JPH05328081A - System for controlling transmission speed - Google Patents

Abstract

PURPOSE:To provide the system for controlling the transmission speed capable of selecting the transmission speed with the highest transmission efficiency at all times. CONSTITUTION:When the transmission of one-block picture information is completed in a step S10, a PPS command is sent in a step S11. In response to it, a PPR command is sent from a reception side to proceed to step S15. In this step, the current effective transmission speed is obtained. Then, the effective transmission speed is compared with the transmission speed lower by one in step S16. As the result of this comparison, when the former is higher than the latter, the current transmission speed is used as it is. If the former is lower than the latter, the latter transmission speed is used. As a result, the transmission speed with the highest transmission efficiency can be selected at all times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission rate control system, and more particularly to a transmission rate control system capable of setting a transmission rate of a facsimile apparatus to an optimum rate suitable for the current state of facsimile communication.

[0002]

2. Description of the Related Art Conventionally, image information is transmitted in frame units, and a receiving station detects image information errors in frame units.
There is a method of retransmitting a frame in which an error has occurred from a transmitting station, that is, an ECM (error collect mode) method.

The conventional transmission rate control method in the facsimile communication determines the transmission rate by paying attention only to the transmission efficiency or the frame error rate, and it is not always possible to select the optimum transmission rate.

Here, the transmission efficiency α and the frame error rate β are defined as follows.

Transmission efficiency α = N0 / N1 frame error rate β = (N1−N0) / N1 = 1−α where N1 is the total number of frames actually transmitted and N0 is N
It is the number of frames obtained by subtracting the number of retransmitted frames from 1 (the number of transmitted frames when there is no error).

In order to solve the above-mentioned drawbacks of the conventional apparatus, for example, in the prior art disclosed in Japanese Patent Laid-Open No. 60-10974, the transmission efficiency α is obtained by measuring the frame error rate β of image information. The product of the transmission efficiency α and the transmission speed f at that time (effective transmission speed) is calculated, and the transmission speed f is controlled so that the value of this product falls within a predetermined range. In other words, when the effective transmission rate falls below the predetermined range, the transmission rate is further reduced, that is, fallback is performed.

[0007]

However, in the above-mentioned prior art, when the transmission efficiency α is the same, there is a problem that the slower the transmission speed f, the easier the fallback occurs. Further, this prior art has a problem that the image information cannot always be transmitted at the highest efficiency when the transmission speed is reduced.

An object of the present invention is to eliminate the above-mentioned problems of the prior art and to provide a transmission rate control system capable of always selecting a transmission rate with the highest transmission efficiency.

[0009]

In order to achieve the above object, the present invention comprises means for comparing the current effective transmission rate with other transmission rates, or other means such as the time required to transmit the number of frames to be transmitted. It is characterized in that it is provided with a means for comparing with the required time of the transmission rate and a means for selecting the transmission rate with the higher effective transmission rate or the shorter required time.

[0010]

According to the present invention, the current effective transmission rate can be compared with other transmission rates during communication, and the larger transmission rate can always be adopted. Therefore, the transmission rate with the highest transmission efficiency should always be selected. You can Alternatively, by comparing the time required to transmit the number of frames to be transmitted with the time required for other transmission rates and always using the smaller transmission rate, the transmission rate with the highest transmission efficiency can always be selected. ..

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing a main part of a first embodiment of the present invention.

In the figure, 1 is a panel of a facsimile apparatus, 2 is a panel control section, 3 is a scanner for reading a transmission original, and 4 is a scanner control section. Reference numeral 5 is a printer, 6 is a printer controller, and 7 is a memory for storing the data read by the scanner 3 or the received data. Also,
8 is a system control unit of the facsimile machine, 9 is a protocol control unit for creating and analyzing each command used in the protocol, 10 is a modem, 11 is a network control unit, and 12 is N.
CU.

