KR101502677B1 - Apparatus and method for channel encoding and decoding in communication system using low-density parity-check codes - Google Patents

Abstract

A method and apparatus for generating various block sizes from a structured LDPC code in a communication system using a low density parity check (LDPC) code, .
The present invention also provides a method for finding a puncturing pattern that guarantees excellent performance by using the structural characteristics of an LDPC code when puncturing is applied to an LDPC codeword generated to support various codeword lengths according to a system requirement, ≪ / RTI >

Description

TECHNICAL FIELD The present invention relates to a method and apparatus for channel coding / decoding in a communication system using a low-density parity-check code,

The present invention relates to a communication system using a low-density parity-check (LDPC) code, and more particularly, to a channel encoding / decoding method and apparatus for generating a specific type of LDPC code .

In wireless communication systems, the performance of a link is significantly degraded due to various noise, fading phenomena, and inter-symbol interference (ISI) of a channel. Therefore, it is essential to develop overcoming techniques for noise, fading and ISI in order to realize high-speed digital communication systems requiring high data throughput and reliability, such as next generation mobile communication, digital broadcasting, and portable Internet. In recent years, error-correcting codes have been actively studied as methods for efficiently restoring information distortion and improving communication reliability.

The LDPC codes are typically represented using graphical representations, and many features can be analyzed through graph theory, algebra, and probability-based methods. Generally, a graph model of a channel code is useful not only for describing codes but also to correspond information of encoded bits to a vertex in a graph and to correspond each bit relation to edges in a graph , It is possible to derive a natural decryption algorithm because each vertex can be regarded as a communication network for exchanging messages determined by each line. For example, trellis-derived decoding algorithms, which can be regarded as a kind of graph, include the well-known Viterbi algorithm and BCJR (Bahl, Cocke, Jelinek and Raviv) algorithms.

The LDPC code can be expressed using a bipartite graph, which is generally defined as a parity-check matrix and is collectively referred to as a Tanner graph. The bipartite graph indicates that the vertices constituting the graph are divided into two different types. In the case of the LDPC code, a binary graph composed of a variable node and a vertex called a check node Is expressed. The variable node corresponds one-to-one to the encoded bit.

1 shows an example of a parity check matrix H ₁ of the LDPC code including four rows and eight columns. Referring to FIG. 1, an LDPC code is generated to generate a codeword having a length of 8 because there are eight columns. Each column corresponds to eight encoded bits.

FIG. 2 is a graph showing a Tanner graph corresponding to H ₁ in FIG.

2, the Tanner graph of the LDPC code includes eight variable nodes x ₁ (202), x ₂ (204), x ₃ (206), x ₄ (208), x ₅ (210) ₆ 212, x ₇ 214 and x ₈ 216 and four check nodes 218, 220, 222 and 224. Here, the i-th column and the j-th row of the parity check matrix H ₁ of the LDPC code correspond to the variable nodes x _i and j-th check nodes, respectively. The value of 1, that is, a value other than 0 at the intersection of the i-th column and the j-th row of the parity check matrix H ₁ of the LDPC code means that the variable node x _i And an edge exists between the jth check node and the jth check node.

In the Tanner graph of the LDPC code, the degree of the variable node and the check node means the number of line segments connected to the respective nodes. This means that in the parity check matrix of the LDPC code, Is equal to the number of non-zero entries. For example, the variable nodes x ₁ 202, x ₂ 204, x ₃ 206, x ₄ 208, x ₅ 210, x ₆ 212, x ₇ 214), x ₈ (216) orders, respectively order 4, 3, 3, 3, 2, 2, 2, and 2, check nodes (218, 220, 222, 224) the order of the is, as each sequence of 6, 5, 5, 5. In addition, the number of non-zero elements in each column of the parity check matrix H ₁ of FIG. 1 corresponding to the variable nodes of FIG. 2 corresponds to the numbers 4, 3, 3, 3, 2, 2, 2, and the number of non-zero elements in each row of the parity check matrix H ₁ of FIG. 1 corresponding to the check nodes of FIG. 2 corresponds to the order 6, 5, 5, 5 And so on.

In order to express the degree distribution for a node of an LDPC code, the ratio of the number of variable nodes with degree _i to the total number of variable nodes is f _i , and the number of check nodes with degree j and the total number Let the ratio of the number of g _j. For example, for the LDPC code to the Figure correspond to the 1 and 2 is _{f 2 = 4/8, f} 3 = 3/8, f 4 = 1/8, i ≠ 2, 3, about 4 f _i = 0, g ₅ = 3/4, g ₆ = 1/4, and g _j = 0 for j? Assuming that the length of the LDPC code is N, that is, the number of columns is N, and the number of rows is N / 2, the density of non-zero elements in the parity check matrix having the above- .

If N increases in Equation (1), the density of 1 in the parity check matrix continues to decrease. Generally, the LDPC code is inversely proportional to the nonzero element density with respect to the code length N, and when N is large, the nonzero element has a very low density. The term low-density in the name of an LDPC code comes from this reason.

FIG. 3 schematically shows an LDPC code adopted as a standard technique in DVB-S2 (Digital Video Broadcasting-Satellite Transmission 2nd generation) which is one of the European digital broadcasting standards.

은 LDPC 부호어 길이고,

은 정보어의 길이이고,

은 패리티 길이를 의미한다. 그리고,

이 성립하도록 정수

과

를 결정한다. 이때,

도 정수가 되도록 한다. 편의상 도 3의 패리티 검사 행렬을 제 1 패리티 검사 행렬 H₁이라 한다. Referring to Figure 3,

Is an LDPC codeword length,

Is the length of the information word,

Denotes the parity length. And,

To establish this constant

and

. At this time,

Is also an integer. For convenience, the parity check matrix of FIG. 3 is referred to as a first parity check matrix H ₁ .

번째 열(column)부터

번째 열까지의 구조는 이중 대각(dual diagonal) 형태이다. 따라서, 패리티 부분에 해당하는 열의 차수(degree) 분포는 그 값이 '1'인 마지막 열을 제외하고 모두 '2'를 가진다.Referring to FIG. 3, a portion corresponding to a parity portion in a parity check matrix,

From the first column

The structure up to the second column is a dual diagonal form. Therefore, the degree distribution of the column corresponding to the parity part has '2' except for the last column in which the value is '1'.

번째 열까지의 구조를 이루는 규칙은 다음과 같다. In the parity check matrix, the portion corresponding to the information word portion, i.e.,

The rules for the structure up to the first column are as follows.

개의 열을

개의 열들로 구성된 복수 개의 그룹으로 그룹화(grouping)하여, 총

개의 열 그룹(column group)을 생성한다. 각 열 그룹에 속해있는 각각의 열을 구성하는 방법은 하기 규칙 2에 따른다. <Rule 1>: In the parity check matrix,

Columns

Grouping into a plurality of groups of four columns,

&Lt; / RTI &gt; column groups. The method for constructing each column belonging to each column group is as follows.

번째

열 그룹의 각 0 번째 열에서의 1의 위치를 결정한다. 여기서, 각

번째 열 그룹의 0 번째 열의 차수를

라 할 때, 각 1이 있는 행의 위치를

이라 가정하면,

번째 열 그룹 내의

번째 열에서 1이 있는 행의 위치

는 하기 <수학식 2>와 같이 정의된다. <Rule 2>: First

th

And determines the position of 1 in each 0th column of the column group. Here,

The order of the 0th column in the ith column group is

, The position of each row with 1

Assuming that,

Within the first column group

The position of the row with 1 in the third column

Is defined as < EMI ID = 2.0 >

번째

열 그룹 내에 속하는 열들의 차수는 모두

로 일정함을 알 수 있다. According to the above rule

th

The order of the columns belonging to the column group is

As shown in Fig.

