KR100376249B1 - An Error-control Method on Variable-length Data Communication - Google Patents

Abstract

The present invention relates to a variable error control method according to a message length in which error detection and error correction can be performed by reconfiguring an error control code according to the case where the total message length is variable, and the present invention relates to a data information field of a message. If is a variable field, storing each step value for the length of the data information field in a table; Determining the length of the additional information field according to the step value for the length of the data information field; And adding the additional information field to the original frame. Therefore, there is an effect of minimizing an error occurring on a transmission path and efficiently transmitting and receiving a message according to a prescribed error rate in communication.

Description

Variable error control method according to message length {An Error-control Method on Variable-length Data Communication}

The present invention relates to a variable error control method according to a message length. More particularly, the present invention relates to a variable error control method according to a message length. The present invention relates to a variable error control method.

In general, data communication corresponds to a kind of information communication for transmitting a digital signal, and replaces arbitrary information with a code in the form of a digital signal, and converts the data into a communication line between computers installed at different locations or between a computer and a terminal. Refers to a communication method used for transmitting and receiving. Unlike telecommunications such as telephones, data communication is a method of transmitting and receiving data in binary code, and thus a data processing technology capable of processing data and a data transmission technology capable of transmitting data are combined.

1 is a block diagram of a general data communication system. As shown in FIG. 1, a general data communication system includes data terminal equipment (DTE) 10, 50, data circuit terminating equipment (DCE) 20, 40, and data. It consists of a data switching equipment (DSE) 30.

The data terminal apparatuses 10 and 50 refer to a terminal or a computer as a subject of data communication, and serve to input / output information and transmit / receive data through a communication network. In this case, the data terminal device 10 is responsible for data transmission, and the data terminal device 50 is responsible for data reception. The data line terminators 20 and 40 are apparatuses for exchanging or encoding all functions or signals for establishing and protecting a connection between the data terminal apparatuses 10 and 50 and the data exchange apparatus 30. A modem is required for connection to a telephone network which is a voice band analog communication network, and a data service unit (DSU) is required for a data communication network. The data exchange device 30 is a device for exchanging data in a network, and is composed of a dedicated line and a switching network, and can be classified into an analog network and a digital communication network in a voice band.

In such a data communication system, when an information is transmitted and received through a wired or wireless transmission path, an information in which an error is mixed with the original information through a transmission device or a transmission medium cannot transmit an accurate meaning at the reception side. Therefore, in order to receive the correct meaning from the received information, a procedure for finding and correcting an error included in the received information is required, that is, an error control technique. In today's increasingly demanding reliability of information, the importance of error control techniques is growing. In general, error control techniques are divided into error detection and error correction.

In order to check whether an error is included in the received information, in addition to the original information to be sent by the sender in advance, an excess amount of data is added separately, and the receiving side checks the excess data, thereby enabling error detection. The most widely used error detection methods are parity check and cyclic redundancy check. Parity check is the simplest error detection method by adding a parity bit at the end of a block of data. A typical example is the case of transferring data as 8 bits by adding one bit to the end of 7-bit ASCII data through ASCII transmission. At this time, the parity bit value is determined in the process of adjusting the number of 1s in 8-bit character information to be even or odd. In general, even parity is often used for synchronous transmissions, and odd parity is often used for asynchronous transmissions.

Cyclic redundancy check (CRC) is one of the most widely used error detection methods with parity check as one method of generating the frame check sequence (FCS), which is various detection codes. The FCS is a bit string for detecting an error in a frame, which is calculated by an arbitrary algorithm at the time of transmission and transmitted with the information frame. The receiving side calculates the FCS by using the same algorithm as the transmitting side only for the information frame among all the received data, and if this value is the same as the received FCS value, it is determined that no error occurred during transmission. Is judged to have occurred.

Therefore, in the general error detection method, the field length of the additional information for error detection is fixed, and the receiving side also detects the error by utilizing the additional information included in the fixed field. For example, in the case of the error detection method using CRC-16, it is comprised as follows.

In general, the control information includes information on the entire message length, and the length information may be omitted when the length of the information data is fixed.

However, such a conventional error detection method has a fixed field length of additional information for error detection, and the receiving side also detects an error using the additional information contained in the fixed field, so that the length of the information data field is variable. There is a problem that the error detection rate is relatively variable so that error detection cannot be efficiently performed.

Accordingly, the present invention has been made to solve the conventional problems as described above, an object of the present invention is to reconstruct the data for error control code according to the case that the total message length of the data to be transmitted is variable accordingly It is to provide a variable error control method according to the message length that can be transmitted and received.

Another object of the present invention is a variable addition by transmitting and receiving data by varying the portion corresponding to the additional information field according to the portion corresponding to the information data field in the case of mixed data without explicit distinction between the information data field and the additional information field The present invention provides a variable error control method according to a message length capable of detecting an error of data by an information field.

1 is a configuration diagram of a general data communication system;

2 is an exemplary view showing a configuration of a data frame according to the present invention;

3 is a flowchart illustrating the operation according to the present invention.

♣ Explanation of symbols for the main parts of the drawing ♣

10,50: data terminal device 20,40: data line termination device

30: data exchange device

In order to achieve the above object, the present invention forms a frame by adding a surplus data bit to the additional information field in addition to the data information field of the message to be sent by the transmitter, and transmits the formed frame to the receiver. An error control method for detecting an error by using the method comprising: storing each step value of a length of the data information field in a table if the data information field of the message is a variable field; Determining the length of the additional information field according to the step value for the length of the data information field; And adding the additional information field to the original frame.

