JPH01238241A - Control system for retransmitting data - Google Patents

Abstract

PURPOSE:To recover error information within a short time while keeping high circuit utilization efficiency by providing a transmission part which transmits an information signal corresponding with an order section shown by a signal which shows two orders transmitted from a reception station to a transmission station. CONSTITUTION:When tenth data I(10) is received by the reception station 2 at (ts) o'clock, for example, a sequence error is detected 22 and the retransmission demand instruction (Prej) (7 and 9) of the data I(7)-I(9) of the transmission order numbers 7-9 are generated by a retransmission demand instruction generation part 24 and transmitted from a transmission part 25 to the transmission station 1. Then, when the instructions (Prej) (7 and 9) are received by the transmission station 1 at (t11) o'clock, the seventh to ninth data I(7)-I(9) is read from a memory 13 by the transmission part 14 and preferentially retransmitted. On the other hand, when the reception station 2 receives the retransmitted data I(7)-I(9) until (t12) o'clock, it substitutes the order of the data I(10) and I(11) and successively outputs the data I(7)-I(11) from the reception station 2.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention provides a method for detecting consecutive errors in each piece of information transmitted to a receiving station. The present invention relates to a data retransmission control method in which the transmitting station retransmits this information by simply transmitting first and last order information to the transmitting station.

(Prior Art) The retransmission request command used in the conventional data retransmission control method is 5REJ (5elective Reject:
REJ (an instruction that requests the retransmission of only one piece of data that caused a sequence error) and REJ (an instruction that requests retransmission of all data after the data that caused a sequence error) were used. . A conventional data retransmission control method using these retransmission request commands will be explained below with reference to FIGS. 6 and 7. .

In Figures 6 and 7, 'l+b+... is time, ■ is data from the transmitting station, and 5rej is 8 from the receiving station.
RBJ retransmission request command, Rej is the data retransmission request command from the receiving station, the numbers in parentheses are data I and retransmission request command 5r
ej represents the transmission order number assigned to ej.

FIG. 6 shows HDLC (High
-1 level Data Link Control
) shows an example of the operation of the data retransmission control method. The transmitting station transmits the first data Ifl+ at time t, time t! The second data I(2+, . . . ) are sequentially transmitted to the receiving station, while the receiving station transmits the first data I(1) at time t3, the second data I(2), and so on at time t4.
. . . The data is received Jliff next time. However, if the receiving station receives the fourth data ■(4) at time t without confirming the reception of the third data I(3), that is, the third data ■(3) )
When the receiving station detects a sequence error in data due to the omission of
The retransmission request command 5rej(
3) Send. The transmitting station issues a retransmission request command 5r at time t6.
Upon receiving ej(a+), the third data I(3) is retransmitted.

That is, the receiving station receives five pieces of data I(1) ~ by time t7.
This means that I(5) has been received. Furthermore, if the receiving station receives the 10th data I (1■) at time t and detects a sequence error while the reception of the 7th to 9th data E(7) to I(9) has not been confirmed. , the receiving station transmits a retransmission request command 5rejf71 for the seventh data (7).In addition, in the HDLC method, until the receiving station confirms the reception of the retransmitted data according to a certain retransmission request command, it does not send another retransmission request. Since the receiving station is prohibited from transmitting commands, after the receiving station confirms the reception of the seventh data (7) at time t0, the receiving station sends a retransmission request command for the eighth data (8). 5rej (send a+. Similarly, time t
The sequence error detected at time t10 is recovered at time t10. That is, the receiving station has received 13 pieces of data I fil - I (13) by time t10.

Figure 7 shows the 8REJ/REJ mode (SREJ and R
12 shows an example of the operation of the data retransmission control method using the HDLC method (a mode in which a retransmission request is made by both an EJ retransmission request command). Similar to Figure 4, the third data (3)
If the receiving station detects a sequence error at time t5 without confirming the reception of , the receiving station issues a retransmission request command 5rej ( 3) Send
At time t, the sequence error is recovered. Furthermore, 7 to 9
If the receiving station detects a sequence error at time t without confirming the reception of data I(7) to data (9), in this case, it takes 3 hours to recover from the /- sequence error. Since it is necessary to retransmit the data of
A retransmission request command Rej (71) is sent.

