KR101503653B1 - Apparatus and method for channel encoding and decoding in communication system using low-density parity-check codes - Google Patents

Abstract

A METHOD FOR A CHANNEL ENCODING IN A SYSTEM USING A LOW-DENSITY PARITY-CHECK, LDPC, CODE. THE METHOD INCLUDES DIVIDING INFORMATION BITS INTO A PLURALITY OF BIT GROUPS, DETERMINING (603) A NUMBER OF INFORMATION BITS TO BE SHORTENED, DETERMINING (605, 607) A NUMBER OF BIT GROUPS TO BE SHORTENED BASED ON THE DETERMINED NUMBER OF INFORMATION BITS TO BE SHORTENED, SHORTENING (609) INFORMATION BITS IN THE DETERMINED NUMBER OF BIT GROUPS ACCORDING TO A PREDETERMINED ORDER, AND LDPC ENCODING (609) SHORTENED INFORMATION BIT.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for channel encoding / decoding in a communication system using a low-density parity check (CPC) code,

The present invention relates to a communication system using a low-density parity-check (hereinafter referred to as LDPC) code, and more particularly, to a system and method for generating an LDPC code having a variable codeword length and a code rate from a given LDPC code And more particularly, to a channel encoding / decoding apparatus and method.

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 code first introduced by Gallager in the 1960s has long been forgotten due to its implementation complexity far surpassing that of the time. However, since the turbo codes found by Berrou, Glavieux, and Thitimajshima in 1993 show performance close to the channel capacity of Shannon, many interpretations on the performance and characteristics of turbo codes have been made, and it has been studied a lot about iterative decoding and graph based channel coding. As a result, the LDPC code is re-studied in the late 1990's and applied iterative decoding based on a sum-product algorithm on a Tanner graph (a special case of a factor graph) corresponding to the LDPC code, Has a performance close to Shannon's channel capacity.

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.

A graphical representation method of the LDPC code will be described with reference to FIGS. 1 and 2. FIG.

1 is 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 of nodes of the LDPC code, the ratio of the number of variable nodes having a degree i to the total number of variable nodes is fi, the number of check nodes having a degree j and the total number of check nodes Let g _{j be the} ratio of 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, for a 4 f _i = 0, g ₅ = 3/4, g ₆ = 1/4, and g _j = 0 for j ≠ 5,6. 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, so that when N is large, the LDPC code has a very low density. The term low-density in the name of an LDPC code comes from this reason.

Next, characteristics of a parity check matrix of a structured LDPC code to be applied in the present invention will be described with reference to FIG. FIG. 3 schematically shows an LDPC code adopted as a standard technique in DVB-S2, which is one of the European digital broadcasting standards.

은 LDPC 부호어의 길이이고,

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 the length of the LDPC codeword,

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. 상기 규칙에 따라 패리티 검사 행렬에 대한 정보를 저장하고 있는 DVB-S2 LDPC 부호의 구조를 쉽게 이해하기 위하여 다음과 같은 구체적인 예를 살펴보자. According to the above rule

th

The order of the columns belonging to the column group is

As shown in Fig. In order to easily understand the structure of the DVB-S2 LDPC code storing information on the parity check matrix according to the above rule, consider a specific example as follows.

As a specific example, the _{N 1 = 30, K 1 =} 15, M 1 = 5, q = 3 , and below these sequences to 1 (for convenience, the 0-th column of the three columns group "weight -1 position sequence Quot;) can be represented by three sequences as follows.

With respect to the position sequence of the row having the zeroth one of the column groups, only the corresponding position sequences are written for each column group as follows.

0 1 2

0 11 13

0 10 14

That is, the i th weight sequence position -1 in the i-th line shows the location of the line for the i th column group sequentially.

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.

인 정보어 비트들을

로 나타내고, 길이가

인 패리티 비트들을

로 나타낸다. A coding process using a DVB-S2 LDPC code characterized by N ₁ = 16200, K ₁ = 10800, M ₁ = 360, and q = 15 has been described as a concrete example. Also, for convenience of explanation,

Information bits

And the length is

Parity bits

Respectively.

. Step 1 : The encoder initializes the parity bits.

.

Step 2 : From the 0th weight-1 position sequence of the stored parity check matrix, the encoder calls the information of the row in which the 1 in the first column group of the information word is located.

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 information bits

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 수식임에 유의한다. In Equation (4)

Respectively,

Lt; / RTI &gt; Note that Equation (4) is an equation 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

의 정보를 독출하고, 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,

about

And reads out 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 encoding is performed through the steps 1 to 6.

In order to apply an LDPC code to an actual communication system, the LDPC code must be designed to meet the data transmission amount 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.

The present invention provides a method and apparatus for channel coding / decoding in a communication system using an LDPC code for generating an LDPC code having a different codeword length from a given LDPC code using shortening or puncturing.

Also, the present invention provides a method and apparatus for channel coding / decoding in a communication system using an LDPC code ensuring optimal performance considering a DVB-S2 structure.

임을 포함하고, 상기 복수의 비트 그룹 중 어느 하나는 BCH(bose-chaudhuri-hocquenghem) 패리티 비트를 포함하고, 상기 BCH 패리티 비트는 단축을 취하지 않는다.
본 발명의 실시 예에 따른 채널 부호화 장치는, 저저밀도 패리티 검사 부호를 사용한 시스템에서 채널 부호화 장치에 있어서, 정보 비트들을 복수의 비트 그룹으로 구분하고, 단축될 정보 비트의 수를 결정하고, 상기 결정된 단축될 정보 비트의 수를 근거로 하여 단축될 비트 그룹의 수를 결정하고, 미리 결정된 순서에 따라서 상기 결정된 비트 그룹의 정보 비트들을 단축하는 단축 패턴 적용부; 및 상기 단축 처리된 정보 비트들을 부호화하는 부호화기를 포함하고, 상기 단축 패턴 적용부는 상기 단축될 정보 비트의 수를 결정하기 위해 단축에 의해 획득될 수 있는 정보 비트 수(K₂)를 결정하고, 부호어 길이가 16200이고, 정보 비트의 길이가 3240인 경우, 상기 미리 결정된 순서에 근거하여 단축될 비트 그룹의 순서는 7, 3, 6, 5, 2, 4, 1, 8, 0이고, 상기 단축 패턴 적용부는 상기 미리 결정된 순서에 따라서 0 번째 비트 그룹부터 (m-1) 번째 비트 그룹까지 해당하는 정보 비트를 단축하고, 상기 미리 결정된 순서에 따라서 m 번째 비트 그룹내의 (3240-K₂-360m) 정보 비트를 단축하고, 여기서, K₂는 단축에 의해 얻어질 수 있는 정보 비트의 수이고, (3240-K₂)는 단축될 정보 비트의 수이고,

