered to be required for switching the channel and is approximately the same as the TO time, and for example, about 0.8 seconds is preferable.

Then, in steps S5 and S6, the T
Dummy data is transmitted instead of the image information until time passes. This dummy data does not reach the partner device (receiver) during the channel switching operation, but the partner device receives the dummy data output after the time T0 has elapsed. Next, when the determination in step S6 becomes affirmative, the process proceeds to step S1 and the transmission of image information is restarted. After that, the image information after the interruption is transmitted, and when the determination in step S3 becomes affirmative, the process proceeds to the next process.

As is clear from FIG. 5, since the self-device sends dummy data without sending image information while communication is interrupted due to channel switching, image information is lost. It is possible to prevent the loss of image information.
Also, since the other device ignores the received dummy data,
The image information before the interruption and the image information after the interruption can be normally combined without causing data loss. Further, since the partner device does not need to add any new function to the conventional receiver, the conventional receiver can be used as it is.

When the self-device and the partner device are G3 facsimile machines, the white run length 0 (that is, 00110) of the terminating code is used as the dummy data.
101) and black run length 0 (0000101111)
It is possible to use an array of alternating. Since the data in which the white and black run lengths 0 are alternately arranged means that there is no data even if the data is actually received by the receiver, the dummy data is originally stored in the receiver. It is not received as image information.

As another example of the dummy data, data of all 0 (hereinafter referred to as 0 fill data) can be used. Generally, if the receiver needs time to process the encoded data, the data and E
Variable-length 0 data is inserted between it and the OL signal. If the 0 fill data is continuously transmitted while the communication path is interrupted by the channel switching, the receiver automatically discards the 0 fill data and does not erroneously receive the dummy data as the original image information. .

Further, as described above, when the data in which the white and black run lengths 0 are alternately arranged and the 0 fill data are used as the dummy data, the probability of a decoding error in the receiver is very small. The trouble that the receiver releases the line does not occur.

Next, a second embodiment of the present invention will be described with reference to FIGS.
Will be described with reference to. FIG. 6 is a flow chart showing the operation of this embodiment, and FIG. 7 is a timing chart of the essential parts of this embodiment. In this embodiment, the ECM (Error Correct Mod
e) This is when the facsimile communication is being performed in the control procedure and when the channel switching signal is received during the transmission of the image information.

In the ECM procedure, the data read by the scanner 22 and coded by the coding device 20 is divided into packet units called frames and transmitted. There is a maximum of 256 frames, and when more data exists, it is divided into blocks.
A flag sequence (specifically, 0
1111110) is used to establish bit synchronization and frame synchronization. Recommendation T. In No. 30, it is specified that the maximum sending time of this flag is T1 timer (that is, 35 ± 5 seconds) or less.

In step S11 of FIG. 6, the connection between the own device and the other device is successful, and the transmission of the image information is executed in frame units. In step S12, it is determined whether a channel switching signal has been received. In the example of FIG. 7, the fourth
An example is shown in which a channel switching signal is received during transmission of the image information of the th frame. As described above, when the channel switching signal is received during the transmission of the image information of the fourth frame, the process proceeds to step S14, the transmission of the image information is immediately stopped, and the number of the frame of which the transmission is stopped is saved.
In addition, channel switching is executed and T time is set. This T time is the same as step S4 in FIG. Next, in step S15, the flag is transmitted. This flag is transmitted in step S16.
Is continued until it becomes affirmative. The T time has elapsed,
If the determination in step S16 is affirmative, step S17
Then, the frame number saved in step S14 is taken out. Then, returning to step S11, the image information of the frame number is retransmitted from the beginning. Step S
At 13, it is determined whether or not all the image information has been transmitted, and if this determination is affirmative, the process proceeds to the next process.
As shown in FIG. 7, a PPS-EOP (partial page signal-end procedure) command is sent. Since the time required for channel switching is 0.7 to 0.8 seconds even in analog type mobile communication, even if the flag is continuously transmitted during this period as in the present embodiment, it is the maximum transmission time of the flag. Satisfies the requirement of (35 ± 5 seconds) or less,
The specifications comply with the recommendations.

Since the partner device can receive the image information of the frame interrupted by the channel switching from the beginning of the frame, it is not necessary to perform the retransmission procedure. Therefore, normal communication can be performed without wasting communication time. For example, if the channel switching is dealt with by the conventional method, the number of data loss frames due to the channel switching becomes 6 frames when the communication speed is 14400 BPS. This frame is the conventional E
When attempting to retransmit by the CM procedure, not only the data of the 6 frames but also the time for transmitting a PPR command which is a control command for retransmitting, the time for controlling the modem, the time required for training the modem, and the signal Time required for transmission / reception is required, and as a result, communication time of about 10 seconds is required. However, according to the present embodiment, only about 1 second of communication time is required, and the effect is great.