When the transmitting station receives the retransmission request command Rej (7) at time t11, it transmits the seventh and subsequent data I(71, I[81, .
. . are retransmitted sequentially, and at time 1. The sequence error detected at t12 is recovered at time t12. Therefore, the receiving station receives 11 pieces of data I fit~T-(l'! by time '10).
;This means that Ik has been received.

A packet as an information signal used in the HDLC described above is shown in FIG. In the same figure (a), the ■ frame is shown, in the same figure (b) the S frame is shown, and in the same figure (
C) shows a U frame. In the figure, only the packet constituent portion of the signal section indicating the order of addition to data, which is an information signal, is illustrated. That is, the same figure (a)
In the (2) frame, 0 is added to the first bit, and a number indicating the order is input into the N(S) area. The next area P
/F is used by the receiving side to confirm that it has indeed received the signal. The same figure (bl) The S frame adds 10 to the first bit, then the S area as a command signal area that separates 8rej and Rrej, the P/F area mentioned in the explanation of the frame, and then the order. There is an area for entering a number.The U frame shown in Figure 8(C) uses a packet with 11 added as the first bit, a modifier bit M, and a P/F signal added. .

(Problem to be Solved by the Invention) However, the above conventional data retransmission control method has the following problems.

In the data retransmission control method using 5REJ mode,
If the receiving station detects a sequence error while the reception of N pieces of data (N is an integer greater than or equal to 1) has not been confirmed,
To recover, the receiving station must send N S-EJ retransmission request commands, and in the HDLC system, it requires at least N round trips between the transmitting station and the receiving station. becomes. For this reason, when N is large or when the propagation delay between the transmitting station and the receiving station is large, the time required to recover from the sequence error increases, and the probability of timeout due to this increases.
Overall, this results in a decrease in the average usage efficiency of the line. for example,
In FIG. 5, it takes time from time t to time t1° to recover from the sequence error caused by the seventh to ninth data I(7) to data I(9).

On the other hand, in the data retransmission control method using 5REJ/REJ mode, if a sequence error that requires retransmission of multiple pieces of data is detected in order to recover, the receiving station requests retransmission by an REJ retransmission request command. Data received by the receiving station between the time when the receiving station detects a sequence error and the time when it receives the first retransmitted data are ignored, even if they are received correctly. For this reason, if the receiving station receives the same data multiple times, the efficiency of line utilization will decrease.

The present invention can recover sequence errors within a short time equivalent to the data retransmission control method using the 5REJ/REJ mode, and can maintain high line utilization efficiency equivalent to the data retransmission control method using the 5REJ mode. This provides a data retransmission control method.

[Structure of the invention]

(Means for Solving the Problem) In order to achieve the above object, in the present invention, an information signal to which a signal indicating the order is added to each transmission information transmitted from the transmitting station is transmitted to the receiving station, In the data retransmission method, the receiving station detects erroneous information when receiving the information signal and retransmits the erroneous information from the transmitting station. an error detection unit that detects whether each of the information signals that have been detected are consecutively erroneous; a signal detection unit that detects a signal indicating the order in which the error has been detected and a signal indicating the order added to the information signal in which an error was detected last;
a retransmission signal transmitting section that transmits a signal indicating the order of the two detected by the signal detecting section to the transmitting station, and the transmitting station receives the two orders transmitted from the receiving station.
The present invention is characterized in that it includes a transmitter that transmits the information signal corresponding to the order section indicated by the signal indicating the order to the receiving station.

(Function) In the data retransmission control system configured as described above, when the receiving station receives consecutive errors in the information signals, the retransmission signal transmitter sends a signal indicating the order in which the first and last pieces of error information are given. Generally, even if the receiving station detects an error in a state where the reception of N pieces of information has not been confirmed, the receiving station will not be able to send N pieces of data with a single retransmission request command. It is possible to request the transmitting station to retransmit the data, and to suppress the retransmission of data that the receiving station has confirmed has been received between the time when the receiving station detects an error and the time when the first retransmitted data is received. It becomes possible to make a request to the station.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a pair of transmitting stations 1 and receiving stations 2 implementing the present invention.
Figure 2 shows the configuration of the transmitting station 1 shown in Figure 1, and Figure 3 shows the configuration of the receiving station 2 shown in Figure 1. has been done.

As shown in FIG. 1, the transmitting station 1 transmits data input to the transmitting station 1 to the receiving station 2. Information received erroneously at the receiving station 2 is sent by a retransmission request command from the transmitting station. The correctly received data is output from the receiving station 2 as data.