Hereinafter, a preferred embodiment of a variable error control method according to a message length according to the present invention will be described in detail with reference to the accompanying drawings.

2 is an exemplary view showing a configuration of a data frame according to the present invention. As shown in Fig. 2, the initial state of data to be transmitted consists of each frame (n, n + 1, n + 2, n + 3, ...), and each frame (n, n + 1, n). +2, n + 3 ...) are composed of control information fields, information data fields, and additional information fields in detail. When the data to be transmitted is not fixed but variable, it is necessary to reconstruct the additional information field for error detection. Although there are various ways to reconstruct the additional information field for error detection, the present invention will be described using the CRC-16 or CRC-32 as an example.

IBM-based floppy disks use 16-bit CRCs and are also used by compressed programs to check for errors during data recovery. The LHA (compressor for MS-DOS) uses a 16-bit CRC, inverting the IBM floppy disk 16-bit CRC. In addition, PKZIP (file decompression software) and ARJ (compression-decompression utility program) use 32-bit CRCs. In the present invention, a process of determining whether the length of the additional information field to be added is 16 bits or 32 bits according to the length of the information data field will be described as an example. Therefore, the data frame to be transmitted is reconfigured to include a field to be added to the original data frame and transmitted to the receiver.

The control information field contains routing information, which includes the source and destination of the message and the message number when the message was created. It also includes the total message length, flag information, activation time, and other information. The information data field contains the actual information to be transmitted over the network from one application program to another application program and is variable depending on the size of the message. The additional information field includes an error control CRC which is calculated before the message is transmitted and added to the end of the frame. Although this additional information field is configured at the end of the frame, some frames may be included in the control information field.

The operation state of the variable error control method according to the message length according to the present invention as described above will be described with reference to the accompanying drawings.

3 is a flowchart illustrating an operation according to the present invention, in which the error control quality is uniform when the length of the information data field of the kth transmitted message is L (k) and the length of the additional information field is P (k). It is assumed that the step value of the information data field for S [k] and the length value of the additional information field corresponding thereto are T [k].

First, a step value of an information data field corresponding to the size of a message to be transmitted is stored in a table (S10). The step value of the information data field varies depending on the length of the information data field. S [1] = 64 when the length of the information data field is 64 to 127 bits, and S [2] = 128 when it is 128 to 255 bits. In this case, T [k] is defined as 16 bits or 32 bits, respectively. For example, when L (1) = 64 bits, S [1] = 64, and when L (2) = 128 bits, S [2] = 128 and L (3) = 80 bits. In the case of S [3] = 64. Here, when S [1] = 64, CRC-16 is used, and when S [2] = 128, CRC-32 is used. The step value of the information data field is predetermined by experts in the art, and 0x8005 is mainly used for CRC-16, and 0x04c11db7 is mainly used for CRC-32.

The sender of the message stores the step value of the information data field in a table, and then determines whether there is a frame to transmit (S20). As a result of the determination, if there is no frame to transmit, it continues to wait until there is a frame to transmit, and if there is a frame to transmit, the frame is read (S30). After reading the frame, it is determined whether the frame is a variable frame (S40), and if it is not a variable frame, the frame is transmitted to the receiving side by a general CRC method of transmitting a fixed frame (S50). The information data field of the n th frame to be read is read (S60).

The field to be added to the additional information field is determined by reading the information data field (S70). For example, when the information data fields of the n, n + 1 and n + 2th frames are 64 bits, 128 bits, and 80 bits, respectively, the additional information field to be added is determined to be 16 bits, 32 bits, and 16 bits. In other words, when the length of the information data field is 64 to 127 bits, the 16-bit side information field is determined. When the length of the information data field is 128 to 255 bits, the 32-bit side information field is determined.

When the additional information field to be added of the frame to be transmitted is determined, it is determined whether the frame processed in the step S70 is the last frame (S80), and if it is not the last frame, after reading the information data field of the next frame, the step ( Returning to step S70, the subsequent steps are repeated (S90), and in the case of the last frame, since the additional information fields of all the frames to be transmitted are determined, the additional information field determined in the step S70 is added to the original frame to add a new frame. After configuring the transmission to the receiving side (S100).

The above description is only for explaining one embodiment, and the present invention is not limited to the above-described embodiment and can be variously changed within the scope of the appended claims. For example, the shape and structure of each component specifically shown in the embodiment of the present invention can be modified.

As described above, according to the variable error control method according to the message length according to the present invention, the error detection additional information field is reconfigured according to the variable message to transmit and receive a message, thereby minimizing an error occurring in the transmission path and during communication. There is an effect that can efficiently send and receive messages in accordance with the error rate specified in.

Claims (4)

delete In addition to the data information field of the message to be sent by the sender, a surplus data bit is added to the additional information field to form a frame, the formed frame is transmitted to the receiver, and the error control method detects an error by the transmitted frame. In If the data information field of the message is a variable field, storing each step value for the length of the data information field in a table; Determining the length of the additional information field according to the step value for the length of the data information field; And adding the additional information field to an original frame to configure the error information. The method of claim 2, And the length of the additional information field is selected using one of a cyclic redundancy check (CRC) -16 and a cyclic redundancy check-32. The method of claim 3, wherein Variable error control according to a message length in which the length of the additional information field is selected using an error correcting code generation polynomial rather than a cyclic redundancy check method and the error correction or detection is performed according to a rule for generating the additional information field. Way.