임을 포함하고, 상기 복수의 비트 그룹 중 어느 하나는 BCH(bose-chaudhuri-hocquenghem) 패리티 비트를 포함하고, 상기 BCH 패리티 비트는 단축을 취하지 않는다.A channel coding method according to an embodiment of the present invention is a channel coding method in a system using a low density parity check code, the method comprising: dividing information bits into a plurality of bit groups; Determining a number of information bits to be shortened; Determining a number of bit groups to be shortened based on the determined number of information bits to be shortened; Shortening information bits of the determined bit group according to a predetermined order; And encoding the shortened information bits, wherein the method further comprises the step of determining the number of information bits (K ₂ ) that can be obtained by shortening to determine the number of information bits to be shortened, 6, 5, 2, 4, 1, 8, 0, the order of the bit groups to be shortened based on the predetermined order is 32, A step of shortening the corresponding information bits from the 0th bit group to the (m-1) th bit group according to the determined order; And shortening the (3240-K ₂ -360m) information bits in the m-th bit group according to the predetermined order, wherein K ₂ is the number of information bits obtainable by the shortening, and 3240-K ₂ ) is the number of information bits to be shortened,

One of the plurality of bit groups includes a bose-chaudhuri-hocquenghem (BCH) parity bit, and the BCH parity bit does not take a short.
A channel encoding apparatus according to an embodiment of the present invention is a channel encoding apparatus in a system using a low-density parity check code, in which information bits are divided into a plurality of bit groups, the number of information bits to be shortened is determined, Determining a number of bit groups to be shortened based on the number of information bits to be shortened and shortening the information bits of the determined bit group according to a predetermined order; And an encoder for coding the shortened information bits, wherein the short pattern application unit determines a number of information bits (K ₂ ) that can be obtained by shortening to determine the number of information bits to be shortened, 6, 5, 2, 4, 1, 8, 0, and the shortened bit group sequence is 7, 3, 6, 5, 2, 4, 1, 8, 0 based on the predetermined order when the length of information bits is 16,200 and the length of information bits is 3240, (3240-K ₂ -360m) in the m-th bit group according to the predetermined order, and the pattern application unit shortens the corresponding information bits from the 0-th bit group to the (m-1) -th bit group according to the predetermined order, Where K ₂ is the number of information bits that can be obtained by the shortening, (3240-K ₂ ) is the number of information bits to be shortened,

One of the plurality of bit groups includes a bose-chaudhuri-hocquenghem (BCH) parity bit, and the BCH parity bit does not take a short.

delete

The present invention proposes a uniaxial pattern, so that there is an effect that substantially no heat is used. Also, 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.

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 is a diagram illustrating 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,
6 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.
7 is a block diagram of a transmitting apparatus using the shortened LDPC code proposed in the present invention;
8 is a block diagram of a transmitting apparatus using the shortened / punctured LDPC code proposed in the present invention.
FIG. 9 is a block diagram of a receiving apparatus using an LDPC code to which the shortening proposed in the present invention is applied.
10 is a block diagram of a receiving apparatus using an LDPC code to which both the shortening and the puncturing are applied according to the present invention.
11 is a flowchart showing a receiving operation in a receiving apparatus according to an embodiment of the present invention;

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.

The present invention proposes a method of supporting an LDPC code having various codeword lengths by using a parity check matrix of a specific type of structured LDPC code. In addition, the present invention proposes a device supporting a variety of codeword lengths and a control method thereof in a communication system using a specific type of LDPC code. In particular, 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 상기 송신기(510)에 의해 전송된 신호를 복조한 후, LDPC 복호기(Decoder)(533)로 출력한다. 그러면, 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. The demodulator 531 of the receiver 530 then demodulates the signal transmitted by the transmitter 510 and outputs the demodulated signal to an LDPC decoder 533. Then, the LDPC decoder 533 transmits an estimate value of the 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 present invention, the LDPC encoder 511 can support various codeword lengths without the need for additional additional storage information using LDPC codes. A specific operation method of the LDPC encoder for supporting the various codeword lengths will be described in detail with reference to FIG.

6 is a flowchart illustrating a coding operation of an LDPC encoder according to an embodiment of the present invention. That is, FIG. 6 is a flowchart illustrating a method for generating an LDPC code having a different codeword length from a parity check matrix of a previously stored LDPC code.

In the present invention, a method of supporting various codeword lengths is called shortening or puncturing.

The shortening method refers to a method of not actually using a specific portion of the parity check matrix for a given parity check matrix. The parity check matrix of the DVB-S2 LDPC code of FIG. 3 will be described in detail to facilitate understanding of the shortening method.