In FIG. 2, one configuration of the transmitting station 1 includes a transmission sequence number generation unit 11 that generates transmission sequence numbers to be assigned in the order in which data is input, and a transmission sequence number generation unit 11 that adds the transmission sequence number generated in the transmission sequence number generation unit 11 to the data. Transmission sequence number addition unit 12
, a memory 13 for storing data to which a transmission sequence number has been added (hereinafter referred to simply as "data" unless otherwise specified), and a transmission sequence number addition section when there is no data to be retransmitted. A transmitting unit 14 transmits input data from the receiving station 2 to the receiving station 2, and when there is data to be retransmitted, reads it from the memory 13 and transmits it, and a receiving unit receives a retransmission request command from the receiving station 2. 15, and a retransmission control section 16 that recognizes the transmission order number of data to be retransmitted based on the received retransmission request command and notifies the transmission section 14 of this.

On the other hand, in FIG. 3, one configuration of the receiving station 2 includes a receiving section 21 that receives data from the transmitting station 1, and a receiving section 21 that extracts the transmission sequence number given to the received data and detects a sequence error. If not, the data is output from the receiving station 2, and if a sequence error is detected, the sequence error detection unit 22 determines the transmission order number of the data that requires retransmission, and the sequence error detection unit 22 detects the sequence error. If a sequence error is detected by the data order replacement unit 23, which outputs the data from the receiving station 2 after rearranging the data whose reception has been confirmed in the order of the transmission sequence number, and the sequence error detection unit 22, a sequence error is detected. A retransmission request command generation unit 24 that generates a retransmission request command including information representing the transmission order number of the first and last data that caused In particular, the sequence error detection unit 22 includes, for example, a transmission sequence number extraction unit 26 that extracts a transmission sequence number from received data, and a memory that stores transmission sequence numbers of data that have been correctly received before. 27, the transmission sequence number extracted by the transmission sequence number extraction unit 26 and the maximum value of the transmission sequence numbers stored in the memory 27 are compared to detect whether or not a jitance error has occurred; If no sequence error occurs,
At the same time as the data is output to the data order replacement section 23, the transmission order number assigned to the data is stored in the memory 27, and if a sequence error is detected, the transmission order number is transmitted to the retransmission request command generation section 24. Comparison part 2
It consists of 8. In addition, the retransmission request command generation unit 2
4 receives, for example, sequence error detection information from the transmission sequence number comparison section 28, and then extracts the transmission j11 number extraction section 26.
and generates a retransmission request command based on the information from the memory 27.

Next, an example of the operation of the present invention will be described with reference to FIGS. 4 and 5. FIG. 5 shows an example of the configuration of Prej. 0 is added to the leading bit, an E(S) area is used to add the first packet number that caused an error, a P/F area is used to confirm reception, and an E is used to add the last packet number that causes an error. It has flourished in the mountain area.

In Figure 4, Prej (a, b) (a,
b) represents a retransmission request command that requests the transmitting station IK to retransmit data with transmission order numbers a to b-1; , among the data transmitted from transmitting station 1, the third data (3) and the seventh to ninth data I (7) to I(
It is assumed that a sequence error requiring retransmission (9) has occurred.

The transmitting station 1 sequentially transmits data I(11, I+21, . . . ) and stores these data in the memory 13. The receiving station 2 transmits the first data I(11, I+21, ...) at time t3.
1), time 1. 2nd data (2) is received respectively. At this time, since no sequence error is detected in the sequence error detection unit 22 of the receiving station 2, the two data I (1) and I C2+ are received through the data order replacement unit 23 without having their order replaced. station 2
is output from. However, the third data
), and the receiving station 2 confirms the reception of the fourth data I(4) at time t, that is, the sequence error of the receiving station 2 is caused by the omission of the third data I(3). When the detection unit 22 detects a sequence error, the retransmission request command generation unit 24 generates a retransmission request command Prej (3, 3) requesting the retransmission of one data item (3) whose transmission order number is 3 to 3. and transmits it to the transmitting station 1 through the transmitter 25. When the transmitting station 1 receives the retransmission request command Prej (3°3) at time t, the retransmission control unit 1
6, the data to be retransmitted is the third data I (3)
After determining that there is one, the transmitting unit 14 receives this information from the retransmission control unit 16, reads the third deque (3) from the memory 13, and adds the new data given from the transmission order number adding unit 12. Retransmission data with priority over data (3
) to send. On the other hand, when the receiving station 2 confirms the reception of the retransmitted data I(3) at time t, the data order replacement unit 23 confirms that the retransmission data I(3) has been received before time t, but the data has not yet been output from the receiving station 2. Data I (41, I
(After performing order permutation with (51), 3 data ■ (3
) to I(5) are sequentially output from the receiving station 2.