Further, 8a, 8b, 8c and 8d are
These are a speed comparison unit, a speed storage unit, an error frame counting unit, and a transmission frame counting unit, which are the main parts of this embodiment. The system control unit 8 itself may have these functions.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG. First, the system control unit 8
When the panel control unit 2 gives a transmission instruction, the scanner control unit 4 requests the transmission document reading. The scanner control unit 4 reads the transmission original by the scanner 3 and stores it in the memory 7.
And the system control unit 8 is notified that the reading is completed.

Therefore, the system control unit 8 has the network control unit 11
Request to call. The network control unit 11 dials the dial number notified by the system control unit 8 from the NCU 12 (step S1).

Next, the system control unit 8 makes a transmission request to the protocol control unit 9. Going to step S2,
The protocol control unit 9 determines whether a non-standard function (NSF) or a digital identification signal (DIS) is received. If this judgment is affirmed, the process proceeds to step S3,
Send non-standard function settings (NSS) and digital command signals (DCS).

In step S4, the NSS or DC
The transmission speed designated by the S command is stored in the speed storage unit 8a. Training is performed in step S5, and a training check (TCF) is transmitted in step S6. Next, in step S7, the reception preparation confirmation (CF
R) is received, and if this determination is negative, the process proceeds to step S8, the transmission speed is lowered by one, and the process is repeated from step S3.

If step S7 becomes affirmative, a training signal is transmitted in step S9, and the flow advances to step S10 to transmit one block (= 256 frames) of image information. Then, in step S11, the partial page signal (P
PS) is sent, and the message confirmation (M
CF) is received. If this determination is affirmative, it means that the image information of one block has reached the receiving side without a data error. On the other hand, in the case of negative, the partial page request (PPR) is received. This PPR
By this, the number of the frame in which the data error is received is notified to the transmitting side.

In step S13, it is determined whether or not there is a next block. If there is a next block, the process proceeds to step S9, training is performed again, and image information is transmitted. On the other hand, when step S13 is negative, the routine proceeds to step S14, where the line disconnection command (DCN) is sent out and the series of processing is ended.

When the process proceeds from step S12 to step S15, in step S15, the transmission frame counting section 8d
The effective transmission rate is calculated based on the value counted by the error frame counter 8c (see FIG. 1). An example thereof is as follows.

If the cumulative number of transmitted frames at 9600 bps is 250 frames and the cumulative number of erroneous frames is 100 frames, the frame transmission success rate and the effective transmission rate are as follows.

Frame transmission success rate = (250-100)
/250=0.6 Effective transmission rate = 9600 × 0.6 = 5760 bps When the effective transmission rate is obtained as described above, the process proceeds to step S16, and it is determined whether the effective transmission rate is higher than the transmission rate one level below. Done. This judgment is based on the speed comparison unit 8a.
(See FIG. 1). In the case of the above example, the effective transmission rate is compared with 7200 bps, which is one transmission rate below 9600 bps.

When the determination is negative, the process proceeds to step S17, the transmission rate is decreased by one, and this transmission rate is stored in the rate storage section 8b. This is notified to the receiving side by a continue correction (CTC) command. Then
It is judged whether or not the correction continuation response (CTR) has been received. When it is judged that the correction continuation response (CTR) has been received, the process proceeds to step S9, and the frame having the transmission error is retransmitted.

If the determination in step S16 is affirmative, the process proceeds to step S18, and it is determined whether or not PPR has been received four times in succession. If this determination is negative, the process returns to step S9, and the frame with the transmission error is retransmitted. On the other hand, when the determination in step S18 is affirmative, the process proceeds to step S19, where the CTC
The command notifies that the transmission rate is not changed, and the process proceeds to step S20. Hereinafter, the above operation is repeated.

In the specific example described above, 9600
The effective transmission rate of bps (= 5760 bps) is 960
Since it is smaller than the transmission rate one bit below 0 bps (= 7200 bps), the determination in step S16 is negative, and the transmission rate is reduced to 7200 bps in step S17.

As described above, according to this embodiment, the steps S15, S16, S17 and S19 are provided.
It is possible to select an optimum transmission rate that matches the current state of facsimile communication.

