JPH073970B2 - Image transmission equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image transmission device for transmitting information such as a facsimile signal from a transmission station to a plurality of reception stations via lines.

2. Description of the Related Art In order to correctly transmit a digital code to a receiving station, an error control system that corrects a transmission line error is required. As an error control method in data transmission, the ARQ (Automatic Repeat Request) method is widely used.

An image transmission apparatus using the conventional ARQ method will be described below with reference to FIG. In FIG. 5, reference numeral 51 is a transmission device, 52 is a transmission control unit for transmitting image information in a fixed amount of frames, 53 is a response information receiving unit for receiving response information, and 54 is an image information line. is there. Reference numerals 55, 59 and 5D are receivers, 56, 5A and 5E are reception control units that receive a frame and determine whether there is a transmission error, and 57, 5B and 5F indicate whether or not the frame is correctly received. Information as response information,
The response information transmitters 58, 5C and 5G for transmitting to the transmitter 51 are response information lines.

The operation of the above configuration will be described below. First, by the transmission control unit 2 in the transmitter 51,
The transmission signal is divided into a fixed amount of frames shown in FIG. 2, and various control information and a code called FCS (Frame Check Sequence) code for detecting an error generated on a transmission line are added to each frame. A frame is constructed by using the frame and is sent to the image information line 54 in frame units. The reception control unit 56 in the reception device 55 can check whether or not there is a transmission line error in the received frame by performing a transmission line error check on the received frame for each frame using the FCS code. The response information transmitter 57 receives a normal reception response (hereinafter, ACK
Called. ), If there is a transmission error in the received frame, an abnormal reception response (hereinafter referred to as NACK) is sent to the response information line 58. Also in the other receiving devices 59 and 5D, the transmission error check is performed on the received frame by each of the reception control units 5A and 5E, and the result is sent to each of the response information transmission units 5B and 5F.
Then, it transmits to the transmitter 51 using the response information lines 5C and 5G. The response information receiving unit 53 in the transmitting device 51
If no ACK is received, a retransmission instruction from the corresponding frame is output to the transmission control unit 52. The transmission control unit 52 retransmits from the frame instructed to retransmit. With the above operation, it is possible to correct a transmission error that has occurred during transmission through the image information line 54.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-described configuration, in order to generally reduce the transmission time, the transmission device 61 does not wait for the reception of response information for a frame when the transmission of a frame is completed. Send the frame. Therefore, it becomes difficult to associate the transmitted frame with the response information by using the response information of only ACK or NACK. In addition, the delay time from the transmission of a frame to the return of response information differs for each receiving device, so to confirm that a frame has been received by all receiving devices without transmission error after the completion of transmission of a certain frame. It is necessary to receive ACK three times. Furthermore, when only the specific receiving device is selected and transmitted, the ACK of only the response information from the selected receiving station must be the target. Therefore, there is a problem that the retransmission management of the transmitting device becomes complicated as the number of receiving devices increases.

The present invention solves the above-mentioned problems of the prior art. By associating a frame with response information, receiving the selection information to the receiving device, and validating the response information of only the selected receiving device, the reception is performed. An object of the present invention is to simplify transmission error correction control by frame retransmission even in a system having a large number of devices.

Means for Solving the Problems The present invention configures a transmission frame for transmission information at regular intervals, receives a transmission signal transmitted with a frame number, and transmits the transmission signal without transmission error. A plurality of receiving devices, each of which includes a determination unit that determines whether or not the determination result has been received, and a response information transmission unit that transmits the maximum frame number as response information among the frame numbers that received the determination result without a transmission error; Selection information transmitting means for transmitting the selection information of the receiving device to which a transmission signal is to be transmitted, a transmission frame for transmitting information at a constant cycle, and a plurality of frames selected by the broadcast communication by adding a frame number. A first transmission control unit for transmitting the transmission signal to the selective receiving device, and a plurality of response information transmitted from response information transmitting means in the selective receiving device. Response information minimum value calculating means for receiving and comparing the response information at regular intervals to calculate the minimum value of the frame number, and sending the response information minimum value, transmitting the transmission signal to the selective receiving device. From the response information expected value calculation unit that calculates the delay cycle time until the response information returns, and calculates the expected arrival time of the response information from the delay cycle time; A transmission including a second transmission control unit that calculates a transmission error frame based on the expected arrival time and the response information minimum value calculated by the response information minimum value calculation unit, and transmits the predetermined frame again to the selective receiving device. It is characterized by an image transmission device including a device.