이고, 앞부분은 길이가

인 정보어 비트들

이 대응되고, 뒷부분은 길이가

인 패리티 비트들

이 대응된다. 통상적으로 정보어 비트들은 0, 1의 값을 자유롭게 가지게 되는데 단축법에서는 단축시킬 특정 부분의 정보어 비트들의 값에 제한을 두게 된다. 예를 들어

에서부터

까지

개의 정보어 비트를 단축한다는 의미는 통상적으로

임을 의미한다. 다시 말하면,

에서부터

까지

개의 정보어 비트에 대한 값을 0으로 제한함으로써 상기 도 3의 DVB-S2 LDPC 부호의 패리티 검사 행렬에서 앞부분의

개의 열을 실질적으로 사용하지 않는 것과 동일한 효과를 얻게 되는 것이다. 단축법이라는 용어는 이러한 이유로 유래되었다. 따라서 본 발명에서 단축을 적용했다는 의미는 단축된 정보어 비트들의 값을 0으로 간주함을 의미하기도 한다. 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. Normally, information bits are free to have values of 0 and 1, but in the shortening method, they limit the values of information bits of a specific part to be shortened. E.g

From

Till

The term &quot; shortening &quot;

. In other words,

From

Till

By limiting the value of the information bits of the DVB-S2 LDPC code of FIG. 3 to 0,

It is possible to obtain the same effect as not substantially using the heat of the rows. The term shortening is derived for this reason. Therefore, in the present invention, the meaning of applying the shortening means that the value of the shortened information bits is regarded as 0.

Since the shortening method can share or generate the position information of the information bits shortened in the transmitting end and the receiving end when the system is set up, even if the transmitting end does not transmit the shortened bits, the receiving end does not transmit the position corresponding to the shortened bits And performs decoding in a state where it knows that the information bit is 0.

이고, 정보어의 길이가

이므로 부호율이

이 되어 처음 주어진 부호율

보다 항상 작게 된다. The shortening method uses the length of the codeword actually transmitted from the transmitting end

And the length of the information word is

Therefore,

Lt; RTI ID = 0.0 &gt;

.

인 LDPC 부호어 중에서

개의 약속된 위치에 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. Next, the puncturing method will be described in detail. 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 LDPC codewords

By not only transmitting the bits in the promised position of &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 the 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.

We now describe the simplification and puncturing method suitable for DVB-S2 LDPC codes. 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.

값이

개의 열에 대응되어 총

개의 열그룹(column group)이 각각 구조적인 형태를 가진다. 따라서 DVB-S2 LDPC 부호는 한 개의

값을 사용하지 않으면

개의 열을 사용하지 않는 것과 동일하다. 이러한 특징을 고려하여 다음과 같은 단축 과정을 제안한다. However, as described in Rules 1 and 2, the DVB-S2 LDPC code has one

The value is

Corresponding to the columns

Each of the column groups has a structural form. Therefore, the DVB-S2 LDPC code is one

If the value is not used

It is the same as not using columns. Considering these characteristics, the following shortening process is proposed.

와 정보어 길이

를 결정한다. 이후, LDPC 부호화기(511)는 저장되어 있는 패리티 검사 행렬의 호출된 정보로부터 요구되는 LDPC 부호의 정보어 길이에 맞는 단축을 취하는데, 하기 605 단계 내지 611 단계와 같은 단축 과정을 진행한다.First, in step 601, the LDPC encoder 511 calls the column group information of the DVB-S2 LDPC code to be shortened. That is, the stored parity check matrix information is called. Thereafter, in step 603, the LDPC encoder 511 calculates the codeword length

And information word length

. Thereafter, the LDPC encoder 511 takes a shortening corresponding to the length of the information word of the LDPC code required from the called information of the stored parity check matrix, and performs a shortening process as in steps 605 to 611 below.

를 결정한다. 여기서

는

보다 같거나 작은 최대 정수를 의미한다.(605 단계) Shortening step 1 :

. here

The

(Step 605). &Lt; RTI ID = 0.0 &gt;

중에서

개의 열그룹에 대한 수열을 선택하고 이를

라 하자. 나머지

개의 열그룹에 대한 수열

는 없는 것으로 간주한다.(607 단계) Shortening Step 2 :

Between

Select the sequence for the column group

Let's say. Remainder

A sequence for a column group

(Step 607)

개의

로부터 규칙 1과 규칙 2를 이용하여 단축된 DVB-S2 LDPC 부호를 생성한다. 이때 단축된 LDPC 부호는 정보어의 길이가

이 됨에 유의한다. 또한 이 값은 항상

보다 크거나 같다.(609 단계) Shortening Step 3 : Shortening selected in Step 2

doggy

And generates a shortened DVB-S2 LDPC code using Rule 1 and Rule 2. [ At this time, the shortened LDPC code has a length of information word

. This value is always

(Step 609)

개의 열을 추가적으로 단축한다.(611 단계) Shortening step 4 : Shortening In the shortened LDPC code generated in step 3

(Step 611). &Lt; RTI ID = 0.0 &gt;

,

,

,

의 특성을 가지는 DVB-S2 LDPC 부호를 이용하여 정보어 비트 중에서 12150 비트들을 단축하여 부호어 길이가

이며, 정보어의 길이가

인 새로운 LDPC 부호를 생성하는 과정을 다음에 자세히 나타낸다. To illustrate the concrete example

,

,

,

The DVB-S2 LDPC code having the characteristics of &lt; RTI ID = 0.0 &gt;

And the length of the information word is

The process of generating a new LDPC code is described in detail below.

. Example of shrinking phase 1 :

.

중에서 4개의 열그룹에 대한 수열을 선택한다. 본 예에서는 아래와 같은 수열을 선택한다. Example of shortening phase 2 : a total of 37

&Lt; / RTI &gt; selects a sequence for four column groups. In this example, the following sequence is selected.

로부터 규칙 1과 규칙 2를 이용하여 단축된 DVB-S2 LDPC 부호를 생성한다. 이때 단축된 LDPC 부호는 정보어의 길이가

이 됨에 유의한다. Example of Shortening Step 3 : Shortening In the example of Step 2, four

And generates a shortened DVB-S2 LDPC code using Rule 1 and Rule 2. [ At this time, the shortened LDPC code has a length of information word

.

Example of shortening step 4 : shorten 1440-1170 = 270 columns in the shortened LDPC code generated in the example of shortening step 3.

The coding is performed based on the shortened LDPC code as described above.

