KR100324202B1 - An Adaptive Error-control Method using Padding Bits - Google Patents

Abstract

The present invention relates to an adaptive error control method using idle bits, the present invention comprising the steps of extracting the length of the information data field from the control information field of the frame; Comparing the length of the information data field allowed for the frame with the length of the extracted information data field to determine whether an idle bit exists; Calculating a maximum value that can utilize idle bits; Reconstructing the additional information field according to the state of the frame. Therefore, by using the idle bits existing when the actual information data field is shorter than the length of the information data field allowed in the data frame, the data can be used to detect or correct errors, thereby improving data transmission efficiency and error detection rate. There is.

Description

An adaptive error-control method using padding bits

The present invention relates to an adaptive error control method using idle bits, and more particularly, to detect or correct an error using idle bits generated when the actual information data length is shorter than the allowed information field length. The present invention relates to an adaptive error control method using idle bits to improve error control capability and to secure desired transmission quality without changing additional procedures or circuits.

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 coded data, and thus, a data communication 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), an error detection code. 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.

Control information field Information data field Additional Information Field

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.

The most commonly used error correcting method is an automatic retransmission (ARQ) method, which corrects an error by requesting a sender to retransmit a block of data after an error is detected. In addition, the forward error correction method is an error control method that simultaneously detects and corrects an error, and has an advantage that the reverse channel is unnecessary and continuous data flow is possible compared to the ARQ method. Due to the large overheads that reduce system efficiency and the complexity of devices and coding, they are not widely used to date.

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.

In addition, when the length of the information data is variable, if a fixed data frame is used, the unused portion of the information data field is filled with a meaningless value such as 0, and then transmitted. Information is generated, which causes a problem in that transmission efficiency and error detection rate are lowered.

Accordingly, the present invention has been made to solve the above-mentioned general problems, and an object of the present invention is to provide a length and initial length of idle bits when the length of the data frame is fixed and the actual data length of the information data field is variable. It is an object of the present invention to provide an adaptive error control method using idle bits that can include an extended additional information field including the length of an additional information field in a data frame to improve data transmission efficiency and error detection rate.

Another object of the present invention is to configure an additional additional information field including an idle bit length in a data frame when using the additional information field having a fixed length of the data frame, and generate the highest order that can utilize the idle bit. It is an object of the present invention to provide an adaptive error control method using idle bits that can construct an additional additional information field by a polynomial to improve data transmission efficiency and error detection rate.

It is still another object of the present invention to provide an adaptive error control method using idle bits capable of correcting an error using an error correction code in an extended additional information field or an additional additional information field.

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

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

3A and 3B are flowcharts 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: extracting a length of an information data field from a control information field of a frame; Comparing the length of the information data field allowed for the frame with the length of the extracted information data field to determine whether an idle bit exists; Calculating a maximum value that can utilize idle bits; Reconstructing the additional information field according to the state of the frame.

In the reconstructing of the additional information field, when the length of the data frame is fixed and the actual data length of the information data field is variable, an extended additional information field including an idle bit and the additional information field is configured, and the length of the data frame is When the fixed additional information field is already used, the idle bit is configured as an additional additional information field to configure an additional information field including the fixed additional information field and the additional additional information field.

In addition, an error correction code is added to an idle bit for transmission, and the error correction code is read to correct an error.

Hereinafter, a preferred embodiment of an adaptive error control method using idle bits according to the present invention will be described in detail with reference to the accompanying drawings.

2A and 2B are exemplary views showing the configuration of a data frame according to the present invention. FIG. 2A is an exemplary view when the length of the data frame is fixed and the actual data length of the information data field is variable. FIG. 2B is a data frame. An example diagram in the case of using an additional information field whose length is already fixed is shown. As shown in Figs. 2A and 2B, 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 a control information field, an information data field and an additional information field in detail, and the information data field includes an idle bit. 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. 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 information data field may include idle bits that do not constitute actual information data, and generally have idle bits when the length of the actual information data field is shorter than the length of the information data field allocated to the data frame. On the other hand, when the actual information data field has the same length as the length of the information data field allocated to the data frame, there is no idle bit. 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.

As shown in Fig. 2A, when the length of the data frame is fixed and the actual data length of the information data field is variable, the idle bit existing in the information data field and the initial additional information field are included (i.e., the extended additional information field). Reconstruct the data frame to be transmitted. In addition, as shown in FIG. 2B, when the additional information field having a fixed length of the data frame is used, the idle information present in the information data field is used as the additional information field because the additional information field is fixed. Additional additional information field) to reconstruct the data frame to be transmitted.

The operation state of the adaptive error control method using the idle bit according to the present invention as described above will be described with reference to the accompanying drawings.

3A and 3B are flowcharts for explaining the operation according to the present invention, when the length of the information data field of the data frame is N and the length of the information data field obtained from the data length information in the control information field is n. In the case that the length of is fixed and the actual data length of the information data field is variable, it is assumed that the length of the additional information field of the data frame is P, and that the additional length of the additional information field is f [k]. In the case of using a fixed additional information field, it is assumed that the length of the fixed additional information field of the data frame is T and the additional length of the additional additional information field is g [k]. In addition, Nn The maximum value of f [k] that satisfies f [k] is F [k], Nn Assume that the maximum value of g [k] that satisfies g [k] is G [k]. Where k = 1,2,3 ...

First, the message sending side stores the generated polynomial of the highest order that can constitute the extended additional information field or the additional additional information field in a table (S10). Here, for example, the 12-bit, 16-bit, and 32-bit generation polynomials of the highest order for each bit are as follows.

