JP2000324321A - Communication control method for mobile phone facsimile - Google Patents

Abstract

(57) [Summary] [Problem] When the state of a transmission path in a wireless section deteriorates in communication of a facsimile for a mobile phone, there is a problem that image signals are retransmitted and transmission takes time. SOLUTION: 1) Phase C (image signal transmission phase)
In, the number of frame retransmissions of the lower layer ARQ is adjusted according to the error rate of the transmission path and the amount of transmission path delay. 2) The operator can set the number of times of retransmission of frames of the lower layer ARQ. 3) The transmitting side instructs the receiving side on the number of frame retransmissions according to the importance of the image signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to RCRSTD-2.
The present invention relates to a facsimile for mobile phones compliant with 7F (ARIB: Standard of the Association of Radio Industries and Businesses). In particular, it relates to communication control in phase C (image signal transmission phase) in the receiving unit.

[0002]

2. Description of the Related Art In recent years, facsimile communication in a mobile environment using a portable telephone has become widespread. For example, a portable telephone is connected to a notebook personal computer, and facsimile transmission / reception using a facsimile application has been used.

[0003] At this time, delay and retransmission of data due to changes in the surrounding radio wave environment and the like have become a serious problem. In order to solve these problems, Japanese Patent Application Laid-Open No. 2-114759 discloses that when an image signal is received line by line in wireless data communication, a reception level is read and the presence or absence of a transmission error of the image signal is detected. At the same time, there is disclosed a technique in which information based on the reception level is recorded at the end of a line of an image signal having a transmission error and notified to an operator so that the operator can take an appropriate action. Also, Japanese Patent Publication No. 60-5
No. 7262 discloses a technique in which when facsimile communication is started, a request to prohibit the channel switching is sent to a line control station (base station) so that the channel switching is not performed during communication.

[0004]

However, even if the above countermeasures are taken, delays and retransmissions of data due to changes in the surrounding radio wave environment are not eliminated. In communication under a weak electric field, disconnection and channel switching do not occur, but a situation where a transmission error always occurs may continue for a long time.

In such a case, in the current communication control method of a portable telephone facsimile, retransmission is repeated forever, and it takes an enormous amount of time to transmit an image signal.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention comprises a step of measuring an error rate of a lower layer ARQ, and a step of measuring the error rate of the lower layer ARQ based on the error rate when the error rate is equal to or higher than a predetermined value. It comprises a step of calculating the number of retransmissions and a step of instructing the lower layer ARQ of the maximum number of retransmissions.

As a result, ARQ to be retransmitted according to the situation
The upper limit of the number of frames can be set, and retransmission is repeated forever, so that transmission of an image signal does not take an enormous amount of time and communication cost is not wasted.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the communication control method for a portable telephone facsimile according to the present invention, the step of measuring an error rate of a lower layer ARQ measures an ARQ frame error rate of a received image signal in a phase C (image signal transmission phase). . In the step of calculating the maximum number of retransmissions of the lower layer ARQ based on the error rate when the error rate is equal to or higher than a predetermined value, it is determined that an upper limit of the number of retransmissions should be specified when the error rate is equal to or higher than a predetermined value. Calculate the maximum number of retransmissions according to. Lower layer ARQ
In the step of instructing the maximum number of retransmissions, the obtained maximum number of retransmissions is instructed to the lower layer ARQ. Lower layer A
The RQ has an effect of restricting the number of times the same frame number is requested as the confirmation or retransmission request frame number in the backward channel control information based on the instructed maximum number of retransmissions.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a flowchart for explaining a communication control method of a portable telephone facsimile according to a first embodiment of the present invention. FIG. 2 is a sequence diagram for explaining the embodiment.

In FIG. 2, reference numeral 1 denotes a transmitting fax unit, 2 denotes a transmitting unit unit, 3 denotes a receiving unit unit, and 4 denotes a receiving fax unit. The transmission path between the transmitting unit 2 and the receiving unit 3 is a wireless section.

The operation will be described below with reference to FIGS.