일때, 3개의 열 그룹의 0 번째 열에 대한 1을 가지는 행의 위치 정보에 대한 3개의 시퀀스는 다음과 같이 나타낼 수 있다. 여기서, 상기 시퀀스는 무게 1 위치 시퀀스(weight-1 position sequence)라고 한다.As a concrete example

, The three sequences for the position information of the row having 1 for the 0 &lt; th &gt; column of the 3 column groups can be expressed as follows. Here, the sequence is referred to as a weight-1 position sequence.

The weight 1 position sequence of the row having the 0th 1 of each column group may be expressed as a sequence in which the weight 1 is located in each column group as follows.

0 1 2

0 11 13

0 10 14

번째 열의

번째 무게 1 위치 시퀀스는

번째 열 그룹에서 1을 가지는 행의 위치 정보를 순차적으로 나타낸 것이다. That is,

Column

The second weight 1 position sequence is

And the position information of the row having 1 in the column group is sequentially shown.

If a parity check matrix is configured using information corresponding to the specific example and < Rule 1 > and < Rule 2 >, an LDPC code having the same concept as the DVB-S2 LDPC code shown in FIG. 4 can be generated.

It is known that the DVB-S2 LDPC code designed through the rules 1 and 2 can be efficiently encoded using a structural form. The steps of the LDPC encoding process using the parity check matrix of the DVB-S2 will be described as follows.

,

,

,

를 특징으로 하는 DVB-S2 LDPC 부호를 이용하는 부호화 과정을 설명하였다. 또한 설명의 편의를 위해 길이가

인 정보어 비트들을

로 나타내고, 길이가

인 패리티 비트들을

로 나타낸다. As a specific example,

,

,

,

A description has been given of a coding process using a DVB-S2 LDPC code. Also, for convenience of explanation,

Information bits

And the length is

Parity bits

Respectively.

. Step 1 : The LDPC encoder initializes the parity bits as follows.

.

Step 2 : The LDPC encoder reads the information of the row where 1 is located in the column group from the 0th weight 1 position sequence of the sequences representing the stored parity check matrix.

0 2084 1613 1548 1286 1460 3196 4297 2481 3369 3451 4620 2622

를 이용하여 하기의 <수학식 3>과 같이 특정 패리티 비트

들을 업데이트한다. 여기서,

는 각각의

값을 의미한다. The called information and the first information bit

As shown in Equation (3) below,

Lt; / RTI &gt; here,

Respectively,

Lt; / RTI >

는

로 표기하기도 하며,

는 이진(binary) 덧셈을 의미한다. In Equation (3)

The

Also,

Means binary addition.

이후의 다음 359개의 정보어 비트

,

에 대해서 먼저 하기의 <수학식 4>에 대한 값을 구한다. Step 3 :

The following 359 information bits

,

First, a value for Equation (4) below is obtained.

는 각각의

값을 의미한다. 상기 <수학식 4>는 <수학식 2>와 동일한 개념의 수학식임에 유의한다. In Equation (4)

Respectively,

Lt; / RTI &gt; Note that Equation (4) is a mathematical expression having the same concept as Equation (2).

에 대해서

을 업데이트한다. 예를 들어

, 즉,

에 대해서 하기의 <수학식 5>와 같이

들을 업데이트한다. Next, an operation similar to Equation (3) is performed using the value obtained from Equation (4). In other words,

about

Lt; / RTI &gt; E.g

, In other words,

As shown below in Equation (5)

Lt; / RTI >

임에 유의한다. 위와 같은 과정을

에 대해서 마찬가지로 진행한다. In the case of Equation (5)

. The above procedure

.

에 대해서 첫 번째 무게 1 위치 시퀀스인

의 정보를 호출하고, 특정

을 업데이트한다. 여기서,

는

을 의미한다.

이후의 다음 359개의 정보어 비트

에 대해서 <수학식 4>를 유사하게 적용하여

를 업데이트한다. Step 4 : As in step 2 above,

The first weight 1 position sequence in

And calls the information

Lt; / RTI &gt; here,

The

.

The following 359 information bits

Equation (4) is applied similarly to Equation

Lt; / RTI >

Step 5 : Repeat steps 2, 3 and 4 for all 360 information bit groups.

Step 6: Finally, the parity bit is determined by Equation (6).

들이 LDPC 부호화가 완료된 패리티 비트들이다. In Equation (6)

Are parity bits for which LDPC coding is completed.

As described above, in the DVB-S2, the LDPC encoding is performed through the process from the step 1 to the step 6.

In order to apply an LDPC code to an actual communication system, it should be designed to meet the data rate required in the communication system. In particular, in a communication system supporting a variety of broadcasting services as well as an adaptive communication system employing a hybrid automatic retransmission request (HARQ) scheme and an adaptive modulation and coding (AMC) scheme, In order to support various data transmission rates, LDPC codes having various codeword lengths are required.

However, in the case of the LDPC code used in the DVB-S2 system as described above, only two codeword lengths are required due to limited use, and each requires an independent parity check matrix. For this reason, it is necessary to support various codeword lengths in order to increase the scalability and flexibility of the system. Especially, in DVB-S2 system, it is necessary to transmit hundreds to thousands of bits of data for transmission of signaling information. Since there are only 16200 and 64800 lengths of DVB-S2 LDPC codes, support for various codeword lengths is essential .

In addition, storing an independent parity check matrix for each codeword length of the LDPC code degrades the memory efficiency. Therefore, a new parity check matrix is not designed, and various codeword lengths are efficiently extracted from the existing parity check matrix As well.

According to an aspect of the present invention, there is provided a method of generating a low density parity check code for generating an LDPC code having a different codeword length using puncturing or shortening from a given LDPC code, The system provides a channel coding / decoding method.

The present invention also provides a method and apparatus for channel coding / decoding in a communication system using a low-density parity-check code that ensures optimal performance considering a DVB-S2 structure.

,
상기 P_j 는 j 번째 패리티 비트 그룹을 나타내고, N ₁은 부호어의 길이, K ₁은 정보어 길이, M ₁은 하나의 패리티 비트 그룹의 길이, 상기 일정한 간격 q는

를 만족하고, K₁ /M₁ 은 정수이고, 상기 수학식은

를 만족하고, 상기 패리티 비트 그룹의 수는 하기 수학식에 의해 결정되고,
<수학식>

상기 A는 천공된 패리티 비트 그룹의 수를 나타내고, N_p 는 천공된 패리티 비트의 수를 나타내고, M₁ 은 하나의 패리티 비트 그룹의 길이를 나타내고, 상기 천공된 패리티 비트의 위치 정보를 결정하는 과정은, A개의 패리티 비트 그룹

내의 모든 패리티 비트가 천공된 것으로 결정하는 과정; 및

패리티 비트 그룹 내의 패리티 비트들 중

개의 패리티 비트가 추가적으로 천공된 것으로 결정하는 과정을 포함하고,
상기 미리 결정된 천공된 패리티 비트 그룹의 순서에 근거하는 상기 천공된 패리티 비트 그룹의 순서는 부호어 길이가 16200이고, 상기 q가 25일 때, 6, 4, 18, 9, 13, 8, 15, 20, 5, 17, 2, 24, 10, 22, 12, 3, 16, 23, 1, 14, 0, 21, 19, 7, 11이다.
본 발명의 실시 예에 따른 채널 복호화 방법은, 저밀도 패리티 검사 부호를 사용하는 시스템에서 채널 복호화 방법에 있어서, 송신기로부터 전송된 신호를 복조하는 과정; 천공된 패리티 비트의 위치 정보를 결정하는 과정; 및 상기 천공된 패리티 비트의 위치 정보를 이용하여 데이터를 복호하는 과정을 포함하고, 상기 천공된 패리티 비트의 위치 정보를 결정하는 과정은, 천공된 패리티 비트의 개수(N_p )를 결정하는 과정; 상기 천공된 패리티 비트의 개수를 근거로 하여 천공된 패리티 비트 그룹의 수를 결정하는 과정; 및 미리 결정된 천공된 패리티 비트 그룹의 순서를 획득하는 과정을 포함하고, 상기 패리티 비트 그룹은 하나의 패리티 비트 그룹 내의 복수의 패리티 비트들이 일정한 간격 q을 가지도록 구성되고, 상기 패리티 비트 그룹은 하기 수학식에 의해 결정되고,
<수학식>