중에서

= 13320/360 - 4 = 33개의 열그룹에 대한 수열 정보를 사용하지 않으므로 단축 단계 2의 예에서는 총

비트를 단축한 것과 같다. 또한 단축 단계 3의 예와 단축 단계 4의 예를 통하여 다시 추가적으로 270 개의 정보어 비트를 단축하였으므로 최종적으로 12150 비트들의 정보어 비트를 단축한 것과 같다. 따라서 상기 실시 예에 따른 결과는

이며, 정보어의 길이가

인 단축된 LDPC 부호이다. According to the above embodiment

Between

= 13320/360 - 4 = Since the sequence information for the 33 column groups is not used,

It is the same as shortening the bit. In addition, since 270 additional information bits are shortened again through the example of the shortening step 3 and the example of the shortening step 4, the information bits of 12150 bits are finally shortened. Therefore, the result according to the embodiment

And the length of the information word is

Is a shortened LDPC code.

As described above, in the present invention, unlike the arbitrary bit unit shortening method which is generally used for shortening the DVB-S2 LDPC code, the structure of the DVB-S2 LDPC code, An efficient shortening method can be applied by using a method that does not use the information on the information.

In step 2 of the shortening process of the DVB-S2 LDPC code, the selection criteria of the sequence for the column group will be briefly summarized as follows.

이며, 정보어의 길이가

인 일반적인 LDPC 부호의 최적의 차수 분포에 대하여 부호어 길이가

이며, 정보어의 길이가

인 DVB-S2 LDPC 부호에서 단축을 취하여 얻은 부호어 길이가

이며, 정보어의 길이가

인 단축된 LDPC 부호의 차수 분포가 거의 유사한 부호를 선택한다. <Criterion 1>: When the codeword length is

And the length of the information word is

The optimal codeword length distribution of a general LDPC code having a codeword length of

And the length of the information word is

The length of the codeword obtained by shortening the length of the DVB-S2 LDPC code is

And the length of the information word is

The sign of the degree of the shortened LDPC code is selected.

<Standard 2>: Among the shortened codes selected in <Reference 1>, a code having a good cycle characteristic on the Tanner graph is selected. In the present invention, the criterion of the cycle characteristics is selected when the minimum length cycle in the Tanner graph is the largest and the number of the minimum length cycles is the smallest.

The optimal order distribution of a general LDPC code in the criterion 1 can be obtained through a density evolution analysis method but is not related to the gist of the present invention.

If there are not many choices for the weight-1 position sequence for the column group, the best performance is obtained by performing a full search on all cases, irrespective of the <criteria 1> and <criteria 2> You may select a sequence for a column group to have. However, the selection criterion for the column group to be applied in the shortening step 2 of the DVB-S2 LDPC code satisfies the above two conditions when the number of the weight-1 position sequences for the column group for the column group is too large The efficiency can be increased by selecting an LDPC code.

For an example of a good sequence obtained by applying the selection criterion of the weight-1 position sequence for the column group to the column group, the DVB-S2 with N ₁ = 16200, K ₁ = 3240, M ₁ = 360, Let's look at the sign. The DVB-S2 LDPC code has a weight-1 position sequence for a column group as follows.

6295 9626 304 7695 4839 4936 1660 144 11203 5567 6347 12557

10691 4988 3859 3734 3071 3494 7687 10313 5964 8069 8296 11090

10774 3613 5208 11177 7676 3549 8746 6583 7239 12265 2674 4292

11869 3708 5981 8718 4908 10650 6805 3334 2627 10461 9285 11120

7844 3079 10773

3385 10854 5747

1360 12010 12202

6189 4241 2343

9840 12726 4977

번째 열 그룹에 대한 1이 있는 행의 위치 정보를 순차적으로 나타낸 것이다. 따라서 상기 DVB-S2 LDPC 부호는 9개의 열그룹으로 구성되어 있음을 알 수 있으며, 정보어의 길이는 9ⅹ360 = 3240 임을 알 수 있다. 만일 단축을 취하여 얻고자 하는 부호어 길이 및 정보어 길이가 각각

,

라 하면, 단축 단계 1부터 단축 단계 4를 이용하여 최적화된 단축 패턴을 찾을 수 있음을 알 수 있었다. The i-th weight-1 position sequence in the i-th line is

1 &lt; / RTI &gt; for the ith column group. Therefore, it can be seen that the DVB-S2 LDPC code is composed of 9 column groups, and the length of the information word is 9 x 360 = 3240. If the codeword length and the information length to be obtained by taking the short axis are

,

, It is found that the shortening pattern optimized can be found by using the shortening step 1 to the shortening step 4.

,

의 값이 매우 가변적일 경우에는

의 값에 따라서 최적화된 단축 패턴이 상관성이 없을 수도 있다. 예를 들어 상기 DVB-S2 LDPC 부호에서 2개의 열그룹을 단축해야 할 경우에 최적의 선택은 4 번째, 8번째 열그룹의 1이 위치한 행에 대한 정보를 사용하지 않는 것이라 할 때, 3개의 열그룹을 선택할 경우에는 1, 5, 6번째 열그룹을 선택하여 단축하는 경우가 최적이 될 수도 있기 때문에 서로 연관성이 없다. 따라서 시스템에서 요구하는

,

의 값이 매우 가변적일 경우에는 최적화된 성능을 위해서는

값에 따라서 최적화된 단축 패턴을 모두 저장해야 된다는 단점이 있다. However,

,

If the value of &lt; RTI ID = 0.0 &gt;

The optimized shortening pattern may not be correlated. For example, in the case of shortening two column groups in the DVB-S2 LDPC code, when it is assumed that the information on the row in which the 1 is located in the 4th and 8th column groups is not used, When selecting a group, it is not relevant because the case of shortening the selection of the first, fifth, and sixth column groups may be optimal. Therefore,

,

If the value is very variable, then for optimized performance

It is necessary to store all of the optimized shortening patterns according to the values.

,

의 값이 매우 가변적일 경우에는 시스템의 효율성을 위해 다음과 같은 방법으로 준최적(suboptimal)의 단축 패턴을 찾을 수 있다. So if your system requires

,

If the value is very variable, we can find a suboptimal shortening pattern for the efficiency of the system in the following way.