When the call connection is completed, the process first enters a phase B (pre-message phase). In phase B, DIS
(Digital identification signal) and DCS (Digital command signal) are transmitted and received, and their capabilities as facsimile are exchanged. The TCF (training signal) is not transmitted to the wireless section. Upon receiving the CFR (reception preparation confirmation), the transmission side determines that the image signal is ready to be transmitted, and shifts to phase C. The receiving side similarly shifts to phase C after sending the CFR and waits for the arrival of the image signal.

The frame structure of DIS, DCS, CFR, etc. is based on ITU-TT. 30 based.

In the case of non-ECM transmission, an image signal is transmitted as it is without being packed in an HDLC frame. In a radio section between the transmitting unit 2 and the receiving unit 3, the signal is divided into ARQ frames by the lower layer ARQ, packed, and transmitted like other signals.

Regarding the frame structure of ARQ, RCRS
Based on TD-27F.

When the electric field strength and handover occur in the radio section and the transmission path quality deteriorates, ARQ frames are retransmitted in the lower layer ARQ.

In the example of FIG. 2, the frame AR of the third frame
An error has occurred in Q3, and retransmission of frame ARQ3 has occurred. This example shows a normal frame ARQ in the third retransmission.
In this example, retransmission is performed many times until normal reception is possible. During retransmission, the transmitting side will send the next AR
Not only can Q frames not be transmitted, but the communication costs during that time are in utter waste.

Therefore, in the first embodiment of the present invention,
First, in step 1, the frame error rate of the lower layer ARQ is measured. Next, in step 2, it is determined whether or not the frame error rate is equal to or higher than a predetermined value.
When the frame error rate is equal to or higher than the predetermined value, it is determined that the upper limit of the number of retransmissions should be specified, and the process proceeds to the next step 3. In step 3, the maximum number of lower layer ARQ retransmissions is calculated based on the frame error rate. At this time, if the frame error rate is high, the maximum number of retransmissions is reduced, and if it is low, the maximum number is increased. For example, the maximum number of retransmissions n is calculated using n = 250 / e where e is the number of frame errors in 5 seconds. For example, if an error of 83 frames is detected in 5 seconds, the maximum number of retransmissions is set to 3.

In step 4, the maximum number of retransmissions determined in step 3 is instructed to the lower layer ARQ. Lower layer A
The RQ limits the number of times the same frame number is requested as the confirmation or retransmission request frame number in the backward channel control information based on the instructed maximum number of retransmissions.
In the example of FIG. 2, the maximum number of retransmissions n is 3, and the frame A
After retransmitting three times, RQ5 gives up reception and requests the next frame ARQ6. Similarly, after retransmitting the frame ARQ6 three times, it gives up the reception and requests the next frame ARQ7. When the transmission channel quality is restored at the time of receiving the frame ARQ7, the image signal is received without retransmission thereafter. That is, when the transmission path quality of the wireless section is deteriorated, the number of ARQ frame retransmissions is limited according to the degree of the deterioration.

As described above, according to the first embodiment of the present invention, even if the quality of the transmission path in the radio section deteriorates and the retransmission of the ARQ frame occurs in the image signal transmission, the maximum retransmission of the ARQ frame is performed. Since the number of times is limited, retransmission is repeated forever, so that it takes a very long time to transmit an image signal, and it is extremely useful without wasting communication cost.

In the first embodiment of the present invention, the maximum number of retransmissions of the lower layer ARQ is adapted to be adaptively changed according to the frame error rate. It goes without saying that a similar effect can be obtained.

(Embodiment 2) FIG. 3 is a flowchart for explaining a communication control method of a portable telephone facsimile according to a second embodiment of the present invention. FIG. 4 is a sequence diagram for explaining the embodiment.

In the figure, reference numeral 1 denotes a transmitting-side fax unit, 2 denotes a transmitting-side unit unit, 3 denotes a receiving-side unit unit, and 4 denotes a receiving-side fax unit. The transmission path between the transmitting unit 2 and the receiving unit 3 is a wireless section.

The operation will be described below with reference to FIGS.