Action The present invention associates the frame transmitted with the above configuration with the response information, and based on the receiving device selection information, regarding the response information from a plurality of selected receiving devices, and when there is no selection, By using the minimum value of the frame number for the response information from all receiving devices as a representative value of all response information, it is possible to easily perform transmission error correction control by retransmission for a system that broadcasts to multiple receiving devices. You can do it.

Example Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block connection diagram of an image transmission apparatus when three of the n receiving apparatuses are selected in the embodiment of the present invention. In FIG. 1, 10 is a transmitting device, 11 is a transmission control unit that performs a frame transmission device, 12 is a response information expected value calculation unit that calculates an expected value of response information, and 13 is a retransmission that calculates a frame number to be retransmitted. A frame number calculator, 14 is a minimum response information calculator, 15 is a receiver selection information transmitter, 16, 17, 18, 1P and 1Q are response information receivers, and 19 is an image information line. 1A, 1B, 1C are receivers, 1
D, 1E, 1F are reception control units that inspect received frames for transmission errors, and 1G, 1H, 1I are transmission devices that use the frame number of frames received without transmission errors as response information.
The response information transmitters 1J, 1K, 1L, 1R and 1S to be transmitted to 10 are response information lines. 1m, 1n, and 10 are unselected receiving devices.

The operation of the above configuration will be described below.
First, in the transmitter 10, the receiver selection information transmitter 15
Transmits information for selecting a receiving device to each receiving device, and selects a specific receiving device from a plurality of receiving devices. In this embodiment, the information for selecting the receiving devices 1A, 1B and 1C is transmitted. At the same time, the response information minimum value calculation unit 14 is also notified of the selection information. The transmission control unit 11 divides the information into fixed bits, adds various control information and an FCS code which is a transmission error detection code, and constructs a frame composed of flags, control information, image information and FCS code shown in FIG. , Is periodically sent to the image information rotation line 19 in frame units.
At this time, the frames are numbered in ascending order from 0 by 1. (Hereinafter, referred to as frame number.) The transmission control unit 11 notifies the response information expected value calculation unit 12 of the frame number being transmitted and the current time (represented by a cycle number).
From the present time (t) and the delay time (D) until the response is returned from the receiving device that takes the longest transmission time, the response information expectation value calculation unit 12 calculates the return time of the response information of the transmission frame according to the first equation. Calculate and prepare a table as shown in FIG.

T = t + D + m (1) (m ≧; constant for absorbing delay time difference) On the other hand, the receiving device 1A selected by the selection information transmitted from the transmitting device, via the image information line 19 , The reception control unit 1D performs a transmission error check on the received frame using the FCS code. The reception control unit 1D notifies the transmission error check device and the frame number to the response information transmission unit 1G. The response information transmitting unit 1G uses the frame shown in FIG. 4 as the received frame number, which is the minimum value of the series of frame numbers of the frames received without transmission error, and sends it to the transmitting device 10 via the response information line. Send out. Similarly, for the other selected receiving devices 1B and 1C, the transmission control unit 1E and 1F also perform a transmission error check on the frames received, and as a result, the response information transmission units 1H and 1I receive a series of received data without transmission error. Using the frame shown in FIG. 4 as the received frame number, the maximum value of the frame numbers is sent to the transmitter 10 as the response information via the response information lines 1K and 1L.

The transmission device 10, the response information received via the response information line 1J, performs a transmission error check using the FCS code in the response information receiving unit 16, the received frame number in the response information received without transmission error, The maximum value is output to the response information minimum value calculation unit 14.

The other selected response information receiving units 17 and 18 also perform a transmission error check on the response information received via the response information lines 1K and 1L, and the received frame number in the response information received without a transmission error. The maximum value of is output to the response information minimum value calculation unit 14. The response information minimum value calculating unit 14 compares the received frame numbers output by the response information receiving units 16, 17, 18 of the selected receiving device with the selection information notified from the receiving device selection information transmitting unit 15. Then, the minimum value MIN (t) of the received frame numbers is output to the retransmission frame number calculation unit 13. In addition, when the selection information is not notified from the reception device selection information transmission unit 15, that is, in the non-selected state, the reception frame numbers from all the reception devices are compared, and the reception frame number minimum value MIN (t) is calculated as the retransmission frame number. Output to section 13.