Next, the functional configuration of the present invention will be described with reference to FIG. In the figure, 1 is a communication control means, 2 is an image information transmission control means for controlling the transmission of image information, and is provided with a dummy data transmission means. Reference numeral 3 denotes a channel switching signal detecting means for detecting a channel switching request from a base station (not shown), and 4 is set when the channel switching signal is received, and a T time timer for measuring the T time. Is. Further, 5 is an image information storage means for storing image information to be transmitted. The image information transmission control means 2 receives a notification from the channel switching signal detecting means 3 that the channel switching signal has been received, and a T time timer 4 notifies that the T time has ended. When the image information transmission control means 2 is notified by the channel switching signal detection means 3 that the channel switching signal has been received, the image information transmission control means 2 suspends the transmission of the image information and sends the dummy data from the dummy data transmitting means. After that, when the notification of the end of the T time is received from the T time timer 4, the resending of the suspended image information is started. The T-timer 4 is not necessarily a necessary constituent element, and any element can be used as long as it can detect the end of channel switching.

[0032]

According to the first aspect of the present invention, when the channel switching signal arrives during the transmission of the image information, the image information can be transmitted to the other device without loss and the channel can be normally switched. There is an effect. According to the invention of claim 2, in addition to the effect of claim 1, the conventional ECM
As compared with the case where the image information is retransmitted by the control procedure, the communication time can be significantly shortened. According to the third aspect of the present invention, the dummy data is created by using the means of the conventional device and is transmitted, so that the image information can be transmitted without loss. Further, the present invention can be realized with a simple device. According to the invention of claim 4, since the receiver discards the received dummy data, the probability of causing a decoding error is very small, and the receiver does not release the line. Further, according to the invention of claim 5, the image information can be transmitted without loss by using a simple means. Also,
The communication time can be significantly reduced as compared with the retransmission of the image information based on the ECM control procedure, and it is possible to occupy an unnecessary line and reduce the communication cost.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a functional configuration of the present invention.

FIG. 2 is a block diagram showing a specific example of the configuration of a facsimile apparatus to which the present invention is applied.

FIG. 3 is a block diagram showing a specific example of a wireless communication device for using the facsimile device in a wireless communication network.

FIG. 4 is a flowchart illustrating the operation of the first exemplary embodiment of the present invention.

FIG. 5 is a timing chart explaining the operation of the first embodiment.

FIG. 6 is a flowchart explaining the operation of the second embodiment of the present invention.

FIG. 7 is a timing chart illustrating the operation of the second embodiment.

FIG. 8 is a timing chart for explaining the operation of the conventional method.

[Explanation of symbols]

1 ... Communication control means, 2 ... Image information control means, 3 ... Channel switching signal detection means, 4 ... T time timer, 5 ... Image information storage means.

Claims (5)

[Claims] 1. A wireless data communication method for performing data communication using a wireless communication network, when transmission of image information receives a channel switching signal, transmission of the image information is interrupted, and dummy data is transmitted. And a step of restarting the transmission of the interrupted image information after the channel switching is completed, the wireless data communication method. 2. A wireless data communication method for performing data communication using a wireless communication network, wherein transmission of image information is interrupted when a channel switching signal is received during transmission of image information by ECM control procedure, Sending flag data, storing the frame number of the image information whose transmission has been interrupted, reading the frame number after the channel switching is completed, and restarting transmission from the beginning of the image information of the frame number A wireless data communication method comprising the steps of: 3. A wireless data communication device for performing data communication using a wireless communication network, channel switching signal detecting means for detecting reception of a channel switching signal, means for detecting the end of the channel switching, and image information. When the channel switching signal is received during transmission, the transmission of the image information is interrupted and dummy data is transmitted, and when the end of the channel switching is detected, the interrupted transmission of the image information is restarted. A wireless data communication device comprising: image information transmission control means. 4. The wireless data communication device according to claim 3, wherein the dummy data is data in which white run length 0 and black run length 0 of terminating codes are alternately arranged,
Alternatively, the wireless data communication device is characterized in that it is continuous 0 data. 5. A wireless data communication apparatus for performing data communication using a wireless communication network, a channel switching signal detecting means for detecting reception of a channel switching signal, a means for detecting the end of the channel switching, and an ECM control. According to the procedure, when the channel switching signal is received during the transmission of the image information, the transmission of the image information transmitted in the frame unit is interrupted and the flag data is transmitted, and when the end of the channel switching is detected, An image data transmission control means for restarting transmission from the beginning of a frame of image information that has been interrupted.