When the call connection is completed, the process first enters a phase B (pre-message phase). In phase B, DIS
(Digital identification signal) and DCS (Digital command signal) are transmitted and received, and their capabilities as facsimile are exchanged. The TCF (training signal) is not transmitted to the wireless section. Upon receiving the CFR (reception preparation confirmation), the transmission side determines that the image signal is ready to be transmitted, and shifts to phase C. The receiving side similarly shifts to phase C after sending the CFR and waits for the arrival of the image signal.

The frame structure of DIS, DCS, CFR, etc. is based on ITU-TT. 30 based.

In the case of non-ECM transmission, an image signal is transmitted as it is without being packed in an HDLC frame. In a radio section between the transmitting unit 2 and the receiving unit 3, the signal is divided into ARQ frames by the lower layer ARQ, packed, and transmitted like other signals.

For the ARQ frame structure, see RCRS
Based on TD-27F.

When a decrease in the electric field strength or handover occurs in the radio section and the quality of the transmission path deteriorates, retransmission of an ARQ frame occurs in ARQ of a lower layer.

In the example of FIG. 4, the third frame AR
An error has occurred in Q3, and retransmission of frame ARQ3 has occurred. This example shows a normal frame ARQ in the third retransmission.
In this example, retransmission is performed many times until normal reception is possible. During retransmission, the transmitting side will send the next AR
Not only can Q frames not be transmitted, but the communication costs during that time are in utter waste.

Therefore, in a second embodiment of the present invention,
First, in step 1, the frame error rate of the lower layer ARQ is measured. Next, in step 2, it is determined whether or not the frame error rate is equal to or higher than a predetermined value.
When the frame error rate is equal to or higher than the predetermined value, it is determined that the upper limit of the number of retransmissions should be specified, and the process proceeds to the next step 3a.
In step 3a, the transmission path quality deteriorates and the lower layer AR
The operator is notified that the error rate of Q is deteriorating.

The operator determines the maximum number of retransmissions of the lower layer ARQ according to the degree of deterioration.

At this time, the operator can consider not only the error rate of the lower layer ARQ but also the content of the image signal being transmitted.

In particular, when the encoding method of the image signal is the MH encoding method, since the encoding unit is completed for each line, the operator can confirm the contents of the already received image signal.

In consideration of the importance of the content of the image signal, the operator may set the maximum number of retransmissions of the ARQ frame to be large if the image signal is important, and set small if the image signal is not so important. it can.

In step 4, the maximum number of retransmissions of the ARQ frame set by the operator in step 3a is instructed to the lower layer ARQ. The lower layer ARQ limits the number of times the same frame number is requested as the confirmation or retransmission request frame number in the backward channel control information based on the instructed maximum number of retransmissions. In the example of FIG. 4, the maximum number of retransmissions n is 3, and the frame ARQ5 is 3
After retransmission, give up the next frame AR
Requesting Q6. After the frame ARQ6 is retransmitted three times in the same manner, it gives up the reception and the next frame ARQ7
Is demanding. When the transmission channel quality is restored at the time of receiving the frame ARQ7, the image signal is received without retransmission thereafter. That is, when the transmission path quality of the wireless section is deteriorated, the number of ARQ frame retransmissions is limited according to the degree of the deterioration.

As described above, according to the second embodiment of the present invention, even when the quality of the transmission path in the radio section is degraded and the ARQ frame is retransmitted in the image signal transmission, the maximum retransmission of the ARQ frame is performed. Since the number of times is limited, retransmission is repeated forever, so that it takes a very long time to transmit an image signal, and it is extremely useful without wasting communication cost.

The difference from the first embodiment of the present invention is that
The point is that the operator is notified that the transmission path quality is degraded and the error rate of the lower layer ARQ is degraded, and the operator sets the maximum number of retransmissions of the ARQ frame.

The operator on the receiving side can check the contents of the received image signal and can set the maximum number of retransmissions according to the importance of the image signal. A suitable maximum number of retransmissions can be set, which is extremely useful in practice.

(Embodiment 3) FIG. 5 is a flowchart for explaining a communication control method of a portable telephone facsimile according to a third embodiment of the present invention. FIG. 6 is a sequence diagram for explaining the embodiment.

