JPH077944B2 - Signal transmission device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal transmission device for transmitting information such as a facsimile signal from a transmitting station to a receiving station via a line.

2. Description of the Related Art In order to correctly transmit a digital code to a receiving station, an error control method for correcting the sending is necessary. ARQ (Automatic Repeat) is used as a control method in data transmission.
A request (Automatic Repeat Request) method is widely used.

Hereinafter, a conventional signal transmission apparatus using the ARQ method will be described with reference to FIG.

In FIG. 5, reference numeral 51 is a transmission device, 52 is a transmission control unit for forming and transmitting a fixed amount of frames, 53 is a response information receiving unit for receiving response information, and 54 is a data line. 55 is a receiving device, 56 is a reception control unit that receives a frame and determines whether or not the received frame is correctly received, and 57 is information that indicates whether or not the received frame is correctly received as response information. A response information transmitting unit for transmitting to 51, and 58 for the response information circuit.

The operation of the above configuration will be described below. First, by the transmission control unit 25 in the transmitter 51,
The transmitted signal is divided into a fixed number of frames, and each frame is constructed by adding various control information and a code called FCS (Freame Check Sequence) to detect errors that occur on the transmission path. , Frame by frame to the data line 54. The reception control unit 56 in the reception device 55 can check whether or not there is an error in the received frame by performing a transmission path error check on the received frame for each frame using the FCS code. The reception control unit 56 notifies the response information transmission unit 57 of information as to whether or not there is an error, and the response information transmission unit 57
If the signal is received correctly, a signal indicating that effect (hereinafter referred to as ACK) is formed for each frame in the same manner as the received frame, and the response information receiving unit uses the response information line 58.
Send to 53. In addition, even if it is erroneously received, a signal to that effect (hereinafter referred to as NACK) is transmitted to the response information receiving unit for each frame. Then, when the ACK signal cannot be received, the response information receiving unit notifies the transmission control unit 52 of an instruction to retransmit from the corresponding frame. The transmission control unit 52 retransmits the frame according to the retransmission instruction from the response information receiving unit 53, and corrects the transmission path error.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-described configuration, in order to shorten the transmission time, the transmission device 51 generally does not wait for the response information to be returned when the transmission of a certain transmission frame is completed. The next transmission frame is transmitted to. Therefore, it becomes difficult to associate the transmitted frame with the response information, and the control of the transmission path error correction by retransmission becomes complicated. There is a problem that the control becomes more complicated in a system with a long delay time.

The present invention solves the above-mentioned problems of the prior art by correlating a transmitted frame with its response information, simplifying transmission line error correction control by retransmission, and further providing a system with a long transmission line delay time. On the other hand, it is an object of the present invention to perform transmission line error correction control that can cope with only changes in parameters and can cope with deviations in delay time, and correctly transmit digital codes to a receiving station.

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 receiving device having a discriminating means for discriminating whether or not it has been received, and a response information transmitting means for transmitting, as response information, the latest frame number among the frame numbers received as the discrimination result without any transmission error; A first transmission control unit that configures a transmission frame at regular intervals and assigns a frame number that changes periodically to send the transmission signal to the receiving device, and is sent from response information transmitting means in the receiving device. A response information receiving device for receiving response information, the delay cycle time from the transmission of the transmission signal to the receiving device until the response information returns, A response information expected value calculation unit that calculates an expected arrival time of answer information, and a transmission error frame by the expected arrival time calculated by the response information expected value calculation unit and the response information received by the response information receiving unit. It is characterized by a signal transmission device comprising a transmission device having a second transmission control unit for detecting and again transmitting a predetermined frame to the reception device.

Effect The present invention has the above-described configuration to associate the transmitted frame with its response information, calculate the delay cycle time, and the expected value of the response information from the transmitted frame, and calculate the transmission error frame from the response information and the expected value. It is possible to perform transmission error control by detecting and retransmitting
It can be applied to both a system with a long delay time and a delay time.

EXAMPLES Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a signal transmission device according to an embodiment of the present invention. In FIG. 1, 10 is a transmitter,
Reference numeral 11 is a transmission control unit for performing frame transmission control, 12 is a response information expected value calculation unit for calculating an expected value of response information, 13 is a frame number calculation unit, 14 is a response information receiving unit, and 15 is a data line. Reference numeral 16 is a receiving device, 17 is a reception control unit for controlling reception of frames, 18 is a response information transmitting unit for transmitting information to the transmitting device 10 whether the received frame is correctly received or erroneous, and 19 is a response information line. is there.