Next, a second embodiment of the present invention will be described with reference to FIGS. Note that FIG. 3 shows functions related to the present embodiment extracted from FIG. 1 for the sake of easy understanding of the description, and FIG. 4 shows only the processing of the parts different from FIG. is there. Therefore, the processing not shown in FIG. 4 is the same as or equivalent to that in FIG.

The present embodiment uses the function of the modem 10 capable of reading out the optimum transmission rate during facsimile communication.

Similar to the first embodiment, in step S15, the transmission frame counting unit 8d and the error frame counting unit 8c are used.
The effective transmission rate is calculated based on the values counted in (see FIG. 3). Next, in step S21, the effective transmission rate is compared with the optimum transmission rate read from the modem 10 in the present embodiment, and if the effective transmission rate is smaller than the optimum transmission rate, step S22.
Go to and set the transmission rate to the optimum transmission rate.
Notify the receiving side with the TC command, and send the speed storage unit 8
Store in b. On the other hand, if the effective transmission rate is higher than the optimum transmission rate, the process proceeds to step S18 to set the PPR to 4
After determining whether or not the signals have been received continuously, if this determination becomes affirmative, the process proceeds to step S19 to notify that the transmission rate is not changed by the CTC command.

As described above, in the present embodiment, the current effective transmission rate is compared with the optimum transmission rate read from the modem 10, and the larger transmission rate is selected. It is possible to select the optimum transmission rate that is suitable for the actual situation.

Next, a third embodiment of the present invention will be described with reference to FIGS. Similar to FIG. 3, FIG. 5 shows the functions related to the present embodiment extracted from the configuration of the facsimile apparatus, 8e is a required time calculation unit, 8f is a required time comparison unit, and The reference numerals indicate the same or equivalent to those in FIG. 1 or FIG. Further, FIG. 6 shows only the processing of the part different from FIG. 2, and the processing not shown in FIG. 6 is the same as or equivalent to that of FIG.

The processes of steps S12 and S15 are
It is similar to the second embodiment. Proceeding to step S31, there is an error in the effective transmission rate obtained in step S15 in the required time calculating unit 8e, and therefore it is necessary to transmit a frame to be retransmitted and a frame not yet transmitted. The time (= t0), that is, the time required for the entire transmission of the remaining data is obtained. The required time t0
An example of how to obtain is described.

Now, 960 obtained in step S15
It is assumed that the effective transmission rate at 0 bps is 7680 bps (frame transmission success rate = 0.8), the number of frames to be retransmitted is 50, and the number of frames not yet transmitted is 0. Then, the current transmission rate (9600b
(ps), the time required for all transmission is as follows.

Time required for transmitting image information = 50 (frame) × 256 (byte / frame) × 8 (bit / byte) / 7680 bps = 13.3 (second) Time required for protocol = 3 (second) × 3 times = 9 (seconds) Time required for all transmissions (t0) = 13.3 + 9 = 22.3
(Second) Note that the time required for the protocol is 1 second for PPS transmission and P
It is similar to that it takes 2 seconds for PR reception. The reason for multiplying three times is that the frame transmission success rate is 0.8 and the number of frames to be retransmitted is 50.

Next, in step S32, the required time (t1) for the entire transmission when the transmission speed is decreased by one is obtained as follows.

In the above-mentioned specific example, the transmission rate reduced by one is 7200 bps. Therefore, the required time t1 can be calculated as follows.

Time required for transmitting image information = 50 (frames) × 256 (bytes / frames) × 8 (bits / bytes) / 7200 bps = 14.2 (seconds) Time required for protocol = 4 (seconds) Time required for (t1) = 14.2 + 4 = 18.2
(Second) The time required for the protocol is the time required for sending and receiving the CTC and CTR commands.

