KR101630114B1 - LDPC Decoding Device and Method Using Min-Sum Algorithm - Google Patents

Abstract

Disclosed are a low density parity check (LDPC) decoding device and an LDPC decoding method using a minimum sum algorithm. The method comprises the following steps: (a) acquiring a difference (d_min) between a first minimum which is the least value in the minimum sum algorithm and a second minimum which is the second least value in the minimum sum algorithm; (b) comparing the difference (d_min) between the first and the second minimums acquired in the step (a) with a preset threshold; and (c) omitting parity check when the difference (d_min) between the first minimum and the second minimum is smaller than the predetermined threshold. According to the present invention, a channel state can be estimated without separate information about a channel to be reflected in decoding, and a computation amount according to repetitive decoding can be reduced.

Description

(LDPC Decoding Device and Method Using Min-Sum Algorithm)

Embodiments of the present invention relate to an LDPC decoding apparatus and method, and more particularly, to an LDPC decoding apparatus and method using a minimum sum algorithm.

In the fourth generation wireless mobile communication system, a high data transfer rate and a low error rate are required to provide various multimedia services to users. More specifically, in the fourth generation wireless mobile communication, a maximum data transmission speed of 100 Mbps is required for high-speed movement, and a maximum data transmission speed of 155 Mbps to 1 Gbps is required for low-speed movement or suspension. Accordingly, in order to perform high-quality and high-reliability communication in a poor transmission environment, channel encoding / decoding technology must be involved.

The channel coding technique can be used in various forms according to the characteristics of a channel. Basically, a technique of encoding / decoding a signal using an error correcting code is commonly used.

The error correction code is used for achieving reliable communication on an unreliable channel. As a typical example, an error correction code is encoded / decoded using a Low Density Parity Check (LDPC) code (hereinafter referred to as LDPC coding) ).

LDPC coding is a coding technique using a simple probabilistic decoding method, and decodes a received signal through iterative decoding. LDPC coding requires that most elements have a zero value and that few elements other than elements having a value of zero have a non-zero value (e.g., a value of 1) It is defined by a parity check matrix.

In the LDPC coding scheme, in each iterative decoding step, a tentative code is generated through tentative decoding, and a test code generated through a parity check is a valid codeword . If the generated test code is not a valid codeword, decryption is repeatedly performed, and if the generated test code is a valid codeword, decryption is stopped. At this time, as the number of decoding increases, the probability that the generated test code is a valid code word increases.

Recently, the use of battery-operated portable electronic equipment such as a smart phone has been rapidly increasing, and research on operation with a low power has been rapidly increasing. The LDPC decoding algorithm performs a parity check for each decoding step, and iterative decoding is continuously performed until the parity check is successful. Therefore, a decoding apparatus and a method for minimizing a decoding operation for low power operation are required.

An aspect of the present invention is to provide an LDPC decoding apparatus and method using a minimization algorithm that can operate at low power.

Another aspect of the present invention is to provide an LDPC decoding apparatus and method using a minimum sum algorithm that can predict a channel state without information on a separate channel state and reflect the decoded channel state to decoding.

Another aspect of the present invention is to provide an LDPC decoding apparatus and method using a least sum algorithm that can reduce the amount of computation according to iterative decoding.

In order to achieve the above object, according to a preferred embodiment of the present invention, there is provided a method of decoding an LDPC using a least sum algorithm, the method comprising: calculating a difference between a first minimum value, which is the smallest minimum value and a second minimum value, (d_min) of the image; (B) comparing a difference (d_min) between the first minimum value and the second minimum value obtained in the step (a) with a preset threshold value; And omitting a parity check if the difference d_min between the first minimum value and the second minimum value is smaller than the preset threshold value.

The first minimum value and the second minimum value are obtained using the check node calculation result.

The method may further include the step (d) of omitting test decryption with the parity check if the difference (d_min) between the first minimum value and the second minimum value is smaller than a preset threshold value.

And performs parity check and test decoding when the difference d min between the first minimum value and the second minimum value is equal to or greater than the preset threshold value.

If it is determined that the parity check is not omitted in the specific iterative decoding step, the steps (a) to (c) are performed for each iterative decoding step, c) is not performed.