In FIG. 6, reference numeral 1 denotes a transmitting fax unit, 2 denotes a transmitting unit unit, 3 denotes a receiving unit unit, and 4 denotes a receiving fax unit. The transmission path between the transmitting unit 2 and the receiving unit 3 is a wireless section.

The operation will be described below with reference to FIGS.

When the call connection is completed, the process first enters a phase B (pre-message phase). In phase B, DIS
(Digital identification signal) and DCS (Digital command signal) are transmitted and received, and their capabilities as facsimile are exchanged.

At this time, the transmission operator uses the maximum number of retransmissions setting means 31 to set the maximum number of ARQ frame retransmissions during image signal transmission. In setting, the operator considers the importance of the image signal.

The maximum number of retransmissions notification unit 32 notifies the receiving side of the maximum number of retransmissions set using NSC (non-standard function command) which is an option signal of DCS.

The receiving side holds the maximum number of retransmissions notified from the transmitting side in the maximum number of retransmissions storage means 33. Thereafter, upon receiving the CFR (reception preparation acknowledgment), the transmitting side determines that the image signal is ready to be transmitted, and shifts to phase C. The receiving side similarly shifts to phase C after sending the CFR and waits for the arrival of the image signal.

The frame structure such as DIS, DCS and CFR is based on ITU-TT. 30 based.

In the case of non-ECM transmission, an image signal is transmitted as it is without being packed in an HDLC frame. In a radio section between the transmitting unit 2 and the receiving unit 3, the signal is divided into ARQ frames by the lower layer ARQ, packed, and transmitted like other signals.

For the ARQ frame structure, see RCRS
Based on TD-27F.

When the electric field strength and handover occur in the radio section and the transmission path quality deteriorates, ARQ frames are retransmitted in the lower layer ARQ.

In the example of FIG. 6, the frame AR of the fifth frame
An error has occurred in Q5, and retransmission of frame ARQ5 has occurred. Conventionally, retransmission is performed many times until normal reception is possible. During the retransmission, the transmitting side cannot not only transmit the next ARQ frame, but also the communication cost during that period is useless.

Therefore, in the third embodiment of the present invention,
In step 3b, the maximum number of retransmissions of the lower layer ARQ stored in the maximum number of retransmissions storage means 33 is obtained.

In step 4, the maximum number of retransmissions of the ARQ frame acquired in step 3b is instructed to the lower layer ARQ. The lower layer ARQ limits the number of times the same frame number is requested as the confirmation or retransmission request frame number in the backward channel control information based on the instructed maximum number of retransmissions. In the example of FIG. 6, the maximum number of retransmissions n is 3, and after retransmitting the frame ARQ3 three times, it gives up reception and requests the next frame ARQ6.
Similarly, since the frame ARQ6 has been normally received at the third time, it is sent to the reception-side FAX unit 4 to request the next frame ARQ7. When the transmission channel quality is restored at the time of receiving the frame ARQ7, the image signal is received without retransmission thereafter.
That is, when the transmission path quality in the wireless section is deteriorated, the number of ARQ frame retransmissions is limited by the maximum number of retransmissions specified in advance on the transmitting side.

As described above, according to the third embodiment of the present invention, even when the quality of the transmission path in the radio section is deteriorated and the retransmission of the ARQ frame occurs in the image signal transmission, the maximum retransmission of the ARQ frame is performed. Since the number of times is limited, retransmission is repeated forever, so that it takes a very long time to transmit an image signal, and it is extremely useful without wasting communication cost.

The difference from the first embodiment of the present invention is that
The point is that the maximum number of retransmissions is limited in advance on the transmission side.
Since the maximum number of retransmissions can be set according to the importance of the image signal sent by the transmission side operator, the maximum number of retransmissions can be set by the transmission side operator by weighing the importance of the image signal and the communication time and cost, Very useful in practice.

In step 3b, the format of the error rate information transmitted is desirably an HDLC frame using a unique FCF terminated between the transmitting unit 2 and the receiving unit 3. ITU-TT.30 as shown in FIG. 7 used in this example
In the case of the NSC defined in the above, a mobile phone facsimile compliant with RCRSTD-27F is discarded by the unit and does not reach the application. Good facsimile communication can be performed without malfunction.