,
상기 P_j 는 j 번째 패리티 비트 그룹을 나타내고, N ₁은 부호어의 길이, K ₁은 정보어 길이, M ₁은 하나의 패리티 비트 그룹의 길이, 상기 일정한 간격 q는

를 만족하고, K₁ /M₁ 은 정수이고, 상기 수학식은

를 만족하고, 상기 패리티 비트 그룹의 수는 하기 수학식에 의해 결정되고,
<수학식>

상기 A는 천공된 패리티 비트 그룹의 수를 나타내고, N_p 는 천공된 패리티 비트의 수를 나타내고, M₁ 은 하나의 패리티 비트 그룹의 길이를 나타내고, 상기 천공된 패리티 비트의 위치 정보를 결정하는 과정은, A개의 패리티 비트 그룹

내의 모든 패리티 비트가 천공된 것으로 결정하는 과정; 및

패리티 비트 그룹 내의 패리티 비트들 중

개의 패리티 비트가 추가적으로 천공된 것으로 결정하는 과정을 포함하고, 상기 미리 결정된 천공된 패리티 비트 그룹의 순서에 근거하는 상기 천공된 패리티 비트 그룹의 순서는 부호어 길이가 16200이고, 상기 q가 36일 때, 27, 13, 29, 32, 5, 0, 11, 21, 33, 20, 25, 28, 18, 35, 8, 3, 9, 31, 22, 24, 7, 14, 17, 4, 2, 26, 16, 34, 19, 10, 12, 23, 1, 6, 30, 15이다.
본 발명의 실시 예에 따른 채널 복호화 장치는, 저밀도 패리티 검사 부호를 사용하는 시스템에서 채널 복호화 장치에 있어서, 송신기로부터 전송된 신호를 복조하는 복조기; 천공된 패리티 비트의 위치 정보를 결정하는 천공 패턴 추정기; 및상기 천공된 패리티 비트의 위치 정보를 이용하여 데이터를 복호하는 복호기를 포함하고, 상기 천공된 패리티 비트의 위치 정보는, 천공된 패리티 비트의 개수(N_p )를 결정하고, 상기 천공된 패리티 비트의 개수를 근거로 하여 천공된 패리티 비트 그룹의 수를 결정하고, 미리 결정된 천공된 패리티 비트 그룹의 순서를 획득함에 의해 결정되고, 상기 패리티 비트 그룹은 하나의 패리티 비트 그룹 내의 복수의 패리티 비트들이 일정한 간격 q을 가지도록 구성되고, 상기 패리티 비트 그룹은 하기 수학식에 의해 결정되고,
<수학식>

,
상기 P_j 는 j 번째 패리티 비트 그룹을 나타내고, N ₁은 부호어의 길이, K ₁은 정보어 길이, M ₁은 하나의 패리티 비트 그룹의 길이, 상기 일정한 간격 q는

를 만족하고, K₁ /M₁ 은 정수이고, 상기 수학식은

를 만족하고, 상기 패리티 비트 그룹의 수는 하기 수학식에 의해 결정되고,
<수학식>

상기 A는 천공된 패리티 비트 그룹의 수를 나타내고, N_p 는 천공된 패리티 비트의 수를 나타내고, M₁ 은 하나의 패리티 비트 그룹의 길이를 나타내고, 상기 천공된 패리티 비트의 위치 정보를 결정하는 것은, A개의 패리티 비트 그룹

내의 모든 패리티 비트가 천공된 것으로 결정하고,

패리티 비트 그룹 내의 패리티 비트들 중

개의 패리티 비트가 추가적으로 천공된 것으로 결정함을 포함하고, 상기 미리 결정된 천공된 패리티 비트 그룹의 순서에 근거하는 상기 천공된 패리티 비트 그룹의 순서는 부호어 길이가 16200이고, 상기 q가 25일 때, 6, 4, 18, 9, 13, 8, 15, 20, 5, 17, 2, 24, 10, 22, 12, 3, 16, 23, 1, 14, 0, 21, 19, 7, 11이다.
본 발명의 실시 예에 따른 채널 복호화 장치는, 저밀도 패리티 검사 부호를 사용하는 시스템에서 채널 복호화 장치에 있어서, 송신기로부터 전송된 신호를 복조하는 복조기; 천공된 패리티 비트의 위치 정보를 결정하는 천공 패턴 추정기; 및 상기 천공된 패리티 비트의 위치 정보를 이용하여 데이터를 복호하는 복호기를 포함하고, 상기 천공된 패리티 비트의 위치 정보는, 천공된 패리티 비트의 개수(N_p )를 결정하고, 상기 천공된 패리티 비트의 개수를 근거로 하여 천공된 패리티 비트 그룹의 수를 결정하고, 미리 결정된 천공된 패리티 비트 그룹의 순서를 획득함에 의해 결정되고, 상기 패리티 비트 그룹은 하나의 패리티 비트 그룹 내의 복수의 패리티 비트들이 일정한 간격 q을 가지도록 구성되고, 상기 패리티 비트 그룹은 하기 수학식에 의해 결정되고,
<수학식>

,
상기 P_j 는 j 번째 패리티 비트 그룹을 나타내고, N ₁은 부호어의 길이, K ₁은 정보어 길이, M ₁은 하나의 패리티 비트 그룹의 길이, 상기 일정한 간격 q는

를 만족하고, K₁ /M₁ 은 정수이고, 상기 수학식은

를 만족하고, 상기 패리티 비트 그룹의 수는 하기 수학식에 의해 결정되고,
<수학식>

상기 A는 천공된 패리티 비트 그룹의 수를 나타내고, N_p 는 천공된 패리티 비트의 수를 나타내고, M₁ 은 하나의 패리티 비트 그룹의 길이를 나타내고, 상기 천공된 패리티 비트의 위치 정보를 결정하는 것은, A개의 패리티 비트 그룹

내의 모든 패리티 비트가 천공된 것으로 결정하고,

패리티 비트 그룹 내의 패리티 비트들 중

개의 패리티 비트가 추가적으로 천공된 것으로 결정함을 포함하고, 상기 미리 결정된 천공된 패리티 비트 그룹의 순서에 근거하는 상기 천공된 패리티 비트 그룹의 순서는 부호어 길이가 16200이고, 상기 q가 36일 때, 27, 13, 29, 32, 5, 0, 11, 21, 33, 20, 25, 28, 18, 35, 8, 3, 9, 31, 22, 24, 7, 14, 17, 4, 2, 26, 16, 34, 19, 10, 12, 23, 1, 6, 30, 15이다.A channel decoding method according to an embodiment of the present invention is a channel decoding method in a system using a low density parity check code, the method comprising: demodulating a signal transmitted from a transmitter; Determining position information of the punctured parity bits; And decoding the data using the punctured parity bit position information, wherein the step of determining the position information of the punctured parity bit comprises: determining a number N _p of punctured parity bits; Determining a number of punctured parity bit groups based on the number of punctured parity bits; And obtaining a sequence of a predetermined punctured parity bit group, wherein the parity bit group is configured such that a plurality of parity bits in one parity bit group have a certain interval q , &Lt; / RTI >
&Lt; Equation &

,
Wherein P _j is the j-th bit represents the parity group, N ₁ is the length of the codeword, K ₁ is an information word length, M ₁ is a single parity bit groups in length, wherein the predetermined interval is q

, K ₁ / M ₁ is an integer, and the equation

, The number of the parity bit groups is determined by the following equation,
&Lt; Equation &