According to another aspect of the present invention, there is provided a method of LDPC decoding using a least sum algorithm, comprising: obtaining a difference (d_min) between a first minimum value which is the smallest minimum value and a second minimum value which is the next smallest minimum value in the minimum sum algorithm ); (B) determining whether the difference (d_min) between the first minimum value and the minimum value is smaller than a preset threshold value and the current number of iterative decoding exceeds the preset reference iteration number; (C) terminating iterative decoding when the difference (d_min) between the first minimum value and the minimum value is smaller than a predetermined threshold and the current number of iterative decodings exceeds a predetermined reference number of repeated iterations, A decoding method is provided.

According to another aspect of the present invention, there is provided a check node / permutable node operation unit that performs a check node operation and a permissible node operation based on a minimum sum algorithm; A minimum value difference obtaining unit for obtaining a difference (d_min) between a first minimum value which is a smallest minimum value outputted in the check node operation and a second minimum value which is a next smallest minimum value; And if the difference d_min between the first minimum value and the second minimum value is less than a preset threshold value, the parity check is skipped, and if the difference d_min between the first minimum value and the second minimum value is equal to or greater than a preset threshold value There is provided an LDPC decoding apparatus using a minimum sum algorithm including a parity check unit for performing a parity check.

According to another aspect of the present invention, there is provided a check node / permutable node operation unit that performs a check node operation and a permissible node operation based on a minimum sum algorithm; A minimum value difference obtaining unit for obtaining a difference (d_min) between a first minimum value which is a smallest minimum value outputted in the check node operation and a second minimum value which is a next smallest minimum value; And an early termination determination unit for terminating iterative decoding when the difference (d_min) between the first minimum value and the minimum value is less than a predetermined threshold value and the current number of iteration decodings exceeds a predetermined reference number of repeated iterations, A decoding apparatus is provided.

According to embodiments of the present invention, there is an advantage that a channel state can be predicted and reflected in decoding without information on a separate channel state.

According to the embodiments of the present invention, it is possible to reduce the amount of calculation according to iterative decoding.

1 is a table showing the relationship between the difference between the first minimum value and the second minimum value and the total number of repetitions.
2 is a graph showing the relationship between the difference (d_min) between the second minimum value and the first minimum value and the total number of repetitions for each SNR.
3 is a block diagram showing a structure of an LDPC decoding apparatus according to a first embodiment of the present invention;
4 is a block diagram illustrating a structure of an LDPC decoding apparatus according to a second embodiment of the present invention;
5 is a flowchart showing a flow of an LDPC decoding method according to the first embodiment of the present invention.
6 is a flowchart showing a flow of an LDPC decoding method according to a second embodiment of the present invention.
FIG. 7 is a diagram for explaining the concept of general LDPC coding; FIG.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

7 is a diagram for explaining the concept of general LDPC coding.

FIG. 7 shows an example of a parity check matrix and a factor graph corresponding to a parity check matrix.

The LDPC code, which is one of the block codes, is defined by a parity check matrix. The LDPC code uses a parity check matrix including a small number of '1' to reduce decoding complexity. In the LDPC code, the decoding may be performed using a sum-product algorithm or a min-sum algorithm, which is a soft decision decoding algorithm.

Here, it is assumed that the (source) data is k bits and the data encoded according to the LDPC code is n bits. At this time, the n bits of encoded data include k bits of data and (n-k) bits of parity. At this time, when it is assumed that k bits of data and parities of (nk) bits correspond to variable nodes and check bits correspond to check nodes, the parity check matrix is a barrierable It can be defined based on the connection relationship between nodes and check nodes.

The LDPC encoding apparatus can generate encoded data with the constraint of Equation (1).

Here, H is an mxn-dimensional parity check matrix, m is the number of check nodes, X is n-bit coded data (codeword), u is k-bit (source) data, Respectively. ≪ / RTI >

The number of 1s included in each column of the parity check matrix is called the permissible node degree. In addition, the number of 1s included in each row of the parity check matrix is called a check node degree. If all the permutable node orders for each column are the same and the check node orders for each row are all the same, the LDPC code is a regular LDPC code, and the variable node degree for each column is different, When the node degree is different, the LDPC code is a non-uniform LDPC code.