CRC-12 = X ¹² + X ¹¹ + X ³ + X ² + X + 1

CRC-16 = X ¹⁶ + X ¹⁵ + X ² +1

CRC-32 = X ³² + X ²⁶ + X ²³ + X ²² + X ¹⁶ + X ¹² + X ¹¹ + X ¹⁰ + X ⁸ + X ⁷ + X ⁵ + X ⁴ + X ² + X + 1

The CRC-12, CRC-16, and CRC-32 operate to expand or add additional information fields by generating FCSs of 12, 16, and 32 bits, respectively.

The sender of the message stores the generated polynomial of the highest order 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 n-th 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 length of the information data field is extracted by reading the control information field of the frame (S60). Thereafter, the length of the information data field allowed in the data frame and the length of the information data field extracted in step S60 are compared (S70) to determine whether there is an idle bit in the information data field (S80). The idle bit exists when the length of the information data field extracted in step S60 is shorter than the length of the allowed information data field. When the length of the extracted information data field is the same as the length of the allowed information data field, the idle bit is set. does not exist.

As a result of the determination in step S80, when it is determined that an idle bit exists in the information data field, a maximum value that can utilize the idle bit is calculated (S90) to generate an extended additional information field or an additional additional information field (S100). . In order to easily explain how to calculate the maximum value and how to generate the extended additional information field or the additional additional information field, when the length of the data frame is fixed and the actual data length of the information data field is variable (hereinafter, referred to as '1'). A case of using a side information) and a case of using an additional information field having a fixed length of a data frame (hereinafter, referred to as 'case 2') will be described.

First, in the case of 1, Nn Since the maximum value of f [k] satisfying f [k] is assumed to be F [k], the value of N is 64 bits, the value of n is 48 bits, the value of P is 16 bits, and f [1] = 1 When f [2] = 8, f [3] = 12, f [4] = 16 ..., F [k] satisfying the above condition becomes 16. Therefore, the length of the extended additional information field for error detection is 32 bits in which the original additional information field and the value of F [k] are added together. Since the original additional information field was 16 bits, CRC-16 should be applied. However, since the newly configured extended additional information field is 32 bits, CRC-32 is applied to provide extended error detection capability.

Next, in the case of 2, Nn as in the case of 1 Since the maximum value of g [k] satisfying f [k] is assumed to be G [k], the value of N is 64 bits, the value of n is 48 bits, the value of T is 16 bits, and g [1] = 1 When G [2] = 8, g [3] = 12 and g [4] = 16, G [k] satisfying the above condition becomes 16. Therefore, the length of the extended additional information field for error detection is 32 bits in which the original additional information field and the value of G [k] are added together. Since the original additional information field was 16 bits, CRC-16 should be applied. However, the newly constructed additional additional information field is 32 bits in which additional additional information fields are added, so that CRC-32 can be applied to provide extended error detection capability. Will be.

If the extended additional information field or additional additional information field of the frame to be transmitted is generated, it is determined whether the corresponding frame is the last frame (S110), and if it is not the last frame, the next frame is read (S120) and the process returns to the step S40. Since the subsequent steps are repeated, and in the case of the last frame, all frames to be transmitted have been determined, a new frame including the extended additional information field or the additional additional information field determined in the step S100 is configured in the original frame and then transmitted to the receiving side. By the end of the process of the present invention (S130).

In another embodiment of the present invention, when an error correction code is added to an extended additional information field or an additional additional information field and transmitted, the receiver may analyze the data frame and automatically correct the error. The error correction code may use a hamming code that is a code for detecting and correcting an error or a Bose-Chaudhuri-Hocquenghem (BCH) code for detecting and correcting an out of order error.

Hamming codes are mainly used for synchronous data transmission and are codes that can correct a single error. The Hamming code is configured by adding an even parity of 3 bits to the 8421 code, and a 7-bit code by adding even parity bits to the 1st, 2nd, and 4th bits. An extended BCH code is a Reed-Solomon (RS) code, which is useful for burst error correction. Other specific hamming code and BCH code creation method is well known to those skilled in the art and will not be described in detail herein.

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 adaptive error control method using idle bits according to the present invention, an error is generated by utilizing idle bits existing when the actual information data field is shorter than the length of the information data field allowed in the data frame. By using it for detection or correction, there is an effect of improving data transmission efficiency and error detection rate.

In addition, when an error on the channel increases, the transmitting side notifies the fact and shortens the length of the information data to be transmitted to increase the length of the idle bits, thereby ensuring a desired transmission quality without changing additional procedures or circuits. It can be effective.

Claims (3)

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 Extracting a length of the information data field from the control information field of the frame; Comparing the length of the information data field allowed in the frame with the length of the extracted information data field to determine whether an idle bit exists; Calculating a maximum value that can utilize the idle bits; And reconstructing the additional information field according to the state of the frame. The method of claim 1, wherein the reconstructing the additional information field If the length of the data frame is fixed and the actual data length of the information data field is variable, an extended additional information field including the idle bit and the additional information field is configured. When the additional information field having a fixed length of the data frame is used, the idle bit is configured as an additional additional information field to configure an additional information field including the fixed additional information field and the additional additional information field. Adaptive error control method using The adaptive error control method according to claim 1 or 2, wherein an error bit is added to the idle bit and transmitted, and the idle bit is corrected by reading the transmitted error correction code.