Where A represents the number of punctured parity bit groups, N _p represents the number of punctured parity bits, M ₁ represents the length of one parity bit group, and determining the position information of the punctured parity bit A group of parity bits

Determining that all of the parity bits in the received signal are punctured; And

Of the parity bits in the parity bit group

And determining that the number of parity bits is additionally punctured,
Wherein a predetermined sequence of said perforated parity bit groups based on the order of the punctured parity bit group is a codeword length is 16200, when the q 25, 6, 4, 18, 9, 13, 8, 15, 20, 5, 17, 2, 24, 10, 22, 12, 3, 16, 23, 1, 14, 0, 21, 19, 7,
A channel decoding method according to an embodiment of the present invention is a channel decoding method in a system using a low density parity check code, the method comprising: demodulating a signal transmitted from a transmitter; Determining position information of the punctured parity bits; And decoding the data using the punctured parity bit position information, wherein the step of determining the position information of the punctured parity bit comprises: determining a number N _p of punctured parity bits; Determining a number of punctured parity bit groups based on the number of punctured parity bits; And obtaining a sequence of a predetermined punctured parity bit group, wherein the parity bit group is configured such that a plurality of parity bits in one parity bit group have a certain interval q , &Lt; / RTI >
&Lt; Equation &

,
Wherein P _j is the j-th bit represents the parity group, N ₁ is the length of the codeword, K ₁ is an information word length, M ₁ is a single parity bit groups in length, wherein the predetermined interval is q

, K ₁ / M ₁ is an integer, and the equation

, The number of the parity bit groups is determined by the following equation,
&Lt; Equation &

Where A represents the number of punctured parity bit groups, N _p represents the number of punctured parity bits, M ₁ represents the length of one parity bit group, and determining the position information of the punctured parity bit A group of parity bits

Determining that all of the parity bits in the received signal are punctured; And

Of the parity bits in the parity bit group

Wherein the order of the punctured parity bit groups based on the order of the predetermined punctured parity bit groups is 16200 when the codeword length is 16, and when the q is 36 , 27, 13, 29, 32, 5, 0, 11, 21, 33, 20, 25, 28, 18, 35, 8, 3, 9, 31, 22, 24, 7, 14, 17, 4, 2 , 26, 16, 34, 19, 10, 12, 23, 1, 6, 30,
A channel decoding apparatus according to an embodiment of the present invention includes a demodulator for demodulating a signal transmitted from a transmitter, the apparatus comprising: a demodulator for demodulating a signal transmitted from a transmitter; A puncturing pattern estimator for determining position information of punctured parity bits; And a decoder for decoding the data using the position information of the punctured parity bit, wherein the position information of the punctured parity bit determines the number N _{P of} punctured parity bits, Determining a number of punctured parity bit groups based on the number of punctured parity bit groups and obtaining an order of a predetermined punctured parity bit group, wherein the parity bit group includes a plurality of parity bits in one parity bit group Wherein the parity bit group is configured to have an interval q , and the parity bit group is determined by the following equation,
&Lt; Equation &

,
Wherein P _j is the j-th bit represents the parity group, N ₁ is the length of the codeword, K ₁ is an information word length, M ₁ is a single parity bit groups in length, wherein the predetermined interval is q

, K ₁ / M ₁ is an integer, and the equation

, The number of the parity bit groups is determined by the following equation,
&Lt; Equation &

Wherein A represents the number of punctured parity bit groups, N _p represents the number of punctured parity bits, M ₁ represents the length of one parity bit group, and determining the position information of the punctured parity bits , A parity bit groups

Lt; RTI ID = 0.0 &gt; parity &lt; / RTI &gt;

Of the parity bits in the parity bit group

Wherein the order of the punctured parity bit groups based on the order of the predetermined punctured parity bit groups is 16200 when the codeword length is 16200 and when q is 25, 6, 4, 18, 9, 13, 8, 15, 20, 5, 17, 2, 24, 10, 22, 12, 3, 16, 23, 1, 14, 0, 21, 19, 7, .
A channel decoding apparatus according to an embodiment of the present invention includes a demodulator for demodulating a signal transmitted from a transmitter, the apparatus comprising: a demodulator for demodulating a signal transmitted from a transmitter; A puncturing pattern estimator for determining position information of punctured parity bits; And a decoder for decoding the data using the position information of the punctured parity bit, wherein the position information of the punctured parity bit determines the number N _{P of} punctured parity bits, Determining a number of punctured parity bit groups based on the number of punctured parity bit groups and obtaining an order of a predetermined punctured parity bit group, wherein the parity bit group includes a plurality of parity bits in one parity bit group Wherein the parity bit group is configured to have an interval q , and the parity bit group is determined by the following equation,
&Lt; Equation &

,
Wherein P _j is the j-th bit represents the parity group, N ₁ is the length of the codeword, K ₁ is an information word length, M ₁ is a single parity bit groups in length, wherein the predetermined interval is q

, K ₁ / M ₁ is an integer, and the equation

, The number of the parity bit groups is determined by the following equation,
&Lt; Equation &

Where A represents the number of punctured parity bit groups, N _p represents the number of punctured parity bits, M ₁ represents the length of one parity bit group, and determining the position information of the punctured parity bits , A parity bit groups

Lt; RTI ID = 0.0 &gt; parity &lt; / RTI &gt;

Of the parity bits in the parity bit group

Wherein the order of the punctured parity bit groups based on the order of the predetermined punctured parity bit groups is 16200 when the codeword length is 16200 and when q is 36, 27, 13, 29, 32, 5, 0, 11, 21, 33, 20, 25, 28, 18, 35, 8, 3, 9, 31, 22, 24, 7, 14, 17, 26, 16, 34, 19, 10, 12, 23, 1, 6, 30,

The present invention can generate a separate LDPC code having a different codeword length by using information of a given parity check matrix in a communication system using an LDPC code.

The present invention also optimizes the performance of a DVB-S2 LDPC code by applying puncturing.

1 is a diagram illustrating an example of a parity check matrix of an LDPC code having a length of 8,
2 shows a Tanner graph of an example of a parity check matrix of an LDPC code having a length of 8,
FIG. 3 is a schematic diagram of a DVB-S2 LDPC code,
4 shows an example of a parity check matrix of a DVB-S2 type LDPC code,
5 is a block diagram of a transceiver of a communication system using an LDPC code,
FIG. 6 illustrates a first example of irregular puncturing applied to the LDPC code of FIG. 4,
FIG. 7 is a diagram illustrating a second example in which regular puncturing is applied to the LDPC code of FIG. 4,
FIG. 8 is a diagram illustrating a third example of applying regular puncturing to the LDPC code of FIG. 4,
9 is a flowchart for generating an LDPC code having a different codeword length from a parity check matrix of a stored LDPC code according to an embodiment of the present invention.
FIG. 10 is a flowchart illustrating an LDPC decoding method in a receiving apparatus when a puncturing pattern according to an embodiment of the present invention is applied. FIG.
11 is a block diagram of a transmission apparatus block using an LDPC code to which the puncturing and shortening proposed in the present invention is applied,
FIG. 12 is a block diagram of a receiving apparatus block using an LDPC code applying puncturing and shortening proposed in the present invention. FIG.

Preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. It should be noted that only the parts necessary for understanding the operation according to the present invention will be described in the following description, and the description of other parts will be omitted so as not to overstep the gist of the present invention.

An embodiment of the present invention proposes a method and apparatus for supporting an LDPC code having various codeword lengths using a parity check matrix of a specific type of structured LDPC code. Also, embodiments of the present invention propose a device supporting a variety of codeword lengths in a communication system using a specific type of LDPC code and a control method thereof. In particular, an embodiment of the present invention proposes a method and apparatus for generating a smaller LDPC code using a parity check matrix of a given LDPC code.

5 is a block diagram of a transceiver block in a communication system using an LDPC code.