First, it is assumed that the selection of one column group is required for shortening. In this case, since only one column group can be selected, the column group having the best performance can be selected. Next, when it is necessary to select two column groups for shortening, the column group having the best performance among the remaining column groups including the one selected column group is selected. In the same way, if it is necessary to select i column groups for shortening, one column group having the best performance among the remaining column groups including the (i-1) column groups selected for the shortening in the previous step is selected do.

값의 변화에 무관하게 안정된 성능을 가질 수 있다는 장점이 있다. Although this method does not guarantee optimal selection,

There is an advantage that stable performance can be obtained irrespective of the change of the value.

,

의 값이 매우 가변적일 경우에는

,

에 따라서 다음의 <표 1>에 나타낸 9 가지 경우와 같은 준최적(suboptimal)의 단축 패턴 구할 수 있었다.(여기서 천공법은 고려하지 않았으므로

의 관계가 있음에 유의한다)For a concrete example,

,

If the value of < RTI ID = 0.0 >

,

The suboptimal shortening pattern as shown in the following Table 1 can be obtained. (Since the puncturing method is not considered here

(Note that there is a relationship of

Range of K ₂ Shortening method

인 경우One)

If In the weight-1 position sequence, the eighth sequence row for the eighth column group
6189 4241 2343
In the information word corresponding to

Shorten the bit. 2)

If All the column groups corresponding to the eighth sequence are shortened in the weight-1 position sequence, and in the case of the fourth column group, the fourth sequence
11869 3708 5981 8718 4908 10650 6805 3334 2627 10461 9285 11120
In the information word corresponding to

Further shortening the bit. 3)

If The column groups corresponding to the eighth row and the fourth row in the weight-1 position sequence are all shortened, and in the case of the seventh column group, the seventh row
1360 12010 12202
In the information word corresponding to

Further shortening the bit. 4)

If The column groups corresponding to the 8th, 4th, and 7th rows are all shortened in the column group information, and the 6th row
3385 10854 5747
In the information word corresponding to

Further shortening the bit. 5)

If The column groups corresponding to the 8th, 4th, 7th, and 6th rows are all shortened in the column group information, and the third row
10774 3613 5208 11177 7676 3549 8746 6583 7239 12265 2674 4292
In the information word corresponding to

Further shortening the bit.
6)

If In the column group information, all the column groups corresponding to the 8th, 4th, 7th, 6th and 3rd rows are shortened, and the fifth row
7844 3079 10773
In the information word corresponding to

Further shortening the bit. 7)

If The column groups corresponding to the 8th, 4th, 7th, 6th, 3th and 5th rows are all shortened in the column group information, and the second row
10691 4988 3859 3734 3071 3494 7687 10313 5964 8069 8296 11090
In the information word corresponding to

Further shortening the bit.
8)

If The column groups corresponding to the 8th, 4th, 7th, 6th, 3th, 5th, and 2nd rows are all shortened in the column group information, and the 9th row
9840 12726 4977
In the information word corresponding to

Further shortening the bit. However, since a part of the column group corresponding to the 9th row corresponds to a 168-bit BCH parity bit by the DVB-S2 encoding method, the column corresponding to the BCH parity is not shortened.
9)

If In the column group information, all the column groups corresponding to the 8th, 4th, 7th, 6th, 3th, 5th, 2nd and 9th rows are shortened,
6295 9626 304 7695 4839 4936 1660 144 11203 5567 6347 12557
528-K ₂ &lt; / RTI _&gt; Further shortening the bit. Here, if K ₂ = 168, it means that only the column corresponding to the BCH parity is left in the DVB-S2 LDPC code, and therefore it is not considered.

The shortening procedure of Table 1 is the order determined according to the criteria 1 and 2, in which the length of the information word is obtained in nine intervals as shown in Table 1 above.

Referring to Table 1, it can be seen that, in accordance with the size of the information word for the required LDPC code, the shortening is sequentially performed for 8, 4, 7, 6, 3, 5, 2, 9, have. That is, the information bits to be shortened according to the order of the columns corresponding to the 8th, 4th, 7th, 6th, 3th, 5th, . In addition, according to the shortening, meaningful information bits which are not fixed to 0 according to the length of the information word are corresponded to the sequence of 1, 9, 2, 5, 3, 6, 7, It is possible to say that. The first column is denoted by the 0th block in order 7, 3, 6, 5, 2, 4, 1, 8, 0 and 1 in the sequence of columns 8, 4, 7, 6, 3, 5, It can also be written in the same form.

,

,

,

의 특성을 가지는 DVB-S2 LDPC 부호의 정보어 비트에 대응되는 부분에서 가장 마지막 열그룹인 9번째 열그룹(상기 수열 기준으로는 8번째 열그룹)의 마지막 168 비트는 BCH 패리티 비트가 대응되기 때문에 단축을 취할 수 없도록 되어 있음에 유의한다. 실제로

인 DVB-S2 LDPC 부호의 경우에는 상기

및

길이를 가지는 LDPC 정보어 비트(LDPC information bit)에 168 비트의 BCH 패리티 비트가 항상 포함되도록 설정되어 있다. Referring to steps 8) and 9) in Table 1,

,

,

,

The last 168 bits of the 9th column group (the 8th column group in the sequence basis) which is the last column group in the part corresponding to the information word of the DVB-S2 LDPC code having the characteristics of the BCH parity bit correspond to the BCH parity bit It should be noted that the shortening can not be taken. in reality

In the case of the DVB-S2 LDPC code,

And

Length LDPC information bits are always set to include 168-bit BCH parity bits.

Table 2 below may be used to simply represent the information of the shortening sequence as shown in Table 1 above.

,

,

,

인 DVB-S2 부호에 대해서 살펴보자. 상기 DVB-S2 LDPC 부호는 다음과 같은 가중치-1 위치 시퀀스들을 가지고 있다. In order to explain another embodiment,

,

,

,

Let's look at the DVB-S2 code. The DVB-S2 LDPC code has the following weight-1 position sequences.