7, the parity check matrix (H) is a barrier block nodes _{(v 1, v 2, ...} v 10) and check nodes _{(c 1, c 2, c} 3, ..., c 5 ). ≪ / RTI > The viable nodes v ₁ , v ₂ , ..., v ₁₀ correspond to coded data, and the coded data includes data bits and parity bits. Also check nodes correspond to check bits. The dimension of the parity check matrix H is 5 x 10 according to the number of the permissible nodes and the number of check nodes.

V ₁ is connected to c ₁ and c ₃ on the factor graph representing the connection relationship between the permissible nodes and the check nodes, so that the first-row one-row one-row and one-column three-row elements of the parity check matrix H '1', and the rest of the elements in the first column are all set to zero. Similarly, since v ₂ is connected to c ₁ and c ₂ , it can be seen that the elements of row 2 row 1 row and column 2 row 2 are '1', and the rest of the elements of row 2 are '0'. In the above-described manner, all elements of the parity check matrix are determined to be either '1' or '0'.

Also, the barrier node degree is equal to the number of lines connected to the respective variable nodes, and the check node degree is the same as the number of lines connected to the respective check nodes. That is, referring to the factor graph of FIG. 7, since two lines are connected to each of the barrier nodes, the variable node degree is '2'. The check node degree is '4'.

When decrypting the coded data according to the above coding method, each of the permutable nodes and the check nodes transmits its decryption result to other connected nodes or receives decryption results of other nodes. That is, when one node receives a decoding result of another node from another node, the one node decodes using the decoding result of the other node and transmits its decoding result to another node connected thereto .

At this time, a decoding operation performed in the check nodes is referred to as a check node operation, and a decoding operation performed in the enabled nodes is referred to as a variable node operation.

A tentative code is generated through a check node operation and a barrier node operation, and the generated test code is checked for a valid codeword through a parity check.

If the generated test code is a valid codeword, the decoding operation is ended. If the test code is not a valid codeword, the decoding operation is repeatedly performed.

Various algorithms such as a summing algorithm and a minimum sum algorithm exist for decoding the encoded LDPC code, and the present invention is applied to an LDPC decoding apparatus and method using a least sum algorithm.

The least-sum algorithm is a function of the LLR-SPA (Log-Likelihood Ratio Sum-Product Algorithm).

The operation performed by the check node in the least sum algorithm is expressed by Equation 2 below.

In Equation (2),? Denotes a coefficient that is multiplied by the minimum sum algorithm, Q denotes a message received from a permissible node, i denotes a check node index, and j denotes a barrier node index.

In the check node, a minimum value among the messages from the barrier node j, which is excluded from itself, must be found. Here, the process of finding the minimum value may be expressed as Equation (3).

therefore

In the least sum algorithm, the first minimum value min1, which is the smallest absolute value and the second minimum value min2, which is the next smallest value are obtained. The operation result computed at the check node is stored and transmitted to the permissible node, including the following information.

{signs, min1, min2, index of min1}

Recently, a modified least sum algorithm has been proposed. The modified minimum sum algorithm conveys the following information to the permissible node.

{signs, min1, (min2-min1), index of min1}

1 is a table showing the relationship between the difference between the first minimum value and the second minimum value and the total number of repetitions.

In FIG. 1, 0 means that decryption has succeeded and the next frame is not passed through iterative decoding.

In FIG. 1,? Denotes the number of repetitions, and the dB value at the top of the table denotes the SNR. Each of the values in the table indicates the difference between the first minimum value and the second minimum value in the repetition count and SNR ).

1, it can be seen that the difference between the first minimum value and the second minimum value has a significant correlation with the SNR. The difference between the first minimum value and the second minimum value in the iterative decoding with a relatively large SNR is larger than the difference between the first minimum value and the second minimum value in the iterative decoding with a relatively small SNR.

For example, if the SNR is 1.5bB, d_min is 0.03538 in the first iteration, and d_min in the first iteration is 0.6578 when the SNR is 5.5dB, which is larger than d_min when the SNR is 1.5dB Can be confirmed.

Also, it can be seen that the value of d_min increases as the number of iterative decodings increases in each SNR.

As the number of iterative decodings increases, the value of d_min gradually increases, and it is confirmed that the iterative decoding is completed by satisfying the parity check in the specific iterative multiple lakes.

As a result, it can be seen from FIG. 1 that the difference between the first minimum value and the second minimum value output from the minimum sum algorithm can be utilized as a reference variable for scheduling in the LDPC iterative decoding algorithm.