는 수신기(530)로 전송되기 전에 송신기(510)의 LDPC 부호화기(encoder)(511)로 입력된다. 그러면 상기 LDPC 부호화기(encoder)(511)는 입력된 메시지

를 부호화하여 출력한 부호화 신호를 변조기(Modulator)(513)로 전송한다. 상기 변조기(513)는 상기 부호화된 신호를 변조한 후 무선 채널(520)을 통해 수신기(530)로 전송한다. 그러면, 수신기(530)의 복조기(Demodulator)(531)는 수신된 신호 r을 복조한 후, 복조된 신호 x를 LDPC 복호기(Decoder)(533)로 출력한다. 상기 LDPC 복호기(533)는 무선 채널(520)을 통해 받은 데이터를 통해 메시지의 추정치(estimatation value)

를 추정해낸다. Referring to FIG. 5,

Is input to the LDPC encoder 511 of the transmitter 510 before being transmitted to the receiver 530. Then, the LDPC encoder (511)

And outputs the coded signal to the modulator 513. [ The modulator 513 modulates the encoded signal and transmits the modulated signal to a receiver 530 through a wireless channel 520. Then, the demodulator 531 of the receiver 530 demodulates the received signal r, and outputs the demodulated signal x to the LDPC decoder 533. [ The LDPC decoder 533 receives an estimate value of a message through the data received through the wireless channel 520,

.

The LDPC encoder 511 generates a parity check matrix according to a codeword length required by the communication system in a predetermined manner. In particular, in the embodiment of the present invention, the LDPC encoder 511 can support various codeword lengths without the need for additional additional storage information using LDPC codes.

In the embodiment of the present invention, a method of supporting various codeword lengths is a method of puncturing or shortening. The puncturing method refers to a method of performing LDPC encoding from a given parity check matrix to generate an LDPC codeword and then not actually transmitting a specific portion of the LDPC codeword. Therefore, at the receiving end, the portion not transmitted is judged as erasure.

The parity check matrix of the DVB-S2 LDPC code shown in FIG. 3 and FIG. 4 will be described in detail to facilitate understanding of the puncturing method.

이고, 앞부분은 길이가

인 정보어 비트들

이 대응되고, 뒷부분은 길이가

인 패리티 비트들

이 대응된다. The parity check matrix of the DVB-S2 LDPC code shown in FIG.

And the front part has a length

Information bits

And the rear portion has a length of

In parity bits

Respectively.

인 이미 생성된 LDPC 부호어 중에서

개의 약속된 위치에 있는 비트들을 단지 전송하지 않음으로써 길이가

인 LDPC 부호어를 전송하는 것과 동일한 효과를 얻는다. 패리티 검사 행렬에서 천공된 비트들에 해당하는 열들은 복호 과정에서 모두 그대로 사용되므로 단축법과는 차이가 있다. The puncturing method is generally applicable to both information bits and parity bits. Also, the puncturing method and the shortening method have a common feature that the codeword length of the code is made small, but unlike the shortening method, the puncturing method is not a concept of limiting the value of a specific bit. The puncturing method is a method of processing a specific part of a specific information word or a generated parity bit by merely transmitting it as an erasure at the receiving end. In other words,

Among the already generated LDPC codewords

By not only transmitting the bits in the promised position of the &lt; RTI ID = 0.0 &gt;

Lt; RTI ID = 0.0 &gt; LDPC codeword. &Lt; / RTI &gt; Since the columns corresponding to the punctured bits in the parity check matrix are used as they are in the decoding process, they are different from the shortening method.

Since the position information of the punctured bits can be shared or estimated by the transmitter and the receiver equally when the system is set up, the receiving end processes the punctured bits only by performing a loss process.

이고, 정보어의 길이는 변함없이

이므로 부호율이

이 되어 처음 주어진 부호율

보다 항상 크게 된다. In the puncturing method, the length of a codeword actually transmitted from the transmitting end is

, And the length of the information word is unchanged

Therefore,

Lt; RTI ID = 0.0 &gt;

Is always greater.

Now, we describe the perforation method and shortening method suitable for DVB-S2 LDPC code. The DVB-S2 LDPC code is a kind of LDPC code having a specific structure as mentioned in the background art. Therefore, it is possible to apply the shortening and puncturing more efficiently unlike the case of the general LDPC code.

,

인 DVB-S2 LDPC 부호로부터 단축법과 천공법을 통하여 우리가 최종적으로 얻고자 하는 LDPC 부호의 부호어 길이와 정보어 길이를 각각

,

이라 하자. 만일 우리가

,

라고 정의하면, DVB-S2 LDPC 부호의 패리티 검사행렬에서

비트만큼 단축을 취하고,

비트만큼 천공을 취하면 부호어 길이와 정보어 길이를 각각

,

인 상기 LDPC 부호를 생성할 수 있다. 이렇게 생성된 상기 LDPC 부호는

또는

일 때, 부호율이

가 되어 일반적으로 DVB-S2 LDPC 부호의 부호율

와는 다르게 되므로 대수적 특성이 변하게 된다. 여기서

인 경우에는 단축이나 천공을 모두 적용하지 않거나 또는 단축만 취한 경우에 해당된다. For convenience of explanation, the length of the codeword and the length of the information word are

,

The length of the codeword and the length of the information word of the LDPC code we ultimately obtain from the DVB-S2 LDPC code

,

. If we

,

, The parity check matrix of the DVB-S2 LDPC code

Taking the bit as short as possible,

If the puncturing is performed by bits, the length of the codeword and the length of the information word are respectively

,

The LDPC code can be generated. The generated LDPC code is

or

, The code rate is

The coding rate of the DVB-S2 LDPC code

And the algebraic characteristic is changed. here

, It is applied when neither shortening nor perforation is applied or only shortening is taken.

이며, 3개의 열 그룹의 0 번째 열에 대한 무게 1 위치 시퀀스가 아래와 같음에 유의한다.The characteristics of applying parity puncturing to the DVB-S2 LDPC code will be described in detail with reference to FIG. 4,

And the weight 1 position sequence for the 0th column of the three column groups is as follows.

0 1 2

0 11 13

0 10 14

번째 열의

번째 무게 1 위치 시퀀스는

번째 열 그룹에서 1을 가지는 행의 위치 정보를 순차적으로 나타낸 것이다. remind

Column

The second weight 1 position sequence is

And the position information of the row having 1 in the column group is sequentially shown.

FIG. 6 is a diagram illustrating an example in which irregular puncturing is applied to the LDPC code of FIG. Since the parity bits punctured in FIG. 6 are processed in the decoder, the performance is not improved in the LDPC decoding process as compared with other bits that are not lost, thereby reducing reliability. As a result, other bits directly connected to the punctured parity bit having a low reliability are also adversely affected by the performance improvement effect in the decoding process. This effect becomes larger as the number of edges directly connected to the punctured bits on the Tanner graph increases.

For example, the bits of the 0th information word corresponding to the 0th column in FIG. 6 are directly connected to the punctured parity bit 2 times, and the 3rd information word corresponding to the 3rd column is directly connected to the punctured parity bit, And the eighth information word corresponding to the eighth column is connected to the punctured parity bit three times. In this case, the order of performance improvement in the decoding process is 3, 0, 8 order. That is, the performance improvement effect is lower as the number of punctured bits increases when the degree of the information node is the same.

Referring to FIG. 6, it can be seen that the number of punctured parities directly connected to each information word is irregular due to an irregular puncturing pattern. Therefore, the reliability of each information bit is also likely to be irregular. In other words, some information bits are better decoded than necessary, but some information bits may suffer severe performance degradation. This irregular puncturing pattern can cause irregularity of the serious reliability of the information bits in the decoding process.

FIG. 7 is a diagram illustrating a second example in which regular puncturing is applied to the LDPC code of FIG. That is, FIG. 7 is an example of applying a specific type of relatively regular puncturing pattern.