20 712 2386 6354 4061 1062 5045 5158

21 2543 5748 4822 2348 3089 6328 5876

22 926 5701 269 3693 2438 3190 3507

23 2802 4520 3577 5324 1091 4667 4449

24 5140 2003 1263 4742 6497 1185 6202

0 4046 6934

1 2855 66

2 6694 212

3 3439 1158

4 3850 4422

5 5924 290

6 1467 4049

7 7820 2242

8 4606 3080

9 4633 7877

10 3884 6868

11 8935 4996

12 3028 764

13 5988 1057

14 7411 3450

번째 행의 수열은

번째 열 그룹에 대한 1이 있는 행의 위치 정보를 순차적으로 나타낸 것이다. 따라서 상기 DVB-S2 LDPC 부호는 20개의 열그룹으로 구성되어 있음을 알 수 있으며, 정보어의 길이는 20ⅹ360 = 7200 임을 알 수 있다. 단축을 취하여 얻고자 하는 부호어 길이 및 정보어 길이가 각각

,

라 할 때, 다음 <표 3>과 같은 준최적화된 단축 패턴을 찾을 수 있다.
remind

The sequence of the second row is

1 < / RTI > for the ith column group. Therefore, it can be seen that the DVB-S2 LDPC code is composed of 20 column groups, and the length of the information word is 20 x 360 = 7200. The length of the codeword and the length of the information word to be obtained by shortening are respectively

,

, We can find a quasi-optimized shortening pattern as shown in the following table.

The additional shortening in the shortening process can be implemented more easily by performing the steps from the rear of the column group in which the additional shortening is performed sequentially or in the order from the front.

6, if puncturing is required, the LDPC encoder 511 applies perforation in the LDPC encoding process in step 613. [ The puncturing method will be briefly described as follows.

,

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

,

라 하고,

라고 정의하면, DVB-S2 LDPC 부호의 패리티 검사행렬에서

비트만큼 단축을 취하고,

비트만큼 천공을 취하면 부호어 길이와 정보어 길이를 각각

,

인 상기 LDPC 부호를 얻을 수 있었다. 이때 만일 편의를 위해 패리티 부분만 천공법을 적용한다고 가정할 때, 패리티의 길이는

이므로 패리티 비트에서

마다 1 비트씩 천공하는 방법이 있다. 하지만 천공법은 이러한 방법 외에도 다양한 방법을 적용할 수 있다. The codeword length and the information word length are respectively

,

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

,

However,

, 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 above-mentioned LDPC code can be obtained. Assuming that the parity part is applied to the parity part only for convenience, the length of the parity is

Therefore,

A method of puncturing one bit at a time. However, in addition to this method, various methods can be applied to the puncturing method.

인 경우에는 천공법을 적용할 필요가 없으며, 이때는 <표 1>에 나타낸 단축법 패턴을 이용하여 DVB-S2 LDPC 부호의 생성 방법과 유사하게 적용하면, 좋은 성능을 가지는 단축된 DVB-S2 LDPC 부호를 얻을 수 있다.

, It is not necessary to apply the puncturing method. In this case, similar to the method of generating the DVB-S2 LDPC code using the shortening pattern shown in Table 1, a shortened DVB-S2 LDPC code Can be obtained.

An example of a transmitting apparatus for realizing the shortening process of the DVB-S2 LDPC code is shown in Fig. 7 is a block diagram of a transmission apparatus using a shortened LDPC code according to an embodiment of the present invention.

The transmission apparatus includes a controller 710, a short pattern application unit 720, an LDPC code parity check matrix extractor 740, and an LDPC encoder 760.

The LDPC code parity check matrix extractor 740 extracts the shortened LDPC code parity check matrix. The LDPC code parity check matrix may be extracted using a memory, received at a transmitting apparatus, or generated at a transmitting apparatus.

The control unit 710 controls the shortening pattern applying unit 720 to determine a shortening pattern according to the length of the information word. The shortening pattern applying unit 720 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 control unit 710 applies a part of the information bits of the LDPC code to the short pattern application unit 720 in a pattern as shown in Table 1 to Table 3. [ ) Is shortened.

The LDPC encoder 760 performs coding based on the shortened LDPC code by the controller 710 and the shortening pattern applying unit 720.

FIGS. 8 and 9 are block diagrams showing a transmitting apparatus and a receiving apparatus for a DVB-S2 LDPC code that simultaneously apply shortening and puncturing.

8 is a block diagram of a transmitting apparatus using a uniaxial / punctured LDPC code according to the present invention.

The transmitting apparatus shown in Fig. 8 is obtained by adding a puncturing pattern applying unit 980 to the transmitting apparatus shown in Fig. Referring to FIG. 8, it can be seen that the shortening is performed in the pre-input stage of the LDPC encoder 860, and the puncturing is performed in the output stage of the LDPC encoder 760.

The puncturing pattern application unit 880 applies puncturing to the output of the LDPC encoder 760. Since the method of applying the puncturing has been described in detail while explaining the step 613 of FIG. 6, the description thereof will be omitted.

FIG. 9 is a block diagram of a receiving apparatus using an LDPC code to which shortening according to an embodiment of the present invention is applied.

FIG. 9 is a diagram for explaining a method for receiving a signal transmitted in a communication system using the shortened DVB-S2 LDPC code and determining a length of a shortened DVB-S2 LDPC code from the received signal, An example of a receiving apparatus for restoring data is shown.

The receiving apparatus includes a control unit 910, a short pattern determination or estimation unit 920, a demodulator 930, and an LDPC decoder 940.

The demodulator 930 receives and demodulates the shortened LDPC code, and transmits the demodulated signal to the shortening pattern determination or estimation unit 920 and the LDPC decoder 940.

Under the control of the controller 910, the shortening pattern determination or estimation unit 920 estimates or determines information on the shortening pattern of the LDPC code from the demodulated signal, and outputs the position information of the shortened bit to the LDPC decoder 940). In the method for determining or estimating the shortening pattern in the shortening pattern determination or estimation unit 920, a shortening pattern stored using a memory may be used, a shortening pattern may be generated using a sequence generator (not shown) A parity check matrix and a given information word length can be obtained using a density evolution analysis algorithm or the like. .