However, when 64 octets are selected as the frame size instead of 256 octets, the above calculation formula 256 (byte / frame) is changed to 64 (byte / frame) according to the selection. Of course, change it. Further, in the above formula, PPS, PPR, CT
The time required for C and CTR is 1 second, 2 seconds, 1 second, and 1 respectively.
It is similar to the second, but H corresponding to each command
If the above calculation is performed with a value obtained by adding 1 second of the preamble to the time required to transmit the DLC frame length as the time required for the command, a more accurate determination will be made.

When the process of step S32 is completed, the process proceeds to step S33, where the required time t0 and t1 are compared in magnitude, that is, the process of whether or not t1 ≥t0 is satisfied is performed by the required time comparison unit 8f. Be seen. Then, if this determination is affirmative, the process proceeds to step S18. On the other hand, if this determination is negative, the process proceeds to step S34 and the CTC
The transmission rate reduced by one with the command is stored in the rate storage unit 8b.

As described above, in the present embodiment, the required time for all transmissions is obtained and the transmission speed with the shorter required time is adopted. The transmission rate can be selected.

Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 7 shows only the processing of the part different from FIG. 2, and the processing not shown in FIG. 7 is the same as or equivalent to that of FIG.

The processes of steps S12 and S15 are
This is similar to the second and third embodiments. When proceeding to step S41, the same processing as step S31 in FIG. 6 is performed to transmit the frame to be retransmitted and the frame not yet transmitted due to an error due to the effective transmission rate obtained in step S15. The required time (= t0) is obtained.

In step S42, the required time (= t2) for all transmissions at the optimum transmission rate read from the modem 10 is obtained.

Then, in step S43, t2 ≥
A determination is made as to whether t0 holds. If this determination is affirmative, the process proceeds to step S18, and if not, the process proceeds to step S44. In step S44, the transmission rate is set to the optimum transmission rate by the CTC command, and the rate storage unit 8b
(See FIG. 5).

As described above, also in this embodiment, the first
As in the case of the third embodiment, it is possible to select an optimum transmission rate suitable for the actual situation of facsimile communication.

Next, a fifth embodiment of the present invention will be described with reference to FIGS.
And it demonstrates with reference to FIG. Similar to FIG. 3, FIG. 8 shows the functions related to the present embodiment extracted from the configuration of the facsimile apparatus. 8g indicates an effective transmission rate storage section, and other symbols indicate the figures. Indicates the same as or equivalent to 3. Further, FIG. 9 shows only the processing of the part different from FIG. 2, and the processing not shown in FIG.
Is the same as or equivalent to. Further, FIG. 10 is a diagram showing a specific example of data stored in the effective transmission rate storage unit 8g.

If the determination in step S12 in FIG. 9 is negative, the process proceeds to step S51. In step S51, the first
The effective transmission rate for the current transmission rate is calculated by the same method as described in the embodiment and stored in the effective transmission rate storage unit 8g. For example, the current transmission rate is 7200
bps and the calculated effective transmission rate is 20
If it is 10 bps, 2010 bps is registered in the effective transmission rate storage unit 8g.

In step S52, the highest effective transmission rate is selected from the effective transmission rates shown in FIG.
In the example of FIG. 10, the effective transmission rate of 2400 bps corresponding to the transmission rate of 2400 bps is selected.

In step S53, it is determined whether the effective transmission rate for the current transmission rate is the same as the highest effective transmission rate selected in step S52.
In the above example, 2010 bps, which is the effective transmission rate with respect to the current transmission rate, is not the same as 2400 bps, which is the highest effective transmission rate selected in step S52, so the determination in step S53 is negative and step S1
Proceed to 7. If the effective transmission rate with respect to the current transmission rate is the largest in FIG. 10, the determination in step S53 is affirmative and the process proceeds to step S18.

In step S17, the CTC command is used to notify that the data will be transmitted at that transmission rate.

At the time of initial setting (initialization) at the time of calling (step S1 of FIG. 2), the same data as the transmission rate, that is, 9600 bps, 7200 bps, 4800 bps, is set as the effective transmission rate of FIG.
2400 bps will be registered.