Even if a relatively regular puncturing pattern is applied, the connection state with the information bit may become non-uniform according to the puncturing pattern. In the case of FIG. 7, the irregular puncturing pattern of FIG. 6 can be further nonuniform.

In the case of an LDPC code having a parity check matrix having a specific structure like the DVB-S2 LDPC code, the connection state between the parity bit punctured according to the puncturing pattern and the information word can be greatly changed.

The present invention proposes a puncturing pattern that provides stable decoding performance by minimizing the non-uniformity of the reliability of information bits during decoding using the structural characteristics of the DVB-S2 LDPC code.

In the example of FIG. 8, since one of the constituent variables in the parity check matrix of FIG. 4 is q = 3, the puncturing pattern in which the interval of the punctured parity bits is kept constant at 3 is applied. As shown in FIG. 8, each information bit is connected to two punctured bits in the same manner.

값에 따라 설정하면 천공된 비트와 정보어 비트 사이의 비균일성이 크게 감소 하는 이유는 DVB-S2 LDPC 부호의 구조에서부터 찾을 수 있다. 이를 설명하기 위하여 상기 도 3을 살펴본다.The spacing of the punctured parity bits

The reason for the non-uniformity between the punctured bits and the information bits is greatly reduced when the value is set according to the value can be found from the structure of the DVB-S2 LDPC code. 3 is a diagram for explaining this.

에 대해

의 배수만큼 차이가 난다. 여기서

은 LDPC 부호어 길이고,

은 정보어의 길이를 의미한다. 더 구체적으로 말하면, 특정 열그룹 내에서 연속적인 두 개의 열에서 1이 위치한 행의 인덱스들은 정확하게 모듈로(modulo)

에 대해

만큼 차이가 난다. Referring to <Rule 1> and <Rule 2> and FIG. 3, the position of '1' in the first column in each column group determines the position of 1 in the remaining columns. In this case, the index of the row in which the 1 is located in the remaining columns is correctly modulo with the index of the row in which 1 is located in the first column,

About

. here

Is an LDPC codeword length,

Is the length of the information word. More specifically, the indexes of the rows where 1 in two successive columns in a particular column group are modulo-

About

.

번째 패리티 비트는

번째 행에 위치한 1과 대응된다. Another feature of the DVB-S2 LDPC code is a partial matrix corresponding to parity in the parity check matrix. Referring to FIG. 3, the parity part has a lower triangular matrix structure with 1s in the diagonal part

Th parity bit

1 &lt; th &gt; row.

간격만큼 패리티 천공이 반복되면, 특정 열그룹 내에서 천공된 패리티 비트와 연결되는 정보어 비트의 선분 수는 최대한 균일하게 된다. 예를 들어

에 대해서

번째 패리티 비트가 천공되고,

에 대해서

번째 패리티 비트가 반복적으로 천공되었다고 가정하자. 그럼 정보어 비트가

번째 패리티 비트와 연결되어 있다는 것은 해당 정보어 비트에 대응되는 열의

번째 행에 1이 있음을 의미한다. 따라서 <규칙 1>과 <규칙 2>에 따라 상기 정보어 비트와 같은 열그룹에 있는 열 중에서 상기 정보어 비트로부터

만큼 떨어져 있는 정보어 비트에 대응되는 열에는

번째 행에 1이 있음을 알 수 있다. 따라서, 천공된

번째 비트와 연결된다. From the structural characteristics of this DVB-S2 LDPC code, it can be seen that when a certain parity is punctured,

If parity puncturing is repeated by an interval, the number of line segments of information bits connected to parity bits punctured in a specific column group becomes as uniform as possible. E.g

about

Th parity bit is punctured,

about

Th parity bit is repeatedly punctured. Then the information bit is

Th parity bit indicates that the column corresponding to the information word bit

Meaning that there is a 1 in the second row. Therefore, according to < Rule 1 > and < Rule 2 &gt;, from among the columns in the same column group as the information bits,

The column corresponding to the information word bits spaced apart by

1 &lt; / RTI &gt; Therefore,

Th bit.

은 LDPC 부호어 길이를 의미하며, 각 열그룹은

개의 열들로 이루어져 있으며

개의 패리티 비트를 천공하는 경우라고 가정하자. 또한 하기의 천공 과정은 도 9의 흐름도에 나타내었다.In the DVB-S2 LDPC code, since the order of variable nodes corresponding to all information words in one column group is the same and one or less of 1s are distributed in one row, when the puncturing pattern is applied, Corresponding information bits are associated with the same number of punctured bits. Therefore, since the connection between the punctured bits and the information bits is regular, it is possible to expect stable decoding in the decoding process. The general procedure for applying the puncturing method described above can be summarized as follows. For convenience of explanation

Denotes an LDPC codeword length, and each column group

Columns.

Suppose that the parity bits are punctured. The following drilling process is shown in the flow chart of FIG.

9 is a flowchart for generating an LDPC code having a different codeword length from a parity check matrix of a stored LDPC code according to an embodiment of the present invention.

Step 1 : The transmitting apparatus generates an existing DVB-S2 LDPC codeword that is shortened or not shortened in step 901.

를 결정하고

를 구한다. 여기서

는

보다 같거나 작은 최대 정수를 의미한다. Step 2 : The number (length) of puncturing in steps 903 and 905 in the transmitting apparatus,

And

. here

The

Means a maximum integer that is equal to or less than.

,

에 대해서 천공될 패리티 비트들

,

, ...,

을 결정한다.

에 대해서

의 값들은 성능을 고려하여 사전에 미리 결정되어 있었다고 가정한다. (여기서

인 관계가 있음에 유의한다.) Step 3 : In the transmitting apparatus, in step 907,

,

The parity bits to be punctured

,

, ...,

.

about

Are assumed to have been determined in advance in consideration of the performance. (here

Please note that there is a relationship.

,

에 대해서 패리티 비트

에 대해서 모두 천공을 적용한다. 여기서 상수 B는 사전이 미리 설정된 0이 아닌 정수이다. Step 4 : In the transmitting apparatus, in step 907,

,

The parity bit

Lt; / RTI &gt; Here, the constant B is a non-zero integer preset in the dictionary.

에 대해서 패리티 비트

를 추가적으로 천공한다.(907 단계)
Drilling Step 5 :

The parity bit

(Step 907)

In step 909, the transmitting apparatus transmits a bit excluding the punctured bits.

개의 패리티가 천공되고, 천공 단계 5에 의해서

개의 패리티가 천공되어 총

개의 패리티가 천공되었음을 알 수 있다. 위와 같이 천공되어 전송된 DVB-S2 LDPC 부호어는 수신 장치에서 수신된 신호로부터 도 10을 참고하여 아래에서 상세히 설명될 복호 과정을 거쳐 원래의 신호로 복원한다.In the drilling step 3 and the drilling step 4,

&Lt; / RTI &gt; parity is punctured,

Parity is punctured and total

It can be seen that the number of parities is punctured. The thus punctured and transmitted DVB-S2 LDPC codeword is decoded from the signal received at the receiving apparatus through a decoding process to be described later in detail with reference to FIG.

,

,

,

의 특성을 가지는 부호이다.
In order to understand the process from the drilling step 3 to the drilling step 5 in the drilling process, a concrete example will be explained as follows. The DVB-S2 LDPC code used here

,

,

,

. &Lt; / RTI &gt;

Example of puncturing step 1 : The transmitting apparatus generates a conventional DVB-S2 LDPC codeword that is not shortened or shortened.

를 결정하고

를 구한다. 여기서

는

보다 같거나 작은 최대 정수를 의미한다. Example of perforation phase 2 : The length of the perforation in the transmission device

And

. here

The

Means a maximum integer that is equal to or less than.

,

에 대해서 천공될 패리티 비트들

,

, ...,

을 결정한다.