[0058]

As described above, according to the present invention, the maximum number of ARQ frame retransmissions is limited even if the quality of the transmission path in the radio section is degraded and the ARQ frame is retransmitted in the image signal transmission. This is extremely useful without repetition of retransmission for eternity and taking an enormous amount of time to transmit an image signal, and without wasteful communication costs.

Further, the quality of the transmission path is degraded and the lower layer AR
Notifying the operator that the error rate of Q is deteriorating, and the operator sets the maximum number of retransmissions of the ARQ frame, so that the receiving-side operator can check the content of the received image signal, The maximum number of retransmissions can be set according to the importance.

Since the maximum number of retransmissions is limited in advance on the transmission side, the operator on the transmission side can set the maximum number of retransmissions according to the importance of the image signal to be transmitted.

[Brief description of the drawings]

FIG. 1 is a flowchart of a communication control method for a mobile phone facsimile according to a first embodiment of the present invention.

FIG. 2 is a sequence diagram of a communication control method of the mobile phone facsimile according to the first embodiment of the present invention.

FIG. 3 is a flowchart of a communication control method for a mobile phone facsimile according to a second embodiment of the present invention.

FIG. 4 is a sequence diagram of a communication control method for a mobile phone facsimile according to a second embodiment of the present invention.

FIG. 5 is a flowchart of a communication control method for a mobile phone facsimile according to a third embodiment of the present invention.

FIG. 6 is a sequence diagram of a communication control method for a mobile phone facsimile according to a third embodiment of the present invention.

FIG. 7 is a diagram showing a data structure of NSC defined in ITU-TT.30.

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 1 transmission-side FAX unit 2 transmission-side unit unit 3 reception-side unit unit 4 reception-side FAX unit 31 maximum retransmission number setting means 32 maximum retransmission number notification means 33 maximum retransmission number storage means

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Harada Politics 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 5C075 AA90 AB06 CA01 CD22 CD25 CE02 CE09 5K067 AA01 BB21 DD27 DD52 EE02 GG07

Claims (9)

[Claims] 1. A communication control method for a facsimile for a mobile phone, comprising: measuring an error rate of a lower layer ARQ; A communication control method for a mobile phone facsimile, comprising: calculating; and instructing a lower layer ARQ a maximum number of retransmissions. 2. The step of instructing the lower layer ARQ on the maximum number of retransmissions, wherein the instruction on the maximum number of retransmissions is ITU-T.
T. 2. The communication control method for a mobile phone facsimile according to claim 1, wherein the communication control is carried out only in a phase C defined in 30. 3. The communication of a portable telephone facsimile according to claim 1, wherein the step of calculating the maximum number of retransmissions of the lower layer ARQ decreases the maximum number of retransmissions when the error rate is high and increases the maximum number of times when the error rate is low. Control method. 4. The lower layer ARQ limits the number of times the same frame number is requested as a confirmation or retransmission request frame number in the backward channel control information specified in RCRSTD-27F based on the specified maximum number of retransmissions. 2. The communication control method for a mobile phone facsimile according to claim 1, wherein: 5. The communication control method for a portable telephone facsimile according to claim 1, wherein the maximum number of retransmissions of the lower layer ARQ is a preset fixed value. 6. When the error rate is equal to or higher than a predetermined value,
2. The communication control method for a portable telephone facsimile according to claim 1, wherein the operator is notified and the maximum number of retransmissions can be set by the operator. 7. The communication control method for a portable telephone facsimile according to claim 1, wherein the transmitting side designates the maximum number of retransmissions to the receiving side in advance. 8. The communication control method for a portable telephone facsimile according to claim 7, wherein the designation of the maximum number of retransmissions by the transmitting side is performed using an NSC message in phase B. 9. A means for measuring an error rate of the lower layer ARQ, a means for calculating a maximum number of retransmissions of the lower layer ARQ based on the error rate when the error rate is equal to or more than a predetermined value, and a maximum number of retransmissions for the lower layer ARQ Means for instructing communication of a mobile phone facsimile.