Furthermore, when the receiving station 2 receives the 10th data IQ■ at time t, while the reception of the 7th to 9th data E(7) to I(9) has not been confirmed, the sequence error detection unit 22 Detects a sequence error and generates a retransmission request command 2
4 is three data elements with transmission order numbers 7 to 9 (
7) - Retransmission Yasugi command Prej requesting retransmission of (9)
(7, 9) and transmits it to the transmitting station 1 through the transmitter 25. When the transmitting station 1 receives the retransmission request command Prej (7, 9) at time t and the 1KM transmission request command '11, the retransmission control unit 16 determines that the data to be retransmitted are the 7th to 9th data e(7) to I ( 9) Determining that there are three, the transmitter 14 reads the seventh to ninth data (7) to (9) from the memory 13 and retransmits them preferentially. On the other hand, the receiving station 2 receives the retransmitted data by time t1□.
Upon receiving 7) to I(9), the data order replacement unit 23 performs order replacement with data I(II, Iαυ), and then transfers the five data ■(7) to αυ from the receiving station 2. Therefore, the sequence error 9 detected at time 1a is outputted sequentially by the 8RE shown in FIG.
The sequence error is recovered by one retransmission request command at time tX□, which is earlier than the sequence error recovery by the J mode data retransmission control method, and the reception Station 2 is able to receive 13 pieces of data I (11 to I (13) by time t1o.

By the way, the retransmission request command P according to the present invention shown in FIG.
By setting a and b equal, rej (a, b) not only works equivalent to the 8R, EJ retransmission request command 8rej (a) shown in FIG. 86 and FIG. By setting the represented information to b, it is possible to perform an equivalent function to the REJ retransmission request command Rej (a) shown in FIG. 7.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to request the transmitting station to retransmit multiple pieces of data by one retransmission request command, and the first retransmission from the time when the receiving station detects an error is possible. Since it is possible for the receiving station to request the transmitting station to suppress retransmission of the data that the receiving station has confirmed reception of until the time when the retransmitted data is received, the probability of timeout occurrence is small and the line utilization efficiency is high. Error information can be recovered within a short period of time while maintaining the error information.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is a configuration diagram of a transmitting station according to an embodiment of the present invention, and the third factor is a configuration diagram of a receiving station according to an embodiment of the present invention. 4 is a time chart showing an example of the operation of the present invention, FIG. 5 is a diagram showing the structure of the packet of the present invention, and FIG. 6 is an example of the operation of the conventional 8REJ mode data retransmission control method. Time chart showing,
FIG. 7 is a time chart showing an operation example of the conventional 8RHJ/RE, T mode data retransmission control method, and FIG. 8 is a diagram showing the conventional packet configuration. 1... Transmission station, 2... Receiving station, 11... Transmission sequence number generation section, 12... Transmission sequence number addition section, 13...
・Memory, 14... Transmitting section, 15... Receiving section, 16
... Retransmission control unit, 21... Receiving unit, 22... Sequence error detection unit, 23... Data order replacement unit, 24
. . . retransmission request command generation unit, 25 . . . transmission unit. Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] An information signal in which a signal indicating the order is added to each transmission information transmitted from a transmitting station is transmitted to a receiving station, and the receiving station detects erroneous information when receiving the information signal,
In this data retransmission method in which erroneous information is retransmitted from the transmitting station, the receiving station includes an error detection unit that detects whether each of the information signals transmitted to the receiving station is consecutively erroneous; A signal indicating the order is added to the information signal in which an error is detected first among the information signals in which an error is successively detected by the detection unit, and a signal is added to the information signal in which an error is detected last. a signal detecting section that detects a signal indicating the two orders detected by the signal detecting section; and a retransmission signal transmitting section that transmits a signal indicating the two orders detected by the signal detecting section to the transmitting station, The data retransmission control system is characterized in that the data retransmission control system is characterized by comprising a transmitter that transmits the information signal corresponding to the order section indicated by the two order signals transmitted from the receiving station to the receiving station. .