에 대해서

의 값들은 천공된 패리티 비트와 정보어 비트의 연결 관계 및 밀도 진화(density evolution) 분석 방법을 이용하여 점근적인(asymptotic) 성능이 우수한 경우를 고려하여 다음과 같이 선택하였다. Example of drilling step 3 : In the transmitting device

,

The parity bits to be punctured

,

, ...,

.

about

Are selected as follows considering the connection relation between the punctured parity bits and information bits and the case where the asymptotic performance is excellent using the density evolution analysis method.

27, 13, 29, 32, 5, 0, 11, 21, 33, 20, 25, 28, 18, 35, 8, 3, 9, 31, 22, 24, 7, 14, 17, 26, 16, 34, 19, 10, 12, 23, 1, 6, 30, 15

에 대해서

번째 무게 1 위치 시퀀스는

값에 대응된다.
In the sequence

about

The second weight 1 position sequence is

Value.

,

일 경우 패리티 비트

에 대해서 모두 천공을 적용한다. (여기서 B의 값은 1로 설정했다.) Example of drilling step 4 :

,

Parity bit

Lt; / RTI &gt; (Where the value of B is set to 1).

에 대해서 패리티 비트

를 추가적으로 천공한다. Example of puncturing step 5 : In the transmitting apparatus

The parity bit

Respectively.

와

의 값들을 정의해 주는 수열 정보와

값을 알면 천공 패턴이 정확하게 정의됨을 알 수 있다. As an example of the puncturing step 5 from the example of the puncturing step 1, the number of bits to be punctured

Wow

The sequence information defining the values of

Knowing the value shows that the puncturing pattern is defined correctly.

,

,

, ...,

)와 같이 표기할 때, 상기 천공 단계의 예를 다음 <표 1>과 같이 더욱 간단하게 나타낼 수 있다. All parity bits of the DVB-S2 LDPC code applied in the example of the puncturing step 1 to the example of the puncturing step 5 are denoted by (

,

,

, ...,

), The example of the puncturing step can be represented more simply as shown in Table 1 below.

,

,

,

의 특성을 가지는 DVB-S2 LDPC 부호에 대해서 <표 2>와 같은 천공 패턴을 구할 수 있다. As another embodiment of the perforating step

,

,

,

The puncturing pattern shown in Table 2 can be obtained for the DVB-S2 LDPC code having the characteristics of FIG.

As described above, in the embodiment of the present invention, unlike the arbitrary puncturing method or simple uniform puncturing method used for perforating the DVB-S2 LDPC code, the DVB-S2 LDPC code is structured by using the structural characteristics of the DVB- An efficient puncturing method capable of stabilizing the performance of the LDPC code can be applied.

A method of determining the order of punctured bits in step 3 of the puncturing of the DVB-S2 LDPC code will be described. The order of punctured bits is determined through a density evolution analysis method and a cycle analysis on a Tanner graph.

The puncturing method not only changes the LDPC codeword length but also has the effect of shortening the codeword length without changing the length of the information word, thereby increasing the code rate. Therefore, in order to obtain the required code rate and codeword length in the system, it is easily solved by applying the shortening method as well as the puncturing method.

,

인 LDPC 부호로부터 단축법과 천공법을 통하여 우리가 최종적으로 얻고자 하는 LDPC 부호의 부호어 길이와 정보어 길이를 각각

,

라 할 때,

,

라고 정의하면, LDPC 부호의 패리티 검사행렬에서

비트만큼 단축을 취하고,

비트만큼 천공을 취하면 부호어 길이와 정보어 길이를 각각

,

인 상기 LDPC 부호를 생성할 수 있다. 이렇게 생성된 상기 LDPC 부호는

또는

일 때, 부호율이

가 되므로

와

을 고려하여 천공 및 단축 길이를 설정하면 된다. As described above, the given codeword length and information word length are

,

The length of the codeword and the length of the information word of the LDPC code that we ultimately obtain through the shortening and puncturing from the LDPC code

,

In other words,

,

, The parity check matrix of the LDPC code

Taking the bit as short as possible,

If the puncturing is performed by bits, the length of the codeword and the length of the information word are respectively

,

The LDPC code can be generated. The generated LDPC code is

or

, The code rate is

Will be

Wow

It is sufficient to set the perforation and shortening length.

10 is a flowchart illustrating a receiving method in a receiving apparatus according to an embodiment of the present invention.

Referring to FIG. 10, the receiving apparatus determines or estimates puncturing / shortening patterns from the signal received in step 1001. In step 1003, the receiving apparatus determines whether a punctured or shortened bit exists.

If the punctured or shortened bit is not present, the receiving apparatus performs decoding in step 1009. [ However, if there is a shortened or punctured bit, the receiving device delivers the puncturing / shortening pattern to the LDPC decoder 1260 in step 1005.

The LDPC decoder 1260 sets the punctured bits to erasure in step 1007 and sets the probability that the value of the shortened bit is 0 to 1 and then performs decoding in step 1009. [

FIG. 11 shows an example of a transmitting apparatus for realizing the puncturing process of the DVB-S2 LDPC code in more detail. 11 is a block diagram of a transmission apparatus using a punctured / shortened LDPC code according to an embodiment of the present invention.

The transmission apparatus includes a controller 1110, a short pattern application unit 1120, an LDPC code parity check matrix extractor 1140, and an LDPC encoder 1160.

The LDPC code parity check matrix extraction unit 1140 extracts the shortened LDPC code parity check matrix. The LDPC code parity check matrix may be extracted using a memory, received in a transmitting apparatus, or generated in a transmitting apparatus.

The control unit 1110 controls the shortening pattern applying unit 1120 to determine a shortening pattern according to the length of the information word. The shortening pattern applying unit 1120 applies a bit having a value of 0 , Or removes a column corresponding to a shortened bit in a parity check matrix of a given LDPC code. As a method for determining the shortening pattern, a shortening pattern may be generated by using a shortening pattern stored using a memory, a shortening pattern may be generated using a sequence generator (not shown), or a density evolution may be performed on a parity check matrix and a given information word length Analysis algorithm or the like.

The LDPC encoder 1160 performs encoding based on the shortened LDPC code by the controller 1110 and the shortening pattern application unit 1120.

The controller 1110 controls the puncturing pattern application unit 1180. The puncturing pattern application unit 1180 determines the number of parity bits to be punctured, divides the parity bits at regular intervals, determines the number of puncturing bits to be punctured within the predetermined interval, Determines a position of a punctured parity bit corresponding to the determined number of punctured bits, and punctures the punctured parity bit corresponding to the determined position repeatedly at the predetermined interval.

12 is a block diagram of a receiving apparatus according to an embodiment of the present invention.

12 shows an example of a receiving apparatus for receiving a signal transmitted from a communication system using the punctured or shortened DVB-S2 LDPC code and for recovering data desired by a user from the received signal.

12, the receiving apparatus includes a control unit 1210, a shortening, puncturing pattern determination or estimation unit 1220, a demodulator 1230, and an LDPC decoder 1240.

The demodulator 1230 receives and demodulates the shortened LDPC code, and transmits the demodulated signal to the shortening pattern determination or estimation unit 1220 and the LDPC decoder 1240.

Under the control of the controller 1210, the shortening and puncturing pattern determination or estimation unit 1220 estimates or determines information on the puncturing or shortening pattern of the LDPC code from the demodulated signal, Information to the LDPC decoder 1240. The method of determining or estimating puncturing and shortening patterns in the shortening, puncturing pattern determination or estimation unit 1220 may include puncturing and shortening patterns stored using a memory, puncturing and shortening using a pre- Pattern, or a density evolution analysis algorithm for the parity check matrix and a given information word length. Also, the punctured bits in the LDPC decoder 1240 are decoded to perform decoding.

If the shortening and puncturing pattern determination or estimation unit 1220 applies both shortening and puncturing to the transmitting apparatus as in the embodiment of the present invention, the receiving apparatus may first perform pattern determination or estimation on the shortening, The pattern determination or estimation for the shortening may be performed first, or both the pattern determination or estimation for the shortening and the pattern determination or estimation for the puncturing may occur.