The controller 910 decodes the shortened bits in the operation of the LDPC decoder 940 to the LDPC decoder 940 because the probability that the shortened bit value is 0 in the LDPC decoder 940 is 1 And decides whether to participate in decryption by using the probability value 1 of 0 of the shortened bits.

When the length of the DVB-S2 LDPC code shortened by the shortening pattern determination or estimation unit 920 is known, the LDPC decoder 940 restores desired data from the received signal.

10 is a block diagram of a receiving apparatus using an LDPC code to which uniaxial and puncturing is applied according to an embodiment of the present invention.

FIG. 10 is a diagram of a short axis, a puncturing pattern determination or estimation unit 1020 instead of the short axis pattern determination or estimation unit 920 of the receiving apparatus of FIG.

In the case where both the shortening and puncturing are applied to the shortening and puncturing pattern judging or estimating unit 1020, the receiving apparatus may first perform pattern determination or estimation for the shortening, or may perform pattern determination or estimation for puncturing first Pattern determination or estimation for shortening, and pattern determination or estimation for puncturing may occur at the same time.

Also, in the LDPC decoder 940, it is necessary to know the information on the shortening and puncturing to be able to decode.

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

The demodulator 930 receives and demodulates the shortened LDPC code in step 1101. [ Then, the shortening pattern determination or estimation unit 920 determines or estimates a shortening / puncturing pattern from the signal demodulated in step 1103.

The shortening pattern determination or estimation unit 920 determines in step 1105 whether there is a shortened or punctured bit.

If the shortened or punctured bit does not exist, the LDPC decoder 940 performs decoding in step 1111. [ However, if there is a shortened or punctured bit, the shortening pattern determination or estimation unit 1020 transmits the location information of the shortened / punctured bit to the LDPC encoder 940 in step 1107.

In step 1109, the LDPC decoder 940 sets the value of the shortened bit as 0 based on the location information of the shortened / punctured bit to 1, sets the punctured bit to erasure In step 1111, LDPC decoding is performed.

Claims (8)

A channel coding method in a system using a low density parity check code,
Dividing information bits into a plurality of bit groups;
Determining a number of information bits to be shortened;
Determining a number of bit groups to be shortened based on the determined number of information bits to be shortened;
Shortening information bits of the determined bit group according to a predetermined order; And
And encoding the shortened information bits,
Further comprising the step of determining a number of information bits (K ₂ ) that can be obtained by shortening to determine the number of information bits to be shortened,
If the codeword length is 16200 and the length of the information bits is 3240, the order of the bit groups to be shortened based on the predetermined order is 7, 3, 6, 5, 2, 4, 1, 8, 0,
A step of shortening a corresponding information bit from a 0th bit group to an (m-1) th bit group according to the predetermined order; And
Further comprising the step of shortening the (3240-K ₂ -360m) information bits in the m-th bit group according to the predetermined order,
Here, K ₂ is the number of information bits that can be obtained by shortening, (3240-K ₂ ) is the number of information bits to be shortened,

, &Lt; / RTI &gt;
Wherein one of the plurality of bit groups includes a bose-chaudhuri-hocquenghem (BCH) parity bit, and the BCH parity bit does not take a short axis. In a channel coding apparatus in a system using a low-density parity-check code,
Determining a number of information bits to be shortened, determining a number of bit groups to be shortened based on the determined number of information bits to be shortened, A shortening pattern applying unit for shortening information bits of a bit group; And
And an encoder for encoding the shortened information bits,
The shortening pattern application unit determines a number of information bits (K ₂ ) that can be obtained by shortening to determine the number of information bits to be shortened,
If the codeword length is 16200 and the length of the information bits is 3240, the order of the bit groups to be shortened based on the predetermined order is 7, 3, 6, 5, 2, 4, 1, 8, 0,
The shortening pattern application unit the previously according to the determined order from the 0th bit group (m-1) th bit group speed the information bits, and in the m-th group of bits according to the predetermined order (3240-K to ₂ - 360m) information bits,
Here, K ₂ is the number of information bits that can be obtained by shortening, (3240-K ₂ ) is the number of information bits to be shortened,

, &Lt; / RTI &gt;
Wherein one of the plurality of bit groups includes a bose-chaudhuri-hocquenghem (BCH) parity bit, and the BCH parity bit is not shortened. A channel decoding method in a system using a low density parity check code,
Demodulating the received signal;
Determining a number of shortened information bits;
Determining a number of shortened bit groups in the plurality of bit groups based on the number of the shortened information bits;
Obtaining an order of a predetermined bit group;
Determining location information of the information bit based on the order of the predetermined bit group; And
And decoding the data considering the position information of the determined shortened information bit,
Further comprising the step of determining a number of information bits (K ₂ ) that can be obtained by shortening to determine the number of said shortened information bits,
If the codeword length is 16200 and the length of the information bits is 3240, the order of the shortened bit groups based on the order of the predetermined bit groups is 7, 3, 6, 5, 2, 4, 1, 8, 0 ego,
Determining that a corresponding information bit from the 0th bit group to the (m-1) th bit group is shortened according to the order of the predetermined bit group; And
Determining that the (3240-K ₂ -360m) information bits in the m-th bit group have been shortened according to the order of the predetermined bit group,
Where K ₂ is the number of information bits that can be obtained by shortening, (3240-K ₂ ) is the number of shortened information bits,