2 is a graph showing the relationship between the difference (d_min) between the second minimum value and the first minimum value and the total number of repetitions for each SNR.

The graph of FIG. 2 is a graph reconstructed from the table of FIG. Referring to FIG. 2, the higher the SNR, the larger the difference between the first minimum value and the second minimum value.

In addition, it can be confirmed that the larger the difference between the first minimum value and the second minimum value, the smaller the number of repetition.

In addition, as the number of repetitions increases in each SNR, the difference between the first minimum value and the second minimum value gradually increases.

In the conventional LDPC algorithm, the SNR is used as a reference variable for setting the minimum repetitive multiple lag and the maximum repetitive multiple lag in the iterative decoding. According to the inventor's research, in the LDPC decoding using the minimum sum algorithm, It can be seen from FIGS. 1 and 2 that the difference (d_min) between the two minimum values has a significant correlation with the SNR.

It will be obvious to those skilled in the art that the LDPC algorithm can be utilized not only for communication but also for various storage devices, and that the minimum value difference d_min can be used as a reference variable for scheduling decoding even in LDPC decoding other than communication.

Hereinafter, an apparatus and method for scheduling decoding using a difference (d_min) between a first minimum value and a second minimum value will be described.

3 is a block diagram illustrating a structure of an LDPC decoding apparatus according to a first embodiment of the present invention.

3, the LDPC decoding apparatus according to the first embodiment of the present invention includes a check node / permissible node operation unit 300, a minimum value difference acquisition unit 310, a parity check unit 320, and a storage unit 330 ).

The check node / permissible node operation unit 300 performs a check node operation and a permissible node operation for each iteration. The check node / barrier block operation unit 300 performs check node operation and barrier node operation according to the minimum sum algorithm, and various known minimum sum algorithms can be used.

In the check node operation, the first minimum value and the second minimum value are obtained, and the first minimum value and the second minimum value are used for the permissible node operation. In the modified least sum algorithm, the difference between the first minimum value and the second minimum value is also used in the computation of the permutable node.

The minimum value difference obtaining unit 310 obtains the difference between the first minimum value and the second minimum value output in the check node calculation process. The first minimum value and the second minimum value are output in the check node operation in a conventional minimum sum algorithm and the minimum value difference can be obtained using the first minimum value and the second minimum value outputted.

In the modified minimum sum algorithm, the difference between the first minimum value and the second minimum value is output, so that it is possible to more easily obtain the minimum value difference.

A first threshold value is stored in the storage unit 310, and the first threshold value is used as basic information for determining whether to perform a parity check in the specific iterative decoding.

The parity check unit 320 determines whether to perform a parity check using the minimum value difference information provided by the first threshold value and minimum value difference obtaining unit 310 stored in the storage unit and performs a parity check when a parity check is required do.

1 and 2, the minimum value difference is correlated with the SNR, and a relatively large number of times of decoding is required in a state where the SNR is low. When a relatively large number of times of decoding is expected, performing a parity check in a specific iterative decoding may serve as an unnecessary load.

For example, if it is anticipated that more than 10 additional iterative decoding is to be performed, it is expected that the parity check will not be successful in the first iterative decoding and the second iterative decoding. Therefore, performing a parity check increases the unnecessary load.

A low minimum value difference means that the transmission / reception state of the signal is not good, meaning that a large number of iterative decoding is required.

Therefore, according to a preferred embodiment of the present invention, the parity check unit 320 operates to omit the parity check when the minimum value difference is smaller than a preset first threshold value.

When the minimum value difference is equal to or larger than a preset first threshold value, the parity check unit 320 normally performs parity check. If the parity check is successful as a result of the parity check, iterative decoding ends.

The operation of determining whether to perform the parity check by comparing the minimum value difference with the first threshold value is performed every iterative decoding.

In the table shown in FIG. 1, when the SNR is 0.5 dB, the minimum value difference in the initial decoding step has a very small value, and it is preferable to omit the parity check in the initial decoding step.

However, when the SNR is 3.5 dB or more, it is preferable to perform the parity check from the first decoding step since the minimum value difference has a very large value even in the initial decoding step.

In the above description, only the parity check operation is omitted when the minimum value difference is smaller than the first threshold value, but the test decoding may be omitted together with the parity check operation.