As described above, according to the present embodiment, the transmission is always performed at the highest effective transmission speed among the effective transmission speeds corresponding to the respective transmission speeds. The same effect can be obtained.

[0053]

As is apparent from the above description, according to the present invention, the effective transmission rate is compared with the effective transmission rate of another transmission rate or is transmitted in the state of currently performing facsimile communication. The time required to transmit the number of frames that should be transmitted is compared with the time required for other transmission rates, and the larger effective transmission rate or the transmission rate having the smaller required time is selected and transmitted. The effect is that the optimum transmission speed that was available can be selected.

As a result, there is also an effect that the communication cost can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an exemplary embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the first embodiment.

FIG. 3 is a block diagram showing a configuration of a main part of a second embodiment.

FIG. 4 is a flowchart for explaining an operation of a main part of the second embodiment.

FIG. 5 is a block diagram showing a configuration of a main part of a third embodiment.

FIG. 6 is a flowchart for explaining the operation of the main part of the third embodiment.

FIG. 7 is a flowchart for explaining the operation of the main part of the fourth embodiment.

FIG. 8 is a block diagram showing a configuration of a main part of a fifth embodiment.

FIG. 9 is a flowchart for explaining the operation of the main part of the fifth embodiment.

FIG. 10 is a diagram showing an example of data stored in an effective transmission rate storage unit.

[Explanation of symbols]

8 ... System control section, 8a ... Non-speed section, 8b ... Speed storage section, 8c ... Error frame counting section, 8d ... Outgoing frame counting section, 8e ... Required time calculating section, 8f ... Required time comparing section, 8g ... Effective transmission Speed memory

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shinichiro Nagoshi 3-7-1, Iwatsuki-shi, Saitama Prefecture Fuji-Zerox Co., Ltd. Iwatsuki Plant (72) Inventor Hiroaki Sakaki 3--7, Iwatsuki City, Saitama Prefecture No. 1 Fuji Xerox Co., Ltd. Iwatsuki Office

Claims (5)

[Claims] 1. A transmission rate control method for a communication method having a plurality of transmission rates, wherein the effective transmission rate corresponding to the transmission rate of the current communication is obtained, and the effective transmission rate A transmission rate; and a means for updating the transmission rate to a transmission rate lower by one when the effective transmission rate is lower than the transmission rate lower by one. control method. 2. A transmission rate control method of a communication method having a plurality of transmission rates, a means for obtaining an effective transmission rate corresponding to the transmission rate of the current communication, the effective transmission rate and a read from a modem. Means for comparing with an optimal transmission rate, when the effective transmission rate is less than the optimal transmission rate,
And a means for updating the transmission rate to the optimum transmission rate. 3. A transmission rate control method of a communication method having a plurality of transmission rates, and means for obtaining a time (t0) required to transmit a predetermined amount of data at the transmission rate of the current communication, A means for determining the time (t1) required to transmit the predetermined amount of data at a transmission rate one level lower than the transmission rate and the magnitude of the times t0 and t1 are compared, and when the former is larger than the latter, the transmission rate is And a means for updating the transmission rate to the transmission rate lower than the transmission rate by one. 4. A transmission rate control method of a communication method having a plurality of transmission rates, a means for obtaining a time (t0) required to transmit a predetermined amount of data at a current communication transmission rate, and a modem. A means for determining the time (t2) required to transmit the predetermined amount of data at the read optimum transmission rate is compared with the time t0 and t2, and when the former is larger than the latter, the transmission rate is optimized. A transmission rate control method, comprising: a means for updating the transmission rate. 5. A transmission rate control method for a communication method having a plurality of transmission rates, wherein the effective transmission rate for each transmission rate is stored, the effective transmission rate is updated, and the updated transmission rate is updated. Means for comparing the effective transmission rate with the maximum effective transmission rate in the storage means, and when the former effective transmission rate is different from that of the latter, adopt the transmission rate corresponding to the latter effective transmission rate. Transmission rate control method characterized in that