, &Lt; / RTI &gt;
Wherein one of the plurality of bit groups includes a bose-chaudhuri-hocquenghem (BCH) parity bit, and the BCH parity bit is not shortened. In a channel decoding apparatus in a system using a low-density parity-check code,
A demodulator for demodulating the received signal;
Determining a number of shortened information bits, determining a number of shortened bit groups in the plurality of bit groups based on the number of the shortened information bits, obtaining a sequence of predetermined bit groups, A short pattern determining unit for determining position information of the shortened information bit based on the order of the bit groups; And
And a decoder for decoding the data in consideration of the determined location information of the shortened information bit,
The shortening pattern determining unit determines the number of information bits (K ₂ ) that can be obtained by the shortening to determine the number of the shortened information bits,
If the codeword length is 16200 and the length of the information bits is 3240, the order of the shortened bit groups based on the order of the predetermined bit groups is 7, 3, 6, 5, 2, 4, 1, 8, 0 ego,
Wherein the shortening pattern determination unit determines that the corresponding information bits from the 0th bit group to the (m-1) th bit group are shortened in accordance with the order of the predetermined bit group, It is determined that the (3240-K ₂ -360m) information bits in the bit group have been shortened,
Where K ₂ is the number of information bits that can be obtained by shortening, (3240-K ₂ ) is the number of shortened information bits,

, &Lt; / RTI &gt;
Wherein one of the plurality of bit groups includes a bose-chaudhuri-hocquenghem (BCH) parity bit, and the BCH parity bit is not shortened. A channel coding method in a system using a low density parity check code,
Dividing information bits into a plurality of bit groups;
Determining a number of information bits to be shortened;
Determining a number of bit groups to be shortened based on the determined number of information bits to be shortened;
Shortening information bits of the determined bit group according to a predetermined order; And
And encoding the shortened information bits,
Further comprising the step of determining a number of information bits (K ₂ ) that can be obtained by shortening to determine the number of information bits to be shortened,
16, 15, 14, 13, 12, 11, 4, 10, 11, 12, 13, 14, 15, 16, 9, 8, 3, 2, 7, 6, 5, 1, 19,
A step of shortening a corresponding information bit from a 0th bit group to an (m-1) th bit group according to the predetermined order; And
Further comprising the step of shortening (7200-K ₂ -360m) information bits in the m-th bit group according to the predetermined order,
Here, K ₂ is the number of information bits that can be obtained by shortening, (7200-K ₂ ) is the number of information bits to be shortened,

, &Lt; / RTI &gt;
Wherein one of the plurality of bit groups includes a bose-chaudhuri-hocquenghem (BCH) parity bit, and the BCH parity bit does not take a short axis. In a channel coding apparatus in a system using a low-density parity-check code,
Determining a number of information bits to be shortened, determining a number of bit groups to be shortened based on the determined number of information bits to be shortened, A shortening pattern applying unit for shortening information bits of a bit group; And
And an encoder for encoding the shortened information bits,
The shortening pattern application unit determines a number of information bits (K ₂ ) that can be obtained by shortening to determine the number of information bits to be shortened,
16, 15, 14, 13, 12, 11, 4, 10, 11, 12, 13, 14, 15, 16, 9, 8, 3, 2, 7, 6, 5, 1, 19,
The shortening pattern application unit the previously according to the determined order from the 0th bit group (m-1) th to the bit group speed the information bits and the preview in accordance with the determined order of the m-th bit group in the (7200-K ₂ - 360m) information bits,
Here, K ₂ is the number of information bits that can be obtained by shortening, (7200-K ₂ ) is the number of information bits to be shortened,

, &Lt; / RTI &gt;
Wherein one of the plurality of bit groups includes a bose-chaudhuri-hocquenghem (BCH) parity bit, and the BCH parity bit is not shortened. A channel decoding method in a system using a low density parity check code,
Demodulating the received signal;
Determining a number of shortened information bits;
Determining a number of shortened bit groups in the plurality of bit groups based on the number of the shortened information bits;
Obtaining an order of a predetermined bit group;
Determining location information of the information bit based on the order of the predetermined bit group; And
And decoding the data considering the position information of the determined shortened information bit,
Further comprising the step of determining a number of information bits (K ₂ ) that can be obtained by shortening to determine the number of said shortened information bits,
The codeword length is 16200 and the length of the information bit is 7200, the order of the shortened bit groups based on the order of the predetermined bit group is 18, 17, 16, 15, 14, 13, 12, 11, 4 , 10, 9, 8, 3, 2, 7, 6, 5, 1, 19,
Determining that a corresponding information bit from the 0th bit group to the (m-1) th bit group is shortened according to the order of the predetermined bit group; And
The pre-determined according to the order of the group of bits and further comprising the step of determining to be a m-th bit in the group (7200-K ₂ -360m) information bit speed,
Where K ₂ is the number of information bits that can be obtained by shortening, (7200-K ₂ ) is the number of shortened information bits,

, &Lt; / RTI &gt;
Wherein one of the plurality of bit groups includes a bose-chaudhuri-hocquenghem (BCH) parity bit, and the BCH parity bit is not shortened. In a channel decoding apparatus in a system using a low-density parity-check code,
A demodulator for demodulating the received signal;
Determining a number of shortened information bits, determining a number of shortened bit groups in the plurality of bit groups based on the number of the shortened information bits, obtaining a sequence of predetermined bit groups, A short pattern determining unit for determining position information of the shortened information bit based on the order of the bit groups; And
And a decoder for decoding the data in consideration of the determined location information of the shortened information bit,
The shortening pattern determining unit determines the number of information bits (K ₂ ) that can be obtained by the shortening to determine the number of the shortened information bits,
The codeword length is 16200 and the length of the information bit is 7200, the order of the shortened bit groups based on the order of the predetermined bit group is 18, 17, 16, 15, 14, 13, 12, 11, 4 , 10, 9, 8, 3, 2, 7, 6, 5, 1, 19,
Wherein the shortening pattern determination unit determines that the corresponding information bits from the 0th bit group to the (m-1) th bit group are shortened in accordance with the order of the predetermined bit group, and it determines that the group of bits in the (7200-K ₂ -360m) information bit is reduced,
Where K ₂ is the number of information bits that can be obtained by shortening, (7200-K ₂ ) is the number of shortened information bits,

, &Lt; / RTI &gt;
Wherein one of the plurality of bit groups includes a bose-chaudhuri-hocquenghem (BCH) parity bit, and the BCH parity bit is not shortened.

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