The operation of the above configuration will be described below.
First, the transmission control unit 11 in the transmission device 10 divides the transmission signal into a fixed amount of frames, adds various control information and FCS code to each frame, and sets the flags, control information,
A frame composed of a digital code and FCS is constructed, and the frame is periodically sent to the data line 15 in frame units. At that time, the frames are numbered in ascending order from 0 to 1. (Hereinafter, referred to as frame number.) The frame number is notified from the frame number calculation unit 13. Transmission control unit
Reference numeral 11 notifies the response information expected value calculation unit 12 of the current time (represented by a cycle number) transmission frame number. The response information expected value calculation unit 12 calculates the return time of the response information of the transmission frame from the equation (1) from the current time (t) and the delay cycle time (D), and creates a table as shown in FIG. create.

T = t + D + m (1) (m ≧ 1; constant for absorbing delay time difference) On the other hand, the frame received via the data line 15 is received by the reception control unit 17 and the received frame is changed for each frame. A transmission line error check is performed using the FCS code to determine whether or not there is an error in the received frame. The reception control unit 17 determines the transmission path error check result and the reception frame number (F (t)).
Is sent to the response information transmitting unit 18. The response information transmitter 18
The highest correctly received frame is formed into a frame number (hereinafter referred to as received frame number (RF (t))) as shown in FIG. 4, and is sent to the response information receiving unit 14 using the response information line 19. Send. That is, the response information transmission unit 14
Has a reception frame counter (RFC), and the result of transmission line error check is 1) When it is correct 2) In case of error RF (t) = RFC.

(However, RFC: Initial value is 0.) The above processing is performed and RF (t) is transmitted as response information. Furthermore, the response information receiving unit 14 notifies the frame number calculating unit 13 of the received response information. Frame number calculator
In 13, the response information expected frame number EXPT is calculated from the current time and the information shown in FIG.
Find (t). EXPT (t) is the frame number shown in FIG. 3 when the current time is the expected response information reception time from FIG. When the response information and the response information expected value frame number satisfy the following conditional expression (2), the frame number calculation unit 13 determines that a transmission error has occurred in the frame number of (RF (t) +1), Retransmission is performed from the frame number of (RF (t) +1) to correct the transmission error.

That is, 1) When RF (t) <EXPT (t) ... (2) (RF (t) +1) is notified to the transmission control unit as the transmission frame number.

2) When RF (t) ≧ EXPT (t) (RF (t) +1) is notified to the transmission control unit as the transmission frame number.

In addition, when the conditional expression (2) is satisfied, retransmission is performed in order from the frame number of (RF (t) +1) to obtain (RF (t) +1).
Conditional expression (2) is not checked until the frame number of is the expected value. Thereafter, the above-mentioned operation is repeated.

As is clear from the above description, the transmission device 10 is provided with the response information expected value calculation unit 12 and the frame number calculation unit to detect the transmission error frame based on the response information and the expected value, and thus the delay time (D) By setting, it is possible to cope with a system with a long delay time, and by setting the value of m, it is possible to cope with any of the delay times.
Error correction control by retransmission can be performed.

As described above, the present invention obtains the expected value of the response information by providing the response information expected value calculation unit and the frame number calculation unit in the transmission device, and when the response information violates the expected value condition, By determining that a transmission error has occurred and performing transmission error control by retransmission, by setting the delay time (D) parameter,
Transmission error control by retransmission can be easily performed even for a system with a long delay time. Further, it is possible to cope with the deviation of the delay time. The signal transmission device having such a transmission error correction control system by retransmission is highly effective for a system having a long one-round delay time such as satellite communication.

[Brief description of drawings]

FIG. 1 is a block connection diagram of a signal transmission device according to an embodiment of the present invention, FIG. 2 is a conceptual diagram of a transmission frame by the device, and FIG. 3 is a frame number by the device and a time when the response information is returned. FIG. 4 is a diagram showing a table showing the relationship, FIG. 4 is a configuration diagram of a response information frame by the device, and FIG. 5 is a block connection diagram of a conventional signal transmission device. 10 ... Transmission device, 11 ... Transmission control unit, 12 ... Response information expected value calculation unit, 13 ... Frame number calculation unit, 14 ... Response information reception unit, 15 ... Data line, 16 ... Reception Equipment, 17 ...
... Reception control unit, 18 ... Response information transmission unit, 19 ... 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 receiving device having a response information transmitting means for transmitting the latest frame number as response information among the frame numbers received as the response information without any transmission error, and a transmission frame for transmitting the transmission information at regular intervals. A first transmission control unit configured to send a transmission signal to the receiving device by giving a frame number that changes periodically, and a response for receiving response information sent from a response information sending unit in the receiving device. Information receiving means, calculating an expected arrival time of the response information from a delay cycle time from the transmission of the transmission signal to the receiving device to the return of the response information. A response error expected value calculation unit that outputs, a transmission error frame is detected by the expected arrival time calculated by the response information expected value calculation unit and the response information received by the response information receiving unit, and a predetermined frame is again detected. A signal transmission device comprising a transmission device having a second transmission control unit for transmitting to the reception device.