Test decryption is a task of deciding decoded data as a preset reference value and deciding a decoded data value to a value of 0 or 1 when hard decision is used.

When the parity check is omitted, it is preferable to omit test decryption to minimize the decoding operation.

On the other hand, if it is determined not to omit the parity check in the specific iterative decoding step, it is preferable not to perform the operation of determining whether to omit the parity check in the iterative decoding step thereafter.

For example, if it is determined that the parity check is skipped in the first iterative decoding step and the second iterative decoding step but the parity check is not omitted in the third iterative decoding step, It is preferable not to perform an operation of performing a check and determining whether or not to omit the parity check.

4 is a block diagram illustrating a structure of an LDPC decoding apparatus according to a second embodiment of the present invention.

4, the LDPC decoding apparatus according to the second embodiment of the present invention includes a decoding unit 400, a minimum value difference obtaining unit 410, an early termination determining unit 420, and a storage unit 430.

The decoding unit 400 performs iterative decoding according to the minimum sum algorithm. The decoding unit performs a check node operation and a permissible node operation, and also performs a parity check and a test decoding operation.

The minimum value difference obtaining unit 410 obtains the difference between the minimum value of the first minimum value and the minimum value of the second minimum value output from the decoding unit 400 in the check node calculation process.

The storage unit 430 stores the second threshold value and the reference iterative bin information.

The early termination determining unit 420 determines whether or not to end the iterative decoding early using the minimum value difference information acquired by the minimum value difference acquiring unit 410, the second threshold value stored in the storage unit, .

If the SNR environment is poor or the transmission data is corrupted due to other reasons, the parity check may not be successful even if the iterative decoding is performed a lot.

In such a case, it is preferable to terminate the iterative decoding prematurely even if the parity check is unsuccessful, rather than performing the iterative decoding continuously. In the present invention, in order to avoid unnecessary operations, the early termination determining unit 420 ends the iterative decoding if the predetermined condition is satisfied.

If the minimum difference value acquired by the minimum difference value acquisition unit 410 is smaller than the second threshold value stored in the storage unit and the current number of iteration decodings is larger than the preset reference iteration iteration count unit 420, .

If the minimum value difference acquired by the minimum value difference obtaining unit 410 is greater than the second threshold value stored in the storage unit or the current iteration number is smaller than the preset reference iteration number, the early termination determination unit 420 performs the next iteration .

The determination of the early termination determination unit 420 is performed every iterative decoding step.

In the second embodiment of the present invention, the early termination of iterative decoding is determined by using the minimum value difference obtainable by the minimum sum decoding algorithm. By avoiding unnecessary iterative decoding using the minimum value difference, .

5 is a flowchart illustrating a flow of an LDPC decoding method according to the first embodiment of the present invention.

Referring to FIG. 5, first, a check node operation using a least sum algorithm is performed (step 500).

When the check node operation is performed, the first minimum value and the second minimum value are output, and a difference d_min between the first minimum value and the second minimum value is obtained using the first minimum value and the second minimum value (step 502).

When the check node operation is performed, a barrier node operation is performed using the first minimum value and the second minimum value output from the check node operation (step 504).

The minimum value difference d_min obtained in step 502 is compared with a first threshold value stored in advance (step 506).

If the minimum value difference d_min is smaller than the preset first threshold value, the parity check and test decoding are omitted and the next decoding is performed (step 508).

When the minimum value difference d_min is greater than a predetermined first threshold value, parity check and test decoding are performed as in the normal repetition step (step 510).

The procedure shown in FIG. 5 is performed for each iterative decoding step.

6 is a flowchart illustrating a flow of an LDPC decoding method according to a second embodiment of the present invention.

Referring to FIG. 6, a check node operation using a least sum algorithm is performed (step 600).

When the check node operation is performed, the first minimum value and the second minimum value are output, and the difference (d_min) between the first minimum value and the second minimum value is obtained using the first minimum value and the second minimum value (step 602).

When the check node operation is performed, a barrier node operation is performed using the first minimum value and the second minimum value output in the check node operation (step 604).

Although not shown in FIG. 6, a parity check operation and test decoding may be additionally performed after the computation of the barrier node.

It is determined whether or not the minimum value difference d_min obtained in step 602 is smaller than a preset second threshold and whether the current number of iterative decoding exceeds the preset reference iteration number (step 606).