The LDPC decoder 1240 performs decoding on the assumption that the probability that the punctured bit is 0 and the probability of 1 are both equal to 1/2. Also, since the probability that the value of the shortened bit is 0 is 1 (i.e., 100%), the shortened bits in the operation of the decoder are not allowed to participate in the operation of the decoder, To participate in.

When the length of the DVB-S2 LDPC code shortened by the shortening pattern determination or estimation unit 1220 is known, the LDPC decoder 1240 restores desired data from the received signal.

11, it can be seen that the shortening is performed in the pre-input stage of the LDPC encoder 1160, and the puncturing is performed in the output stage of the LDPC encoder 1160. However, in the receiver of FIG. 12, the LDPC decoder 1240 can decode information about puncturing and shortening in the decoder at the same time.

Claims (16)

delete A channel decoding method in a system using a low density parity check code,
Demodulating a signal transmitted from a transmitter;
Determining position information of the punctured parity bits; And
And decoding the data using the punctured parity bit position information,
Wherein the step of determining the position information of the punctured parity bit comprises:
Determining a number N _p of punctured parity bits;
Determining a number of punctured parity bit groups based on the number of punctured parity bits; And
Obtaining a sequence of predetermined punctured parity bit groups,
Wherein the parity bit group is configured such that a plurality of parity bits in one parity bit group have a constant interval q ,
The parity bit group is determined by the following equation,
&Lt; Equation &

,
Wherein P _j is the j-th bit represents the parity group, N ₁ is the length of the codeword, K ₁ is an information word length, M ₁ is a single parity bit groups in length, wherein the predetermined interval is q

, K ₁ / M ₁ is an integer, and the equation

Lt; / RTI &gt;
The number of the parity bit groups is determined by the following equation,
&Lt; Equation &

Where A represents the number of punctured parity bit groups, N _p represents the number of punctured parity bits, M ₁ represents the length of one parity bit group,
Wherein the step of determining the position information of the punctured parity bit comprises:
A parity bit group

Determining that all of the parity bits in the received signal are punctured; And

Of the parity bits in the parity bit group

And determining that the number of parity bits is additionally punctured,
Wherein a predetermined sequence of said perforated parity bit groups based on the order of the punctured parity bit group is a codeword length is 16200, when the q 25, 6, 4, 18, 9, 13, 8, 15, Wherein in the system using a low-density parity-check code, the number of channels is 20, 5, 17, 2, 24, 10, 22, 12, 3, 16, 23, 1, 14, 0, 21, 19, 7, Decoding method. A channel decoding method in a system using a low density parity check code,
Demodulating a signal transmitted from a transmitter;
Determining position information of the punctured parity bits; And
And decoding the data using the punctured parity bit position information,
Wherein the step of determining the position information of the punctured parity bit comprises:
Determining a number N _p of punctured parity bits;
Determining a number of punctured parity bit groups based on the number of punctured parity bits; And
Obtaining a sequence of predetermined punctured parity bit groups,
Wherein the parity bit group is configured such that a plurality of parity bits in one parity bit group have a constant interval q ,
The parity bit group is determined by the following equation,
&Lt; Equation &

,
Wherein P _j is the j-th bit represents the parity group, N ₁ is the length of the codeword, K ₁ is an information word length, M ₁ is a single parity bit groups in length, wherein the predetermined interval is q

, K ₁ / M ₁ is an integer, and the equation

Lt; / RTI &gt;
The number of the parity bit groups is determined by the following equation,
&Lt; Equation &

Where A represents the number of punctured parity bit groups, N _p represents the number of punctured parity bits, M ₁ represents the length of one parity bit group,
Wherein the step of determining the position information of the punctured parity bit comprises:
A parity bit group

Determining that all of the parity bits in the received signal are punctured; And

Of the parity bits in the parity bit group

And determining that the number of parity bits is additionally punctured,
Wherein a predetermined sequence of said perforated parity bit groups based on the order of the punctured parity bit group is a codeword length is 16200, when the q 36 days, 27, 13, 29, 32, 5, 0, 11, 21, 33, 20, 25, 28, 18, 35, 8, 3, 9, 31, 22, 24, 7, 14, 17, 4, 2, 26, 16, 34, 19, 1, 6, 30, and 15, respectively. delete delete delete delete delete delete In a channel decoding apparatus in a system using a low-density parity-check code,
A demodulator for demodulating the signal transmitted from the transmitter;
A puncturing pattern estimator for determining position information of punctured parity bits; And
And a decoder for decoding data using position information of the punctured parity bits,
Wherein the position information of the punctured parity bits includes:
Determining a number of punctured parity bits ( N _p ), determining a number of punctured parity bit groups based on the number of punctured parity bits, and obtaining a sequence of a predetermined punctured parity bit group And,
Wherein the parity bit group is configured such that a plurality of parity bits in one parity bit group have a constant interval q ,
The parity bit group is determined by the following equation,
&Lt; Equation &

,
Wherein P _j is the j-th bit represents the parity group, N ₁ is the length of the codeword, K ₁ is an information word length, M ₁ is a single parity bit groups in length, wherein the predetermined interval is q

, K ₁ / M ₁ is an integer, and the equation

Lt; / RTI &gt;
The number of the parity bit groups is determined by the following equation,
&Lt; Equation &

Where A represents the number of punctured parity bit groups, N _p represents the number of punctured parity bits, M ₁ represents the length of one parity bit group,
Determining the position information of the punctured parity bits,
A parity bit group

Lt; RTI ID = 0.0 &gt; parity &lt; / RTI &gt;

Of the parity bits in the parity bit group

&Lt; / RTI &gt; of parity bits are additionally punctured,
Wherein a predetermined sequence of said perforated parity bit groups based on the order of the punctured parity bit group is a codeword length is 16200, when the q 25, 6, 4, 18, 9, 13, 8, 15, Wherein in the system using a low-density parity-check code, the number of channels is 20, 5, 17, 2, 24, 10, 22, 12, 3, 16, 23, 1, 14, 0, 21, 19, 7, Decoding device. In a channel decoding apparatus in a system using a low-density parity-check code,
A demodulator for demodulating the signal transmitted from the transmitter;
A puncturing pattern estimator for determining position information of punctured parity bits; And
And a decoder for decoding data using position information of the punctured parity bits,
Wherein the position information of the punctured parity bits includes:
Determining a number of punctured parity bits ( N _p ), determining a number of punctured parity bit groups based on the number of punctured parity bits, and obtaining a sequence of a predetermined punctured parity bit group And,
Wherein the parity bit group is configured such that a plurality of parity bits in one parity bit group have a constant interval q ,
The parity bit group is determined by the following equation,
&Lt; Equation &

,
Wherein P _j is the j-th bit represents the parity group, N ₁ is the length of the codeword, K ₁ is an information word length, M ₁ is a single parity bit groups in length, wherein the predetermined interval is q

, K ₁ / M ₁ is an integer, and the equation

Lt; / RTI &gt;
The number of the parity bit groups is determined by the following equation,
&Lt; Equation &

Where A represents the number of punctured parity bit groups, N _p represents the number of punctured parity bits, M ₁ represents the length of one parity bit group,
Determining the position information of the punctured parity bits,
A parity bit group

Lt; RTI ID = 0.0 &gt; parity &lt; / RTI &gt;

Of the parity bits in the parity bit group

&Lt; / RTI &gt; of parity bits are additionally punctured,
Wherein a predetermined sequence of said perforated parity bit groups based on the order of the punctured parity bit group is a codeword length is 16200, when the q 36 days, 27, 13, 29, 32, 5, 0, 11, 21, 33, 20, 25, 28, 18, 35, 8, 3, 9, 31, 22, 24, 7, 14, 17, 4, 2, 26, 16, 34, 19, 1, 6, 30, and 15, respectively, in the system using the low-density parity-check code. delete delete delete delete delete

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