On the other hand, the response information expected value calculation unit 12 determines the current time t and the third time.
From the table shown in the figure, the received frame number EXPT (t) expected to have no transmission error is calculated and output to the retransmission frame number calculation unit 13. The retransmission frame number calculation unit 13 determines that a transmission error has occurred in the frame number of {MIN (t) +1} when the response information and the expected value of the response information satisfy the equation (2) below. , {MIN (t) +1)}
Retransmit from the frame number of and correct the transmission error. That is, MIN (t) <EXPT (t) ... (2) {MIN (t) +1} is notified to the transmission control unit as the transmission frame number.

When the condition (2) is satisfied, {MIN
(T) +1} frame numbers are sequentially retransmitted, and after the retransmission frame number is output, the frame number EXPT (t) output by the response information expected value calculation unit 12 is the frame number {MIN (t) The retransmission frame number output operation is not performed until it matches +1}.

As is clear from the above description, the transmission device 10 is provided with the reception device selection information transmission unit 15, the response information minimum value calculation unit 14, and the response information expected value calculation unit 12 to transmit information to a plurality of reception devices. It is possible to easily detect a transmission error and correct the error by resending the system.

Although the embodiment of the present invention shows a case where three receivers are selected for n receivers and information is transmitted to the receivers, the selected receivers are m receivers (provided that m <n is a positive receiver). integer)
The present invention is also applicable to the case where

EFFECTS OF THE INVENTION As described above, according to the present invention, by providing a transmitting device with a receiving device selection information transmitting unit, a response information expected value calculating unit and a response information minimum value calculating unit, information is simultaneously transmitted to a plurality of receiving devices. When transmitting, it is easy to detect transmission errors and correct by retransmission. Further, an increase or decrease in the number of receiving devices can be easily dealt with only by changing the parameter of the selection information, and the system can be easily changed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block connection diagram of an image transmission apparatus according to an embodiment of the present invention, FIG. 2 is a conceptual diagram of a transmission frame by the apparatus, and FIG. 3 is a frame number by the apparatus and its number. FIG. 4 is a diagram showing a table relating to the time at which response information is returned, FIG. 4 is a conceptual diagram of a response information frame by the device, and FIG. 5 is a block connection diagram of a conventional image transmission device. 10 ... Transmitting device, 11 ... Transmission control unit, 12 ... Response information expected value calculating unit, 13 ... Retransmission frame number calculating unit, 14 ... Response information minimum value calculating unit, 15 ... Receiving device selection information transmission Department,
16,17,18,1P, 1Q …… Response information receiver, 19 …… Image information line, 1A, 1B, 1C, 1m, 1O …… Receiver, 1D, 1E, 1F …… Reception controller, 1G , 1H, 1I …… Response information transmitter, 1J, 1K, 1L, 1R, 1S
...... Response information line.

Claims (1)

[Claims] 1. A transmission frame is formed with respect to transmission information at regular intervals, a transmission signal transmitted with a frame number is received, and it is determined whether or not the transmission signal is received without a transmission error. And a plurality of receiving devices each having a response information sending unit for sending the maximum frame number as response information among the frame numbers received the determination result without a transmission error, and sending the transmission signal. Selection information sending means for sending the selection information of the receiving device, constructing a transmission frame for the transmission information at a constant cycle, and adding the frame number to the selected selective receiving device by broadcast communication. A first transmission control unit for transmitting a signal, receiving a plurality of response information transmitted from the response information transmitting means in the selective receiving device, and transmitting the response information. Response information minimum value calculating means for calculating the minimum value of the frame number by comparing at fixed intervals and sending it as the response information minimum value, from transmitting the transmission signal to the selective receiving device until the response information is returned. And a response information expected value calculation unit that calculates the expected delay time of the response information from the delay period time, and the expected arrival time calculated by the response information expected value calculation unit, and the response information. An image transmission apparatus comprising: a transmission apparatus including a second transmission control unit for calculating a transmission error frame based on the response information minimum value calculated by the minimum value calculation means, and again transmitting a predetermined frame to the selective reception apparatus.