If the minimum value difference d_min is smaller than the preset second threshold value and the current number of iterative decoding exceeds the preset reference iterative number, the process is terminated without performing iterative decoding (step 608).

If the minimum value difference is larger than the preset second threshold value or the current iteration number does not exceed the preset reference iteration number, the next iteration is normally performed (step 610).

The above-described technical features may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware device may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

As described above, the present invention has been described with reference to particular embodiments, such as specific elements, and limited embodiments and drawings. However, it should be understood that the present invention is not limited to the above- Various modifications and variations may be made thereto by those skilled in the art to which the present invention pertains. Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

Claims (12)

An LDPC decoding method using a least sum algorithm,
(A) obtaining a difference (d_min) between a first minimum value that is the smallest minimum value and a second minimum value that is the next smallest minimum value in the minimum sum algorithm;
(B) comparing a difference (d_min) between the first minimum value and the second minimum value obtained in the step (a) with a preset threshold value;
And omitting the parity check if the difference d_min between the first minimum value and the second minimum value is smaller than the preset threshold value. The method according to claim 1,
Wherein the first minimum value and the second minimum value are obtained using a check node computation result. The method according to claim 1,
And a step (d) of omitting test decryption, which is an operation of deciding decrypted data as a preset reference value when the difference (d_min) between the first minimum value and the second minimum value is smaller than a predetermined threshold value LDPC decoding method using a least sum algorithm. The method according to claim 1,
And deciding the parity check and decoded data as a preset reference value when the difference d_min between the first minimum value and the second minimum value is equal to or greater than the preset threshold value, For LDPC decoding. The method of claim 1, wherein
The steps (a) to (c) are performed for each iterative decoding step,
(B) and (c) are not performed in the iterative decoding step after the iterative decoding step when it is determined that the parity check is not omitted in the specific iterative decoding step . An LDPC decoding method using a least sum algorithm,
(A) obtaining a difference (d_min) between a first minimum value that is the smallest minimum value and a second minimum value that is the next smallest minimum value in the minimum sum algorithm;
Determining whether a difference (d_min) between the first minimum value and the second minimum value is smaller than a preset threshold value and whether the current number of iterative decoding exceeds the reference repeated iterations preset in order to judge whether the iterative decoding ends prematurely );
When the difference (d_min) between the first minimum value and the second minimum value is smaller than a predetermined threshold value and the current iteration number exceeds the preset reference iteration number to judge whether the iteration ending early, the iteration decoding is ended Wherein the step (c) comprises the step (c). The method according to claim 6,
Wherein the first minimum value and the second minimum value are obtained using a check node computation result. An LDPC decoding apparatus using a least sum algorithm,
A check node / barrier node operation unit performing a check node operation and a permissible node operation based on a minimum sum algorithm;
A minimum value difference obtaining unit for obtaining a difference (d_min) between a first minimum value which is a smallest minimum value outputted in the check node operation and a second minimum value which is a next smallest minimum value; And
Wherein if the difference d_min between the first minimum value and the second minimum value is less than a preset threshold value, the parity check is skipped, and if the difference d_min between the first minimum value and the second minimum value is equal to or greater than a predetermined threshold value, And a parity check unit for performing a check of the LDPC code. delete 9. The method of claim 8,
Wherein when the difference d min between the first minimum value and the second minimum value is smaller than a predetermined threshold value, the parity check unit omits test decoding, which is an operation of deciding the decoded data as a preset reference value, For example. The method of claim 8, wherein
Wherein the parity check unit does not omit the parity check in the iterative decoding step after the iterative decoding step if it is determined that the parity check is not omitted in the specific decoding step. An LDPC decoding apparatus using a least sum algorithm,
A check node / barrier node operation unit performing a check node operation and a permissible node operation based on a minimum sum algorithm;
A minimum value difference obtaining unit for obtaining a difference (d_min) between a first minimum value which is a smallest minimum value outputted in the check node operation and a second minimum value which is a next smallest minimum value; And
When the difference (d_min) between the first minimum value and the second minimum value is smaller than a preset threshold value and the current iteration number exceeds the preset reference iteration number to judge whether the iteration decoding ends prematurely, And a termination determination unit for determining the termination of the LDPC decoding.

Images